Journal of Arid Environments 188 (2021) 104464

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Journal of Arid Environments

journal homepage: www.elsevier.com/locate/jaridenv

Intercropping forage cactus and sorghum in a semi-arid environment

improves biological efficiency and competitive ability through
interspecific complementarity
Alexandre Maniçoba da Rosa Ferraz Jardim a, b, Thieres George Freire da Silva a, b, *,
Luciana Sandra Bastos de Souza a, George do Nascimento Araújo Júnior a, b,
Hygor Kristoph Muniz Nunes Alves b, Marcondes de Sá Souza a, Gherman Garcia Leal de Araújo c,
Magna Soelma Beserra de Moura c
a
Agrometeorology Laboratory, Unidade Acadêmica de Serra Talhada, Universidade Federal Rural de Pernambuco, Serra Talhada, Pernambuco, Brazil
b
Department of Agricultural Engineering, Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Brazil
c
Empresa Brasileira de Pesquisa Agropecuária, Petrolina, PE, Brazil

A R T I C L E I N F O A B S T R A C T

Keywords: The intercropping systems of species adapted to conditions of water deficit, such as sorghum (Sorghum spp.) and
Competitiveness indices forage cacti (Nopalea spp. and Opuntia spp.), can contribute to an improvement in the biomass yield of semi-arid
Opuntia agricultural areas. This study aimed to evaluate the performance of intercropping cactus and sorghum as well as
Nopalea
the biological efficiency and competitive ability of forage cactus clones and sorghum cultivars. The experiment
Sorghum
was carried out in the Brazilian semi-arid region, in a randomised block design with 15 treatments and four
Forage quality
replications. The treatments consisted of three forage cactus clones (‘IPA Sertânia’—IPA, ‘Miúda’—Miu and
‘Orelha de Elefante Mexicana’—OEM) and three sorghum cultivars (‘467’, ‘SF11’ and ‘2502’) under single
configuration and the maximum number of combinations to comprise the intercropping systems. In terms of fresh
and dry matter (221.73 and 47.04 Mg ha− 1, respectively), the cactus-sorghum intercropping was 47% and 3.5
times more productive in terms of fresh and dry matter than the cactus single systems, with no effect on the
quality of the forage. The forage cactus clones were dominant over the sorghum cultivars. The OEM-‘467’
configuration offered better stability (lower mortality), biological efficiency and crop competitiveness when
compared to the single systems.

1. Introduction the use of intercropping species tolerant to drought stress could be a

solution to water scarcity in the region (Liu et al., 2018).
The semi-arid region of Brazil, with rainfall ranging from 400 to 800 In an intercropping system, species adapted to conditions of a water
mm year− 1, is the wettest and largest semi-arid environment in the deficit, such as sorghum and forage cacti, could increase biomass crop
world, with an area of 982,566 km2 (Moura et al., 2018). This area production through improved nutrient, water and radiation use effi­
represents 18.2% of the country, 53% of the north-eastern region and ciency (Chimonyo et al., 2018; Diniz et al., 2017; Lima et al., 2018a) in
includes 1,133 municipalities. Its population is around 22 million, most addition to production synergy. Despite being forage species, sorghum
of whom live in rural areas. In this region, water autonomy for irrigation and cactus have different photosynthetic metabolisms. The first, of type
purposes is limited, both in quantity and quality (i.e. brackish water), C4, with daytime carbon assimilation, has a high potential for biomass
preventing the setting up of large irrigated areas. The scarcity of water production, high economic return, sugar and biofuel production, toler­
for irrigation directly influences crop biomass growth, development and ance to water deficit and water use efficiency, when compared to other
production (Jha and Srivastava, 2018; Mbarki et al., 2018). Therefore, crops of the same metabolism, in addition to adaptability to arid and

* Corresponding author. Academic Unit of Serra Talhada, Rural Federal University of Pernambuco, PO Box: 063, 56909535, Serra Talhada, Pernambuco, Brazil.
E-mail addresses: alexandremrfj@gmail.com (A.M.R.F. Jardim), thieres.silva@ufrpe.br (T.G.F. Silva), sanddrabastos@yahoo.com.br (L.S.B. Souza), georgejunior_
91@hotmail.com (G.N. Araújo Júnior), hygorkristoph22@gmail.com (H.K.M.N. Alves), marcondes.sa33@gmail.com (M.S. Souza), gherman.araujo@embrapa.br
(G.G.L. Araújo), magna.moura@embrapa.br (M.S.B. Moura).

https://doi.org/10.1016/j.jaridenv.2021.104464
Received 13 February 2020; Received in revised form 24 September 2020; Accepted 3 February 2021
Available online 15 February 2021
0140-1963/© 2021 Elsevier Ltd. All rights reserved.
A.M.R.F. Jardim et al. Journal of Arid Environments 188 (2021) 104464

semi-arid environments (Roby et al., 2017). The second, a CAM (cras­ of 1.45 g cm− 3.
sulacean acid metabolism) type, with stomatal closure during the day
and nocturnal carbon assimilation, has a greater adaptive capacity to 2.2. Species under study and experimental design of the area
abiotic factors; it has the relevant characteristics as does sorghum and a
positive response to irrigation (Diniz et al., 2017). The plant materials used were the forage cactus clones ‘IPA Sertânia’
The cactus-sorghum intercropping promotes water complementarity [IPA] and ‘Miúda’ [Miu], both from the species N. cochenillifera (L.)
in the cropping system, as the photosynthetic metabolism of forage Salm-Dyck and ‘Orelha de Elefante Mexicana’ [OEM] from the species
cactus favours gas exchange at night, whereas, in sorghum, gas exchange O. stricta (Haw.) Haw., which are all resistant to the cochineal scale bug
occurs during the day; therefore, this configuration reduces the water (Dactylopius opuntiae Cockerell, 1929; Hemiptera: Dactylopiidae). In
lost to the atmosphere (Lima et al., 2018a). In addition, the combination addition, the dual-purpose sorghum cultivars ‘467’, ‘SF11’ and ‘2502’
of cactus and sorghum in animal feed can maximise animal perfor­ (S. bicolor (L.) Moench) were used.
mance. Moraes et al. (2019) recommend a diet composed of 36.6% Before sowing the crops, the soil was initially prepared by ploughing,
forage cactus cladodes, 29.0% maize silage and 34.4% concentrate. On harrowing and furrowing. The forage cactus clones were planted in
the other hand, Nascimento et al. (2008) cited that although sorghum February 2016 and grown under rainfed conditions until January 2017.
silages have a lower production potential than that of maize, their In February 2017, the forage cactus clones were irrigated before the
rusticity and adaptation to limiting growth conditions, such as high harvest conducted in March 2017 for the subsequent growth of sorghum
temperatures and water scarcity, remain the principal factors that cultivars. The plants were uniformly cut (first cycle of forage cactus),
characterise sorghum. leaving the basal cladodes (i.e. cladodes inserted into the soil) and the
The benefits of intercropping agriculturally important crops, first-order cladodes (cladodes arising from the basal cladodes). The
compared to single systems, are due to the better use of resources on a practice of keeping the first-order cladodes was adopted because it en­
temporal and spatial scale since the ecological niche in the environment sures heavy sprouting of the crop and minimises the effects of shading by
causes a reduction in interspecific competition and promotes comple­ the intercropping on the productivity of the forage cactus (Diniz et al.,
mentarity between the two species (Chimonyo et al., 2018). 2017; Lima et al., 2018b).
Studies of intercropped systems aimed at evaluating the interspecific The irrigation was carried out based on the actual crop evapotrans­
interactions of cactus clones and sorghum cultivars under irrigation with piration (Queiroz et al., 2016); the plants were later harvested in June
low-quality water are still rare in the literature since there are no studies 2018 (second cycle of forage cactus). The cladodes were vertically
that report the use of multiple intercropping in these species. When inserted into the soil (90◦ ), leaving 50% of the lower extremity in the soil
intercropped, these species may undergo changes in growth rates and in a system of bilateral cladode alignment, spaced 1.0 × 0.2 m apart (i.e.
the dynamics of using biophysical resources; however, a productive 50,000 plants ha− 1). Sorghum was planted at a spacing of 1.0 m between
advantage is still expected when adopting this practice (Diniz et al., rows, sown in furrows 0.05 m deep in March 2017, with the stand
2017; Lima et al., 2018a). The application of biological indices to thinned 28 days after seedling emergence to leave 20 plants per linear
intercropping systems helps in understanding crop competitiveness, metre (i.e. 200,000 plants ha− 1). In the intercropping systems, the sor­
economic benefits and ideal cropping configurations (clones versus ghum was sown parallel to and 0.25 m from the basal cladodes of the
cultivars) (Sadeghpour et al., 2013; Chimonyo et al., 2018). forage cactus.
This study aimed to evaluate the performance of intercropping cac­ The sorghum was grown over four consecutive production cycles
tus with sorghum as well as the biological efficiency and competitive during the 2017 to 2018 season of the second cycle of the forage cactus.
ability of forage cactus clones and sorghum cultivars, to make recom­ The first cycle in each cultivar had a period of 120 days after emergence,
mendations for their use in intercropping in an irrigated semi-arid with cutting carried out in July 2017. In the second cycle, cultivar ‘2502’
environment as a guarantee of lower seasonality and greater diversity was sown at 71 days after cutting (DAC), and cultivars ‘467’ and ‘SF11’
of forage production. were sown at 92 DAC. In the third cycle, cultivar ‘2502’ was sown at 94
DAC, and cultivars ‘467’ and ‘SF11’ were sown at 102 DAC. In the fourth
2. Material and methods and final cycle, cultivar ‘2502’ and cultivars ‘467’ and ‘SF11’ were sown
at 84 and 85 DAC, respectively.
2.1. Description of the site Two mineral fertilisations of NPK were performed throughout the
experimental area, the first as a base dressing in January and the second
The experiment was conducted at the Serra Talhada Academic Unit as cover in August 2017, in the formulation, 14-00-18 + 16 S, applying
of the Rural Federal University of Pernambuco (UFRPE/UAST), in Serra 525 kg ha− 1 (73.5 kg N ha− 1, 94.5 kg K2O ha− 1 and 84 kg S ha− 1)
Talhada in the state of Pernambuco, Brazil (7◦ 56′ 20′′ S, 38◦ 17’ 31” W throughout the experimental period, as per Diniz et al. (2017). Crop
and 499 m), during two consecutive seasons (2016/2017 and 2017/ treatments in the experimental area were carried out constantly to
2018). According to the Köppen classification, the climate in the region enable favourable conditions for the crops to develop.
is type BSwh’, semi-arid, with rainfall during the warmer months and The experimental design was of randomised blocks with 15 treat­
drought during the cold months of the year (Alvares et al., 2013), with ments (cropping systems), with four replicates, where three forage
minimum and maximum monthly air temperatures of 20.1 and 32.9 ◦ C, cactus clones and three sorghum cultivars were each grown in a single
respectively, a relative air humidity close to 63%, mean rainfall of 642 cropping system, with nine intercropping systems based on the combi­
mm year− 1 and an atmospheric demand of 1,800 mm year− 1, resulting nations of clones and cultivars: IPA, Miu, OEM, ‘467’, ‘SF11’, ‘2502’,
in a deficit of 1,143 mm year− 1 (Pereira et al., 2015; Silva et al., 2015). IPA-‘467’, IPA-‘SF11’, IPA-‘2502’, Miu-‘467’, Miu-‘SF11’, Miu-‘2502’,
The relief of the experimental area was flat, and the soil was a typic OEM-‘467’, OEM-‘SF11’ and OEM-‘2502’. Each treatment consisted of
Eutrophic Ta Haplic Cambisol, which when sampled at a depth of four plots (replications), totalling 60 experimental units, which
0.00–0.20 m, gave the following physical and chemical results: pH(water) comprised four rows, each with 25 cactus plants, giving a total area of
of 5.95, electrical conductivity of the saturated soil extract (ECe) of 0.32 60 m2 (Fig. 1). One working plot consisted of the two central rows, with
dS m− 1, P(Mehlich-1) of 168.96 mg dm− 3, K+ of 13.8 cmolc dm− 3, Na+ of 46 working plants (the plants at either being discarded), giving a total
1.09 cmolc dm− 3, Ca2+ of 3.45 cmolc dm− 3, Mg2+ of 1.90 cmolc dm− 3, H working area of 16.4 m2.
+ Al of 0.6 cmolc dm− 3, sum of bases (SB) of 20.25 cmolc dm− 3, cation Irrigation was carried out utilising a drip system with a flow rate of
exchange capacity (CEC) of 20.85 cmolc dm− 3, base saturation (V%) = 1.75 ± 0.14 L h− 1, at a working pressure of 101.32 kPa and a coefficient
97.15%, Corganic of 4.6 g kg− 1, organic matter of 7.93 g kg− 1, sand of of uniformity of 95%, with spacing between emitters of 0.20 m. The
828.6 g kg− 1, silt of 148.25 g kg− 1, clay of 23.15 g kg− 1 and bulk density water used was from an artesian well located near the experimental area

2
A.M.R.F. Jardim et al. Journal of Arid Environments 188 (2021) 104464

Fig. 1. Representation of the experimental area and cropping systems (A), an example of the arrangement of the intercropping system (B) and examples of the
arrangements of the single systems of forage cactus and sorghum (C).

and presented a mean electrical conductivity of 1.51 dS m− 1, and it was period of intercropping, the rainfall was concentrated from February to
classified as of high salinity (C3), according to Richards (1954): pH was July in 2017 and from February to May in 2018, giving a total cumu­
6.84, Na+ was 168.66 mg L− 1 and K+ was 28.17 mg L− 1. lative rainfall of 997 mm. The months from August to January make up
Irrigation management was adopted based on the water requirement the dry season. Supplemental irrigation totalled 623.21 mm (1.4 mm
of the forage cactus (as it was the main crop), using a crop coefficient day− 1). The ETo presented a mean value of 4.71 mm day− 1 during the
(Kc) of 0.52, as per Queiroz et al. (2016). The meteorological data to experimental period (i.e. with a maximum of 7.53 mm day− 1 and a
determine the replacement of the soil water were collected daily from an minimum of 0.40 mm day− 1), for a total atmospheric demand of
automatic weather station belonging to the National Institute of Mete­ 2,431.32 mm.
orology, located 20 m from the experimental area. To determine the
reference evapotranspiration (ETo), the Penman-Monteith method 2.3. Biomass yield in the forage cactus and sorghum
standardised by FAO Bulletin 56 (Allen et al., 1998) was used. Fig. 2
shows the values for ETo, rainfall and irrigation applied during the The total fresh and dry biomass (Mg ha− 1) of each cycle of the forage
experimental period. cactus cladodes was measured at harvest. The plants from the working
In the experimental period with only single system cactus (first cycle plot were harvested, and once they were weighed on a precision scale (to
of forage cactus) the rainfall and ETo were 512 mm (1.3 mm day− 1) and obtain the fresh weight), they were broken up and placed in paper bags.
2,252 mm (5.86 mm day− 1), respectively. During the experimental These were identified and left in a forced-air ventilation oven at 65 ◦ C to
constant weight (Sadeghpour et al., 2013). In addition, the basal and
first-order cladodes were left on the plants in the field when cutting.
For the sorghum cultivars, the biomass was determined from the
production of fresh and dry biomass (Mg ha− 1) in the shoots (i.e. stem +
leaves + panicle). Forage production was obtained by harvesting the
plants from two linear metres of the central rows of each working plot,
cut 0.10 m above the ground. Three representative sorghum plants were
selected from the working plot, making it possible to estimate the dry
matter after they were dried in a forced-air oven at 65 ◦ C (Sadeghpour
et al., 2013).
After weighing and drying the biomass from the crops (second cycle
of forage cactus and four cycles of sorghum), it was individually ground
in a Willey type mill (1.0 mm sieve) and placed in properly identified
polyethylene bags. A bromatological analysis was then carried out for
total dry matter (TDW), crude protein (CP), total carbohydrates (TC),
total nitrogen (TN), neutral detergent fibre (NDF), acid detergent fibre
(ADF), ether extract (EE), mineral matter (MM), ash (Ash) and in vitro
Fig. 2. Environmental conditions and water availability via irrigation during
dry matter digestibility (DIVDM), as per a methodology proposed by
the experimental period for the municipality of Serra Talhada, Pernambuco, AOAC (1990) and Van Soest et al. (1991).
Brazil. Note: The dashed red line indicates the start of the intercropping.

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A.M.R.F. Jardim et al. Journal of Arid Environments 188 (2021) 104464

2.4. Application of the indices of biological efficiency and competitive [ ] [ ]

(Ysc ) (Ycs )
ability Asc = – (9)
(Yss ⋅ Zsc ) (Ycc ⋅ Zcs )
The biological efficiency of the cactus-sorghum intercropping was
where Zcs is the proportion of forage cactus intercropped with sorghum
obtained through the indices described below from the yield of the
(20%: 50,000 plants ha− 1) and Zsc is the proportion of sorghum inter­
second cycle of the forage cactus and four cycles of the sorghum. The
cropped with forage cactus (80%: 200,000 plants ha− 1). If Acs is greater
land equivalent ratio (LER), which consists in the utilisation of the
than 0, the competitive ability of the forage cactus is superior to that of
relative land area, analysing the biological efficiency of the crops in a
the sorghum, otherwise the sorghum is more competitive; if Acs is equal
single system and an intercropping system, was obtained from Equation
to 0, both crops are equally competitive.
(1) (Liu et al., 2018):
The actual loss and/or gain in yield (ALGY) was calculated using
[ ]
(Ycs ) (Ysc ) Equation (10), which expresses the proportional loss and/or gain in
LER = + (1)
(Ycc ) (Yss ) yield in intercropping systems compared to the single systems. The
competitiveness ratio (CR) was also calculated using Equations (11) and
where Ycs and Ysc are the productivity of the forage cactus and sorghum, (12); this assesses the competitive capacity and advantage of the cactus
respectively, both in intercropping systems and Ycc and Yss are the and sorghum in the system, respectively.
productivity of the forage cactus and sorghum, respectively, in a single [ ( ) ] [ ( ) ]
100 100
system. When the LER is greater than 1.0, there is an advantage in using ALGY = LERc ⋅ − 1 + LERs ⋅ − 1 (10)
Zcs Zsc
the intercropping system, affording a greater land equivalent ratio when
compared to the single system; when LER is less than 1.0, it signals a [ ]
(LERc ) (Zsc )
disadvantage in using the intercropping system, caused by interspecific CRc = ⋅ (11)
(LERs ) (Zcs )
competition, and if LER is equal to 1, there is no advantage in
intercropping. [ ]
(LERs ) (Zcs )
The area time equivalent ratio (ATER), land equivalent coefficient CRs = ⋅ (12)
(LERc ) (Zsc )
(LEC) and the system productivity index (SPI), in turn, help in evaluating
the biological efficiency of intercropping cactus and sorghum and are where LERc is the partial land equivalent ratio of the forage cactus, LERs
calculated using Equations (2)–(4), respectively (Diniz et al., 2017; Xiao is the partial land equivalent ratio of the sorghum, Zcs is the proportion
et al., 2018). of forage cactus intercropped with sorghum and Zsc is the proportion of
[ ]
(LERc ⋅ tc ) + (LERs ⋅ ts ) sorghum intercropped with forage cactus.
ATER = (2) All the procedures for calculating the indices shown above were
(tcs )
followed as per Sadeghpour et al. (2013) and Diniz et al. (2017).
LEC = (LERc ⋅ LERs ) (3)
[ ] 2.5. Economic index
(Ycc )
SPI = ⋅ Ysc + Ycs (4)
(Yss )
The economic costs to analyse the viability of the intercropping
system were determined utilising the monetary advantage index (MAI)
where LERc is the partial land equivalent ratio of the forage cactus, LERs
in Equation (13), considering the net revenue of the system (NR) for
is the partial land equivalent ratio of the sorghum, tc is the time in days
each treatment, as per Baxevanos et al. (2017):
of the forage cactus cycle, ts is the time in days of the sorghum cycle and
[ ]
tcs is the total time of the cultivation system. (LER − 1)
MAI = NR ⋅ (13)
Among the indices of competitive ability, the coefficient of relative (LER)
density (K) was used, which expresses the advantage and relative
dominance of one crop over the other (Diniz et al., 2017; Xiao et al., where MAI is the monetary advantage index (BRL ha− 1) and NR is the
2018), determined using the mathematical expressions shown below net revenue per hectare (BRL ha− 1), which is calculated by subtracting
(Equations (5)–(7)): the total operating cost of inputs and services from the gross revenue.
The fixed commercial value for the fresh forage matter of the cactus and
K = (Kcs ⋅ Ksc ) (5)
sorghum was set at 150.00 and 450.00 BRL Mg− 1, respectively (National
Supply Company, 2020).
(Ycs ⋅ Zsc )
Kcs = (6)
(Ycc − Ycs ) ⋅ Zcs
2.6. Statistical analysis
(Ysc ⋅ Zcs )
Ksc = (7)
(Yss − Ysc ) ⋅ Zsc The data for the total biomass yield were compared among the 15
cropping systems with four replications. For the single systems of forage,
where Kcs is the coefficient of the relative density of the cactus over the cacti were summed for the productivity of the first and second cycles.
sorghum, Ksc is the coefficient of the relative density of the sorghum over Sorghums were summed as the productivity of four cycles (first, second,
the cactus. If the value of K > 1, it shows that the intercropping system third and fourth cycles). In the intercropping systems, total biomass
has an advantage in yield over the single system; if the value of K = 1, it yields were obtained from the sum of the productivity of the two cycles
indicates no advantage in system yield; and if K < 1, it shows a disad­ of forage cactus (first and second) and the four cycles of sorghum (first,
vantage in production compared to the single system. second, third and fourth). The indices of biological efficiency and
The aggressiveness index (A) was determined using the mathemat­ competitive ability were compared between the nine intercropping
ical expressions described below (Equations (8) and (9)). systems, with four replications. The data were submitted to tests of
[
(Ycs )
] [
(Ysc )
] normality, homoscedasticity and analysis of variance (ANOVA one-way)
Acs = – (8) by the F-test (P < 0.05), considering as the only factor the cropping
(Ycc ⋅ Zcs ) (Ysc ⋅ Zsc )
systems. When significant, the mean values were compared by Tukey’s
test at a level of 0.05 probability. The data were transformed when
necessary to meet the conditions of the parametric analysis. All

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A.M.R.F. Jardim et al. Journal of Arid Environments 188 (2021) 104464

statistical analyses were carried out using the R software (R Core Team, 3.2. Chemical composition of the forage
2019).
Table 2 shows the chemical and bromatological composition of the
3. Results forage cactus cladodes and the sorghum in the single and intercropped
systems at the end of the crop cycle. The results for each of the chemical-
3.1. Yield of the cropping systems bromatological variables of the forage cacti in the different configura­
tions did not differ (P > 0.05), showing that there was no effect from
In the first cycle of the forage cactus, without the intercropping with intercropping on the quality of the forage. For the sorghum, there were
sorghum cultivars, the clone OEM showed, in general, the most satis­ also no differences in the chemical-bromatological variables, except for
factory yields (fresh matter: FM and dry matter: DM) among the cacti dry matter (P > 0.05) (Table 2), which was greater in sorghum ‘2502’
(on average, FM = 96.82 Mg ha− 1 and DM = 5.12 Mg ha− 1), followed by intercropped with OEM (41.91%).
the clone Miu (on average, FM = 55.75 Mg ha− 1 and DM = 3.41 Mg
ha− 1) and then the clone IPA (on average, FM = 22.84 Mg ha− 1 and DM 3.3. Biological efficiency and competitive ability of the systems
= 1.32 Mg ha− 1).
In turn, during the second cycle, in general, the cactus-sorghum Table 3 shows the values for the indices of biological efficiency and
intercropping systems were 47% and 3.5 times more productive in the monetary advantage of the intercropping systems. The results for the
terms of fresh and dry matter, respectively, than the single-cactus sys­ partial land equivalent ratio of the forage cactus (LERc) did not differ
tems. In comparison to the single-sorghum systems, the increase was between the cactus-sorghum configurations. On the other hand, the
52% in terms of fresh matter; however, in terms of dry matter, a partial land equivalent ratio of sorghum (LERs) differed between culti­
reduction of 57% was observed. On average, the productivities of fresh vars showing higher values when intercropped with IPA and Miu, which
matter in the intercropped, single-cactus and single-sorghum systems resulted in higher values for the total land equivalent ratio (LERTotal).
were 221.73 Mg ha− 1, 150.82 Mg ha− 1 and 145.92 Mg ha− 1, respec­ But in general, in each of the configurations, the values for LERTotal were
tively. In terms of dry matter productivity, the averages of the values greater than 1.0, ranging from 1.02 to 1.93.
were of 221.73 Mg ha− 1, 150.82 Mg ha− 1 and 145.92 Mg ha− 1 for the The results for the area-time equivalent ratio (ATER) did not differ
intercropped, single-cactus and single-sorghum systems, respectively. between the intercropping systems (P > 0.05). They were, however,
Table 1 shows that the cactus-sorghum cropping system with the greater than 1.0, except for the OEM-‘SF11’ configuration, which ob­
highest fresh matter yield was the Opuntia sp. clone (OEM) intercropped tained a value for ATER of 0.95 (P > 0.05) (Table 3). For the land
with sorghum cultivar ‘467’, although there was no difference relative to equivalent coefficient (LEC), a productive advantage is established when
other systems (OEM-‘SF11’, OEM-‘2502’, IPA-‘SF11’, Miu-‘467’ and the LEC is greater than 0.25 (or 25%), which happened in most of the
Miu-‘SF11’). The systems with the lowest yields of fresh matter were configurations except the OEM-‘SF11’ intercropping (LEC = 0.24).
IPA-‘2502’ and Miu-‘2502’ (P < 0.05). Despite this, the system productivity index (SPI) was high (12.57). The
In terms of dry matter, the cactus-sorghum cropping systems with the greatest SPI among the cropping configurations was for OEM inter­
highest yields were the Nopalea sp. clones (IPA and Miu) intercropped cropped with ‘467’ (17.57 Mg DM ha− 1) (P < 0.05); but there was no
with the sorghum cultivars ‘467’ and ‘SF11’, a result of the high pro­ difference when intercropped with the other two cultivars (‘2502’ and
ductivity of these two cultivars, as the two forage cactus clones exhibited ‘SF11’). This result is consistent with those presented in Table 1.
a high mortality rate (IPA with 81.62 ± 1.45%, Miu equal to 71.68 ± However, the monetary advantage index (MAI) was higher for the
3.71% and OEM at 8.56 ± 1.29%). The low mortality rate of the OEM IPA-‘SF11’ configuration (26518.44 BRL ha− 1, P < 0.05), followed by
shows the high stability of the cultivation of this clone under irrigation the Miu-‘467’, IPA-‘467’, Miu-‘SF11’ and OEM-‘467’ intercropping.
conditions. The systems with the lowest yields of dry matter were IPA- Although the contribution of fresh matter from Nopalea in these con­
‘2502’ and Miu-‘2502’ (P < 0.05). figurations was not low (Table 1), the intercropping systems showed
For the forage single-cactus system, during the second cycle, the positive values for MAI because of the sales value of the sorghum, which
OEM had the best performance for fresh and dry matter, showing no is higher than that of forage cactus (450.00 versus 150.00 BRL Mg− 1
difference from its intercropping with the three sorghum cultivars fresh matter, respectively). The lowest value for MAI was in the OEM-
(OEM-‘467’, OEM-‘SF11’ and OEM-‘2502’; P > 0.05, Table 1). This ‘SF11’ intercropping (− 325.52 BRL ha− 1), reflecting the low sorghum
result shows the high productive potential of the clone OEM even under production.
intercropping with sorghum. For the sorghum, it can be seen from Table 4 shows the values for the competitive ability index of the
Table 1 that at the end of the four cycles, cultivars ‘467’ and ‘SF11’ in the forage cactus clones intercropped with the sorghum cultivars. The co­
single systems achieved high accumulated yields of fresh matter (μFM = efficients of the relative density of the cactus over the sorghum (Kcs) and
182.34 Mg ha− 1) and dry matter (μDM = 64.60 Mg ha− 1) (P < 0.05). of the sorghum over the cactus (Ksc) did not differ between the inter­
Furthermore, these values did not differ from the intercropping with cropping systems (P > 0.05). However, values greater than 1.0 were
IPA-‘467’ (μFM = 182.82 Mg ha− 1 and μDM = 61.41 Mg ha− 1), IPA-‘SF11’ seen for the configurations OEM-‘467’, OEM-‘SF11’, IPA-‘467’ and Miu-
(μFM = 220.89 Mg ha− 1 and μDM = 64.57 Mg ha− 1), Miu-‘467’ (μFM = ‘SF11’, which implies advantages in their use (Table 4). The higher
197.75 Mg ha− 1 and μDM = 57.47 Mg ha− 1) and Miu-‘SF11’ (μFM = values for the competitiveness ratio of the cactus, CRc, compared to
187.41 Mg ha− 1 and μDM = 51.80 Mg ha− 1). Due to its small size and low those of the sorghum, CRs, demonstrate the more-significant competi­
biomass accumulation, cultivar ‘2502’ had the lowest biomass yields in tiveness of the forage cactus clones compared to the sorghum cultivars,
both systems (Table 1). During the third cycle of cultivars ‘467’ and confirming the interspecific competition. This result is confirmed by the
‘SF11’, yields were lower than during the fourth cycle; this trend was not aggressiveness of the forage cactus over the sorghum (Acs), which was
seen for the ‘2502’ cultivar. greater than the aggressiveness of the sorghum over the cactus (Asc)
Individual yields of the intercropped forage cactus clones showed no (Table 4).
statistically significant reductions in fresh and dry matter production From the index for the actual loss or gain in yield of the cactus
when compared to the single systems (P > 0.05); however, there was an (ALGYc), although showing no significant difference, it can be said that
average decrease of 27% and 19% for OEM, 38% and 42% for IPA and the yields obtained from adopting the intercropping systems were
42% and 36% for Miu. This trend was also found in the sorghum, but satisfactory, with values ranging from 236.12 to 506.70, i.e. greater than
with reductions of 25% and 22% for ‘467’, 27% and 34% for ‘SF11’ and 1.0. The same gain was seen in the sorghum (ALGYs), but with differ­
42% and 34% for ‘2502’, respectively. ences between the configurations. Higher values for ALGYc compared to
ALGYs, show the more-significant contribution of the cactus to the final

5
 A.M.R.F. Jardim et al.
Table 1
The productivity of fresh matter (FM, Mg ha− 1) and dry matter (DM, Mg ha− 1) in single and intercropped systems of forage cactus clones (Opuntia and Nopalea) and sorghum cultivars (four cycles) (Sorghum bicolor (L.)
Moench).
Crop cycles Intercropped treatments (Fresh matter, Mg ha− 1) Single treatments (Fresh matter, Mg ha− 1)

OEM OEM OEM IPA IPA IPA Miu Miu Miu OEM IPA Miu ‘467’ ‘SF11’ ‘2502’
‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’ Single Single Single Single Single Single

Yc cycle1 98.31a 87.05 ab 99.57a 23.38bc 29.28bc 14.93c 57.32abc 49.27abc 31.55bc 102.35a 23.77bc 39.82abc – – –
†
Ys cycle1 24.74bcd 21.04cd 8.17d 52.21 ab 57.50 ab 20.94cd 52.57abc 43.84abc 14.75d – – – 49.61abc 72.22a 28.42bcd
Ys cycle2 31.00bcd 22.95cde 5.31e 44.94 ab 61.69a 17.86de 46.61 ab 46.85 ab 12.31de – – – 49.60 ab 44.26abc 18.06de
Ys cycle3 20.50bc 13.84bc 10.24c 26.56 ab 23.76abc 17.54bc 24.56abc 21.52abc 13.21bc – – – 36.09a 26.20 ab 14.96bc
Ys cycle4 19.59bcd 18.57bcd 4.37d 33.23 ab 28.59abc 8.83cd 26.10abc 26.15abc 7.92cd – – – 43.42a 34.78 ab 20.13bcd
Ys Total 95.83bcd 76.40d 28.09e 156.94 ab 171.54a 65.17de 149.84 ab 138.36abc 48.19de – – – 178.72a 177.46a 81.57cd
Yc cycle2 132.28 ab 98.92abc 106.39abc 25.88c 49.35c 32.03c 47.91c 49.05c 32.49c 154.86a 57.54bc 74.14abc – – –
Ysystem 228.11a 175.32 ab 134.48bcd 182.82 ab 220.89a 97.20cde 197.75 ab 187.41 ab 80.68de 154.86abc 57.54e 74.14de 178.72 ab 177.46 ab 81.57cde
YTotal 326.45a 262.38 ab 234.07 ab 206.23bc 250.19 ab 112.16cd 255.09 ab 236.70 ab 112.26cd 257.21 ab 81.31d 113.95cd 178.72bcd 177.46bcd 81.57d
1
Crop cycles Intercropped treatments (Dry matter, Mg ha− ) Single treatments (Dry matter, Mg ha− 1)
OEM OEM OEM IPA IPA IPA Miu Miu Miu OEM IPA Miu ‘467’ ‘SF11’ ‘2502’
‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’ Single Single Single Single Single Single
6

Yc cycle1 5.39a 4.73 ab 5.08a 1.33bc 1.73abc 0.82c 3.81abc 3.29abc 2.55abc 5.29a 1.38bc 2.51abc – – –
Ys cycle1 7.42bcd 6.35cd 3.73d 21.51 ab 20.73abc 9.25bcd 18.88abc 15.72bcd 6.42cd – – – 18.33abcd 32.23a 11.69bcd
Ys cycle2 12.85bcd 8.99cd 3.86d 19.54 ab 24.83a 10.49bcd 19.07 ab 19.17 ab 7.85d – – – 19.56 ab 17.76abc 11.16bcd
Ys cycle3 5.58bc 3.33c 4.65bc 7.14abc 6.40bc 8.60 ab 7.03abc 5.30bc 6.61bc – – – 12.02a 7.16abc 5.56bc
Ys cycle4 6.19abc 5.73abc 1.54c 11.54a 8.80 ab 2.83bc 8.56 ab 7.20abc 2.75bc – – – 12.43a 9.70a 6.27abc
Ys Total 32.04bcd 24.40cd 13.78d 59.73a 60.76a 31.17bcd 53.54 ab 47.39abc 23.63d – – – 62.34a 66.85a 34.68bcd
Yc cycle2 11.56a 8.27abc 9.34 ab 1.68c 3.81bc 2.22c 3.93bc 4.41bc 2.81bc 12.05a 4.42bc 5.83abc – – –
†
Ysystem 43.60bcd 32.67cde 23.12ef 61.41 ab 64.57 ab 33.39cde 57.47 ab 51.80abc 26.44de 12.05 fg 4.42g 5.83g 62.34 ab 66.85a 34.68cde
YTotal 49.02cd 37.43de 28.22ef 62.75bc 66.31b 34.24de 61.31bc 55.11bc 29.01ef 17.34 fg 5.81g 8.34g 124.72a 133.72a 69.40b

Mean values followed by the same letters on a line do not differ statistically by Tukey’s test at 0.05 probability level.
OEM - ‘Orelha de Elefante Mexicana’; IPA - ‘IPA Sertânia’; Miu - ‘Miúda’; Sorghum cultivars - ‘467’, ‘SF11’ and ‘2502’.
Yc cycle1 - Yield of the 1st cycle of forage cactus without intercropping (Opuntia or Nopalea).
Ys Total - Data relative to the sum of the four productive cycles of the sorghum cultivars.

Journal of Arid Environments 188 (2021) 104464

Yc cycle2 - Yield of the 2nd cycle of forage cactus with intercropping (Opuntia or Nopalea).
Ysystem - Yield of the cactus-sorghum systems, cactus single systems or sorghum single systems.
YTotal - Sum of the yield of all cultivation system cycles (single and intercropped with forage cactus (1st and 2nd cycles) and sorghum).
† Data transformed by the square-root method (x+0.5).
A.M.R.F. Jardim et al. Journal of Arid Environments 188 (2021) 104464

Table 2
Chemical-bromatological parameters of the forage cactus clones (Opuntia and Nopalea) in a single cultivation system and intercropped with sorghum (Sorghum bicolor
(L.) Moench).
Variable (g kg− 1) ‡
Forage cactus clones intercropped with sorghum cultivars ‡
Single clones

OEM OEM OEM IPA IPA IPA Miu Miu Miu OEM IPA Miu
‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’ Single Single Single

TDM 7.92 7.28 7.86 6.36 6.80 6.01 7.34 7.92 7.65 6.95 6.86 6.99
CP 4.01 4.65 4.06 3.57 4.51 4.80 4.07 3.24 2.14 4.09 4.10 3.76
TC 74.77 74.55 74.95 74.35 70.00 69.52 73.21 76.38 73.21 70.95 70.39 65.46
EE 1.22 0.97 0.96 1.10 1.97 1.60 0.99 0.92 1.51 1.74 0.84 2.60
NDF 16.86 17.13 18.59 24.46 16.25 16.22 13.83 15.07 9.00 19.74 17.17 29.13
ADF 3.09 3.10 3.36 7.99 3.59 3.74 2.73 3.04 4.28 3.57 3.52 3.39
MM 19.99 19.81 20.01 20.97 23.51 24.06 21.72 19.45 23.12 23.21 24.66 28.17
DIVDM 76.50 77.64 81.03 89.61 84.90 79.90 82.82 85.81 81.11 80.07 87.24 83.47
Variable (g kg− 1) ⁂
Sorghum cultivars intercropped with forage cactus clones ⁂
Single clones
‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’ ‘467’ ‘SF11’ ‘2502’
OEM OEM OEM IPA IPA IPA Miu Miu Miu Single Single Single
TDM 28.13b 28.11b 41.91a 31.40b 28.99b 28.93b 29.39b 28.92b 31.90b 25.64c 25.03c 28.16b
CP 11.25 7.52 11.89 11.09 5.28 9.05 9.49 12.82 10.27 9.85 9.76 10.53
TC 81.45 85.40 81.15 81.03 87.16 83.40 83.47 77.99 81.62 83.11 82.48 81.07
EE 1.31 1.41 2.25 1.35 1.45 1.55 1.42 1.62 2.00 1.72 1.68 1.85
NDF 50.95 53.99 36.38 54.37 54.71 44.52 53.61 64.72 44.25 51.75 52.62 53.09
ADF 29.20 26.36 16.26 21.67 27.48 20.31 27.10 32.66 20.05 26.58 27.15 24.84
MM 5.98 5.65 4.70 6.52 6.10 5.98 5.60 7.56 6.11 5.31 6.07 6.52
DIVDM 60.67 65.88 74.37 63.97 64.33 68.72 55.50 61.35 73.29 64.01 59.98 63.21

OEM - ‘Orelha de Elefante Mexicana’; IPA - ‘IPA Sertânia’; Miu - ‘Miúda’. Sorghum cultivars - ‘467’, ‘SF11’ and ‘2502’; TDM - Total dry matter; CP - Crude protein; TC -
Total carbohydrates; EE - Ether extract; NDF - Neutral detergent fibre; ADF - Acid detergent fibre; MM - Mineral matter; DIVDM - In vitro dry matter digestibility.
⁂
Chemical and bromatological data relative to the final cycle of the sorghum crop. ‡Chemical and bromatological data relative to the cycle two of the forage cactus.
Mean values followed by the same letters on a line do not differ statistically by Tukey’s test at 0.05 probability level.

Table 3
Indices of biological efficiency in forage cactus clones (Opuntia and Nopalea) intercropped with sorghum cultivars (Sorghum bicolor (L.) Moench).
‡
Treatment LERc LERs LERTotal ATER LEC SPI MAI

OEM-‘2502’ 0.81 0.42 ab 1.23 ab 1.14 0.34 14.53 ab − 30.05d

OEM-‘467’ 1.01 0.50 ab 1.51 ab 1.41 0.50 17.57a 11,217.38b
OEM-‘SF11’ 0.66 0.36b 1.02b 0.95 0.24 12.57abc − 325.51d
IPA-‘2502’ 0.64 1.00a 1.64 ab 1.42 0.42 7.23c 1652.53c
IPA-‘467’ 0.47 0.98a 1.45 ab 1.24 0.41 6.25c 13,775.37b
IPA-‘SF11’ 0.99 0.94 ab 1.93a 1.73 0.81 8.29bc 26,518.44a
Miu-‘2502’ 0.47 0.72 ab 1.19 ab 1.04 0.34 6.81c − 303.85d
Miu-‘467’ 0.69 0.91 ab 1.60 ab 1.41 0.57 8.90bc 15,168.34b
Miu-‘SF11’ 0.78 0.72 ab 1.50 ab 1.34 0.57 8.53bc 13,086.74b

OEM - ‘Orelha de Elefante Mexicana’; IPA - ‘IPA Sertânia’; Miu - ‘Miúda’. Sorghum cultivars - ‘467’, ‘SF11’ and ‘2502’; LERc - Partial land equivalent ratio of the forage
cactus; LERs - Partial land equivalent ratio of the sorghum; LERTotal - Total land equivalent ratio; ATER - Area time equivalent ratio; LEC - Land equivalent coefficient;
SPI - System productivity index (Mg DM ha− 1); MAI - Monetary advantage index (BRL ha− 1). Mean values followed by the same letters within the same index do not
differ statistically by Tukey’s test at 0.05 probability level. ‡Data relative to the 2nd of forage cactus.

Table 4
Indices of competitive ability in forage cactus clones (Opuntia and Nopalea) intercropped with sorghum cultivars (Sorghum bicolor (L.) Moench).
‡
Treatment Kcs Ksc K CRc CRs Acs Asc ALGYc ALGYs ALGY

OEM-‘2502’ − 28.61 0.20 − 8.30 ab 8.54a 0.13 3.55 − 3.55 407.06 51.81 ab 458.88
OEM-‘467’ 19.50 0.26 2.7 ab 8.21 ab 0.13 4.44 − 4.44 506.70 62.21 ab 568.91
OEM-‘SF11’ 29.97 0.15 4.18 ab 7.45 ab 0.14 2.87 − 2.87 331.82 44.63b 376.46
IPA-‘2502’ − 0.34 0.62 − 0.58 ab 4.08 ab 7.36 1.96 − 1.96 320.89 124.24a 445.14
IPA-‘467’ 8.77 3.88 19.61a 2.20b 2.18 1.14 − 1.14 236.12 121.93a 358.05
IPA-‘SF11’ − 14.01 0.72 − 19.40b 4.94 ab 0.73 3.77 − 3.77 494.96 117.33 ab 612.29
Miu-‘2502’ 4.18 − 0.49 − 0.59 ab 2.86 ab 0.41 1.49 − 1.49 238.96 89.48 ab 328.44
Miu-‘467’ − 1.50 0.28 0.96 ab 3.75 ab 0.43 2.31 − 2.31 345.58 113.63 ab 459.22
Miu-‘SF11’ 21.10 0.81 20.39a 4.33 ab 0.24 3.00 − 3.00 390.14 89.22 ab 479.35

OEM - ‘Orelha de Elefante Mexicana’; IPA - ‘IPA Sertânia’; Miu - ‘Miúda’. Sorghum cultivars - ‘467’, ‘SF11’ and ‘2502’; Kcs - Coefficient of relative density of the cactus
over the sorghum; Ksc - Coefficient of relative density of the sorghum over the cactus; K - Coefficient of relative density; CRc - Competitiveness ratio of the cactus; CRs -
Competitiveness ratio of the sorghum; Acs - Aggressiveness of the cactus over the sorghum; Asc - Aggressiveness of the sorghum over the cactus; ALGYc - Actual loss or
gain in yield of the cactus; ALGYs - Actual loss or gain in yield of the sorghum; ALGY - Actual loss or gain in yield. Mean values followed by the same letters within the
same index do not differ statistically by Tukey’s test at 0.05 probability level. ‡Data relative to the 2nd of forage cactus.

7
A.M.R.F. Jardim et al. Journal of Arid Environments 188 (2021) 104464

increase in gain of the intercropping. producer to replant the area. During the sorghum off-season, the supply
of forage cactus can partially meet the nutritional demands of animals,
4. Discussion especially at critical times of the year (Diniz et al., 2017; Moraes et al.,
2019).
4.1. Yield of the cropping systems The high yields of forage matter seen for OEM in the single cropping
systems (P > 0.05) and in the OEM-‘467’ intercropping are greater than
The yield of forage cactus in the first cycle, which was conducted in those reported by Lima et al. (2018b) when studying the OEM clone (i.e.
rainfed conditions, was less than the yield of the second cycle, which was 15,625 plants ha− 1) irrigated with brackish water in the Brazilian
irrigated (Table 1). The use of irrigation and intercropping with the semi-arid region during the second crop cycle, under annual cutting and
sorghum during the second cycle of the forage cactus, when the plants intercropped with sorghum ‘2502’ (112,500 plants ha− 1). In this same
are stabilised, increases the forage production. The adoption of inter­ area, Diniz et al. (2017), who used an intercropping of OEM (i.e. 15,625
cropping systems in semi-arid environments can improve the use of plants ha− 1) with the sorghum cultivar ‘SF15’ (170,000 plants ha− 1),
natural resources due to the interspecific complementarity of crops of also obtained lower yields than those obtained in the present study
local agricultural importance that have high biological efficiency and during the third production cycle under annual cutting.
competitive ability. In this study, the performance of forage cactus These results may be related to the cropping density of the cactus in
clones and sorghum cultivars was investigated to suggest the most the present study (i.e. 50,000 plants ha− 1), which was higher than in
suitable irrigated cropping configuration for the Brazilian semi-arid re­ conventional systems (<30,000 plants ha− 1). In addition, the OEM clone
gion. In the cropping systems used, whether single systems or inter­ displays high adaptability and aggressiveness (Rule and Hoffmann,
cropping, the water management adopted was based on the water 2018), with a positive response to increases in density, as seen by
demand of the forage cactus, which is lower than that of the sorghum, Dubeux Jr. et al. (2006) and Souza et al. (2017), when evaluating
which ensured regular minimum irrigation, complementing rainfall densities of from 5,000 to 40,000 plants ha− 1. This reduction in the
events, but eventually resulted in a water deficit in the sorghum. individual yield of the forage cactus in intercropping systems was ex­
The forage cactus, being a cactus, has a high tolerance to water pected (Diniz et al., 2017; Kimura et al., 2018; Lima et al., 2018b);
stress, with superior yields in years of regular rainfall or with minimal however, when the yield was added to that of sorghum ‘467’ or ‘SF11’,
irrigation events (Pereira et al., 2015; Silva et al., 2015). On the other the results were similar or superior to those of the single crops.
hand, although sorghum is tolerant to water deficits, Bell et al. (2018) The use of sorghum as a secondary crop in intercropping systems can
affirm that inadequate irrigation management in a semi-arid environ­ promote more-resilient and more-stable crops due to its high adaptive
ment reduces the yield of agricultural crops, especially during stages capacity, especially in environments of low fertility and under condi­
with a higher water requirement, resulting in the mortality of the crop tions of water deficit. Moreover, several sorghum cultivars show satis­
during the cycle and compromising production. This explains the lower factory performance in dry matter production (Samarappuli and Berti,
yields of cultivars ‘467’ and ‘SF11’ during the third cycle (Table 1), 2018). The cultivars ‘467’ and ‘SF11’ in the single system presented high
when higher yields were expected than during the fourth cycle. How­ yields of fresh and dry matter (P > 0.05). The results presented in this
ever, these cultivars have longer cycles, larger sizes and a supposedly study were superior to those reported by Samarappuli and Berti (2018),
higher water demand compared to ‘2502’, which, during the third cycle, who, when working with two hybrid cultivars of forage sorghum
did not show the same tendency for a loss in yield as the other two (non-BMR (Brown midrib) and BMR (brachytic dwarf) in single and
cultivars. intercropping systems, achieved mean production values of 12.8 and
The use of intercropping improves the use of natural resources (i.e. 17.7 Mg forage dry matter ha− 1 in a single system.
water, land, radiation and nutrients) while reducing the individual yield
of each crop in the different configurations. But this loss in yield may 4.2. Chemical composition of the forage
also be related to the release of allelopathic compounds by the roots (e.g.
sorgoleone), which, due to phytotoxic activity, results in less microbial The chemical and bromatological composition of the forage cactus
activity, lower gas exchange and inhibition (Gimsing et al., 2009). A was not affected by the adoption of the intercropping systems (Table 2).
reduction in yield was also reported by Borghi et al. (2013) for sorghum These properties depend on the age of the cladodes (Hernández-Urbiola
intercropped with Marandu grass (Brachiaria brizantha Stapf) and et al., 2011), environmental factors and time of harvest (Méndez et al.,
Mombasa grass (Panicum maximum Jacq.); however, these effects tended 2015). For the sorghum, only the dry matter was modified in the
not to be severe due to the outstanding high radiation use capacity of the cactus-sorghum configuration and was greater in cultivar ‘2502’ inter­
sorghum. cropped with OEM (41.91%) (Table 2). Sorghum ‘2502’ is smaller,
The better performance of the Nopalea clones (IPA and Miu) in especially as an intercropping, which reduces water accumulation in the
configurations with the ‘467’ and ‘SF11’ cultivars should be interpreted cell structures, thereby increasing the matter concentration. Similar
with caution since their yields were associated more with the produc­ results for total sorghum dry matter were reported by Wannasek et al.
tivity of the sorghum than that of the forage cactus. Cultivars ‘467’ and (2017). The other bromatological properties of the sorghum were not
‘SF11’ are phenotypically different from ‘2502’, with greater stem modified in the cactus-sorghum configuration; the same might not be
heights, later cycles and a larger numbers of nodes, which increase seen in intercropping systems with other forage grasses, as reported by
biomass production (Shukla et al., 2017). On the other hand, the high Borghi et al. (2013). The use of the cactus-sorghum intercropping can
mortality rates of the two clones, IPA (81.62 ± 1.45%) and Miu (71.68 bring several benefits to production systems. Due to forage cactus hav­
± 3.71%), especially under irrigation, had a significant impact on the ing small amounts of dry matter and crude protein, sorghum comple­
productivity of the forage cactus, facilitating the development of the ments the animal diet, reducing the costs of protein supplementation
sorghum cultivars. Plant mortality in these two clones has been reported (Hernández-Urbiola et al., 2011). In addition, its tolerance to water
in field observations by researchers, as a result of the occurrence of stress ensures reduced forage seasonality (Moraes et al., 2019; Nasci­
phytopathogens that benefit from the high level of moisture in the soil mento et al., 2008).
(Guevara et al., 2003). Although the OEM clone showed a reduction in
individual productivity in the intercropping systems, it also showed 4.3. Biological efficiency and competitive ability of the systems
lower mortality (8.56 ± 1.29%), thereby ensuring greater stability for
the cactus. In the long term, therefore, its adoption in irrigated inter­ The LERc revealed that the contribution of the forage cactus to the
cropping systems reduces forage seasonality and ensures longevity for overall performance of the cactus-sorghum intercropping system does
the cactus, with lower costs for acquiring cladodes and less need for the not depend on the clone type of sorghum cultivar. On the other hand, the

8
A.M.R.F. Jardim et al. Journal of Arid Environments 188 (2021) 104464

LERs showed that the sorghum cultivars intercropped with the Nopalea production.
clones collaborated more in the intercropping system, with a more In terms of the indices of competitive ability, the Kcs and Ksc of the
obvious effect on LERTotal in the IPA-‘SF11’ configuration (1.93) OEM-‘467’, OEM-‘SF11’, IPA-‘467’, Miu-‘2502’ and Miu-‘SF11’ config­
(Table 3). However, despite this, each cactus-sorghum configuration urations presented values greater than 1.0, which implies an advantage
presented a value for LERTotal greater than 1 (1.02–1.93), with a mean in their use. In intercropping systems, crop yields are expected to be
value of 1.45. This value shows that the cactus-sorghum intercropping lower than those of the single systems. However, in the present study, for
system, irrespective of the cactus clone or sorghum cultivar, favours a some configurations (OEM-‘2502’, IPA-‘2502’, IPA-‘SF11’, Miu-‘2502’
45% increase in system production, i.e. to equal the yield of this system, and Miu-‘467’), negative values were found for Kps, Ksp and K (Table 4),
it would be necessary to plant an additional 0.45 ha if it were decided to showing that the performance of the crops in the single systems was less
use one of the crops in a single system. This result agrees with the study than the yield when intercropped. These results can be confirmed by
by Diniz et al. (2017), who showed a value for LERTotal of 1.51 for the observing the values of CRc and CRs.
‘Orelha de Elefante Mexicana’ intercropped with sorghum cultivar In each configuration, the aggressiveness of the forage cactus over
‘SF15’ in a semi-arid environment. the sorghum (Acs) was greater than the aggressiveness of the sorghum
Including OEM, the mean contribution of the intercropping system to over the cactus (Asc) (Table 4). These results express the relevance of
the land equivalent ratio was 25%, irrespective of the sorghum cultivar. aggressiveness in cactus-sorghum systems. Although the results for Asc
Whereas, with Nopalea, it was 67% for ‘IPA Sertânia’ and 43% for show negative responses, the values are much higher than those re­
‘Miúda’. In turn, the sorghum cultivars contribute 52%, 48% and 35% ported by Borghi et al. (2013), in which the sorghum crop did not pre­
for ‘467’, ‘SF11’ and ‘2502’, respectively. These results confirm that the sent any dominant characteristics, including in intercropping systems
use of the cactus-sorghum intercropping system is important and viable, with other forage plants. Diniz et al. (2017) also showed that the OEM
from better land use (i.e. biophysical resources) to significant increases forage cactus was more dominant than the ‘SF15’ sorghum.
in final yield. For the sorghum-cowpea (Vigna unguiculata (L.) Walp.) According to Borghi et al. (2013), the length of exposure to inter­
and sorghum-calabash (Lagenaria siceraria (Molina) Standl.) configura­ cropping is an interesting characteristic, affording gains in the biomass
tions, Chimonyo et al. (2016) obtained values for LERTotal of 1.54 and yield of the crops. The ALGY index (Table 4) expresses whether the
1.44, respectively, confirming that sorghum is an excellent species for intercropped systems had an advantage or disadvantage in their use
the complementarity and stability of intercropped production systems, when compared to the single systems. It was found that the forage cactus
and it minimises the loss of soil water through evaporation to the at­ showed high gains, higher than those of the sorghum, and despite not
mosphere during the day, due to the protection and closing of the can­ differing between configurations, each system had a high value for
opy. Results such as this show that the cactus-sorghum configuration is ALGY. The monetary advantages of the intercropping systems studied
promising, as cropping forage cactus is of great importance to the live­ here show natural resources harnessed by the crops, generating more
stock sector (Lima et al., 2018b). sustainable agricultural systems. These results agree with the other
Results for the ATER greater than 1.0 (μ = 1.30), except for the OEM- indices under analysis, thereby validating the efficiency and advantage
‘SF11’ configuration (0.95, Table 3), indicate an advantage for the of intercropping systems, as also noted by Diniz et al. (2017).
cactus-sorghum intercropping system. Diniz et al. (2017) also found a
value for ATER of 1.30 for OEM intercropped with the ‘SF15’ cultivar, 5. Conclusions
grown over 12 months and two cycles respectively. A productive
advantage is established when the LEC is greater than 0.25 (or 25%). In Water deficit affects crop growth, development and yield, especially
this study, except for the OEM-‘SF11’ configuration (LEC = 0.24), in in arid and semi-arid environments, where the availability of soil water
each of the other intercropping systems, the LEC was greater than 0.25, is even more dynamic and seasonal. The low water autonomy for irri­
with a mean value of 0.47. Diniz et al. (2017) obtained a LEC equal to gation purposes of these environments prevents the setting up of large
0.58. The greater SPI in the OEM configurations (OEM-‘467’, irrigated areas. As such, the adoption of techniques such as intercrop­
OEM-‘SF11’ or OEM-‘2502’), shows an increase in dry matter produc­ ping helps to improve the use of natural resources. This study evaluated
tion with the adoption of these intercropping systems. the advantages of intercropped forage cactus clones and sorghum cul­
The highest values for MAI in the IPA-‘SF11’ configuration, followed tivars compared to their single systems as a way of recommending their
by Miu-‘467’, IPA-‘467’, Miu-‘SF11’ and OEM-‘467’, are related to the use in the Brazilian semi-arid region to increase diversity and forage
performance of the intercropping systems on land use, i.e. on the production and reduce the seasonality of feed for the herds. The sor­
effective LERTotal of the system (Baxevanos et al., 2017). Although the ghum cultivar ‘467’ showed potential for intercropping with the three
fresh-matter contribution of the Nopalea clones is not high (Table 1), the forage cactus clones; however, the ‘IPA Sertânia’ and ‘Miúda’ clones,
systems presented a positive MAI, as the sale value of sorghum is higher both of the genus Nopalea, display high plant mortality, which hinders
than that of forage cactus (450.00 versus 150.00 BRL Mg− 1, respec­ their use under irrigation. The indices of biological efficiency and
tively). Using an intercropping system of forage cactus and sorghum, competitive ability showed that several of the cactus-sorghum inter­
Lima et al. (2018b) found that the economic benefits are greater when cropping systems evaluated here were categorised as advantageous,
compared to a single cactus system, as the total forage available for sale with no impact on the quality of the forage. However, the configuration
favours higher economic returns, as does the sale price. These results of ‘Orelha de Elefante Mexicana’ with sorghum cultivar ‘467’ offered
agree with the findings of the present study for most of the intercropping better stability (lower mortality rate when irrigated) for the cactus, with
systems, except OEM-‘2502’, Miu-‘2502’ and OEM-‘SF11’, which have a biological efficiency and competitiveness when compared to the single
negative MAI (Table 3), resulting in economic loss during the first year systems, ensuring lower seasonality and greater diversity of forage
of the system. production. The analyses also showed that the forage cactus and sor­
In the configurations with a negative MAI (OEM-‘2502’, OEM-‘SF11’ ghum intercropped system is more profitable compared to the single
and Miu-‘2502’), this was linked to the low sorghum production, a result simple system of forage cactus. This result suggests further research to
of interspecific competition, which promoted unsatisfactory results be carried out with different crop densities, evaluating this configura­
during the first year of production. According to Vlachostergios et al. tion under different systems of water management, calculating the water
(2018), the MAI is an aid in understanding the revenues generated by demand, the cutting intensity of the forage cactus, the maximum
intercropped systems; however, it is common for some configurations to regrowth of sorghum in the intercropping, the levels of fertilisation and
result in a negative MAI. Lima et al. (2018b) cite that in many cases, modelling of the yield gap estimates and adaptation to different climate-
irrigated production systems of intercropped cactus and sorghum change scenarios.
become profitable only from the second year of forage cactus

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A.M.R.F. Jardim et al. Journal of Arid Environments 188 (2021) 104464

CRediT authorship contribution statement Hernández-Urbiola, M.I., Pérez-Torrero, E., Rodríguez-García, M.E., Hernández-
Urbiola, M.I., Pérez-Torrero, E., Rodríguez-García, M.E., 2011. Chemical analysis of
nutritional content of prickly pads (Opuntia ficus indica) at varied ages in an organic
Alexandre Maniçoba da Rosa Ferraz Jardim: Formal analysis, harvest. Int. J. Environ. Res. Publ. Health 8, 1287–1295. https://doi.org/10.3390/
Investigation, Writing - original draft. Thieres George Freire da Silva: ijerph8051287.
Conceptualization, Methodology, Writing - original draft, Supervision, Jha, S., Srivastava, R., 2018. Impact of drought on vegetation carbon storage in arid and
semi-arid regions. Remote Sens. Appl. Soc. Environ. 11, 22–29. https://doi.org/
Project administration, Funding acquisition. Luciana Sandra Bastos de 10.1016/j.rsase.2018.04.013.
Souza: Conceptualization, Methodology. George do Nascimento Kimura, E., Fransen, S.C., Collins, H.P., Stanton, B.J., Himes, A., Smith, J., Guy, S.O.,
Araújo Júnior: Formal analysis, Investigation. Hygor Kristoph Muniz Johnston, W.J., 2018. Effect of intercropping hybrid poplar and switchgrass on
biomass yield, forage quality, and land use efficiency for bioenergy production.
Nunes Alves: Formal analysis, Investigation. Marcondes de Sá Souza: Biomass Bioenergy 111, 31–38. https://doi.org/10.1016/j.biombioe.2018.01.011.
Formal analysis, Investigation. Gherman Garcia Leal de Araújo: Lima, L.R., Silva, T.G.F., Jardim, A.M.R.F., Souza, C.A.A., Queiroz, M.G., Tabosa, J.N.,
Conceptualization, Methodology, Resources, Funding acquisition. 2018a. Growth, water use and efficiency of forage cactus sorghum intercropping
under different water depths. Rev. Bras. Eng. Agrícola Ambient. 22, 113–118.
Magna Soelma Beserra de Moura: Conceptualization, Methodology, https://doi.org/10.1590/1807-1929/agriambi.v22n2p113-118.
Funding acquisition. Lima, L.R., Silva, T.G.F., Pereira, P.C., Morais, J.E.F., Assis, M.C.S., 2018b. Productive
economic benefit of forage cactus-sorghum intercrop systems irrigated with saline
water. Rev. Caatinga 31, 191–201. https://doi.org/10.1590/1983-
21252018v31n122rc.
Declaration of competing interest
Liu, X., Rahman, T., Song, C., Yang, F., Su, B., Cui, L., Bu, W., Yang, W., 2018.
Relationships among light distribution, radiation use efficiency and land equivalent
The authors declare that they have no known competing financial ratio in maize-soybean strip intercropping. Field Crop. Res. 224, 91–101. https://
interests or personal relationships that could have appeared to influence doi.org/10.1016/j.fcr.2018.05.010.
Mbarki, S., Cerdà, A., Zivcakas, M., Brestic, M., Rabhi, M., Mezni, M., Jedidi, N.,
the work reported in this paper. Abdelly, C., Pascual, J.A., 2018. Alfalfa crops amended with MSW compost can
compensate the effect of salty water irrigation depending on the soil texture. Process
Saf. Environ. Protect. 115, 8–16. https://doi.org/10.1016/j.psep.2017.09.001.
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