Relay Intercropping Research Articles

Planting Density and Time of White Lupine Relay Intercropping in TEFF (Eragrostis tef (Zucc.) Trotter) in Burie District, North Western Ethiopia

The experiment was conducted during 2015/16 main rainy season in Burie District, North Western Ethiopia with an objective of evaluating the potential of lupine relay intercropping with different density and rely time of lupine in teff. Factorial combinations of 3 relay intercropping time(after 4,6,and 8 weeks of teff sowing),2 inter-row spacing (40cm and 60cm) and 2 intra-row spacing of lupine (20cm and 30cm), totally 12 treatment combinations, and 2 sole cropping of teff and lupine were laid out in randomized complete block design at three replications. The collected was subjected to ANOVA using SAS (9.2) software. LER and MAI were calculated to evaluate the yield advantage of lupine relay intercropping for which the highest LER (1.62) and MAI (20402.42 birr/ha) was obtained from early intercropping accompanied with narrower intra and inter row spacing of lupine. Keywords: rely intercropping, LER, M AI DOI: 10.7176/JBAH/11-19-01 Publication date: October 31 st 2021

Annual intercropping suppresses weeds: A meta-analysis

Intercropping has been advocated as an environmentally benign method to suppress weeds in agriculture. However, it is not evident from the literature what size of weed suppressive effect is achieved on average by intercropping, and how species choice and crop management affect this effect. We conducted a global meta-analysis of published data to quantify the effect of intercropping on weed biomass in annual arable intercrops grown for their final product. We searched the literature to identify all papers reporting usable experimental data and extracted 339 data records from 39 publications containing data from 76 independent experiments. Two metrics of weed suppression were defined to assess the weed suppressive effect of intercropping: the ratio of observed weed biomass in an intercrop to weed biomass in the less weed suppressive sole crop (Rweak), and the ratio of weed biomass in the intercrop to weed biomass in the more weed suppressive sole crop (Rstrong). On average, weed biomass in the intercrop was substantially and significantly (58%) lower (Rweak = 0.42) than in the less suppressive sole crop. No significant difference was found between weed biomass in the intercrop and weed biomass in the more weed suppressive sole crop, even though weed biomass tended to be slightly larger in the intercrop than in the more weed suppressive sole crop (Rstrong = 1.08). Findings were consistent across different groups of species combinations, such as maize/legume and small-grain cereal/legume intercrops. Intercrops with an additive design had stronger weed suppression than intercrops with a replacement design. In the latter, a mixed arrangement gave stronger weed suppression than a row design, while spatial arrangement did not affect weed suppressive ability in additive designs. No significant effects on weed biomass were found of simultaneous vs. relay intercropping, and of nitrogen fertilizer input. The Rweak decreased significantly with the land equivalent ratio in additive intercrops but not in replacement intercrops, while Rstrong was unrelated to LER in both designs. The results confirm that intercropping is generally a useful approach for suppressing weeds in annual crop cultivation. Further work is needed to disentangle the contributions of species density, species traits and mixing ratio to weed suppression in intercropping.

Gravity Reduced Nitrogen Uptake via the Regulation of Brace Unilateral Root Growth in Maize Intercropping

Water, nutrient, light, and interspecific facilitation regulation of soil physicochemical properties and root morphology modulate nitrogen (N) uptake in cereal and legume intercropping systems. However, maize root morphological plasticity and N uptake capability response to gravity in the intercropping system remains to be determined. In this study, maize was grown under 20 cm (I20), 40 cm (I40), and 60 cm (I60) of narrow row spacing in an intercropping system (maize–soybean strip relay intercropping) and equal row spacing of monoculture (M) in a 2-year field experiment. As a supplementary for the field experiment, maize root barrier and plant inclination experiments were conducted. Plant inclination, brace root morphology, N uptake, indole-3-acetic acid (IAA) level, IAA synthesis genes, and grain yield were assessed. The result showed that the plant inclination increased with decreasing narrow row spacing in intercropping system. Also, the brace unilateral root growth ratio (BURR) increased with increasing plant inclination in intercropping treatments. The plant inclination experiment showed the BURR achieved 94% after inclination at 45°. BURR tended to be positively correlated (p = 0.00) with plant inclination. Thus, gravity (plant inclination) causes brace unilateral root growth. The IAA concentration of stem nodes in the wide row increased with increasing plant inclination, while the IAA accumulation decreased in the narrow row. The Zmvt2 and ZM2G141383 genes (associated with IAA biosynthesis) were highly expressed in a wide row. There was a strong correlation (p = 0.03) between the IAA concentration of wide row and the BURR. Therefore, gravity regulates the IAA level, which affects BURR. In addition, the brace root number, volume, and surface area were decreased when BURR was increased. Subsequently, the leaf N, cob N, and kernel N accumulation were reduced. These organs N and grain yield in I60 were not significantly different as compared to the control treatment. The excessive brace unilateral root growth was not conducive to N uptake and increased yield. Our results suggest that gravity is essential in regulating root morphology plasticity by regulating IAA levels and decreasing N uptake capacity. Furthermore, these results indicate that plant inclination can regulate root phenotype and N uptake of maize and by adjusting the spacing of narrow maize row, we can improve the N uptake and yield of the maize–soybean strip relay-intercropping system.

Evaluation of Biochemical Traits and Dry Matter Remobilization of Barley (Hordeum vulgare L.) in Relay Intercropping with Chickpea (Cicer arietinum L.) under Deficit Water Stress Conditions

Evaluation of Biochemical Traits and Dry Matter Remobilization of Barley (Hordeum vulgare L.) in Relay Intercropping with Chickpea (Cicer arietinum L.) under Deficit Water Stress Conditions

Economical Efficacy of Weed Management Options in Groundnut + Pigeonpea Relay Intercropping System

Aims: To evaluate the effect of different weed management options on the economics in groundnut + pigeonpea relay intercropping on medium black clayey soils of Junagadh .
 Study Design: Field experiment was conducted at Junagadh during kharif 2019-20 and 2020-21 in Randomized Block Design with three replications to evaluate the effect of different weed management options on the economics in groundnut + pigeonpea relay intercropping on medium black clayey soils. The treatments comprised of: pendimethalin 0.9 kg ha-1 as PE fb interculturing and hand weeding at 45 DAS, pendimethalin 0.45 kg ha-1 + oxyfluorfen 0.09 kg ha-1 as PE fb interculturing and hand weeding at 45 DAS), interculturing and hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as POE, interculturing and hand weeding at 15 DAS fb quizalofop p ethyl 40 g ha-1 at 45 DAS as POE, interculturing and hand weeding at 15 DAS fb propaquizafop 70 g ha-1 at 45 DAS as POE, pendimethalin 0.9 kg ha-1 as PE fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as POE, pendimethalin 0.9 kg ha-1 as PE fb quizalofop p ethyl 40 g ha-1 at 45 DAS as POE, pendimethalin 0.9 kg ha-1 as PE fb propaquizafop 70 g ha-1 at 45 DAS as POE (T8), weed free, and unweeded control (T10).
 Place and duration of the study: Instructional Farm, Department of Agronomy, College of Agriculture, Junagadh Agricultural University, Junagadh during kharif seasons of 2019-20 and 2020-21.
 Methodology: on the basis of prevailing local charges. The gross realization in terms of rupees per hectare. A net return of each treatment was calculated by deducting the total cost of cultivation from the gross returns.
 Result: Significantly higher amount of gross returns were recorded with the weed free treatment (T9), which was closely followed by interculturing and hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as PoE (T3). Statistically higher net returns and higher net returns and B:C ratio were registered with interculture and hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as PoE (T3).

Transcriptional Responses of Fusarium graminearum Interacted with Soybean to Cause Root Rot.

Fusarium graminearum is the most devastating pathogen of Fusarium head blight of cereals, stalk and ear of maize, and it has recently become a potential threat for soybean as maize-soybean strip relay intercropping is widely practiced in China. To elucidate the pathogenesis mechanism of F. graminearum on intercropped soybean which causes root rot, transcriptional profiling of F. graminearum at 12, 24, and 48 h post-inoculation (hpi) on soybean hypocotyl tissues was conducted. In total, 2313 differentially expressed genes (DEGs) of F. graminearum were annotated by both KEGG pathway and Gene Ontology (GO) analysis. Among them, 128 DEGs were commonly expressed at three inoculation time points while the maximum DEGs were induced at 24 hpi. In addition, DEGs were also rich in carbon metabolism, ribosome and peroxisome pathways which might contribute to carbon source utilization, sexual reproduction, virulence and survival of F. graminearum when infected on soybean. Hence, this study will provide some basis for the deep understanding the pathogenesis mechanism of F. graminearum on different hosts and its effective control in maize-soybean strip relay intercropping systems.

Compact maize canopy improves radiation use efficiency and grain yield of maize/soybean relay intercropping system.

Maize/soybean relay intercropping system is a popular cultivation system to obtain high yields of both crops with reduced inputs. However, shading by maize decreases the photosynthetically active radiation, reaching the soybean canopy in maize/soybean relay intercropping system, which reduces soybean radiation use efficiency and competitiveness. Here, we reveal that compact maize in maize/soybean relay intercropping system enhances the photosynthetically active radiation transmittance, leaf area index, dry matter production, radiation use efficiency, and competitiveness of soybean and compensates the slight maize yield loss by substantially increasing soybean yield. In this experiment, soybean was relay intercropped with different maize types (SI, spreading maize; SII, semi-compact maize; and SIII, compact maize) in maize/soybean relay intercropping system, and all the relay intercropping treatments were compared with sole cropping systems of soybean and maize. Results revealed that SIII significantly enhanced the soybean radiation use efficiency (by 77%, from 0.35 g MJ-1 in SI to 0.61 g MJ-1 in SIII) and total radiation use efficiency (soybean radiation use efficiency + maize radiation use efficiency) of maize/soybean relay intercropping system (by 5%, from 3.53 g MJ-1 in SI to 3.73 g MJ-1 in SIII). Similarly, SIII improved the competitiveness (by 62%, from 0.58% in SI to 0.94% in SIII) of soybean but reduced the competitiveness (by 38%, from 1.73% in SI to 1.07% in SIII) of maize, which, in turn, considerably increased soybean yield by maintaining maize yield. On average, over the 2 years, in SIII, relay-intercropped soybean produced 89% of the sole soybean yield, and relay-intercropped maize produced 95% of the sole maize yield. Besides, treatment SIII achieved the mean highest land equivalent ratio value of 1.84 in both years. Thus, enhanced radiation use efficiency of soybean, especially during the co-growth period, was the primary factor responsible for the high productivity of the maize/soybean relay intercropping system.

Radiation Dynamics on Crop Productivity in Different Cropping Systems

Global demand for food has always been on the increase due to the increase of the population in this world. Intercropping is one of the alternatives of agronomic practices that is widely practiced in ensuring food security and enhancing yield stability. Strip, mixed, and relay intercropping can be practiced to increase crop production. In addition to achieving a successful intercropping system, factors such as suitable crops, time of sowing, maturity of the crop, and plant density need to be considered before and during planting. Besides, practiced intercropping becomes a useful cropping system to increase efficient resource utilization, enhance biodiversity, promote soil health, enhance soil fertility, erosion control, yield advantage, weed, pest, and disease control, insurance against crop failure, ecosystem and modification of microclimate, market instability, and increase farmers income. Crop productivity in any types of cropping system implemented relies primarily on the interception of photosynthetically active radiation (PAR) of crop canopy and conversion of intercepted radiation into biomass or known as radiation use efficiency (RUE). Both PAR and RUE are important measurements that have significant roles in crop growth and development in which the accessibility of these radiation dynamics is connected with the leaf area index and crop canopy characteristics in maximizing yield as well as total productivity of the crop component in intercropping systems.

Effect of mono‐, relay‐, and double‐crop systems on yield and profitability

AbstractDiversification and intensification of cropping systems are of interest due to the potential for increased farm income. However, yield and profitability of multi‐crop systems need to be understood, especially in northern environments where the growing season is short. The objective of this study was to evaluate yield and profitability of monocrop (MC), relay‐intercrop (RI), and double‐crop (DC) systems. A 3‐yr field study was conducted in northwest Ohio with nine cropping systems, including winter wheat (Triticum aestivum L.), red clover (Trifolium pretense L.), soybean (Glycine max L.), and oat (Avena sativa L.) grown in MC, RI, and DC systems. System yield was calculated by summing crop yield within a cropping year. Cropping system profitability was estimated by subtracting costs that varied across treatments from gross revenue. Winter wheat + RI red clover had the highest system yield (11.1–11.4 Mg ha−1 yr−1). However, profit was the greatest with wheat planted in wide row (38 cm row width) + RI red clover cropping system ($1,252 ha−1 yr−1) followed by wheat planted in narrow row (19 cm row width) + RI red clover ($1,140 ha−1 yr−1) and MC soybean ($919 ha−1 yr−1). This suggests that producers interested in diversifying their cropping systems may increase profitability with a winter wheat + RI red clover system, provided there is a market for red clover forage. However, if producers do not have a market for red clover, the MC soybean system would offer greatest profitability and reduce workload compared with a multi‐crop system.

Estimating the contribution of plant traits to light partitioning in simultaneous maize/soybean intercropping.

Spatial configuration and plant phenotypic plasticity contribute to increased light capture in relay intercropping, but there is little information on whether these factors also increase light capture in simultaneous intercropping. We developed and validated a three-dimensional functional-structural plant model to simulate light capture in maize and soybean sole crops and intercrop scenarios, using species traits observed in sole crops and intercrops. The intercrop maize phenotype had 2% greater light capture than the sole crop phenotype in a pure stand. The soybean intercrop phenotype had 5-10% lower light capture than the sole crop phenotype in a pure stand. The intercrop configuration increased the light capture of maize by 29% and reduced the light capture of soybean by 42%, compared with the light capture expected from sole crops. However, intercrop configuration only marginally affected total light capture by the intercrop system (+1%). Testing of individual soybean plant traits revealed that plasticity in leaf dimensions was the main reason for differences in light capture by soybean in simulated sole crops and intercrops. The results of this study illustrate a major shift of light capture from shorter species (soybean) to the taller component (maize) in a simultaneous strip intercrop. Plastic plant traits modulate this overall effect, but only marginally.

Competition Effects and Productivity in Oat–Forage Legume Relay Intercropping Systems under Organic Farming Conditions

Cereal-legume intercropping is important in many low-input agricultural systems. Interactions between combinations of different plant species vary widely. Field experiments were conducted to determine yield formation regularities and plant competition effects of oat (Avena sativa L.)–black medick (Medicago lupulina L.), oat–white clover (Trifolium repens L.), and oat–Egyptian clover (T. alexandrinum L.) under organic farming conditions. Oats and forage legumes were grown in mono- and intercrops. Aboveground dry matter (DM) measured at flowering, development of fruit and ripened grain, productivity indicators, oat grain yield and nutrient content were established. The results showed that oats dominated in the intercropping systems. Oat competitive performance (CPo), which is characterized by forage legumes aboveground mass reduction compared to monocrops, were 91.4–98.9. As the oats ripened, its competitiveness tendency to declined. In oat–forage legume intercropping systems, the mass of weeds was significantly lower compared to the legume monocrops. Oats and forage legumes competed for P, but N and K accumulation in biomass was not significantly affected. We concluded that, in relay intercrop, under favourable conditions, the forage legumes easily adapted to the growth rhythm and intensity of oats and does not adverse effect on their grain yield.

Effects of nitrogen and maize plant density on forage yield and nitrogen uptake in an alfalfa–silage maize relay intercropping system in the North China Plain

Sustainable production of high-yielding and high-quality forages such as alfalfa (Medicago sativa L.) is critically important for fast-growing animal husbandry regions such as the North China Plain (NCP). Alfalfa production in this region is limited during the hot-rainy summer period from July–September, but these conditions may allow the production of intercropped silage maize (Zea mays L.) following spring harvests of alfalfa to boost the overall forage production. In this study, an alfalfa–silage maize (AM) relay intercropping system was evaluated in a field experiment from 2017 to 2019 to assess the impact of maize nitrogen (N) fertilization rates of 0, 60, 120, and 180 kg N ha–1 and maize plant densities of 30,000, 45,000, and 60,000 plants ha–1 on the forage yield and N uptake. The AM system was compared with alfalfa monocropping (AA) and silage maize monocropping (MM) controls. The 3-yr average land equivalent ratio (LER) and land equivalent ratio for nitrogen yield (LERN) of AM ranged from 1.05 to 1.37 relative to AA and MM, indicating that intercropping was advantageous for improving the overall forage production and N utilization. Intercropping reduced the maize yield by 23–30 % and the maize N yield by 26–35 % compared with the monocultured maize across 3 years. Increasing N fertilization and maize plant density often enhanced the maize yield and N uptake in the AM system. The alfalfa stand density in AM was negatively affected by the increased maize plant density and was 30–55 % lower than that in AA. Spring forage production of alfalfa in the AM and AA systems was similar in most cases, but yields in the AM system were reduced in 2018 and 2019 when maize was grown with the highest N rate (180 kg N ha–1) and the highest plant density (60,000 plants ha–1). On the basis of the system yield, N yield, and LER, the AM system with a maize plant density of 45,000 plants ha–1 fertilized at 120 kg N ha–1 was the most advantageous and could be recommended as an alternative cropping system in the NCP to increase forage yields with a relatively low input of N.

Effect of NPK Fertilization Strategies on Growth, Yield, Nutrient Use Efficiency and Economic Benefits of Relay Intercropped Wheat in Cotton

Effect of NPK Fertilization Strategies on Growth, Yield, Nutrient Use Efficiency and Economic Benefits of Relay Intercropped Wheat in Cotton

Agronomic practice and performance of organic farms in different environmental conditions in Lithuania

ABSTRACT The aim of this study was to determine the impact of plant diversity and agricultural practices on crop productivity on organically managed mixed and arable farms under different natural conditions. Organic farms in three regions of Lithuania, differing in landscape homogeneity, soil quality and farming intensity, were evaluated. The results showed that there were arable farms in all regions, regardless of the soil fertility and the largest number of mixed farms was in Western Lithuania. On the mixed farms, perennial forage grass prevailed in the cropping structure, whilst cereals were the main crops on the arable farms with grain legumes grown to restore soil fertility. Short crop rotations and a low diversity of crops predominated. The average grain yields of the winter and spring cereals and the grain legumes were 3283, 2539 and 2917 kg ha−1, respectively. The productivity of the cereals and grain legumes depended on the region, and for spring cereals also on the interaction between region and farm type. Significantly lower yields of winter and spring cereals were recorded on the arable farms in East Lithuania, compared with the arable farms in the other regions. For organic farming systems, especially for arable farms, it was recommended to explore and implement the use of mixed or strip relay intercrops and multicultural cropping systems or blocks, thereby increasing spatial and temporal crop diversity and using plants that provide ecological services (e.g. legume swards). Reduced tillage practice to increase humification of plant residues in the soil was also recommended.

Strip-width determines competitive strengths and grain yields of intercrop species in relay intercropping system

Maize/soybean relay intercropping system (MSR) is a popular cultivation method to obtain high yields of both crops with reduced inputs. However, in MSR, the effects of different strip widths on competitive strengths and grain yields of intercrop species are still unclear. Therefore, in a two-year field experiment, soybean was relay-intercropped with maize in three different strip-width arrangements (narrow-strips, 180 cm; medium-strips, 200 cm; and wide-strips, 220 cm), and all intercropping results were compared with sole maize (SM) and sole soybean (SS). Results showed that the optimum strip-width for obtaining high grain yields of maize and soybean was 200 cm (medium-strips), which improved the competitive-ability of soybean by maintaining the competitive-ability of maize in MSR. On average, maize and soybean produced 98% and 77% of SM and SS yield, respectively, in medium-strips. The improved grain yields of intercrop species in medium-strips increased the total grain yield of MSR by 15% and land equivalent ratio by 22%, which enhanced the net-income of medium-strips (by 99%, from 620 US $ ha−1 in wide-strips to 1233 US $ ha−1 in medium-strips). Overall, these findings imply that following the optimum strip-width in MSR, i. e., strip-width of 200 cm, grain yields, and competitive interactions of intercrop species can be improved.

Agroecology in North African irrigated plains? Mapping promising practices and characterizing farmers’ underlying logics

In the irrigated plains of North Africa, the sustainability of productive resources is subject to multiple threats linked to the prevailing productivist model of irrigated agriculture. These threats, such as soil degradation and unequal access to resources, markets, and information, prompt farmers to mobilize depleting natural resources, including soil and water, in an often environmentally unsustainable way. In order to sustain their farming systems and consequent incomes, farmers sometimes update their strategies by setting-up alternative farming practices. This study aims at mapping and analyzing such existing local farming practices with agroecological potentials. Our approach is based on direct observations combined with 150 interviews of farmers in three major irrigated plains in North Africa, namely, the Merguellil, Upper Cheliff, and Saiss plains, respectively, in Tunisia, Algeria, and Morocco. This study shows that a wide range of alternative practices with agroecological potential are emerging (or exist) locally, against the flow of the dominant agricultural model which is rather in favor of intensive practices. The most common practices are developed to improve soil fertility management (production of manure tea, integration of legumes in crop successions), increase per surface agricultural production (relay intercropping, intercropping, agroforestry), or provide multiple ecosystem services (diversification, livestock integration). These practices are jointly used, mostly to (i) increase land-use efficiency, and hence face land fragmentation; (ii) diversify their cropping strategy, and spread out market-related risks; and (iii) reduce expensive production costs related to irrigation and chemical fertilization. The gradient of adoption observed according to national contexts suggests a strong influence of contrasting socio-political and historical factors at the regional to national levels. The analysis of logics in implementing such practices by farmers indicates that economic reasons take precedence over environmental concerns. As such, these practices can be seen as (i) an access to low-cost strategies for small farmers or (ii) a pathway to international markets for agribusiness farmers. Taming the extensive local knowledge related to ecological intensification strategies, as identified in this study, can help to pave the way for a more sustainable agriculture, in this intensively cultivated region of the world.

Farm size and smallholders’ use of intercropping in Northwest China

Intercropping, i.e. the cultivation of crop species mixtures, can potentially reduce pressure on land resources by generating higher yields through exploitation of complementarities between crop species. Although intercropping is practiced on a non-negligible proportion of China’s arable land, little is known about the factors that influence farmers’ decisions to use intercropping. In this study we develop a theoretical framework that distinguishes exogenous factors from endogenous factors in farmers’ activity choices in general and the use of intercropping in particular. We apply this framework in an empirical analysis of socio-economic factors affecting the use of traditional and novel relay intercropping systems, with a special focus on the impact of farm size, using primary data collected among 299 farmers in Gaotai County, northwest China. We find that large farms do no not plant more land with the traditional wheat/maize intercrop as compared to small farms, while land planted with the two novel intercrops is significantly larger on large farms. Availability of machinery has no negative effect on the area under intercropping, and has a significant positive effect on the use of one novel intercrop type. Our results confirm that risk considerations do not play a role in relay intercropping use decisions of Chinese farmers. We conclude that positive yield and natural resource effects of intercropping can still be realized if the ongoing farm scale enlargement policy is combined with a policy promoting novel intercropping types, particularly those types that can make use of already available machinery.

Recovery growth and water use of intercropped maize following wheat harvest in wheat/maize relay strip intercropping

Recovery growth is common in relay intercropping systems and is a feasible practice for increasing total productivity of these systems. Previous studies have focused on the description of recovery growth, but the physiological changes and water use assessment during the recovery growth period remain unclear. A field experiment was conducted in Yangling, Shaanxi province, China during the 2014–2015 and 2015–2016 growing seasons to investigate maize physiological characteristics, root morphology, and transpiration efficiency during the recovery growth period. Three cropping systems (sole wheat, sole maize, wheat/maize intercropping) and two water treatments (supplementary irrigation and rainfed) were evaluated. Wheat was more competitive than maize during the intercropping co-growth period. During the co-growth period, the aboveground dry matter of intercropped wheat was 20.1 %–37.8 % greater than for sole wheat and water consumption was 14.9 %–15.9 % greater than for sole wheat. However, plant height and aboveground dry matter of intercropped maize during the co-growth period were less than for sole maize. Total root length of intercropped maize under supplementary irrigation initially exhibited rapid growth after wheat harvest, especially in the border rows. Subsequently, aboveground dry matter showed recovery growth, with final aboveground dry matter (2-yr average) of border rows and inner rows being 1 % and 4.5 %, respectively, greater than sole maize dry matter. Relative chlorophyll content and photosynthetic rate of intercropped maize were 4.3 %–19.2 % and 1.7 %–15.9 %, respectively, higher than observed for sole maize under irrigated conditions. Transpiration efficiency of intercropped maize during the recovery period was 10 % and 50.9 % greater than observed for sole maize under irrigated conditions in 2015 and 2016, respectively. Some recovery growth did occur under rainfed conditions, but it did not completely compensate for the growth reduction that occurred during the co-growth period. Supplementary irrigation promoted recovery growth of intercropped maize. Recovery growth improves intercropped maize grain yield and efficient use of water resources.

Optimized planting time and co‐growth duration reduce the yield difference between intercropped and sole soybean by enhancing soybean resilience toward size‐asymmetric competition

AbstractSelecting optimum planting time (PT) in maize–soybean relay intercropping system (MSRI) is important to obtain higher intercrop yields because planting time decides the co‐growth duration and competitive ability of intercrop species in MSRI. However, little is known on how planting time (co‐growth duration) changes the interspecific interaction resulting in a seed‐yield difference between intercropping and sole cropping system. Therefore, this field study was initiated to determine the effects of changing co‐growth duration on competitive interactions, growth, and yield of intercrop species under MSRI. The sole soybean and relay‐cropped soybean were planted on PT1 (15–20 May, 90 days of co‐growth duration in MSRI); PT2 (5–10 June, 70 days of co‐growth duration in MSRI); and PT3 (25–30 June, 50 days of co‐growth duration in MSRI) to generate different size‐asymmetric competition between component crops in MSRI. Results showed that sole soybean produced the mean highest (2.93 t/ha) seed yield under PT2, and the mean lowest (2.51 t/ha) seed yield under PT1. However, in MSRI, PT3 increased the soybean yield by 29.1% and 13.3% compared to PT1 and PT2, respectively. The PT3 also increased the maize yield by 7.4% and 2.9% than PT1 and PT2, respectively, and it reduced the yield differences of maize and soybean between relay intercropping and sole cropping systems. In MSRI, decreased co‐growth duration promoted the soybean plants to achieve the higher crop growth rate, and biomass accumulation, which ultimately improved the soybean resilience toward size‐asymmetric competition created by maize plants. Furthermore, as compared to PT1 and PT2, planting time PT3 significantly increased the competitive ratio (by 10.1% and 17.3%, respectively) of soybean plants. Overall, the PT3 achieved the average highest land equivalent ratio of 1.63, which is significantly higher than PT1 (by 12.3%) and PT2 (by 10.6%). In conclusion, this study implied that in MSRI, the determination of proper soybean planting time (co‐growth duration) is one of the most critical factors to reduce the competition between the intercrops and to obtain higher crop yields.

Maize relay intercropping with fodder crops for small-scale farmers in central Brazil

AbstractRelay intercropping of maize with fodder crops is a promising option for sustainable intensification of dairy small-scale farms in the Cerrado of Brazil. Twenty-six intercropping trials were conducted on farmers’ fields with the following experimental treatments: sole maize crop cropping (MS), maize-Brachiaria intercropping (MB) and maize-pigeon pea intercropping (MP). The trials were managed by the farmers, i.e. choice of conventional tillage (CT) versus no-tillage (NT), sowing dates, fertilization and weed control. Maize grain yield varied strongly across the farmer fields, from 100 to 5900 kg ha−1 in the MS treatment, 500 to 6900 kg ha−1 in MP and 300 to 5500 kg ha−1 in MB. Intercropping did not significantly affect maize grain yields under NT, but yields were reduced under CT in one out of two seasons. Maize yields in the intercropped systems were also higher under NT than CT. Total biomass productivity was significantly higher in the maize-fodder than in the sole maize system. An increased interval between sowing of maize and fodder crop significantly reduced the fodder crop biomass. Relay intercropping, especially in combination with NT, is a promising option if crop calendars and fertilization are properly managed by farmers to reduce interspecific competition between the maize and fodder crop.