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Declining soil fertility and climate change have led to a reduction in potato yield and thus negatively affected the livelihood of communities that rely on the crop. A study was conducted in Nyandarua County, Kenya, for two seasons to evaluate the potential of potato-legume intercropping in enhancing N and P uptake and use efficiencies and on potato fresh tuber and equivalent yield (PEY). Potato equivalent yield compares system performance by converting the yield of legume crops into equivalent potato yield based on prevailing market prices. Treatments comprised two potato-legume intercrops: lima bean (Phaseolus lunatus L.) and lupin (Lupinus albus L.), and two inorganic fertilizers: Di-ammonium phosphate (18:46:0), composite NPK (17:17:17), and a no input control. Treatment combinations were as follows: (i) sole potato, (ii) potato-lima beans and (iii) potato-lupin intercrops. Fertilizers were applied to each of the three cropping systems separately. Higher N uptake was found in sole potato (73.5 kg ha−1), which was more than double that recorded in potato-lupin (35.9 kg ha−1) and 60% more than that recorded in potato-lima beans intercrop (46.8 kg ha−1). On the other hand, N use efficiency was higher in potato-lupin (240.6 kg PEY kg−1 N supply) and sole potato (238.6 kg PEY kg−1 N supply) and lowest in potato-lima beans (139.0 kg PEY kg−1 N supply). Intercropping resulted in a decrease in fresh tuber yield by more than 70% while the equivalent yield decreased by almost 15 Mg ha−1. The application of fertilizer did not enhance the recovery of the yield loss. The study establishes that the choice of companion legumes in intercropping can significantly influence nutrient uptake and use efficiency, and thus the yield of the potato crop. [ABSTRACT FROM AUTHOR]

Cereal/legume intercropping is becoming a popular production strategy for higher crop yields and net profits with reduced inputs and environmental impact. However, the effects of different spatial arrangements on the growth, grain yield, nitrogen uptake, and land-use advantage of wheat/soybean relay intercropping are still unclear, particularly under arid irrigated conditions. Therefore, in a three-year field study from 2018 to 2021, soybean was relay intercropped with wheat in different crop configurations (0.9 m, narrow strips; 1.8 m, medium strips; and 2.7 m, wide strips), and the results of intercropping systems were compared with their sole systems. Results revealed that intercrops with wide strips outperformed the narrow and medium strips, when the objective was to obtain higher total leaf area, dry matter, nitrogen uptake, and grain yield on a given land area due to reduced interspecific competition between intercrops. Specifically, at maturity, wide strips increased the dry matter accumulation (37% and 58%) and its distribution in roots (37% and 55%), straw (40% and 61%), and grains (30% and 46%) of wheat and soybean, respectively, compared to narrow strips. This enhanced dry matter in wide strips improved the soybean's competitive ability (by 17%) but reduced the wheat's competitive ability (by 12%) compared with narrow strips. Noticeably, all intercropping systems accumulated a significantly higher amount of nitrogen than sole systems, revealing that wheat/soybean relay intercropping requires fewer anthropogenic inputs (nitrogen) and exerts less pressure on the ecosystem than sole systems. Overall, in wide strips, intercropped wheat and soybean achieved 62% and 71% of sole wheat and soybean yield, respectively, which increased the greater total system yield (by 19%), total land equivalent ratio (by 24%), and net profit (by 34%) of wide strips compared to narrow strips. Our study, therefore, implies that the growth parameters, grain yields, nutrient accumulation, and land-use advantage of intercrop species could be improved with the proper spatial arrangement in cereal/legume intercropping systems. [ABSTRACT FROM AUTHOR]

Interrow spacing of intercrop species directly affects yield and competition indices such as land equivalent ratio of intercropping. The objectives of this research were to analyze (i) the maize and soybean yields under different spatial arrangements in maize-soybean relay strip intercropping (MSR) and (ii) the interspecies competition to provide a basis for optimization of rowspacing in MSR. The field trial was conducted in 2011 and 2012 at the Research Farm of the Sichuan Agricultural University in Ya'an to determine the impacts of various interrow planting distances on yield and competition indices in cereal (maize crop)-legume (soybean crop) relay strip intercropping. Three planting arrangements were utilized based on the distance between maize-maize, maize-soybean, and soybean-soybean as (T1) 50, 40, and 70 cm, (T2) 50, 50, and 50 cm, and (T3) 50, 60, and 30 cm, respectively, and comparison was made with the sole maize (SM) and sole soybean (SSB). Experimental results revealed that grain yield of maize crop was improved with enhancing row spaces between maize and soybean, while "low-high-low" trend was observed for soybean yield in T1, T2, and T3, respectively, in both years. Competitive ratio, aggressivity, and relative crowding coefficient were consistently greater for maize than soybean in all treatments. The highest LER (1.67) was reported in T2 treatment, which was 9% and 4% higher than in T1 and T3, respectively. Higher LER explains that both crops are facilitating each other in a positive way and increase the average net income of T2 as compared to T1 and T3. Enhancing distance between maize-soybean rows with reducing distance between soybean rows put pressure on soybean due to intraspecific competition. Combined results of competitive indices and economic analysis showed that intercrops performed at their maximum in treatment T2. Therefore, the maximum intercropping advantages can be achieved by changing the row spacing, which determines the competitive relationship and productivity of MSR. [ABSTRACT FROM AUTHOR]

This study examined the adaptation level of climate-smart agricultural (CSA) practices among the farmers and the factors influencing the adoption of CSA practices in the Fujian Province, China. In this study, questionnaire survey data was analyzed, and 600 respondents were randomly selected as sample through randomly sampling technique. Descriptive statistics, adoption level index (ALI), and binary logit model were used for data analyses. These results indicated a moderate adoption level of CSA practices in the Fujian Province. Use of improved varieties, conservation tillage, fallow cropping, new technology, and intercropping were prevalent CSA practices among the farmers in the study area. In addition, farmers were not very interested in using herbicides on their farmlands, and only 20% of the respondents used herbicides in the Fujian Province. Except for Nindge village in the Fujian Province, all other studied villages have adapted to using organic fertilizer (around 50% of total respondents). However, more than 60% of respondents have claimed they still use chemical weed/insect/disease control in their farmlands. Age and working experience of farmers were the most influencing factors affecting the increase in the adoption of CSA practices among the farmers, and to the results of the binary logit model, education was not significant. Landholding, loan access, and access to agricultural extensions and organizations considerably impacted the adoption level of CSA practices among the farmers in the Fujian Province. Finally, this study will be helpful to decision-makers to make appropriate decisions to minimize the impact of climate change on agriculture and improve the standard of human life and food security. [ABSTRACT FROM AUTHOR]

By exploiting the complementarities between intercrops, cereal/legume intercropping provides an opportunity to increase legume production with sustained cereal yield. However, little is known about how legume choice and spatial configurations affect the performance and economic viability of legume-based wheat intercropping, especially in arid-irrigated conditions. We conducted this study to investigate the complementarity of three different legumes (chickpea, soybean, and pea) with wheat and determine the appropriate strip width for intercrops. A three-year study (2021−2023) was conducted to evaluate the effects of legume choice and spatial configuration (narrow strips of 0.6 m (NS) and partially wide strips of 1.2 m (pWS) for each intercrop) on wheat/soybean, wheat/pea, and wheat/chickpea intercropping, and results were compared with their sole systems for dry matter, nitrogen (N) and phosphorus (P) uptake, yield, and economic returns. We also quantified the intensity of the net biodiversity effect (NE), complementarity effect (CE), and selection effect (SE) for yield, N (NE N , CE N , and SE N), and P (NE P , CE P , and SE P) gains of legume-based wheat intercropping systems. Our results show that intercrops achieved the highest dry matter, nutrient uptake, and grain yield with pWS compared to NS. The intercropped chickpea, soybean, and pea achieved 67–71%, 55–62%, and 62–70% of their sole system yield. The intercropped wheat with chickpea, soybean, and pea produced 66–69%, 57–62%, and 62–66% of sole wheat yield, respectively. Results also confirmed a positive NE with both NS and pWS, mainly due to the higher CE, which ranges from 37% to 104% of NE under all intercropping systems. The nutrient uptake gain with NS and pWS ranged from −3.4 kg ha−1 to 101.5 kg ha−1 (NE N) and − 0.2 kg ha−1 to 13.8 kg ha−1 (NE P). On average, maximum LER (1.36), NE (1012 kg ha−1), NE N (86 kg ha−1), and NE P (12 kg ha−1) were obtained with pWS in wheat/chickpea, followed by wheat/pea and wheat/soybean intercropping. Overall, wheat/pea intercropping with pWS generated the highest net profit (2014, 1533, and 1394 USD ha−1 in 2021, 2022, and 2023, respectively), which was primarily linked to the high market price of pea than chickpea and soybean. These results imply that legume choice and spatial configurations influenced complementary and facilitation interactions between intercrops, and wheat/chickpea and wheat/pea intercropping with pWS could be adopted as a productive cropping strategy for obtaining higher and diverse crop yields with reduced land and nutrients than the sole wheat system. [Display omitted] • The potential of legume-based wheat intercropping systems in arid-irrigated areas has not been fully explored. • The study aimed to identify a wheat/legume intercropping combination that can increase land productivity with reduced inputs. • Net biodiversity effect and its components helped us to understand the trade-offs and complementarities between intercrops. • Wheat/chickpea intercropping had the best complementarity compared to wheat/pea and wheat/soybean intercropping. • Legume-based wheat intercropping have significant growth potential to improve the net income of resource-poor farmers. [ABSTRACT FROM AUTHOR]

Sustainable increases in crop production require efficient use of resources, and intercropping can improve water use efficiency and land productivity at reduced inputs. Thus, in a three-year field experiment, the performance of maize/soybean strip intercropping system differing with maize plant density (6 maize plants m-2, low, D1; 8 maize plantsm-2,medium, D2; and 10 maize plantsm-2, high, D3) was evaluated in comparison with sole maize or soybean cropping system. Results revealed that among all intercropping treatments, D2 had a significantly higher total leaf area index (maize LAI + soybean LAI; 8.2), total dry matter production (maize dry matter + soybean dry matter; 361.5 g plant-1), and total grain yield (maize grain yield + soybean grain yield; 10122.5 kg ha-1) than D1 and D3, and also higher than sole maize (4.8, 338.7 g plant-1, and 9553.7 kg ha-1) and sole soybean (4.6, 64.8 g plant-1, and 1559.5 kg ha-1). The intercropped maize was more efficient in utilizing the radiation and water, with a radiation use efficiency of 3.5, 5.2, and 4.3 g MJ-1 and water use efficiency of 14.3, 16.2, and 13.3 kg ha-1mm-1, while that of intercropped soybean was 2.5, 2.1, and 1.8 g MJ-1 and 2.1, 1.9, and 1.5 kg ha-1 mm-1 in D1, D2, and D3, respectively. In intercropping, the land and water equivalent ratios ranged from 1.22 to 1.55, demonstrating that it is a sustainable strategy to improve land and water use efficiencies; this maximization is likely associated with the species complementarities for radiation, water, and land in time and space, which resulted in part from competition avoidance responses that maximize the economic profit (e. g., 1300 US $ ha-1 in D2) over solemaize (798 US $ ha-1) or sole soybean (703 US $ ha-1). Overall, these results indicate that optimizing strip intercropping systems can save 20-50% of water and land, especially under the present scenario of limited resources and climate change. However, further research is required to fully understand the resource capture mechanisms of intercrops in intercropping. [ABSTRACT FROM AUTHOR]

Intercropping Moldavian balm with mung bean is an ecological approach for improving resource productivity. A field experiment was conducted over two growing seasons (2018 and 2019) to determine the effect of fertilizer application on yield and essential oil (EO) productivity of Moldavian balm intercropped with mung bean. The experiment had a two‐factor randomized complete block design (RCBD) with three replicates. The first factor comprised of five cropping patterns: Moldavian balm sole crop (MBs), mung bean sole crop (MGs), one row each of Moldavian balm +mung bean (1MB:1MG), two rows each of Moldavian balm +mung bean (2MB:2MG), and three rows of Moldavian balm +two rows of mung bean (3MB:2MG). The second factor comprised four fertilizer sources: no fertilizer application (C, control), 100% chemical fertilizer (NPK), 50% chemical fertilizer +100% bacterial fertilizer (NPK+BF), and 100% bacterial fertilizer +100% mycorrhizal fungi (BF+MF). The sole crop fertilized with NPK+BF produced the highest seed yields for MG (1189 kg/ha) and MB (7027 kg/ha), while 3MB:2MG fertilized with NPK+BF had the highest nutrient contents. Moldavian balm produced the highest EO content and yield in 2MB:2MG fertilized with NPK+BF. The EO of MB mainly comprised geranyl acetate (30–39%), geranial (20–31%), neral (18–24%), and geraniol (3–8%). In addition, the 3MB:2MG intercropping treatment fertilized with NPK+BF had the highest land equivalent ratio (LER = 1.35). We recommend an intercropping ratio of 2MB:2MG fertilized with NPK+BF is recommended as an alternative and eco‐friendly strategy for farmers to improve EO quantity and quality. [ABSTRACT FROM AUTHOR]

This study evaluates the effects of intercropping patterns, plant growth‐promoting rhizobacteria and arbuscular mycorrhizal fungi (AMF) on seed yield and yield components of black cumin (Nigella sativa L.) and fenugreek (Trigonella foenum‐graecum L.), as well as the essential oil and fatty acid profile of black cumin. A two‐year two‐factorial field experiment was conducted in 2015 and 2016 to investigate intercropping of black cumin and fenugreek in five ratios and biofertilizer application as AMF and bacteria. Intercropping reveals higher concentrations of nitrogen and phosphorus compared with monocropping, whereas monocropping inoculated with bacteria shows the highest seed yield of both fenugreek (151 g m−2) and black cumin (148 g m−2). Regarding the quality of black cumin, the combination of a black cumin:fenugreek‐intercropping pattern of 66:34 with bacteria fertilization is most promising, as it shows i) the maximum essential oil content, oil yield, and fixed oil content, ii) the highest contents of thymol and p‐cymene, iii) the highest content of linoleic acid, and iv) the maximum land equivalent ratio. Conclusively, bacteria fertilization and black cumin:fenugreek‐intercropping pattern of 66:34 helps improving essential oil, fixed oil quality, and quantity of black cumin, thus creating a more sustainable cultivation system for black cumin and fenugreek. [ABSTRACT FROM AUTHOR]

Global pressures on the land require a shift to efficient land uses that meet economic and dietary demands and are within planetary boundaries. Important anthropogenic emissions from sugarcane fields around the world and sluggish consumption of resources during the initial canopy growth of this crop provide a chance to leverage the potential of intercropping to make better use of the available resources. We conducted this study to test whether intercropped soybean with appropriate spatial arrangements have the potential to yield near to its sole system by taking up the under-utilized land and nutrients during the initial 3–4 months of the sugarcane growth. A three-year field study (2020–2022) was conducted to analyze the effects of different spatial arrangements on sugarcane/soybean intercropping (two soybean rows intercropped between every two sugarcane rows; 2S2Sc, and three soybean rows intercropped between every two sugarcane rows; 3S2Sc) and compare them with corresponding sole systems in terms of crop growth, nitrogen (N) and phosphorus (P) uptake, grain/cane yields, land productivity, and economic returns. Results showed that intercrops achieved 91–94% of sole cane yield and 66–81% of sole soybean grain yield, which was mainly due to the improved canopy cover resulting from soybean intercropping during the early cane growth in 2S2Sc and 3S2Sc. The land productivity and nutrient use advantage under sugarcane/soybean intercropping, estimated as the total land equivalent ratios for land, N, and P, were 1.58–1.75 (LER L), 1.72–1.87 (LER N), and 1.38–1.67 (LER P), respectively, which in turn substantially increased the net profit of 2S2Sc (USD 2191, 1426, and 1014 ha-1) and 3S2Sc (USD 1888, 1190, and 780 ha-1) compared to sole sugarcane (USD 1752, 967, and 575 ha-1) in 2020–21, 2021–22, and 2022–23, respectively. The increase in net profit under intercropping was mainly due to the additional soybean grain yield that was obtained from the capture of resources that are not used by sugarcane during its early canopy development phase, most importantly, without investing any extra capital on land preparation, irrigation, labor, and fertilizers. Our results show that sugarcane/soybean intercropping could be adopted as a potential cropping system for obtaining higher yields with reduced cultivation and anthropogenic inputs (N and P), and it will put less pressure on the environment than sole sugarcane cropping system by increasing production without increase in inputs and lowering the land requirement of the agricultural output. • Intercrops efficiently consumed the under-utilized resources of sole sugarcane. • Soybean yield from the scrapped resources of sole sugarcane added more profitability. • Intercrops produced higher crop yields with reduced anthropogenic inputs (N and P). • Higher resource use advantage than sole crops (LER L : 1.66; LER N : 1.79; LER P : 1.52). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Selecting 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. [ABSTRACT FROM AUTHOR]

Intercropping advantage occurs only when each species has adequate time and space to maximize cooperation and minimize competition between them. A field experiment was conducted for two consecutive years between 2013 and 2014 to investigate the effects of maize and soybean relay strip intercropping systems on the uptake and utilization of nitrogen, phosphorus, and potassium. The treatments included "40:160" (T1, maize narrow and wide row spacing of 40 and 160 cm, where two rows of soybean with a 40 cm row were planted in the wide rows. The area occupation ratio of maize and soybean both were 50% of the every experimental block), "80:120" (T2, maize narrow and wide row spacing of 80 and 120 cm, the soybean planting was the same as T1 treatment. The area occupation ratio of maize and soybean were 60% and 40% of the every experimental block), "100:100" (T3, one row of maize and one row of soybean with a 100-cm row. The area occupation ratio of maize and soybean was the same as T1 treatment), sole cropping of maize (CK1, The area occupation ratio of maize was 100% of the every experimental block), and sole cropping of soybean (CK2, The area occupation ratio of soybean was 100% of the every experimental block). The results show that, compared with the sole cropping system (sole maize), the economic yields in T1, T2, and T3 treatments increased by 761, 536, and 458 kg·ha−1, respectively, and the biological yields increased by 2410, 2127, and 1588 kg·ha−1. The uptake and utilization of nitrogen, phosphorus, and potassium in T1, T2, and T3 treatments were significantly higher than those in sole crops, and the nutrient advantage is mainly due to nutrient uptake rather than nutrient use efficiency. The land equivalent ratio values in T1, T2, and T3 treatments were 1.43, 1.32, and 1.20, respectively. In particular, the economic and biological yield in T1 treatment exhibited potential as an intercropping pattern. [ABSTRACT FROM AUTHOR]

Strip width management is a critical factor for producing higher crop yields in relay intercropping systems. A 2‐year field experiment was carried out during 2012 and 2013 to evaluate the effects of different strip width treatments on dry‐matter production, major‐nutrient (nitrogen, phosphorus, and potassium) uptake, and competition parameters of soybean and maize in relay intercropping system. The strip width (SW) treatments were 0.40, 0.40, and 0.40 m (SW1); 0.40, 0.40, and 0.50 m (SW2); 0.40, 0.40, and 0.60 m (SW3); and 0.40, 0.40, and 0.70 m (SW4) for soybean row spacing, maize row spacing, and spacing between soybean and maize rows, respectively. As compared to sole maize (SM) and sole soybean (SS), relay‐intercropped maize and soybean accumulated lower quantities of nitrogen, phosphorus, and potassium in all treatments. However, maize in SW1 accumulated higher nitrogen, phosphorus, and potassium than SW4 (9%, 9%, and 8% for nitrogen, phosphorus, and potassium, respectively). Soybean in SW3 accumulated 25% higher nitrogen, 33% higher phosphorus, and 24% higher potassium than in SW1. The improved nutrient accumulation in SW3 significantly increased the soybean dry matter by 19%, but slightly decreased the maize dry matter by 6% compared to SW1. Similarly, SW3 increased the competition ratio value of soybean (by 151%), but it reduced the competition ratio value of maize (by 171%) compared to SW1. On average, in SW3, relay‐cropped soybean produced 84% of SS seed yield and maize produced 98% of SM seed yield and achieved the land equivalent ratio of 1.8, demonstrating the highest level in the world. Overall, these results suggested that by selecting the appropriate strip width (SW3; 0.40 m for soybean row spacing, 0.40 m maize row spacing, and 0.60 m spacing between soybean and maize rows), we can increase the nutrient uptake (especially nitrogen, phosphorus, and potassium), dry‐matter accumulation, and seed yields of relay‐intercrop species under relay intercropping systems. [ABSTRACT FROM AUTHOR]

In China, maize-soybean relay-intercropping system follow the two main planting-patterns: (i) traditional relay-intercropping; maize-soybean equal row planting, where soybean experience severe maize shading on both sides of plants, and (ii) modern relay-intercropping; narrow-wide row planting, in this new planting pattern only one side of soybean leaves suffer from maize shading. Therefore, in this study, changes in morphological traits, cytochrome content, photosynthetic characteristics, carbon status, and the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were investigated at 30 days after treatment (DAT) in shade-tolerant soybean variety Nandou-12 subjected to three different types of shading conditions; normal light (NL, all trifoliate-leaves of soybean plants were under normal light); unilateral shade (US, all right-side trifoliate-leaves of soybean plants from top to bottom were under shade while all the left-side of trifoliate-leaves from top to bottom were in normal light); bilateral shade (BS, all trifoliate-leaves of soybean plants were under complete shade). Compared with BS, US conditions decreased plant height and increased stem diameter, leaf area, and biomass at 30 DAT. Biomass distribution rates to stem, petiole and leaves, and photosynthetic characteristics were markedly improved by the US at all sampling stages, which proved to be a better growing condition than BS with respect to shade tolerance. The enhanced net photosynthesis and transpiration rates in the left-side leaves (LS) of soybean plants in US, when compared with the LS in BS, allowed them to produce higher total soluble sugar (by 70%) and total soluble protein (by 17%) at 30 DAT which reduce the adverse effects of shading at right-side leaves (RS) of the soybean plants. Similarly, soybean leaves under US accumulated higher proline content in US than the leaves of BS plants. Soybean leaves grown in shading conditions (LS and RS of BS and RS of US) developed antioxidative defence-mechanisms, including the accelerated activities of SOD, POD, APX, and CAT. Comparatively, soybean leaves in US displayed lower activity levels of the antioxidative enzymes than the leaves of BS plants, showing that soybean plants experienced less shade stress in US as compared with BS treatment. Overall, these results indicate that the association of improved photosynthetic characteristics, sugar and protein accumulation and optimum antioxidative defences could be an effective approach for growing soybean in intercropping environments. Slight shading could be an effective approach for growing soybean in intercropping systems. Soybean responds to slight shade by producing larger leaves to intercept more sunlight. Compared with severe-shading, soybean maintained the optimum chlorophyll contents, high net photosynthetic rate, and improved antioxidant enzyme activities under slight-shading. Through configuring the space deployment in the intercropping system, slight shade could be helpful for optimum growth and yield. Redesigning photosynthesis through slight shade for intercropping systems could meet global food and bioenergy demand. [ABSTRACT FROM AUTHOR]

A half-root stress is a half portion of the root system exposed to treatment while the remaining half portion kept under normal conditions. A half-root stress including half-root drought stress, half-root nutrient stress, and half-root salinity stress has become a general approach to improve plant performance and adaptability. Plants produce some chemical signals in stressed part of root, and other parts sense these signals to improve the acclimation and adaptive responses to environmental stresses. Plants adapt the compensatory functions and discriminate the systemic and local regulatory mechanisms, but the understanding of these mechanisms is controversial. Chemical signals (Abscisic acid, sap pH, cytokinins, content of malate, amino acid, and ureide) have been involved in root to shoot signaling under half-root stress. Furthermore, naturally appeared half-root stress in intercropping systems could be an additional attribute of half-root stress approach. Therefore, much more study is required to elaborate its acceptability in intercropping. In this review, we summarized the current knowledge and identified some key future researches areas regarding half-root stress approach. [ABSTRACT FROM AUTHOR]

Without developing new agronomic practices, present rates of improvement in seed yields of cereal crops globally are insufficient to fulfil the estimated increasing food demand for 2050 and beyond. Intercropping is one of the agricultural practices that can lead to greater crop yields. However, there exists leaf redundancy for maize in intercropping systems, and the top canopy leaves shade more competent leaves at middle strata of maize plants. Therefore, this work aimed to elucidate the effect of leaf excision treatments in maize to understand the optimum leaf area of maize plants under a maize–soybean relay‐intercropping system (MSR) and a sole cropping system (SM). The effects of four‐leaf excision treatments (T1, 0; T2, 2; T3, 4; T4, 6 leaves excised from the top of maize plants until 7 days after silking) on light interception, leaf area index (LAI), photosynthetic characteristics, total biomass accumulation at blistering stage (BS), dough stage (DS) and physiological maturity (PM), and seed yield of maize were investigated through field experiments for 2 years under MSR and SM. Results showed that, under MSR and SM, as compared to control (T1), optimum excision of leaves (T2) from the top of maize plants significantly improved the light interception (by 25, 18 and 16% at BS, DS and PM, respectively) to lower strata leaves and accelerated the biomass partitioning to maize seeds (by 13 and 12% at DS and PM, respectively). Importantly, plants under T2 exhibited higher green leaf area than control, that is, excision the top two leaves led to an increase in LAI at PM by 10%, suggesting that leaf senescence under T2 was delayed which enhanced the photosynthetic rate at PM by 7% in 2017 and 6% in 2018. Relative to T1, maize under T2 produced 19 and 13% higher maize yield under MSR and SM, respectively, and relay‐cropped maize had 90% of SM seed yield. These results suggest that by manipulating the canopy structure of maize plants we can enhance the biomass accumulation and seed yield of maize crops under MSR and SM. [ABSTRACT FROM AUTHOR]

Background: Maize-soybean relay-intercropping (MSR) is a famous system of crop production in developing countries. However, maize shading under this system directly affects the light quality and intensity of soybean canopy. This is a challenging scenario in which to implement the MSR system, in terms of varieties selection, planting pattern, and crop management since the duration of crop resource utilization clearly differs. Methods: Therefore, this experiment aimed to elucidate the effect of leaf excising treatments from maize top to fully clarify the needs and balance of light quality and intensity of intercrop-soybean under MSR in field conditions. The effects of different leaf excising treatments (T0, no removal of leaves; T2, removal of two topmost leaves; T4, removal of four topmost leaves; T6, removal of six topmost leaves from maize plants were applied at first-trifoliate stage (V1) of soybean) on photosynthetically active radiation transmittance (PART), red to far-red ratio (R:FR), morphological and photosynthetic characteristics and total biomass production at second-trifoliate stage (V2), fifth-trifoliate stage (V5), and flowering-stage (R1) of soybean were investigated through field experiments for 2-years under MSR. Results: As compared to T0, treatment T6 increased the PART and R:FR ratio at soybean canopy by 77% and 37% (V2), 70% and 34% (V5), and 41% and 36% (R1), respectively. This improved light environment in T6 considerably enhanced the leaf area index, SPAD values and photosynthetic rate of soybean plants by 66%, 25% and 49% at R1, respectively than T0. Similarly, relative to control, T6 also increased the stem diameter (by 29%) but decreased the plant height (by 23%) which in turn significantly increased stem breaking strength (by 87%) by reducing the lodging rate (by 59%) of soybean plants. Overall, under T6, relay-cropped soybean produced 78% of sole soybean seed-yield, and relay-cropped maize produced 81% of sole maize seed-yield. Our findings implied that by maintaining the optimum level of PART (from 60% to 80%) and R:FR ratio (0.9 to 1.1), we can improve morphological and photosynthetic characteristics of soybean plants in MSR. Therefore, more attention should be paid to the light environment when considering the sustainability of MSR via appropriate planting pattern selection. [ABSTRACT FROM AUTHOR]

Different planting patterns affect the light interception of intercrops under intercropping conditions. Here we revealed that narrow-wide-row relay-intercropping improves the light interception across maize leaves in wide rows (60cm) and narrow rows (40cm), accelerated the biomass production of intercrop-species and compensated the slight maize yield loss by considerably increasing the soybean yield. In a two-year experiment, maize was planted with soybean in different planting patterns (1M1S, 50:50cm and 2M2S, 40:60cm) of relay-intercropping, both planting patterns were compared with sole cropping of maize (M) and soybean (S). As compared to M and 1M1S, 2M2S increased the total light interception of maize leaves in wide rows (WR) by 27% and 23%, 20% and 10%, 16% and 9% which in turn significantly enhanced the photosynthetic rate of WR maize leaves by 7% and 5%, 12% and 9%, and 19% and 4%, at tasseling, grain-filling and maturity stage of maize, respectively. Similarly, the light transmittance at soybean canopy increased by 218%, 160% and 172% at V2, V5 and R1 stage in 2M2S compared with 1M1S. The improved light environment at soybean canopy in 2M2S considerably enhanced the mean biomass accumulation, and allocation to stem and leaves of soybean by 168%, and 131% and 207%, respectively, while it decreased the mean biomass accumulation, and distribution to stem, leaves and seed of maize by 4%, and 4%, 6% and 5%, respectively than 1M1S. Compared to 1M1S, 2M2S also increased the CR values of soybean (by 157%) but decreased the CR values of maize (by 61%). Overall, under 2M2S, relay-cropped maize and soybean produced 94% and 69% of the sole cropping yield, and the 2M2S achieved LER of 1.7 with net income of 1387.7 US $ ha-1 in 2016 and 1434.4 US $ ha-1 in 2017. Our findings implied that selection of optimum planting pattern (2M2S) may increase the light interception and influence the light distribution between maize and soybean rows under relay-intercropping conditions which will significantly increase the intercrops productivity. Therefore, more attention should be paid to the light environment when considering the sustainability of maize-soybean relay-intercropping via appropriate planting pattern selection. [ABSTRACT FROM AUTHOR]

Crop type and temporal synchronization are crucial for improving the productivity of intercropping systems, especially with reduced inputs (nitrogen, N, and phosphorus, P). However, the effects of crop type and temporal dynamics on nutrient uptake and yield advantage of cereal/legume intercropping systems are still unclear. The objective of this study was to assess the effects of different temporal dynamics of intercrops on growth, nutrient-use advantage, land productivity, and economic viability of cereal/legume intercropping systems under arid irrigated conditions. In this field study, we used the equal land proportion for all intercrops in both intercropping systems: wheat/chickpea intercropping (wheat/chickpea), where legume (chickpea) was the first-sown crop; and wheat/soybean intercropping (wheat/soybean), with cereal (wheat) being the first-planted crop), and all strip intercropping results were compared with their sole systems: sole chickpea (SCp), sole wheat (SW), and sole soybean (SS). Here, we revealed that the improved complementarity and facilitation interactions in wheat/chickpea linked with better phenological synchronization between wheat and chickpea, which resulted in higher relative grain yields, primarily gained from greater biomass accumulation and its translocation towards ears/pods, seeds, and seed weight, than the wheat and soybean in wheat/soybean. Similarly, the intercropped wheat accumulated a significantly higher N (15%) and P (14%) under wheat/chickpea than in wheat/soybean, whereas, in legumes, the N and P uptake of chickpea in wheat/chickpea was 19% and 13% higher than that of soybean in wheat/soybean, respectively. On average, in wheat/soybean, wheat and soybean achieved 62% of SW and 58% of SS yields, while in wheat/chickpea, wheat and chickpea produced 71% and 67% of SW and SCp yields, respectively, demonstrating the advantage of sowing legumes earlier than cereals in intercropping systems. Overall, in wheat/chickpea, the system-level nutrient- and land-use advantage, measured as the land, nitrogen, and phosphorus equivalent ratios, were 1.38, 1.59, and 1.62, respectively, which increased the net profit of wheat/chickpea by 55% compared to wheat/soybean, suggesting that intercropping systems require fewer anthropogenic inputs to produce higher crop yields than sole systems. Our results contribute to understanding the effects of crop type and temporal synchronization of intercrop species for maximizing the land productivity of cereal/legume intercropping systems in arid irrigated regions. • Legume-based wheat intercropping systems were tested in arid irrigated conditions. • Crop combination is important for higher yield in cereal/legume intercropping. • Cereal/legume intercropping accumulated more nutrients than sole crops. • Wheat/chickpea intercropping achieved higher LER than wheat/soybean intercropping. [ABSTRACT FROM AUTHOR]

Water imbalance condition (WIC) in a maize-soybean relay intercropping system is the main abiotic stress limiting biomass production and seed yield and, consequently, seed-quality. This experiment was started to study the effects ofWIC on soybean, in which two soybean genotypes ND12 and C103 were grown in pots with roots split equally between two soil column and sixWIC treatments (%) T1 (100), T2, (100:50), T3 (100:20), T4 (50:50), T5 (50:20), and T6 (20:20) field capacity on both sides of soybean roots were used. Results showed that both genotypes responded significantly to WIC treatments for all the parameters; however, the level of response differed between genotypes. Maximum osmoprotectants (except proline), biomass, yield and yield-related traits and superior seed quality were observed with ND12. Among WIC treatments, T2 and T3 produced 94% and 85%, and 93% and 81% of T1 biomass and yield, respectively. Similarly, treatments T2 and T3 also improved the oil quality by maintaining the content of unsaturated fatty acids and isoflavone content, while opposite trends were observed for protein content. Overall, moderate water reduction (T2 and T3) can improve soybean seed-quality and by selecting drought-resistant genotypes we can increase the soybean yield under intercropping systems. [ABSTRACT FROM AUTHOR]

Intercropping is an important agronomic practice adopted to increase crop production and resource efficiency in areas with intensive agricultural production. Two sequential field trials were conducted in 2015–2016 to investigate the effect of shading on the morphological features, leaf structure, and photosynthetic characteristics of soybean in a maize-soybean relay-strip intercropping system. Three treatments were designed on the basis of different row configurations A1 (“50 cm + 50 cm” one row of maize and one row of soybean with a 50 cm spacing between the rows), A2 (“160 cm + 40 cm” two rows of maize by wide-narrow row planting, where two rows of soybean were planted in the wide rows with a width of 40 cm, and with 60 cm row spacing was used between the maize and soybean rows), and CK (sole cropping of soybean, with 70 cm rows spacing). Results showed that the photosynthetically active radiation transmittances of soybean canopy at V5 stage under A2 treatment (31.1%) were considerably higher than those under A1 (8.7%) treatment, and the red-to-far-red ratio was reduced significantly under A1 (0.7) and A2 (1.0) treatments compared with those under CK (1.2). By contrast with CK, stem diameter, total aboveground biomass, chlorophyll content and net photosynthetic rate decreased significantly except plant height under A1 and A2. The thickness of palisade tissue and spongy tissue of soybean leaf under A1 and A2 were significantly reduced at V5 stage compared with CK. The leaf thicknesses under A1 and A2 were lower than those in CK by 39.5% and 18.2%, respectively. At the R1 stage of soybean (after maize harvest), the soybean plant height, stem biomass, leaf biomass and petiole biomass under A1 and A2 treatments were still significantly lower than those under CK, but no significant differences were observed in Chl a/b, Pn, epidermis thickness and spongy tissue thickness of soybean leaves in A2 compared with CK. In addition, the soybean yields (g plant-1) under A1 and A2 were 54.69% and 16.83% lower than those in CK, respectively. These findings suggested that soybean plants can regulate its morphological characteristics and leaf anatomical structures under different light environments. [ABSTRACT FROM AUTHOR]

Aphids are considered as major menace in limiting the crop yields. Keeping in view the losses caused by aphids, the present study was conducted to investigate comparative effect of different companion crops viz., barley, berseem, lucerne, wheat, maize, fennel seed, onion and garlic on aphid population in canola sown as border and intercrop. Results showed that minimum aphids population (46.00 and 49.50 aphids plant-1) was observed in garlic sown as border and intercrop with canola and gave an enhanced grain yield of 1796.30 Kgha-1 and 2222.22 Kgha-1, respectively., Whereas canola plots with barley sown as border and intercrop showed significantly higher numbers of aphids (299.67 and 299.83 aphidsplant-1) with a lower grain yield of canola 602.42 Kgha-1 and 648.14 Kgha-1, respectively. While canola alone produced 740.75 and 787.02 Kgha-1 harboring 299.17 and 243.17 aphids plant-1, respectively in border and intercrop. It is suggested that the aphid infestation can be minimized by the use of companion crops like garlic, onion and fennel seeds. [ABSTRACT FROM AUTHOR]

Intercropping improves crop productivity in dryland farms, but little information is available on its application to irrigated land. Therefore, a three-year field trial was conducted to compare two maize-soybean strip-intercropping planting patterns (two-rows of maize intercropped with two-rows of soybean [2M2S] or -three rows of soybean [2M3S]) were studied with sole maize (SM) and sole soybean (SS) systems. Our results showed that wider-strips of soybean grown as 2M3S had significantly higher leaf area index (LAI; 19%), total dry matter accumulation (TDM; 15%), and grain yield (21%) than the narrower 2M2S strips; this is likely related to the reduced effects of maize shading on soybean. Slightly decreased LAI (4%), TDM (8%), and grain yield (5%) of maize were found in 2M3S. On average, intercropped maize and soybean produced 80% and 52% in 2M2S and 76% and 63% in 2M3S compared to SM and SS yields, respectively, demonstrating the dominance of maize over soybean when intercropped. Similarly, maize was a stronger competitor for water than soybean, with partial water equivalent ratio of 0.81 in 2M2S and 0.78 in 2M3S, while that of soybean was 0.54 in 2M2S and 0.66 in 2M3S. In the intercropping systems, the land equivalent ratio ranged from 1.31 to 1.45, and the water equivalent ratio ranged from 1.32 to 1.49, exhibiting that maize-soybean strip-intercropping is a productive strategy to maximize water use efficiency. The results suggest that the maize-soybean strip-intercropping system may be a productive and sustainable strategy to improve the water use efficiency and land productivity under irrigated conditions. This strategy could benefit agriculture with cleaner, and more efficient production under a global scenario of constrained land and water resources. However, more studies are needed to evaluate the feasibility of intercropping systems in various growing conditions. • Maize-soybean strip intercropping system shows great potential with irrigation in the semi–arid region. • The average LER (1.37) of intercropping systems demonstrates high relative LUE than sole crops. • Maize was a stronger competitor for land and water than soybean in intercropping systems. • The mean WER (1.40) of intercropping systems shows high relative WUE compared to sole crops. [ABSTRACT FROM AUTHOR]

• Delayed maize leaf senescence in maize-soybean relay-intercropping can increase the resource use efficiency. • Under narrow-wide-row planting pattern in maize-soybean relay-intercropping, maize yield is constrained. • Compared to the equal-row planting pattern, the narrow-wide-row planting pattern increased soybean grain-yield by 147%. • Overall, the total land equivalent ratio value of maize-soybean relay-intercropping in narrow-wide-row planting pattern was increased by 22% compared to the equal-row planting pattern. Different planting pattern affects the leaf senescence of maize under intercropping systems, which regulate the grain yield of maize plants. In this study, we observed that a narrow-wide-row planting pattern in maize soybean relay intercropping system (MS) improved the leaf greenness and green leaf area, delayed the leaf senescence process in maize and increased the photosynthetic rate of maize leaves during the reproductive stages of maize in MS. In a three-year field experiment, soybean was relay-intercropped with maize under different planting patterns (1M1S, "50 cm + 50 cm" 1-row of maize and 1-row of soybean with an equal row distance of 50 cm; and 2M2S, "40 cm + 160 cm" narrow-wide-row planting pattern, where 2-rows of maize were planted in narrow rows, and 2-rows of soybean were planted in wide rows, and 60 cm distance was maintained between the rows of maize and soybean) of MS, and both planting patterns of MS were compared with sole cropping systems of maize and soybean. Compared with 1M1S, planting pattern 2M2S significantly increased the number of green leaves (by 36%), leaf greenness (by 17%), and leaf nitrogen content (by 13%) at the dent stage (R5). The improved leaf nitrogen content in 2M2S at R5 significantly increased the green leaf area (by 16%, from 4170 cm2 plant−1 in 1M1S to 4960 cm2 plant−1 in 2M2S) of maize, indicating that leaf senescence of maize plants was delayed, which in turn significantly enhanced the photosynthetic rate of maize leaves at R5 by 57% in 2017, 75% in 2018 and 49% in 2019 than 1M1S. Overall, in 1M1S and 2M2S, relay-cropped maize produced 100%, and 89% of sole maize yield and relay-cropped soybean produced 27% and 66% of sole soybean yield, respectively. Importantly, compared to 1M1S, the decline of maize yield by 11% in 2M2S was compensated by a substantial increase in soybean yield by 147%, and 2M2S achieved the highest land equivalent ratio value of 1.54 compared to the land equivalent ratio value of 1.27 in 1M1S. Our results suggest that by selecting the appropriate planting pattern or stay-green maize hybrids, we can improve the land equivalent ratio of maize soybean relay intercropping system. [ABSTRACT FROM AUTHOR]

• We evaluated defoliation effects on biomass-production and nutrients uptake of maize and soybean under maize-soybean relay-intercropping system (MS). • Defoliation of two-leaves from the top of maize plants (T 2) increased the biomass-production and nutrients uptake in maize and soybean under MS. • Relay-cropped maize and soybean produced 107% and 65% of the sole-yield, respectively in T 2 defoliation-treatment. • The T 2 defoliation-treatment achieved the highest land equivalent ratio of 1.73 with a net profit of 1297.3 $ ha−1. Upper canopy leaves of maize decrease the light-transmittance at middle-strata-leaves of maize and soybean canopy in maize-soybean relay-intercropping systems (MS). This affects the uptake of nutrients and distribution patterns in various plant organs of intercrop species in MS. Judicious defoliation of maize plants in MS could help to alleviate this problem and improve nutrient uptake and intercrop yields. In a two-year field experiment with MS, including the measurements of biomass production, nutrients uptake, and distribution at the organ level, and grain yields of intercrop species, maize plants were subjected to four-leaf defoliation treatments to improve the light-transmittance of maize and soybean plants. Defoliation of the topmost two-leaves (T 2), four-leaves (T 4), six-leaves (T 6) was compared to no defoliation (T 0). Compared to T 0 , treatment T 2 improved the uptake of nitrogen (N), phosphorus (P), and potassium (K) in each plant part of maize by 23, 12, and 11% (grain), 22, 19, and 13% (straw), and 28, 14, and 18% (root), respectively. Defoliation also enhanced the uptake of N, P, and K in each plant part of soybean by 5, 5, and 10% (grain), 10, 17, and 13% (straw), and 14, 11, and 11% (root), respectively. The improved nutrient uptake in T 2 increased the total biomass and its distribution in the root, straw, and grain of soybean and maize by 15 and 13%, and 21 and 15%, 20 and 14%, 7 and 10%, respectively compared to T 0. On average, over two years, under T 2 , relay-cropped maize obtained 107% of the sole-yield, and relay-cropped soybean obtained 65% of the sole-yield. The T 2 defoliation treatment also achieved the highest land equivalent ratio of 1.69 and 1.77, with a net profit of 1301.6 $ ha−1 and 1293.4 $ ha−1 in 2017 and 2018, respectively. Following the optimum defoliation treatment of maize in maize-soybean intercrops, i.e., defoliation of the topmost two-leaves, the nutrient uptake can be increased, and the nutrient partitioning over plant organs be better balanced. Optimum defoliation, therefore, enhances the productivity of maize-soybean intercropping systems. [ABSTRACT FROM AUTHOR]

Intercropping has been considered as a kind of a sustainable agricultural cropping system. In southwest China, maize/soybean strip intercropping has commonly been practised under local limited agricultural land resources. However, heavy rainfall in combination with high humidity and low temperatures cause severe pod and seed deterioration in the maturity and pre-harvesting stages of intercropped soybean. Numerous Fusarium species have been reported as the dominant pathogens of soybean root rot, seedling blight, as well as pod field mold in this area. However, the diversity and pathogenicity of Fusarium species on soybean pods remain unclear. In the current study, diseased soybean pods were collected during the cropping season of 2018 from five different intercropped soybean producing areas. A total of 83 Fusarium isolates were isolated and identified as F. fujikuroi, F. graminearum, F. proliferatum, and F. incarnatum-equiseti species complex based on morphological characteristics and phylogenetic analysis of the nucleotide sequence of EF1-α and RPB2 genes. Pathogenicity tests demonstrated that all Fusarium species were pathogenic to seeds of the intercropped soybean cultivar Nandou12. Fusarium fujikuroi had the maximum disease severity, with a significant reduction of seed germination rate, root length, and seed weight, followed by F. equiseti, F. graminearum, F. proliferatum, and F. incarnatum. Additionally, the diversity of Fusarium species on soybean pods was also considerably distinct according to the geographical origin and soybean varieties. Thus, the findings of the current study will be helpful for the management and resistance breeding of soybean pod decay in the maize/soybean intercropping system. [ABSTRACT FROM AUTHOR]

Shading conditions adversely affect flower-number and pod-number of soybeans under maize-soybean relay-intercropping (MSR). Here we reveal that leaf-removal from maize-canopy improves the photosynthetically active radiation (PAR) transmittance and dry-matter production (DMP) of soybean (especially during the co-growth phase), and compensates the maize seed-yield loss by considerably increasing soybean seed-yield. In a two-year experiment with MSR, maize-plants were subjected to different leaf-removal treatments to increase the PAR-transmittance of soybean; removal of the topmost two-leaves (R2), four-leaves (R4), six-leaves (R6), with no-removal of leaves (R0). Leaf-removal treatments improved the PAR-transmittance, photosynthetic-rate, and morphological-characteristics of soybean under MSR. At 90 days after sowing, the dry-matter of pods, and seeds was increased by 25%, and 32%, respectively under R6 than R0. Importantly, enhanced PAR-transmittance and DMP under R6 enabled soybean to initiate a greater number of flowers 182.2 plant−1 compared to 142.7 plant−1 under R0, and it also decreased the flower-abscission (by 13%, from 54.9% under R0 to 47.6% under R6). These positive responses increased the pod-number by 49% and seed-number by 28% under R6 than R0. Overall, under R6, relay-intercropped soybean produced 78% of sole-soybean seed-yield, and relay-intercropped maize produced 81% of sole-maize seed-yield and achieved the land equivalent ratio of 1.59. [ABSTRACT FROM AUTHOR]

Planting arrangements affect radiation use efficiency (RUE) and competitiveness of intercrop species in intercropping systems. Here, we reveal that narrow‐wide‐row planting arrangement in maize‐soybean relay‐intercropping system increases the dry matter and competitiveness of soybean, increased the RUE of maize and soybean, and compensates the yield loss of maize by substantially increasing the yield of soybean. In this field study, maize was planted with soybean in different planting arrangements (P1, 20:180, P2, 40:160; P3, 60:140, and P4, 80:120) of relay intercropping, all the relay‐intercropping treatments were compared with sole crops of maize (SM) and soybean (SS). Results showed that P1 improved the total RUE 3.26 g/MJ (maize RUE + soybean RUE) of maize and soybean in relay‐intercropping system. Compared to P4, treatment P1 increased the soybean competition ratio (CR) values (by 55%) but reduced the maize CR values (by 29%), which in turn significantly improved the yield of soybean by maintaining the maize yield. Generally, in P1, soybean produced 82% of SS yield, and maize produced 88% of SM yield, and it achieved the land equivalent ratio of 1.7. These results suggest that by maintaining the appropriate planting distances between maize and soybean we can improve the competitiveness and yield of intercrop species in relay‐intercropping system. [ABSTRACT FROM AUTHOR]

Photosynthesis is dependent on the density and quality of light that reaches chloroplasts. Shade conditions are characterized by changes in light density and quality. These changes, which are represented by the red to far-red (R/Fr) ratio of light, directly affect the photosynthetic capacity of soybean in close-planting and intercropping systems. We postulated that high far-red light under shade conditions would improve crop photosynthesis. Herein, we conducted a quantitative proteomic analysis through the isobaric tagging for relative and absolute quantification approach to investigate the response of photosynthetic proteins to the interaction between light intensity and quality. We identified 7834 proteins (P value < 0.05, FC > 1.3) from soybean leaves. Among these proteins, 98 are associated with differential chloroplast accumulation under shade (S, low light intensity and low R/Fr ratio) and normal light (N, normal light intensity and normal R/Fr ratio) conditions. Additionally, 134 are associated with differential chloroplast accumulation under low light (L, low light intensity and normal R/Fr ratio) and N conditions. Eight representative proteins that are involved in photosynthesis were differentially regulated under L and S treatments. These proteins included one protein involved in porphyrin and chlorophyll metabolism, three proteins involved in light-harvesting chlorophyll protein complex, and four proteins involved in photosynthesis. Among the eight differentially regulated proteins under L and S treatments, five up-regulated proteins (protochlorophyllide reductase; light-harvesting complex II chlorophyll a/b binding protein [Lhcb1]; Lhcb2; photosystem I subunit II; and plastocyanin [PetE]) and three down-regulated proteins (Lhcb4; Ferredoxin-1; and NADPH:quinone oxidoreductase [NQO]) were validated through quantitative reverse-transcription polymerase chain reaction and Western blot methods L and S treatments decreased net photosynthesis rate ( P n ) but increased chlorophyll content; thylakoid stacking; and photosystem II (PSII), PSI, and electron transport associated protein levels. Likewise, N and S treatments decreased PetE and NQO protein expression levels. This effect, in turn, decreased P700 oxidation. In addition, the higher far-red light of the S treatment than that of the L treatment increased P n by up-regulating the gene expressions of differential proteins. We conclude that light intensity directly affects photosynthesis by regulating the expression of photosynthetic proteins. High far-red light, however, can improve the photosynthetic capacity of plants under shade conditions. [ABSTRACT FROM AUTHOR]

Aboveground and belowground interactions are crucial in the over-yielding of intercropping systems. However, the relative effects of aboveground and belowground interactions on yields of intercrops in maize ( Zea mays L.) and soybean [ Glycine max (L.) Merr.] relay intercropping systems are still unclear. Field experiments, including measurements of biomass, grain yield, and photosynthetic parameters, were conducted in 2013–2014 to analyze the advantages and effects of aboveground and belowground of interspecies interactions on yield. To analyze the aboveground interactions of intercrops for light interception, this study adopted three different row configurations [(P1) “160 cm + 40 cm” and (P2) “120 cm + 80 cm” maize wide-narrow row planting, where two rows of soybean with a 40-cm row width were planted in the wide rows, and (P3) “100 cm +100 cm” maize equal-row planting, where one row of maize and one row of soybean with a 50-cm spacing between the adjacent rows of both crops]. Moreover, to identify interspecies belowground competition, no root separation (R1) and root separation (R2) were employed between adjacent maize and soybean rows. The photosynthetically active radiation (PAR) transmittances of maize wide-row were significantly higher than those of maize narrow-row at the sixth leaf stage (jointing stage), twelfth leaf stage (bell stage), and tasseling stage. Specifically, PAR transmittances decreased as maize narrow-row spacing increased. No significant differences in the PAR transmittances of maize narrow-row or wide-row were found between the R1 and R2 conditions. Similarly, no significant differences between intercrop biomass and grain yield were observed between the R1 and R2 conditions. By contrast, different row configuration treatments exhibited significant differences in biomass (whole growth period for soybean and after tasseling stage for maize), grain yield and photosynthetic parameters of intercrops. These results implied that aboveground interactions, such as mutual shading, have more significant contributions to intercrop advantages than belowground interactions. In addition, the intercropped maize yields increased as maize narrow-row spacing (from P1 to P3 treatment) increased. However, contrasting trends were found for intercropped soybean yield and land equivalent ration (LER). No significant differences in LER were observed between R1 and R2 conditions in different row configurations. P1 treatment exhibited the maximum LER (1.64 for 2013 and 1.83 for 2014) and mixed yield (7430 kg ha −1 for 2013 and 9559 kg ha −1 for 2014), but the lower maize yield compared with P2 and P3 treatments. This result suggested that reducing the competitive ability of maize while increasing that of soybean significantly improves intercropping advantage in maize-soybean relay intercropping systems. [ABSTRACT FROM AUTHOR]

Crop diversity results in inters-specific interactions which defines the productivity and resource utilization efficiency of intercropping systems. However, little attention was paid to the below ground interactions of the maize (Zea mays L.) and soybean (Glycine max (Linn.) Merr.) in relay strip intercropping, and how these two crop species compete for resources by stimulating root development and water uptake, still remains unclear. Therefore, in our three-year field experiment, in addition to the continuous planting of maize/soybean relay strip intercropping(MS1), traditional maize/soybean intercropping (MS5), sole maize (M) and sole soybean (S), we swapped the maize and soybean rows (MS2) and also used nylon net (MS3) and plastic sheet (MS4) barriers between swapped rows to study the root distribution and water use efficiency, and the significance of inter-specific root interactions for corresponding yield responses of maize and soybean in relay strip intercropping. Our results showed the advantage of maize/soybean relay strip intercropping (LER1.46–2.00) over the sole cropping, with row swapping treatment (MS2) showing the highest yield (5360.35 kg ha−1) and land equivalent ratio (LER 1.98). In addition, intercropping promoted the root growth and distribution of the both crops, with lateral expansion to the middle inter-row spaces during the co-growth period, resulting in 72.15% and 15.72% greater root length density of maize and soybean, respectively. Importantly, compared to monocrops, the unseparated planting patterns (MS1, MS2, MS5) showed lower decrease in WUE, with MS2 treatment showing the lowest decrease of WUE in maize (0.71%) and soybean (2.69%). In contrast, the highest decrease in water use efficiency of maize (32.30% and 27.79%) and soybean (33.65% and 29.23%) was always found in separated planting pattern MS4 and MS4 respectively, signifying the importance of inter-specific root interactions for high productivity and resource use efficiency of intercropping. Furthermore, swapping of rows also reduced the maize dominance (Ams 0.09 and Kms 1.46) and competitive pressure between maize and soybean, which caused highest yield increase in maize and lowest yield decrease in soybean in MS2. Altogether, these results showed that intercropping allows the absorption of more soil water through better root proliferation and inter-specific root interaction while the swapping of 2 rows of maize and 2 rows of soybean (MS2) enhances it even more, resulting in higher WUE and productivity of maize-soybean relay strip intercropping. Therefore, in southwest China and other regions with same attributes, the findings of this study could be served as a cleaner and environment friendly production practice to get more return from the maize/soybean relay strip intercropping. • Maize/soybean relay strip intercropping is more productive than sole cropping. • Interspecific interactions promote root growth and resource use efficiency. • Hinderance in interspecific interactions causes significant yield losses. • Swapping maize and soybean rows decreases the competitive pressure. [ABSTRACT FROM AUTHOR]

• Intercropping potato and legume improved productivity compared to pure stand. • Optimum population ratio of potato to legume was 1:2.4. • Yield loss decreased with an increasing proportion of legumes. • The intercropped potato was more aggressive in utilizing available resources than intercropped legume. • Intercropping potato and legume resulted in higher economic returns than pure stands. Intercropping is gaining popularity in developing countries as a viable strategy for diversifying cropping systems to ease food insecurity, given that arable land is shrinking, and demand for food crops is increasing due to rapid population growth. A field experiment was conducted in 2015 and 2016, to examine the biological and economic viability of two intercropping systems (potato-dolichos and potato-bean planted in two potatoes to legume population density ratios: 1.1:2 and 1: 2.4) and their corresponding pure stands. Intercropping systems were also evaluated based on five competition indices: relative crowding coefficient (K), aggressivity (A), competitive ratio (CR), intercropping advantage (IA) and actual yield loss (AYL). Although biological feasibility revealed that intercropping decreased the yield of intercrops compared with respective monocultures; the economic assessment of different cropping systems indicated that intercropping resulted in a higher remuneration (gross and net income) than pure stands. Intercropping potato with a high population of legume (in 1: 2.4 patterns), resulted in not only higher system productivity but also potato equivalent yield compared to 1.1:2. Intercropping proved to be advantageous with AYL decreasing with increasing proportion of the legumes, whereas IA increased as the population of legumes increased. With regard to competition between the intercrops, the potato was more aggressive (A of potato was positive, and its CR > 1) in all cropping systems, and it dominated over legume (that had negative A values and CR < 1). Aggressivity and dominance capacity was higher in 1: 2.4 than 1.1:2 series. These results suggest that potato-legume intercropping may provide viable intensification options, especially for smallholder farmers. [ABSTRACT FROM AUTHOR]