Maize-soybean Strip Intercropping Research Articles

Light recovery after maize harvesting promotes soybean flowering in a maize-soybean relay strip intercropping system.

Moving from sole cropping to intercropping is a transformative change in agriculture, contributing to yield. Soybeans adapt to light conditions in intercropping by adjusting the onset of reproduction and the inflorescence architecture to optimize reproductive success. Maize-soybean strip intercropping (MS), maize-soybean relay strip intercropping (IS), and sole soybean (SS) systems are typical soybean planting systems with significant differences in light environments during growth periods. To elucidate the effect of changes in the light environment on soybean flowering processes and provide a theoretical basis for selecting suitable varieties in various planting systems to improve yields, field experiments combining planting systems (IS, MS, and SS) and soybean varieties (GQ8, GX7, ND25, and NN996) were conducted in 2021 and 2022. Results showed that growth recovery in the IS resulted in a balance in the expression of TERMINAL FLOWER 1 (TFL1) and FLOWERING LOCUS T (FT) in the meristematic tissues of soybeans, which promoted the formation of new branches or flowers. IS prolonged the flowering time (2-7 days) and increased the number of forming flowers compared with SS (93.0 and 169%) and MS (67.3 and 103.3%) at the later soybean flowering stage. The higher carbon and nitrogen content in the middle and bottom canopies of soybean contributed to decreased flower abscission by 26.7 and 30.2%, respectively, compared with SS. Canopy light environment recovery promoted branch and flower formation and transformation of flowers into pods with lower flower-pod abscission, which contributed to elevating soybean yields in late-maturing and multibranching varieties (ND25) in IS.

Quantifying the effects of plant density on soybean lodging resistance and growth dynamics in maize-soybean strip intercropping

Quantifying the effects of plant density on soybean lodging resistance and growth dynamics in maize-soybean strip intercropping

Recent soybean subsidy policy did not revitalize but stabilize the soybean planting areas in Northeast China

With over 80 % of soybean demand dependent on imports, China has implemented multiple soybean stimulation policies to improve its soybean self-sufficiency. Northeast (NE) China, the leading soybean-producing region in China, produces more than half of the soybean in the country, and it is unclear whether agricultural policies had substantial effects on soybean planting areas and cropping patterns in NE China. Here, we generated annual crop maps at 10-m resolution in NE China during 2017–2021, and found that recent soybean producer subsidy policy released in 2017 has not revitalized but only stabilized the soybean planting areas in NE China, with a decline (−27.9 %) during 2020–2021 due to the high comparative benefits of maize cultivation. We found that a routine maize-soybean rotation system that might dominate the cropping patterns instead of the soybean subsidy policy. The effects of the routine rotation were more prevelant in the 2300–2700 ℃ d of the ≥ 10 ℃ accumulated temperature in NE China. The lower net profits of soybean than maize cultivation could be the major reason for the stagnant soybean planting areas, which could be attributed to the low yield of soybean and could not turn the tide only rely on limited producer subsidies. The soybean producer subsidy led to a stabilization of soybean planting areas, which could pave the way for future growth, and further actions are needed to stimulate soybean production in NE China, for example, maize-soybean rotation and maize-soybean strip intercropping which could achieve both productivity and sustainability.

Maize–legume intercropping promote N uptake through changing the root spatial distribution, legume nodulation capacity, and soil N availability

Legume cultivars affect N uptake, component crop growth, and soil physical and chemical characteristics in maize–legume intercropping systems. However, how belowground interactions mediate root growth, N fixation, and nodulation of different legumes to affect N uptake is still unclear. Hence, a two-year experiment was conducted with five planting patterns, i.e., maize–soybean strip intercropping (IMS), maize–peanut strip intercropping (IMP), and corresponding monocultures (monoculture maize (MM), monoculture soybean (MS), and monoculture peanut (MP)), and two N application rates, i.e., no N fertilizer (N–) and conventional N fertilizer (N+), to examine relationships between N uptake and root distribution of crops, legume nodulation and soil N availability. Results showed that the averaged N uptake per unit area of intercrops was significantly lower than the corresponding monocultures. Compared with the monoculture system, the N uptake of the intercropping systems increased by 31.7–45.4% in IMS and by 7.4–12.2% in IMP, respectively. The N uptake per plant of intercropped maize and soybean significantly increased by 61.6 and 31.8%, and that of intercropped peanuts significantly decreased by 46.6% compared with the corresponding monocultures. Maize and soybean showed asymmetrical distribution of roots in strip intercropping systems. The root length density (RLD) and root surface area density (RSAD) of intercropped maize and soybean were significantly greater than that of the corresponding monocultures. The roots of intercropped peanuts were confined, which resulted in decreased RLD and RSAD compared with the monoculture. The nodule number and nodule fresh weight of soybean were significantly greater in IMS than in MS, and those of peanut were significantly lower in IMP than in MP. The soil protease, urease, and nitrate reductase activities of maize and soybean were significantly greater in IMS and IMP than in the corresponding monoculture, while the enzyme activities of peanut were significantly lower in IMP than in MP. The soil available N of maize and soybean was significantly greater increased in IMS and IMP than in the corresponding monocultures, while that of IMP was significantly lower than in MP. In summary, the IMS system was more beneficial to N uptake than the IMP system. The intercropping of maize and legumes can promote the N uptake of maize, thus reducing the need for N application and improving agricultural sustainability.

Appropriate Bandwidth Achieved High Yield Via Shrinking Maize Intraspecific Competition in an Additive Maize-Soybean Strip Intercropping

Appropriate Bandwidth Achieved High Yield Via Shrinking Maize Intraspecific Competition in an Additive Maize-Soybean Strip Intercropping

Modelling soybean and maize growth and grain yield in strip intercropping systems with different row configurations

Abstract Intercropping of two or more crop species increases the efficiency of resource use and often produces a greater yield per unit land area. The relative efficiency of intercropping depends on row configuration, but there is a shortage of modelling-based evaluation of alternative intercropping options due to the inadequacy of standard process-based crop models to simulate resource capture, growth and yield formation when the canopy is spatially structured in strips. We implemented a light interception model for strip crops into the APSIM Classic model and combined it with a quasi-Bayesian approach to derive the model parameters to simulate crop growth and grain yield in maize-soybean strip intercropping. We used 4 years of field data for 5 different row configurations to derive key model parameters for simulation of light interception, LAI dynamics, biomass growth and grain yield of maize and soybean intercrops. Key model parameters (e.g. RUE, k etc.) were found to change with row-spacing and configuration, posing challenges to simulate different configurations with a single parameter set. The potential ranges of these key parameters were derived by constraining the model to observed data. The model can be potentially used to evaluate impact of planting configurations on productivity of strip intercropping systems, but the variability of key model parameters among configuration treatments calls for further in-depth research to improve modelling physiology of strip intercrops.

Effect of shading on accumulation of soybean isoflavonoid under maize-soybean strip intercropping systems

ABSTRACTMaize-soybean strip intercropping system is an important ecological planting system; the wide development of intercropped soybean has contributed to the soybean industry in China. Soybean growth and seed production were affected by the shading from maize. Previous studies confirmed that relay strip intercropping shading facilitates the accumulation of isoflavone glucosides but does not take advantage of the accumulation of isoflavone aglycone. However, the regulation of isoflavones accumulation under strip intercropping system was unknown; in which soybean and maize were sown at the same time, and soybean was mainly shaded in the reproductive stage. In order to reveal the effects of intercropping shading on the isoflavones accumulation in soybean seed, two independent field experiments were conducted in eastern China. We compared the isoflavones profiles of soybean seeds, which were grown under various maize-soybean intercropping systems with different shade levels. The results showed that the intercropping shading was not benefited to the accumulation of soy-isoflavones, including aglycones and isoflavones glycosides and various forms of isoflavones were decreased with the decline of photosynthetic active radiation. Multivariate statistical analysis and significance analysis showed that acylated isoflavones may be more susceptible to intercropping shading.Abbreviations: HCA: Hierarchical cluster analysis; PAR: photosynthetically active radiation; PCA: Principal component analysis; LC-MS: Liquid chromatography mass spectrometer.

Relationships among light distribution, radiation use efficiency and land equivalent ratio in maize-soybean strip intercropping

Maize (Zea mays)-soybean (Glycine max) intercropping is popular in many developing countries because of its high land equivalent ratio (LER). However, very few studies have explored the reason of its high LER, and the relationships between light distribution and the variations in radiation use efficiency (RUE) and LER in different intercropping arrangements. In this study, we conducted field experiments with different row arrangements of intercropping patterns from 2013 to 2015. The three different strip intercropping (SI) row arrangements were 0.2 m, 0.4 m, and 0.7 m (SI1); 0.4 m, 0.4 m, and 0.6 m (SI2); and 0.6 m, 0.4 m, and 0.5 m (SI3) for maize row distance, soybean row distance, distance between maize and soybean rows, respectively. The results showed that, as compared to single row intercropping, the strip intercropping increased the PAR at top of soybean canopy by 1.42 (SI3), 1.67 (SI2) and 1.93 (SI1) times, and increased the PAR at maize leaves close to the ear by 1.02 (SI3), 1.11 (SI2) and 1.12 (SI1) times. Moreover, the increased PAR at crucial positions in SI potentially improved the photosynthetic rate (Pn) for maize leaves close to the ear and radiation use efficiency (RUE) of maize by 1.08 and 1.09 times (averaged by SI1, SI2 and SI3), respectively, and improved the Pn of leaves at top of canopy and intercepted PAR of soybean by 1.75 and 1.36 times (averaged by SI1, SI2 and SI3), respectively. Compared to monoculture, SI also enhanced the RUE of intercropped maize (by 1.18 times) and soybean (by 1.51 times), which compensated for the partial yield loss caused by decreased crop intercepted PAR. Overall, in SI, intercropped maize achieved 90% of the monoculture yield, and intercropped soybean achieved 47% of the monoculture yield. With the expanding gap width for growing soybeans under a fixed bandwidth (2 m), the increasing intercepted PAR of intercropped soybean alleviated the interspecific competition disadvantage of soybean, while the reduction of maize row width decreased the dominant interspecific competition of maize. By adjusting the distances, we suggest that the optimal gap width for growing soybeans is 1.6 m-1.8 m, and the best maize row distance is 0.4 m. The SI2 achieved LER of 1.42, representing the leading level in the world.