Abstract
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.
Highlights
Shading conditions adversely affect flower-number and pod-number of soybeans under maizesoybean relay-intercropping (MSR)
Our findings showed that the mean maximum soybean seed-yield was produced under treatment sole soybean (SS), while in leaf removal treatments under MSR, the average highest soybean seed-yield was measured in R6, with an improvement of 30% in 2017 and 27% in 2018 as compared to R0 (Table 3)
Our results revealed that different leaf defoliation levels had positive effects on soybean growth and development in MSR
Summary
Shading conditions adversely affect flower-number and pod-number of soybeans under maizesoybean relay-intercropping (MSR). 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 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. Soybean is a responsive crop to shading conditions[9], and under MSR soybean plants suffer from maize shading, especially during their co-growth phase from germination to flowering[8,10] which increased the seedling height[11] and reduced the initial dry matter edu.cn) www.nature.com/scientificreports/. Shading conditions reduce the plant growth rate, decrease the flower, and pod number in soybean[25].
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