Responses of Soybean Dry Matter Production, Phosphorus Accumulation, and Seed Yield to Sowing Time under Relay Intercropping with Maize

Abstract

Soybean production under maize–soybean relay-intercropping system (MSICS) is vulnerable to shading. A study was initiated to investigate the effects of three sowing-times: ST1, 90; ST2, 70; and ST3, 50 days of co-growth period and two phosphorus-rates: P0, 0; and P60, 60 kg P ha−1 on soybean under MSICS. Results revealed that ST3 significantly increased the photosynthetically active radiations, leaf area index, and photosynthetic rate by 72% and 58%, and 61% and 38%, and 6% and 8%, respectively, at full-flowering and full-pod stage of soybean than ST1. Treatment ST3, increased the total dry-matter (TDM) and the highest TDM was reached at full-seed (R6) stage. Similarly, ST3 considerably increased the dry-matter partitioning to pods and seeds, relative to ST1, soybean under ST3 at R6 had 35% and 30% higher pod and seed dry-matter, respectively. Moreover, ST3 exhibited the maximum seed-yield (mean 1829.5 kg ha−1) for both years of this study. Soybean under ST3 with P60 accumulated 38% higher P, and increased the P content in pods and seeds by 36% and 33%, respectively at R6 than ST1. These results imply that by selecting the appropriate sowing-time and phosphorus-rate for soybean, we can increase the TDM and seed-yield of soybean under MSICS.

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

“…The planting time of soybean in MSRI not only influenced the growth, but it also affected the flowering time, and yield components (Table 2), our findings are consistent with the results of previous reports (Zhang et al, 2008). It is estimated that when maize and soybean co-growth duration increases from 50 days to 90 days, it significantly reduces the initial biomass of soybean (Ahmed et al, 2018), which at later stages considerably reduced the pods plant −1 , seed weight (g) and number of seeds plant −1 (Table 2), which in turn decreased the soybean seed yield in MSRI (Figure 4a,b), it might be due to the strong asymmetrical competition with maize for longer growth duration. Therefore, under MSRI, adjustments in the planting time of soybean can promote the growth and development of soybean plants, and by maintaining optimum co-growth duration, we can improve soybean biomass accumulation and seed yield by reducing the negative effects of maize shading on soybean plants.…”

“…In MSRI, when soybean emerges, the soybean seedlings come under maize shade and receive fever nutrients, light and water for its growth and development (Feng et al, 2019;Raza, Khalid, Zhang, Feng, et al, 2019). Thus, soybean grows abnormally because of strong aboveground competition from maize plants in MSRI ( Figure 5; Ahmed et al, 2018;Wu et al, 2017). In addition, the difference between the competitive abilities of soybean and maize in MSRI has been evident, and this competitive ability of intercrop species has changed with planting time due to the initial growth advantage of maize with changing planting time or with plant structure and size during the co-growth duration (Andersen et al, 2007).…”

Optimum leaf excision increases the biomass accumulation and seed yield of maize plants under different planting patterns

“…Improved photosynthetic characteristics are one of the major factors for biomass production (Raza et al, ). It had been described that TBA is directly related to PAR interception (Ahmed et al, ; Kiniry, Bean, Xie, & Chen, ). Differences in PAR interception changes the photosynthetic rate of maize plants and TBA, leaves at the middle strata or below the ear leaf being the major source of carbohydrates in maize (Maddonni & Otegui, ).…”

“…Differences in PAR interception changes the photosynthetic rate of maize plants and TBA, leaves at the middle strata or below the ear leaf being the major source of carbohydrates in maize (Maddonni & Otegui, ). Thus, decrease in PAR interception at the middle strata leaves can decrease TBA in maize plants (Ahmed et al, ; T. Liu et al, ). Previous results proposed that an optimum leaf excision (T 2 ) from maize plants after silking stage (R 1 ) under SM and MS R can increase TBA, which in turn increases the availability of assimilates for grain production (T. Liu et al, ).…”

Narrow‐wide‐row planting pattern increases the radiation use efficiency and seed yield of intercrop species in relay‐intercropping system

“…In most of the previous investigations, they examined the impacts of shading and light intensity on the yield parameters of sole‐cropped soybean (Feng et al, ; F. Yang et al, ). The soybean dry matter and yield in relay intercropping have been found to be lesser than sole‐cropped soybean (Ahmed et al, ). Therefore, it is important to evaluate an appropriate planting pattern (row spacing) which can enhance the resources efficiency in intercropping systems especially radiation use efficiency.…”