Responses of photosynthetic characteristics and dry matter formation in waxy sorghum to row ratio configurations in waxy sorghum-soybean intercropping systems

摘要

In intercropping systems, microclimate environment, especially light environment induced by row ratio configurations, is crucial to crop productivity. However, little information is available on how waxy sorghum canopy light environment is affected by row ratio configurations in waxy sorghum-soybean intercropping systems. Hence, field experiments were conducted in 2019 and 2020 to study the responses of photosynthetic characteristics, dry matter formation, and yield performance of waxy sorghum to seven treatments: sole waxy sorghum (SW), sole soybean (SS), two rows of waxy sorghum alternated with one row of soybean (2W1S), two rows of waxy sorghum alternated with two rows of soybean (2W2S), three rows of waxy sorghum alternated with one row of soybean (3W1S), three rows of way sorghum alternated with two rows of soybean (3W2S), and three rows of way sorghum alternated with three rows of soybean (3W3S). The results showed that intercropping increased the photosynthetically active radiation (PAR) and leaf area index (LAI) of waxy sorghum compared to SW treatment. This increase in PAR and LAI increased the photosynthetic characteristics of waxy sorghum canopy, including chlorophyll content (SPAD value), net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and stomatal limitation value (Ls). These changes resulted in increased dry matter accumulation, its distribution, and promoted the dry matter transportation from vegetative organs to grain in waxy sorghum. Likewise, intercropping increased the grain number per spike and 1000-grain weight of waxy sorghum, and ultimately increased the land equivalent ratio (LER). Moreover, the 2W1S treatment showed the most suitable light environments and greatest resource utilization to obtain the highest LER and economic benefits. Based on the present results, we suggested that the 2W1S should be used as optimal row ratio configuration of waxy sorghum-soybean system to attain maximum benefits.