Abstract
The objective of this study was to assess the impact of the time and rate of co-incorporation of Chinese milk vetch (CMV) with chemical fertilizers on rice quality and associated factors in South China. Here, a pot experiment with an orthogonal design L(9) (3(3)) was conducted to study the effect of the co-incorporation practices on rice quality, leaf chlorophyll, nutrient uptake and soil property. Results showed that co-incorporation of CMV (5288 kg dry CMV ha(- 1)) with chemical fertilizers (108 kg nitrogen (N) ha(- 1), 23 kg phosphorus (P) ha(- 1), and 89 kg potassium (K) ha(- 1)) on 7 day before the early rice transplanting (T(4)) increased methionine and lysine contents by 29.2% and 46.4%, and increased starch and amylopectin by 10.3% and 11.6% compared with those at the conventional level of chemical fertilizer input (137 kg N ha(- 1), 30 kg P ha(- 1), and 56 kg K ha(- 1)) (T(0)), respectively (P < 0.05). This was likely attributed to interactions among leaf chlorophyll, N uptake and soil property. The statistical analyses indicated that grain N content, the transport coefficient for N, leaf chlorophyll, soil organic matter, pH, the relative abundances of Actinobacteriota, Patescibacteria, and Rozellomycota were significantly correlated with quality traits of rice grain (P < 0.05). Overall, the T(4) treatment can modulate leaf chlorophyll, N uptake, soil chemical and microbial properties, and further improve amino acid, starch compositions and contents of rice grain.