Influence of Wheat Straw Return on Yield and Grain Quality in Different Direct-Seeding Rice Production Systems

Abstract

Direct-seeding methods have received growing interest from rice growers. Wheat straw return is an important measure in rice-wheat rotation system. This study aimed to investigate the influence of wheat straw return on the yield and grain quality in different direct-seeding rice production systems. A split-plot design was adopted for the on-farm trial. The main plots were treated with and without wheat straw return. Dry and wet direct-seeding rice production systems were used in the split plots. The results showed that the yield of direct-seeding rice was reduced by 4.2–7.3% due to wheat straw return, which may be related to a negative effect of wheat straw return on the tiller number (p < 0.05) and biomass accumulation (p < 0.05). Additionally, the content of the amylose and protein of the grain of direct-seeding rice decreased by 4.3–5.5% and 6.0–6.8%, respectively, due to wheat straw return. Furthermore, wheat straw return increased the chalkiness area and the chalkiness degree of the grain of direct-seeding rice, which may be related to the reduced protein content of the grain. However, wheat straw return improved the taste score of the cooked rice (p < 0.05) and the breakdown of the rapid viscosity analyzer (RVA) parameters (p < 0.05), and reduced the setback of the RVA parameters, probably related to an increase in the stickness of the cooked rice (p < 0.05) caused by the reduced amylose content of the grain. When compared to a dry direct-seeding rice production system, a wet direct-seeding rice production system has advantages in the tiller number (p < 0.05) and biomass accumulation, thus increasing the yield and resulting in a lower content of protein and protein components, which reduces both the chalkiness area and chalkiness degree of the grain. However, by using the wet direct-seeding method, the amylose content of the grain improved; hence, the stickness of the cooked rice (p < 0.05) and the breakdown of the RVA parameters decreased, and the setback of the RVA parameters increased. The above results indicated that wheat straw return reduced the yield, nutritional quality, and appearance quality of direct-seeding rice but improved the cooking quality of the grain. Although using the wet direct-seeding method is beneficial to improving the yield, it negatively impacts the grain quality of direct-seeding rice.