Effects of returning wheat straw to farmland and irrigation pattern on grain setting traits and quality of super rice

Environmental conditions during grain filling stages can affect grain setting traits and quality of rice. To have high yield and quality of super rice, the effects of returning wheat straw to farmland and irrigation patterns on yield characteristics and qualities of superior and inferior grains of the super rice cultivar 'Yongyou 8' were investigated. Returning wheat straw to farmland included two treatments all wheat straw return (T1) and no wheat straw return (T0) while the irrigation patterns included three treatments alternate wetting and moderate soil drying (W1), in which soil was re-watered when 15?20 cm soil water potential reached ?20 kPa; alternate wetting and severe soil drying (W2), in which soil was re-watered when 15?20 cm soil water potential reached ?40 kPa; and water-saving irrigation (W0). The results showed that irrigation patterns significantly influenced grain setting traits during rice grain filling stage. Compared with the W0, W1 significantly enhanced 1000-grain weight, grain setting rate and grain plumpness index, while W2 showed the contrary effects. The grain setting traits of T1 treatment were better than those of T0. The interactions of T1 and W1 improved the grain setting traits of 'Yongyou 8'. Compared with T0, T1 increased head milled rice rate (HMRR), crude protein content (CPC) and setback viscosity (SBV), but decreased percentage of chalky kernel (PCK), chalkiness degree (CD), amylase content (AC), gel consistency (GC) and breakdown viscosity (BDV). Compared with W0, W1 increased HMRR, PCK, CD, GC, BDV while it decreased AC, CPC and SBV. However, rice grain quality was bad under W2 treatment. The regulatory roles of different treatments in inferior grains were significantly greater than those in superior grains on the grain quality. In the case of T1, W1 coordinated the relationship between the grain setting traits and rice grain quality of 'Yongyou 8'.