Effects of S-3307 on Rice Grain Filling and Yield

The effects of S-3307 (Uniconazole) by soaking seeds or spraying at booting stage with different concentrations (0, 10,20,40 and 80 mg/L) on grain filling and yield were studied with the hybrid rice combination Shanyou 63 as the material. The results showed that S-3307 had different effects on superior and inferior grains. The filling of superior grains was inhibited, while that of inferior grains was promoted, so the weight of inferior grains was increased to some extent. The grain-filling processes of superior and inferior grains were simulated with Richards equation, i.e., W=A/(1+Be -kt) 1/N, and the grain-filling parameters were derived from this equation. In the equation parameters, the ultimate grain weight (A) was decreased and the time reaching the maximum filling rate (T max.G) was prolonged in superior grains after S-3307 treatment, but the filling duration (T) of inferior grains was lengthened, and the average filling rate (Va) and ultimate grain weight (A) of inferior grains were increased S-3307 increased rice yield through significantly increasing the grains per panicle and the grain dry weight per panicle. If the time of using S-3307 was different, the optimal concentrations were different. When the concentrations were 40 mg/L and 20 mg/L for soaking and spraying, respectively, the grain yield was highest.