Influence of different sowing date and harvest time on rice filling stage, yield and grain quality

Objective  To study the appropriate sowing time of different rice varieties, and ensure high quality and yield of rice.

Method  Six restorer lines and their 12 combinations were used as materials sowed on four dates (6 d intervals). The two-factor two-data without repeated observation model and LSD test were used to analyze differences of grain yield, grain filling stage, processing quality and appearance quality among different sowing dates and harvest periods.

Result  Sowing date significantly influenced brown rice rate of restorer line and had no significant effects on grain yield, grain filling period, milled rice rate, head milled rice rate, chalkiness rate and chalkiness. There was no significant difference among grain yields of Ⅱ-you combinations sowed on different dates. Yixiangyou combinations were significantly influenced at the 4th period, but weren't at the 1st-3rd period. Sowing date significantly influenced rice milling and appearance quality of hybrid combinations. Sowing delay reduced the brown rice rate, chalkiness rate and chalkiness degree, but didn's influence the total milled rice rate and head rice rate. Harvesting delay increased the brown rice rate, chalkiness rate and chalkiness degree, but reduced the total milled rice rate and head rice rate at the 4th period.

Conclusion  After March 27, sowing delay significantly decreased yield of restorer lines and hybrid combinations in Southern Sichuan Province, but not the ratio of length to width. The yield most significantly decreased for rice sowed from early to middle of April. Compared with restorer lines, sowing date has more influence on filling stage, rice milling quality and appearance quality of hybrid combinations. Delaying harvest time will cause poor processing quality and appearance quality of hybrid rice grains.