Exploring the effects of sowing date and ecological points on the yield of semi-winter wheat is of great significance.  This study aims to reveal the effects of sowing date and ecological points on the climate resources associated with wheat yield in the Rice–Wheat Rotation System.  With six sowing dates, the experiments were carried out in Donghai and Jianhu counties, Jiangsu Province, China using two semi-winter wheat varieties as the objects of this study.  The basic seedlings of the first sowing date (S1) were planted at 300×10⁴ plants ha⁻¹, which was increased by 10% for each of the delayed sowing dates (S2–S6).  The results showed that the delay of sowing date decreased the number of days, the effective accumulated temperature and the cumulative solar radiation in the whole growth period.  The yields of S1 were higher than those of S2 to S6 by 0.22–0.31, 0.5–0.78, 0.86–0.98, 1.14–1.38, and 1.36–1.59 t ha^–1, respectively.  For a given sowing date, the growth days increased as the ecological point was moved north, while both mean daily temperature and effective accumulative temperature decreased, but the cumulative radiation increased.  As a result, the yields at Donghai County were 0.01–0.39 t ha^–1 lower than those of Jianhu County for the six sowing dates.  The effective accumulative temperature and cumulative radiation both had significant positive correlations with yield.  The average temperature was significantly negatively correlated with the yield.  The decrease in grain yield was mainly due to the declines in grains per spike and 1 000-grain weight caused by the increase in the daily temperature and the decrease in the effective accumulative temperature.

Mechanical transplanting with carpet seedlings (MC) and mechanical direct seeding (MD) are newly developed planting methods, which increase in popularity and planted area each year. Knowing the difference for yield and rice quality under different planting methods is of great importance for the development of high quality and yield cultivation techniques under mechanical conditions. Therefore, three kinds of japonica rice including hybrid japonica rice, inbreed japonica rice, and soft rice were adopted as materials. And the differences in the quality of processing, appearance, cooking and eating quality, nutrition, and the rapid viscosity analyzer (RVA) profile were studied to reveal the effects of planting methods on yield and quality of different types of japonica rice. Results showed that the milled rice and head rice rates under MC was significantly higher than those under MD, and the processing quality of inbreed japonica rice was the most stable. Compared with MC, length/width ratio of rice under MD was significantly increased, and chalkiness rate, size, and degree were significantly decreased. The protein content under MD was lower than that under MC. MC showed higher peak viscosity and breakdown value than MD. The taste value was the greatest for soft rice, followed by inbreed japonica rice, and then by japonica hybrid rice, with no significant differences resulting from planting methods. Compared with MC, MD significantly improved the appearance quality, though processing quality and nutritional quality were decreased. And there was no significant difference in cooking and eating quality between MC and MD. Under different planting methods, the appearance quality of inbreed japonica rice changed the most and the processing quality was the most stable. The nutritional, cooking and eating quality of soft rice changed the least. Therefore, according to the different planting methods and market needs, selecting the appropriate rice varieties can reduce the risks in rice production and achieve good rice quality.