| The experiments were carried out at Yangzhou (with cv. Yangmai158. 9356 and Ningmai9th as material) and Donghai (with cv. Wanmai38, 9356, Xuzhou25 as material) in Jiangsu province from 1999 to 2001. The seven sowing dates were set up to study on the influence on growth safety, grain yield and its components, grain quality in wheat. The results showed as follows:According to the mean temperature of December to February, warm winter (0.5 more then mean of all year), normal winter and cold winter (0.5 less then mean of all year) types were classified for weather data of Yangzhou from 1954 to 2001 and from 1983 to 2001. Recently ten years, there were seven years warm winters and three normal winters in Yangzhou, four warm winters and five normal winters in Donghai. The wheat growing season is prone to warm. The wheat growth were impacted significantly. According to key factors to wheat growing, for example, the first day of mean temperature less 0 , exceeding 3 and exceeding 10 , it showed the delaying wintering, early regreening, the ability of resisting frost descended.The days of all growth stages in wheat were shortened with the delay of sowing date. The jointing stage, heading stage and maturity were delayed respectively. As the jointing dates had change remarkably, the days from sowing to jointing were increased , the days of jointing to heading were shorted extremely and the days of heading to ripening had prolonged slightly in springness wheat with the delay of sowing dates. As the jointing date were stability, the days from sowing to jointing were shorted extremely, the days from jointing to heading and from heading to ripening were increased slightly in half winterness wheat with the delay of sowing dates.According to the wheat clock model, the temperature and light model were established about different varieties. Combining with weather data, the earliest criticalsowing dates were analyzed on the different wheat in Yangzhou and Donghai. Under the 70% of guarantee, the earliest critical sowing date of safety jointing on springness wheat was from October 26 to October 28 in Yangzhou, on wintemess wheat was from September 28 to September 30 and springness wheat was October 23 in Donghai.Wheat yield were regulated remarkably at different sowing dates. The relationship of yield and the sowing date appeared square curve. The sowing dates of maximum yield were different because of locations and varieties. According to the relationship of accumulated temperature( 0 ) before winter and yield, refer to the data of weather data. The appropriate sowing dates of Yangmai158, 9356 and Ningmai9th were from October 19 to November 4, from October 21 to November 5 and from October 14 to October 29 in Yangzhou, respectively. The appropriate sowing dates of Wanmai38. 9356 and Xuzhou25 were from September 24 to October 18, from October 16 to October 22 and from September 30 to October 22 in Donghai, respectively.Different sowing dates had some impact on quality of the wheat of bulk density, flour yield, the protein content, dry and wet gluten content, the starch content, the ratio of amylose and amylopectin. There were different in varieties. With the delay of sowing dates, bulk density and flour yield increased obviously in Yangzhou. But in Donghai bulk density and flour yield declined slightly. Except for freezing injury, with the delay of sowing date, the protein content increased. The content of amylose firstly went up then went down. With the delay of sowing date, the content of amylopectin added in Yangzhou. The content of amylopectin of wanmai38 firstly went up then went down, 9356 and xuzhou25 firstly went down then went up. Except for wanmai38, ratio of amylopectin contents and amylose contents firstly went down then went up with the delay of sowing dates. Without freezing injury, soft gluten wheat should be sowed early, the moderate and strong gluten wheat should be sowed later.According to safety, high yield and good quality, the springness wheat, cv. Yangmai158, 9356 and Nuigmai9th, should be... |
