Effects of Late Sowing on Yield,Quality,Photosynthetic Source Succession and Loadability Characteristics of Rape
[Objective]This study aimed to explore the regulation mechanism of late sowing on succession of photosynthetic sources (leaf and silique shell),source loadability,yield and quality in rape.[Method]The experiment was conducted in the Dafeng District,Yancheng city of Jiangsu Province,and Nanjing of Jiangsu Province in 2022-2023.The main factors sowing dates were set up at 6 levels,October 17th (SD1),October 23rd (SD2),October 29th (SD3),November 4th (SD4),November 10th (SD5),and November 16th (SD6),and the secondary factors were two conventional varieties:Nannongyou 4 (strong cold resistance) and Zheyou 51 (medium cold resistance).The effects of different sowing dates on dynamic change characteristics of leaf area index (LAI),pod area index (PAI) and source succession,source loadability and rape yield and quality were investigated.[Result](1) The later the sowing dates,the younger the pre-winter seedling age,and the lower the overwintering survival rate.The latest safe date of late-sowing rapeseed in the lower reaches of Yangtze River was the end of October,and the pre-winter seedling age was more than 5 leaves.The sowing date was postponed to November,the leaf age of rape decreased to 1.2-3.6 leaves,and the average overwintering survival rate was less than 30％.The average overwintering rate of Nannongyou 4 in November was 30.9％,which was 14.5％ higher than that of Zheyou 51.(2) During the latest safe sowing period,the yield of rapeseed decreased significantly with the delay of sowing dates,and the decrease of plant silique number and 1000-seed weight were the most direct factors causing the decrease of oilseed yield.With the delay of sowing date,compared with SD1,the yield of SD2 and SD3 decreased by 9.6％ and 29.0％,the number of plant silique number decreased by 6.1％ and 23.9％,and the 1000-seed weight decreased by 4.4％ and 6.5％,respectively.The average content of fat and protein in Nannongyou 4 was 42.9％ and 25％,which in Zheyou 51 was 47.9％ and 22.7％,respectively.(3) With the delay of sowing dates,the maximum LAI and PAI of rape decreased significantly,the slow growth rate before LAI reaching the peak and the fast decline rate after LAI reaching the peak both decreased,and the rapid growth rate of PAI slowed down.The later the sowing dates,the earlier the LAI and PAI succession points (the lower the effective accumulated temperature),and the lower the LAI and PAI succession points (the lower the LAI and PAI succession point).The photosynthetic source and source succession dynamic characteristic values of Nannongyou 4 were generally better than those of Zheyou 51.(4) With the delay of sowing date,the leaf area decreased faster than the seeds yield and pod area,caused the leaf loadability gradually increased,while the silique loadability gradually decreased.Insufficient leaf source and seeds sink were the main reasons for the yield reduction of late sowing.The leaf and shell loadability of Nannongyou 4 was both higher than that of Zheyou 51.[Conclusion]Within the latest safe sowing period of rapeseed in the lower reaches of Yangtze River,it was advisable to select cold-resistant,high-yield and high-oil varieties with suitable photosynthetic source succession point and high source load,to reduce yield loss caused by late sowing.
rape (Brassica napus L.)late sowingleaf area indexpod area indexsuccession of photosynthetic sourcesloadabilityyieldquality
万方数据
维普
