Effects of uniconazole rate on agronomic traits and physiological indexes of rapeseed blanket seedling

Mechanized transplanting of rapeseed(Brassica napus L.)blanket seedling is an innovative cultivation technology.Cultivating high quality blanket seedling to ensure high survival rate of seedling after transplanting is the key of the technology.The effects of different uniconazole rates of 0,0.5,1.0,1.5 and 2.0 mg/tray,spraying at one leaf and one heart stage,on selected agronomic traits,physiological indexes and survival rate of two rapeseed cultivars(‘Qinyou 100 and’Yangyou 90)were investigated in 2018 and 2019.Our results showed that the plant height decreased significantly with the increase of uniconazole rate.However,the collar diameter increased significantly with the increase of uniconazole rate up to 1.5 mg/tray,and the leaf area,dry weights of root and shoot increased with increased uniconazole rate up to 1.0 mg/tray.The root to shoot ratios,N concentrations of root and shoot with the uniconazole rates of 1.0 and 1.5 mg/tray were higher than those with other treatments.As uniconazole rate increasing,gibberellin(GA)and auxin(IAA)concentrations of root and shoot decreased,while abscisic acid(ABA)concentrations increased,and cytokinin(CTK)concentrations topped at uniconazole rate of 1.0 mg/tray and decreased thereafter.The seedling survival rates with 1.0 and 1.5 mg/tray were greatly higher than those in other treatments.Regression analysis suggested plant survival rate was positively related to CTK concentrations and negatively to GA concentrations of root and shoot.To achieve high survival rate after mechanized transplanting,our study revealed that the uniconazole applied at a rate of 1.0 mg/tray was recommended as the best,followed by 1.5 mg/tray.The findings would help to enhance qualities of rapeseed blanket seedling and to promote popularization of mechanized transplanting of rapeseed production.

Effect of N-fertilizer Application on Yield,Grain Quality and N-fertilizer Use Efficiency of the Rapeseed Cultivars with Normal and High Oil Content

In this study,seed yield,quality and N-fertilizer use efficiency in rape(Brassica napus L.) were researched in normal oil content cultivar(Yangyou 6) and two high oil content cultivars(Zhongshuang 11 and Zheyou 50). Results showed that the average oil content of all treatments in Yangyou 6,Zhongshuang 11 and Zheyou 50 was 42. 87%,47. 37% and 48. 28%,respectively. The average protein content of all treatments in Yangyou 6,Zhongshuang 11 and Zheyou 50 was 24. 15%,22. 71% and 21. 84%,respectively. The increased ratio of total nitrogen accumulation amount in Yangyou 6 was higher than that in Zhongshuang 11 and Zheyou 50. Among three cultivars,the total protein accumulation amount in Yangyou 6 was highest,and the total oil accumulation amount was highest in Zheyou 50. With increasing nitrogen fertilization,the value of different parameters of N-fertilizer use efficiency decreased. The average N use efficiency in Yangyou 6 was 68. 70%,which was higher than that in Zhongshuang 11 and Zheyou 50(65. 06% and 60. 30%,respectively). The average N-fertilizer agronomic use efficiency in Yangyou 6 was also highest among three cultivars,which was 8. 97 kg seed / kg N. On the contrary,the average N-fertilizer physiological use efficiency in Zhongshuang 11 and Zheyou 50 was 13. 03 kg seed / kg N and 13. 84 kg seed / kg N,respectively,which was higher than that in Yangyou 6(12. 91 kg seed / kg N). Differences in partial factor productivity of N-fertilizer were slight among three cultivars.