Effects of uniconazole on seedling quality and yield of different sowing density mechanical transplanting rice

In order to develop the suitable technology for seedling nursery and increase the yield of mechanical transplanting middleseason indica hybrid rice,the experiment of two factors of uniconazole and sowing density was conducted in plastic tray seedling nursery using the variety‘Huiliangyou 6',and then the effects of uniconazole and sowing density on seedling quality,transplant quality and yield of rice were researched.The results showed that the seedling quality decreased rapidly with the increasing of sowing density in the same chemical regulation treatment.There existed a decreasing trend in the number of roots,dry weight per 100 plants,basal stem width and root vigor.Meanwhile,the MDA content of seedling leaf was significantly increased.There was no significant difference in seed setting rate and 1 000-grain weight among the different sowing density treatments.The number of effective panicles showed an increasing trend within the sowing density range from 8 000 to 18 000 grains·m-2,but decreasing from18 000 to 30 000 grains·m-2.Finally,the yield of rice displayed the same trend as the number of effective panicles.The yield of 18 000 grains·m-2treatment was significantly higher than that of other treatments.There existed significant effects of uniconazole on seedling quality and yield of different sowing density.The method of soaking seeds with 100 mg·L-1uniconazole and spraying seedling leaf with 150 mg·L-1uniconazole in 2.5 leaf age was better than the other chemical regulation method and control.It not only significantly increased the seedling quality and transplant quality,but also promoted seedling turn green and increased the number of effective panicles,grains per pancile and seed setting rate significantly,so that the yield was significantly increased.Accroding to the characters of mechanical transplanting middleseason indica hybrid rice,soaking seeds with 100 mg·L-1uniconazole and spraying seedling leaf with 150 mg·L-1uniconazole in 2.5leaf age combined the sowing density of 18 000 grains·m-2was the better seedling nursery method.It can help to keep great seedling quality,transplant quality,and stabliz 1 000-grain weight and increase the number of effective panicles,grains per pancile and seed setting rate.The sink and its effective filling rate were significantly enhanced.Finally,the yield was significantly increased.