Abstract:

In order to explore the effects of paclobutrazol and uniconazole on the cold resistance of a new rapeseed cultivar ‘Qinyou 1618’, seedlings at 6-7 leaf stage were sprayed with 150 mg/L (C1) and 300 mg/L (C2) paclobutrazol, and 80 mg/L(C3) and 160 mg/L(C4) uniconazole, respectively. The effects of paclobutrazol and uniconazole on the growth regulation, physiological characteristics and cold resistance of seedlings were studied. The results showed that the treatment of 150 mg/L paclobutrazol (C1) or 80 mg/L uniconazole (C3) on the rapeseed seedlings at 6-7 leaf stage could effectively reduce the stem height, the stem and leaf dry matter amount, and the maximum leaf length and width, but had no significant effect on the number of green leaves. The treatments could effectively increase the root diameter, root length, lateral root number, root dry matter amount, and root-shoot ratio, thus forming strong seedlings. Under the treatments, the content of chlorophyll and soluble sugar and the net photosynthetic rate of leaves increased, while the relative electrical conductivity, the percentage of dead plants over winter and the freezing injury index decreased. Therefore, the cold resistance of the cultivar was improved.

Key words: rapeseed, Qinyou1618, paclobutrazol, uniconazole, seedling characteristics, cold resistance