Abstract:

Shandong is a typical planting area of spring potato in China. Spring potato is susceptible to occasional low temperature injury at the seedling stage, which has become an important abiotic stress factor in potato production in Shandong Province. If there are no remedial measures taken on low temperature or cold damage, the potato yield will be reduced or the yield will be ruined. In this study, the low temperature stress of potato at -2℃ was simulated, after 3 days of low temperature stress, 0.2%, 0.4%, 0.6% and 0.8% humic acid was sprayed. By detecting the physiological and biochemical indicators of potatoes after spraying different concentrations of humic acid, the mitigation effect of spraying humic acid on chilling injury of potatoes was explored and the best spraying concentration of humic acid was found out. The results showed that, under low temperature stress, spraying humic acid could increase the water content of potato leaves, reduce the electrical conductivity of leaves, which could resist chilling injury; at the same time, spraying humic acid could increase the leaves^, chlorophyll content, enhance the photosynthetic capacity; under low temperature stress, spraying humic acid significantly affected the potato leaves antioxidant system at seedling stage, which was manifested by increasing the potato leaves soluble protein content, improving the potato leaves^, antioxidant enzyme activity, reducing the accumulation of peroxides in plants, ensuring the normal oxidation reduction potential in plants, and enhancing their cold resistance. The effect of spraying 0.6%-0.8% humic acid on growth of recovering plant was better, and the effect of spraying 0.4%-0.6% humic acid on improving the activity of leaf antioxidant system enzymes was better.

Key words: low temperature stress, potato, humic acid, soluble protein, chlorophyll, antioxidant enzyme, per oxidation substance