Abstract: A water control experiment of potato was conducted in Shenyang Agricultural University from April to July, 2021. Potato flowering period and tuber expansion period were selected, and the mild drought (relative soil moisture during flowering period is 50% and that during tuber expansion period is 60%), moderate drought (relative soil moisture during flowering period is 40% and that during tuber expansion period is 50%) and severe drought (relative soil moisture during flowering period is 30% and that during tuber expansion period is 40%) and control (relative soil moisture during flowering period is 70% and that during tuber expansion period is 80%), rewatering treatment was carried out after 5 days of drought at all levels in each growth period, and the rewatering level was controlled to the control level. The effects of drought stress and post-drought rewatering on photosynthetic characteristics, chlorophyll fluorescence, growth and yield of potato were studied. The results showed that the stomatal conductance and net photosynthetic rate of leaves under drought stress during flowering and tuber expansion period were significantly lower than those under control, moreover, the photochemical quenching coefficient and light energy conversion ratio of leaf photosystem II were significantly decreased, whereas the non-photochemical quenching coefficient was significantly increased. Rewatering after 5 days of mild drought during flowering period, the leaf net photosynthetic rate increased by more than 20% compared with that of drought treatment, but the recovery degrees under moderate and severe drought during tuber expansion period were very small. Leaf area index and dry matter weight decreased by 17.6%−50.3% and 23.4%−51.4% under different drought treatments compared with control. Compared with the control, the potato yield under different drought treatments decreased by 1.0%−19.6% during flowering period, whereas that decreased by 8.6%−30.5% during tuber expansion period. The reduction in potato yield caused by drought during tuber expansion period was greater than that during flowering period. In conclusion, drought stress can inhibit the growth process of potato leaves, reduce photosynthetic products, and ultimately lead to the reduction in yield. Rewatering in time can alleviate the effects of drought stress on potato and achieve the stable and high yield of crops.

Key words: Potato, Drought stress, Post-drought rewatering, Photosynthetic characteristics, Chlorophyll fluorescence, Growth and yield