Effects of flooding stress on seed germination and physiological metabolism of peanut

Objective This study aimed to investigate effects of different flooding durations on the germination abi-lity and physiological metabolism of peanut seeds，so as to provide theoretical support for the research and development of flooding tolerance regulation technologies in peanuts.Method Two peanut varieties with different waterlogging tolerance—waterlogging-tolerant Yuhua 37 and waterlogging-sensitive Yuanza 9847—were selected as materials， and the peanut seeds that normally germinated without flooding treatments were taken as CK. Two flooding treatments （2-d and 4-d durations） were applied during the germination stage to measure physiological parameters including germination characteristics of seeds， post-treatment osmoregulatory substances content， antioxidant capacity， and respiratory enzyme activity across different treatments to analyze the effects of flooding stress on physiological metabolism of peanut at the germination stage.Result Flooding stress affected the germination quality of the two varieties，showing in the weakened germination potential，decreased germination rate， declined germination index， and vigor index，with the average germination time increased significantly （P<0.01）. The waterlogging-tolerant variety Yuhua 37 enjoyed significantly better germination potential， higher osmotic substance content and stronger antioxidant capacity under flooding stress compared with the waterlogging-sensitive variety Yuanza 9847. After flooding treatments for 2 days and 4 days，the germination potential of Yuhua 37 was 1.46 and 1.86 times that of Yuanza 9847； for Yuhua 37， the soluble sugar content was 36.60% and 28.50% higher，the soluble protein content was 30.42% and 6.54% higher， the triphosadenine （ATP） content was 19.65% and 219.36% higher，and the malondialdehyde （MDA） content was 13.26% and 31.43% lower compared with Yuanza 9847. With increasing flooding duration， Yuhua 37 showed decreased alcohol dehydrogenase （ADH） activity and increased the lactate dehydrogenase （LDH） activity，but in Yuanza 9847， both ADH and LDH activities increased，indicating that anaerobic respiration was differed between the two varieties under flooding stress—Yuhua 37 relied on lactic acid fermentation，while Yuanza 9847 relied on both ethanol fermentation and lactic acid fermentation.Conclusion Flooding stress during germination period affects the osmoregulatory substances content，antioxidant capacity and respiration of peanut seeds，leading to decreased germination potential and germination index，thereby influencing germination and seedling emergence quality of peanut. Under flooding stress， waterlogging-tolerant variety Yuhua 37 could keep a high osmoregulatory substances content， strong antioxygen ability and moderate respiration metabolism， so as to ensure that seeds maintain high germination ability under flooding stress.