Abstract:

To reveal the effects of floodwater temperature on morphology and physiology of rice seedlings, rice genotypes with different submergence tolerance were used: IR64Sub1 (tolerant), IR42 (sensitive), Gangyou 725 and Taiyou 398 (main cultivar). Seedlings were submerged twenty-five days after sowing at two water temperature for 0, 3, 6, 9 and 12 days. The results showed that the oxygen concentration in the 20℃ floodwater was higher than that in 30℃ floodwater, the oxygen concentration decreased drastically in 30℃ floodwater than 20℃ floodwater with in creasing submergence days. The shoot elongation percentage was higher when seedlings were submerged in 30℃ floodwater than 20℃ floodwater condition. The same response was found in the tolerant variety IR64Sub1, but the shoot elongation percentage was the lowest among four varieties. The difference in shoot elongation of IR42 between two floodwater temperature was biggest after 9-day and 12-day submergence. Non-structural carbohydrate concentrations and leaf SPAD value were lower under 30℃ floodwater temperature than 20℃temperature floodwater condition. This findings help to understand the cause of high survival of rice submerged in low temperature floodwater.

Key words: flooding, water temperature, sugar concentration, starch concentration, survival percentage

摘要：

为了研究淹涝水温对具有不同耐淹能力水稻材料形态和生理的影响,明确淹涝水温对水稻幼苗耐涝能力影响的机理,采用盆栽试验,选取导入耐淹基因的耐淹品种IR64Sub1和淹水敏感品种IR42以及耐淹能力较强的品种冈优725和泰优398,设计20℃和30℃两种水温进行淹水处理,淹水时间分为0, 3, 6, 9和12 d。结果表明较低淹水温度下,水中的溶氧量显著高于高水温处理;随着淹水时间延长,高水温处理溶氧量下降速度显著快于低水温处理。高水温条件下水稻幼苗株高增长率要显著高于低水温处理,虽然高水温处理下耐涝品种株高增长率也显著增加,但是增长量要显著低于其他材料。高水温处理水稻茎鞘内可溶性糖和淀粉消耗高于低水温处理,但随着淹水时间的延长两种温度处理间差异逐渐变小,较低的水温可以减少叶片叶绿素降解速率。因此,降低淹水温度可以提高淹水条件下水稻幼苗的成活率。以上结果揭示了低水温可以减少茎鞘的伸长,减少非结构性碳水化合物的消耗及叶绿素的降解,从而水稻淹涝后能维持较高的成活率。这些发现有助于理解较低洪涝水温下水稻存活更长时间的机理。

关键词: 洪涝灾害, 水温, 可溶性糖含量, 淀粉含量, 成活率