基于时积温的水稻耐热性鉴定方法研究

Identification method for heat resistance of rice based on accumulated hourly temperature

【目的】研究水稻受高温危害时时积温与其颖花相对结实率的关系,探讨水稻耐热性鉴定方法,为指导水稻耐热新品种鉴定选育提供参考。【方法】以超级稻桂两优2号、优质杂交稻良丰优339和耐热品种N22为材料,利用人工气候室进行控温盆栽,设置不同温度胁迫水平(35和38℃)及胁迫持续时间(2、4、6、8和10 d),产生不同的危害时积温,采用实时抽出穗标记法测定高温胁迫处理下的颖花结实率,以自然条件生长植株的结实率为对照,测定颖花相对结实率。【结果】随高温胁迫的加重,各水稻品种的颖花结实率均逐渐降低;采用32℃为危害温度阈值,时积温与相对结实率间呈负指数关系(Y=116.7e^-0.01x),r^2=0.84*,P<0.05),以相对结实率为50%测算的时积温约85℃·h,其对应的温度胁迫处理为35℃连续处理5 d或38℃连续处理3 d,此时的实际时积温为90℃·h。【结论】利用人工气候室进行水稻开花期高温处理,在自然光照、相对湿度80%条件下,38℃高温连续处理3 d,每天9:30~15:30温度恒定连续处理6 h,达到危害时积温90℃·h,以自然条件下生长植株的结实率为对照,计算其相对结实率。该指标可科学有效地鉴定区分水稻品种间的耐热性差异。

[Objective ]The relationship between accumulated hourly temperature and spikelet fertihty rate was studied to explore evaluation method for rice heat resistance, in order to provide reference for identification and breeding of new heat-tolerant rice varieties. [Method ]Using super rice Guiliangyou 2, high-quality hybrid rice Liangfengyou 339, and heat-resistant rice variety N22 as materials, the pot experiments were conducted in phytotron by setting different stress temperatures （35 and 38 ~C） and continuous stress times （2, 4, 6, 8, 10 d）, resulting in generating different accumulated hourly temperatures, and the spikelet fertility rate was determined using real-time heading panicle label method under different heat-stress treatments, with relative spikelet fertility rate in natural environment as CK. [ Result]The results showed that, the spikelet fertility rate of all rice varieties decreased gradually with increase of heat stress. Taking 32℃ as heat-stress temperature threshold, there was a negative exponential relationship between accumulated hourly temperature and relative spikelet fertility rate （Y=116.7e-0.01x, r2=0.84＊, P〈0.05）. When the relative spikelet fertility rate was 50%, the calculated accumulated hourly temperature was 85℃·h, and the corresponding temperature-stress treatments were at 35 ℃ for 5 continuous days or 38℃ for 3 continuous days, resulting in actual accumulated hourly temperature up to 90℃ oh. [Conclusion]Pot experiments can be conducted in phytotron with natural lighting and relative humidity of 80%, the rice plants are treated with temperature-stress of 38 ℃ for 3 continuous days from 9：30 to 15：30 per day, with accumulated hourly temperature of 90 ℃ .h, using rice plants in natural environment as CK, then the relative spikelet fertility rate is calculated. Therefore, the evaluation method for rice heat resistance is scientific and effective with relative spikelet fertility rate as evaluation index.