低温逆境对马铃薯叶片光合作用的影响

Effects of low temperature stress on photosynthesis in potato leaves

为评价低温胁迫下不同马铃薯品种的光合适应性,以7个马铃薯普通栽培品种和2个湖南马铃薯地方种为材料,分析低温(5、10℃,以20℃为对照)对马铃薯光合作用的影响。结果表明:马铃薯净光合速率随环境温度的降低而下降,所有供试材料表现出相同的变化趋势,但不同材料之间的下降幅度存在差异,与20℃相比,金山薯、中寨黄皮、中薯3号和中薯5号10℃时最大净光合速率的下降幅度分别为51.0%、33.4%、44.5%和42.6%,费乌瑞它和湘马铃薯1号的下降幅度均为14%～17%,以上供试材料与对照的差异均达显著水平(P<0.05),克新系列(1、3、4号)的降幅在4.5%以内,与对照的差异无统计学意义(P﹥0.05);10℃下所有供试马铃薯材料的表观量子速率、光饱和点、光补偿点、气孔导度和蒸腾速率均显著低于对照(P<0.05),费乌瑞它、中薯3号和湘薯1号在5℃时的最大净光合速率分别为9.85、7.54、5.13μmol/(m2/s),以上3种材料的气孔导度为对照的25%～30%,其他供试马铃薯材料的光合作用则基本停止;随着环境温度由20℃降到5℃,马铃薯叶片胞间CO2浓度先下降后升高。综合考虑,认为5℃下马铃薯光合作用的特点可以作为对其进行耐寒性评价的依据。

The effects of low temperature stress on photosynthesis in leaves of seven regular potato cultivars and two Hunan endemic potato species have been studied. The results showed that the photosynthetic rate （Pn） was significantly reduced with decreasing environmental temperature for all the species, however, every species exhibited different declining rate. For example, the maximum net photosynthetic rates（Pnmax） between 10 ℃ and 20 ℃ treatments of Jinshanshu, Zhongzaihuangpi, Zhongshu3, Zhongshu5, Xiangshul, Favorita were reduced by 51.0%, 33.4%, 44.5%, 42.6%, 14% and 17% respectively, where the Pnmax variations in these two groups of treatments reach significant level（P〈0.05）. On the other hand, the decreasing rates of Pnmax Of Kexin series （1, 3, 4） were within 4.5% , and insignificant variations were found between 10 ℃ and 20 ℃ treatmetus（P 〉 0.05）. The apparent quantum yield（AQY）, the light saturation points（LSP）, the light compensation points（LCP）, stomatal conductance（Gs） and transpiration rate （Tr） were significantly decreased under 10 ℃ temperature stress（P〈0.05）.The Pnmax values of Favorita, Zhongshu3 and Xiangshul under 5 ℃ temperature stress were 9.85, 7.54, 5.13 μmol/（m2·s） respectively, while Pn values of the other materials were essentially zero. Increased intercellular CO2 concentration （Ci） were observed after an obvious declination when the environmental temperature decreased from 10 ℃ to 5 ℃. The above results indicate that the photosynthetic rateunder 5 ℃ low temperature stress can be served as a promising index in for evaluation of seedling cold tolerance.