We investigated the effect of night chilling on the photosynthetic physiology of two eultivars of mango ( Mangifera rnindica) 'Choke Anand' and 'Khieo Sawoei'. The potted mango seedlings of both cultivars were grown under the full light rnand 50% daylight for one year. In the following winter season (February 2006), the seedlings were moved to a cold storrnage room maintaining 4℃ for seven consecutive nights and returned to their original places during the rest of the day. Photosynthetic physiology was measured before, during the treatment, and during 10 days after the treatment. Chill-night treatment resulted in strong suppression in net photosynthesis ( Pn ), stomatal conductance ( g, ), and maximum photochemical rnefficiency of PSU ( Fv/Fm ), and increased non-photochemical quenching (NPQ) for both cultivars. Overall, the chillingrninduced photosynthetic suppression was stronger in seedlings grown in full sunlight than in 50% daylight. The decrease in rnFv/Fm was stronger in 'Khieo Sawoei' than in 'Choke Anand' cultivar, and the increase of NPQ was relatively higher in rn'Choke Anand' compared to 'Khieo Sawoei' cultivar. Night chilling resulted in a decrease in chlorophyll content and increase in the carotenoid: chlorophyll ratios, the malondialdehyde (MDA) contents, membrane leakage, as well as compatible solutes (total soluble sugar and proline) under both irradiances. After termination of the chilling treatment, the recovery of Fv/Fm was relatively quicker in 'Choke Anand' than in 'Khieo Sawoei' cultivar. Both cultivars showed a complete rnrecovery after seven days of termination of the chilling treatment. These results showed that 'Khieo Sawoei' was more senrnsitive to chilling than 'Choke Anand', and shading significantly alleviated the chilling-induced photoinhibition.%研究了夜间低温对两个芒果(Mangifera indica)品种翡翠芒(Khieo Sawoei)和四季芒(Choke Anand)光合生理的影响.两个芒果品种的幼茼盆栽于全光和50%相对光强下一年.在第二年的冬季,连续7天晚上将芒果幼苗移到4℃的冷库中,白大保持原条件.于低温处理前、处理期间和结束低温处理后10天中测定芒果幼苗的光合生理特征.结果表明,夜间低温导致两个芒果品种的净光合速率、气孔导度和光系统Ⅱ的最大光化学效率(Fv/Fm)降低、非光化学猝灭(NPQ)上升.夜间低温对生长在全光下的芒果幼苗光合作用的抑制比50%光下的更重.翡翠芒的Fv/Fm比四季芒下降的更多,但后者的NPQ上升更多.夜间低温还导致两种光下芒果幼苗叶片的叶绿素含量下降,类胡萝卜素/叶绿素比值、丙二醛含量、膜的透性和可溶性化合物(可溶性总糖和脯氨酸)上升.解除低温胁迫后,四季芒Fv/Fm的恢复比翡翠芒的快.解除低温胁迫7天后二者的F发、Fv/Fm能完全恢复.上述结果表明,翡翠芒对低温更敏感,遮荫可以明显缓解两个芒果品种低温引起的光抑制.
展开▼
