The effect of night chilling on gas exchange and chlorophyll fluorescence of two mango cultivars growing under two irradiances.
Elsheery N. I., Wilske B., Cao KunFang
Author Affiliation: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China.
Acta Botanica Yunnanica 30 : 447-456
Abstract : We investigated the effect of night chilling on the photosynthetic physiology of two cultivars of mango (Mangifera indica) 'Choke Anand' and 'Khieo Sawoei'. The potted mango seedlings of both cultivars were grown under the full light and 50% daylight for one year. In the following winter season (February 2006), the seedlings were moved to a cold storage room maintaining 4°C 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 (gs), and maximum photochemical efficiency of PSII (Fv/Fm), and increased non-photochemical quenching (NPQ) for both cultivars. Overall, the chilling-induced photosynthetic suppression was stronger in seedlings grown in full sunlight than in 50% daylight. The decrease in Fv/Fm was stronger in 'Khieo Sawoei' than in 'Choke Anand' cultivar, and the increase of NPQ was relatively higher in '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 recovery after seven days of termination of the chilling treatment. These results showed that 'Khieo Sawoei' was more sensitive to chilling than 'Choke Anand', and shading significantly alleviated the chilling-induced photoinhibition.