Effect of Rewatering on Chlorophyll Content of Platycladus orientalis Seedlings After Drought

A pot experiment was conducted to investigate the influence of different degree of drought stress and soil water after rewatering on chlorophyll content of one-year-old Platycladus orientalis seedlings. The drought resistance response of chlorophyll content of P. orientalis seedlings and the recovery and compensation effect of rewatering were investigated. The findings indicated that with the extension of drought stress time, the chlorophyll content of P. orientalis seedlings decreased slowly, and with the aggravation of soil water stress degree, the chlorophyll content decreased first and then increased. The chlorophyll content of seedlings under 40% soil relative water content with 60 d drought stress decreased compared with control. The content of chlorophyll a, chlorophyll b, total chlorophyll and chlorophyll a/b decreased 15.4%, 14.0%, 15.1% and 1.6% respectively, the P. orientalis seedlings chlorophyll content showed a compensation effect and chlorophyll fluorescence values had risen up to the control treatment level after the 3d of rewatering. The chlorophyll a, chlorophyll b and total chlorophyll of P. orientalis seedlings growing in 70% soil relative water content condition increased 24.8%, 30.1% and 25.8% after 9d of rewatering, while chlorophyll a/b decreased 4.0% compared with control. Different duration of drought stress and different degree of soil water stress have an effect on the chlorophyll content of P. orientalis seedlings, however, P. orientalis seedlings gradually adapted to this stress conditions by adjusting their own physiological response mechanism, and recover timely after rewatering which showed a compensation effect.