Effects of drought and rewatering on growth and photosynthetic physioecological characteristics of Xanthoceras sorbifolia.

Abstract

An experiment was conducted to examine the effects of drought and rewatering on growth and photosynthetic physioecological characteristics of Xanthoceras sorbifolia, with 2-year-old seedlings as test materials. There are three treatments, i.e., light drought stress (soil water content 14.3%-16.2%), moderate drought stress(10.6%-12.5%) and severe drought stress (6.8%-8.7%), with the control (21.8%-23.7%). The results showed that with the increases of drought stress, the dry mass per plant, height, basal diameter, leaf number, and leaf area significantly decreased, and length of the main root and the secondary root increased. The gas exchange parameters gradually decreased with the increases of drought stress. The level of Pn was caused by stomatal factors from 10:00 to 14:00 and by non-stomatal factors after 14:00. Apparent CO2 use efficiency (CUE) of X. sorbifolia was obviously increased under the moderate and severe drought stress. With the increases of drought stress, Fv/Fo, Fv/Fm, qP, ETR and ФPS2 gradually decreased, and NPQ gradually increased. The changes of all those characters after rewatering were contrary to those after drought. After rewatering for eight days, Fv/Fo, Fv/Fm, qP, ETR, ФPS2 were significantly higher than that of drought stress treated for 30 days. With the increases of drought stress, SOD and POD activities and MDA content gradually increased, but CAT activity decreased, showing the contrary changes after rewatering. After rewatering, the root activity under drought stress increased. X. sorbifolia was strongly resistant to heavy drought stress, and thus could be widely used as energy or garden plants in garden landscaping in North China.