| Due to the foehn effect and topographical enclosure, the valleys in the mountainous areas of southwestern China have a special dry and hot climate, and host savanna or semi-savanna vegetations. Plants grown in these valleys often suffer from multiple stresses mainly including drought, high radiation and high temperature, and they may develop various complicated mechanisms to adapt these stressful habitats during the long-term evolution. In the present study, we investigated the ecophysiological responses to different levels of water deficit and light intensity in two-year-old seedlings of Terminthia paniculata, which is one of the dominant species in Yuanjiang savanna valley. The physiological adaptive mechanisms of T. paniculata seedlings to drought and high irradiance and the interactions of soil moisture and light intensity were explored. In addition, we examined the relationships between leaf reflectance data and various leaf physiological parameters by statistical correlation analyses, in order to test the feasibility of leaf reflectance measurements as a rapid and nondestructive approach for assessing plant physiological status. Two light levels (100% and 50% daylight) and 4 different water treatments (soil relative water contents were kept at 85%～90%, 65%～70%, 45%～50% and 25%～30%, respectively) were used in our experiment. One month after drought treatments initiated, leaf water status, gas exchange, chlorophyll fluorescence, leaf reflectance, photosynthetic pigment contents, leaf mass area, saturated osmotic potential, relative conductivity, free proline contents, malondialdehyde (MDA) contents and antioxidant enzyme activity of the seedlings were measured. The results showed that:(1) Leaf relative water content (RWC) and leaf water potential (Ψ) declined with increased level of water deficit. However, none of them declined by a large extent, and the magnitude of decrease in RWC was much less than that inΨ. These results indicated...
|
PDF Full Text Request