Abstract
Drought stress is a key environmental factor limiting the growth and productivity of plants. The purpose of this study was to investigate the physiological responses of Camptotheca acuminata (C. acuminata) to different drought stresses and compare the drought tolerance between the provenances Kunming (KM) and Nanchang (NC), which are naturally distributed in different rainfall zones with annual rainfalls of 1000–1100 mm and 1600–1700 mm, respectively. We determined relative water content (RWC), chlorophyll content [Chl(a+b)], net photosynthesis (Pn), gas exchange parameters, relative leakage conductivity (REC), malondialdehyde (MDA) content and superoxide dismutase (SOD) and peroxidase (POD) activities of C. acuminata seedlings under both moderate (50% of maximum field capacity) and severe drought stress (30% of maximum field capacity). As the degree of water stress increased, RWC, Chl(a+b) content, Pn, stomatal conductance (Gs), transpiration rate (Tr) and intercellular CO2 concentration (Ci) values decreased, but water use efficiency (WUE), REC, MDA content and SOD and POD activities increased in provenances KM and NC. Under moderate and severe drought stress, provenance KM had higher RWC, Chl(a+b), Pn, WUE, SOD, and POD and lower Gs, Tr, Ci, and REC in leaves than provenance NC. The results indicated that provenance KM may maintain stronger drought tolerance via improvements in water-retention capacity, antioxidant enzyme activity, and membrane integrity.
Highlights
Drought stress is a key environmental factor limiting the growth and productivity of plants (Chaves and Oliveira, 2004)
Compared to the non-stressed seedlings, the Chl(a+b) content of the leaves in provenance NC decreased by 56.9% under severe drought stress, whereas the Chl(a+b) content in provenance KM decreased by only 48.4% under severe drought stress (Figure 1C)
Our results clearly suggest that C. acuminata provenance KM, which grows in a lower rainfall area, maintained stronger drought tolerance than provenance NC, which grows in a higher rainfall area, by increasing antioxidant enzyme activity and alleviating membrane permeability and lipid peroxidation
Summary
Drought stress is a key environmental factor limiting the growth and productivity of plants (Chaves and Oliveira, 2004). It is true for perennial tree species because they will likely face several water shortages during their lifespan (Perdiguero et al, 2013). Understanding the adaptive responses of tree species that will face these situations is of the utmost interest for plant production. Drought stress has adverse effects on trees, including leaf water loss, growth inhibition, decreased photosynthetic activity, damaged organelle structures, induced chlorophyll degradation and even accelerated aging processes (Munne-Bosch et al, 2001; Lei et al, 2006; Xiao et al, 2009).
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