Physiological responses to drought and shade in two contrasting Picea asperata populations

Abstract

The responses of photosynthetic gas exchange, chlorophyll fluorescence, activities of antioxidant enzymes and lipid membrane peroxidation of two contrasting Picea asperata Mast. populations to 30% of full sunlight (shade) and full sunlight (sun) were investigated under well-watered and drought conditions. Two contrasting populations were from the wet and dry climate regions in China, respectively. For both populations tested, drought resulted in lower needle relative water content (RWC), CO 2 assimilation rate (A), stomatal conductance (gs) and effective PSII quantum yield (Y), and higher non-photochemical quenching (qN), superoxide dismutase (SOD), ascorbate peroxidase (APX) activities as well as malondialdehyde (MDA) levels and electrolyte leakage in sun plants, whereas these changes were not significant in shade plants. For the wet climate population, shade plants showed higher chlorophyll contents (Chla, Chlb and Chla þ b) than sun plants under both well-watered and drought conditions. Our study results implied that shade, applied together with drought, ameliorated the detrimental effects of drought. On the other hand, compared with the wet climate population, the dry climate population was more tolerant to drought in the sun treatment, as indicated by less decreases in A and mass-based leaf nitrogen content (N mass ), more responsive stomata, greater capacity for non-radiative dissipation of excitation energy as heat (analysed by qN), and higher level of antioxidant enzyme activities as well as lower MDA content and electrolyte leakage. These results demonstrated that the different physiological strategies were employed by the P. asperata populations from contrasting climate regions when the plants were exposed to drought and shade.

Effect of drought and ABA on growth, photosynthesis and antioxidant system of Cotinus coggygria seedlings under two different light conditions

“…An explanation for this phenomenon could be that there is a lower stress pressure as well as a reduced need for ROS removal in shade plants. The result indicated that shade mitigated the deleterious effects of drought (Duan et al, 2005). Furthermore, under shade, the positive effects of ABA on the drought effect became more evident.…”

Growth Characteristics, Physiological and Metabolic Responses of Teak (Tectona Grandis Linn. f.) Clones Differing in Rejuvenation Capacity Subjected to Drought Stress

“…This increase in cellular damage appeared to reflect impairments in the equilibrium between the ROS production and antioxidant defence systems, which also indicated that photoprotection and antioxidant substances were not sufficient enough to protect against cell membrane damage caused by ROS. Drought stress-induced damage on the cellular membranes has been reported also in many previous studies DUAN et al, 2005;ELSHEERY and CAO, 2008;XIAO et al, 2009). …”

“…Drought stress-induced decrease in RWC has been reported in many previous studies (DUAN et al, 2005;ELSHEERY and CAO, 2008;XIAO et al, 2009).…”

“…The contents of photosynthetic pigments in plants subjected to drought stress are known to decline (DUAN et al, 2005;ELSHEERY and CAO, 2008). Drought condition decreased the chlorophyll content considerably in both the teak clones.…”

“…Fluctuations in water availability, including periods of drought, may become more common, and due to this the available water in the soil is reduced and adverse atmospheric conditions are cause of continuous loss of water in plants (SAXE et al, 2001). It is well known that drought affects morphological, physio-biochemical and molecular processes in plants resulting in growth inhibition, stomata closure with consecutive reduction of transpiration, decrease in chlorophyll content and inhibition of photosynthesis, protein changes and differential responses of antioxidative enzymes (ZHU, 2002;ASHRAF et al, 2004;YIN et al, 2005;DUAN et al, 2005;XIAO et al, 2008;CHAVES et al, 2009) to cope with osmotic changes in their tissues. Teak (Tectona grandis Linn.…”