Physiological Response Of Sapindus Seedlings Under Drought Stress

The response mechanism of Sapindus Seedlings to drought sress was studied in different water stress and drought time through two comparative methods, the water controllable pot planting and the PEG penetration stressing. The compressive evaluation on drought-resistance of Sapindus Seedlings was drawn from study the dynamic changes of plant morphology, physiological and biochemical characters and their relationship. The main results were as follows:(1) In plot experiment, with the reducing of relative soil water, plant height, stem diameter, biological yield, Chl a, Chl b, Chl (a+b) content and photo synthetic parameters decreased significantly; in addition to Ci; REC, Ci, MDA, Pro, SSC and SPC content were significantly increased; SOD, CAT and POD increased first and then decreased, and the highest point was in ms; Chl a/b and Caro content showed a trend of wavy falling. Under severe water stress and medium water stress, various physiological and biochemical indexes change greater than mild water stress.(2) In plot experiment, as the extension of stress time, plant height, stem diameter, biological yield, REC, SOD and POD, MDA, Pro and SPC content, etc. have been increasing; root vigor, WUE, CAT activity, SSC and caro content, etc. showed a trend of decline after rising first; Ci showed a trend of rising wave; Chl a, Chl b, Chl (a+b), Pn, Tr, Gs showed a trend of wavy falling. And P=0.05significant level between the groups.(3) Under PEG simulated drought stress, with the increase of the concentration of PEG, overall, SOD, POD, CAT, MDA, REC, Pro, SSC, SPC, WUE and Ci showed significant upward trend;Pn, Tr and Gs showed a significant downward trend; when stressed6h, chl a, chl a, Caro, chl a/b, chl (a+b) of photo synthetic pigment indexes increased gradually with the increase of PEG concentration, and they were significantly higher than control.They began to decline after6h, and lower than controls12h later and gradually reached significant level.(4) Under PEG simulated drought stress, as the extension of stress time, REC, Ci, WUE and first increased and then decreased before they were on the rise trend; SOD, POD and CAT activity decreased befor6h, but not reached significant level. Then increased gradually after6h, and P=0.05significant level between the groups. Photosynthetic indexs showed rising trend after the first drop, and reached the biggest after6h.Tr and Gs’s trend were wavy downward, Pn decline change was linear with time.(5) PEG simulated drought stress and Potted controlled drought stress had the same result, and all indexes were among a strong linear relationship. By principal component analysis, MDA, Pro, SSC, SPC, SOD, POD, CAT, these indicators contribute most Suggests that these indicators closely associated with drought resistance, can be used as no diagnostic index of Sapindus drought-resistant research(6) In plot experiment, we rehydrated after water stress42d, all the tested plants gradually returned to normal several. Suggests that physiological and biochemical mechanisms of Sapindus can help it resists drought stress, and Sapindus has strong drought tolerance which can be used to carry out ecological afforestation experiment in chongqing and surrounding areas, especially the karst landforms of the southeast of chongqing land barren, where rocky desertification is severe, mountains are short of water.To sum up, we suggest to irrigate to ensure the normal growthl under the condition of25%or so of the severe water stress for1month.