Physiological Response And Evaluation Of Drought Resistance In Fifteen Mulberry Varieties

Using a movable rain shelter to keep of precipitation, field experiments on the leaf water conservation, the membrane super oxidation, protection enzyme system anti-oxidation capability, photosynthesis and photosynthetic response of fifteen mulberry varieties, which were three years old and conducted under different soil moisture treatments. By testing and analysising of many indexes, the results as follows:1、Under drought stress, water retention capacity of mulberry varieties leaf water conservation increased and reached their maximum, and then declined, the water saturation deficit, chlorophyll a and chlorophyll b increased under different drought stress.2、Under drought stress, the active oxygen scavenging system was suppressed, electrical conductivity and proline increased, MDA, SOD and CAT increased under moderate drought stress and then decreased, soluble sugar increased under mild drought stress, POD and soluble protein reduced till mild drought stress and then inhanced. SOD, CAT and POD combined together to reduce the damage which caused by membrane lipid peroxidation.3、Under drought stress, photosynthetic rate, transpiration rate and stomatal conductance dropped significantly, and intercellular CO2concentration decreased in the initial stress stage and mild stress and increased under moderate and serious stress. Water use efficiency showed two trends of up-down and up-down-up under water stress.4、Under the different treatments, the light response curve and the CO2response curve showed the same trends, which were that suitable water>rehydration>moderate stress>serious stress. Under water stress, maximum net photosynthetic rate, apparent quantum yield, light saturation point, dark respiration rate, photosynthetic ability, carboxylation efficiency, CO2saturation point and photorespiration rate showed a decreasing trend, but light compensation point and CO2compensation point was an increasing trend.5、Evaluated the drought resistance of mulberry varieties comprehensively, under moderate drought stress, the result showed that the drought resistence order was Hong guo2, Ao yu, Tai wan46c019, Ri ben hu cheng, Tian sheng1, Bei fang hong, Lv shen zi,8632, Hong bao shi, Tai wan72c002, Bai yu wang, Ning xia hong, Hong guo1, Da10, Yi chuan hong. Under serious drought stress, the order was Hong guo2,Ri ben hu cheng, Lv shen zi, Tai wan46c019, Ao yu,8632, Tian sheng1, Bei fang hong, Tai wan72c002, Hong bao shi, Bai yu wang, Ning xia hong, Da10, Hong guo1, Yi chuan hong. From the result, we known that Hong guo2, Ri ben hu cheng, Tai wan46c019, Ao yu had the strongest drought-resistence among15mulberry varieties, and they could be the best choice for planting in the drought region.