The Study On The Rsistance Drought And Salt Of Different Provenances Maclura Pomifera

One-year-old cutting of Maclura pomifera from the United States was taken as the experimental material,under the condition of drought stress and salt stress,the physiological characteristics and changes of the intra-structures of the different provenances of Maclura pomifera was analyzed,some results had been gained as the following:(1) Under the drought stress, the exterior morphogenesis of Maclura pomifera appeared a series of changes along with the time, mainly concentrated in leaf color and in the terminal bud.Under the salt stress,the edge of leaves became dry.There were a resistant difference between the different provenances of Maclura pomifera.(2) Under the drought stress, the membrane permeability and MDA contents decreased continually of Maclura pomifera, which showed the cell membrane seriously damaged in the intention stress. Under the salt stress,with the time of salt stress and the intension of salt stress,in contrast to the check,the contents of MDA showed a trend of increasing.(3) Under the drought stress, the chlorophyll contents decreased of Maclura pomifera with the time of stress and the intension of stress.Under the salt stress, with the time of salt stress and the intension of salt stress,the chlorophyll contents gradually declined firstly and rase later.(4) Under the drought stress, the activity of SOD and POD in Maclura pomifera were down firstly and up later. Under the salt stress, the change of SOD and POD activity in Maclura pomifera was complex, which rised or falled sometimes.Under the low salinity, the enzyme activity increased firstly and dropped later ,but it could be increased for a period of time by itself.(5) Under the drought stress, the proline contents showed a trend of increasing,but the souble protein contents decreased hardly with the drought stress time.Under the salt stress,the proline contents showed a trend of increasing too,but the souble protein contents showed increasing or declining during the course of salt stress.(6) Under the drought stress, the root vigor of Maclura pomifera decreased with the intention stress. Under the salt stress,the root vigor was up firstly when the intention stress increased,but it was down when the salinity over certain density.(7) Under the drought stress, the palisade tissue cell became shorter and the cells clearance was wider than that of check and the number of chloroplast became more less.Under the salt stress,in contrast to the check,the palisade tissue became thicker, the sponge tissue cell became bigger and arranged more looser, the aqueous tissue was developed, which tended to be fleshy.(8) Based on the systematical and comprehension analyses,the order of drought resistance from the strong to the weak was Missouri1,Texas>Nebraska,Italy >Louisiana,Missouri2; the order of salt resistance from the strong to the weak was Italy,Missouri1>Texas,Missouri2>Nebraska,Louisiana. The experiment indicated that the Maclura pomifera was morderately resistant to salt stress (0.3% salinity) and some of seedling could still survive for a long time under 0.6% salinity circumstance...