Response Of Simmondsia Chinensis S. To Drought And Heat Stress And The Adaptability Of The Introduction

In this research, we tooke Simmondsia chinensis (Link) schneider as the trial materials, which is in natural distribution in the United States and Mexico. We treated seedlings with drought and heat stress, associated its cell membrane system, osmotic adjustment system, photosynthetic system to study the respond to those stress treatments. The adverse stress resisitance mechanisms were discussed. Then we could find ways to improve the tolerance of drought and heat stress, and to select superior germplasm resources. This research will provide theoretical guidance to the cultivation and production of the S. chinensis. Our main research results are as followings:1.With the extension of the time of water stress, the aboveground biomass ratio of total biomass of S. chinensis was decreased,while the underground biomass gradually increased. Besides, the leaf relative water content and IAA levels were reduced; free proline content, SOD activity, CAT activity, POD activity, MDA content, soluble sugar content, soluble protein content, ABA content rised in different degrees.2.During the stress period (7 days),Pn increased slightly,but in the water stress procecess, Pn decreased dramatically.After 28 days,the decreased rate of Pn decreased, and till the 49 days, Pn was close to 0.The Stomatal conductance's change trend was basically parallel with Pn.And the water utilization efficiency in the 14th days was the highest.The ability of the tolerance to drought stress of the seven kinds of provenanc as follows: Z2>Z1>Z3>Z5>Z6>Z7>Z4.3.The leaf water content decreased and the membrane permeability increased under the heat stress.The POD activity was significantly higher than the control at T1 treatment.However, POD activity of different provenanc seedlings showed different variation trends at T2 treatment.Under the heat stress,MDA content showed unobvious changes and proline content increased significantly.The content of soluble protein increased at first and then decreased with the increament of heat stress degree. The ability of the tolerance to heat stress of the seven kinds of provenanc as follows: Z2>Z1>Z5>Z6>Z3>Z4>Z7.4.The daily change of Pn was bimodal under T1 treatment,the seedling showed "midday depression" phenomenon.The diurnal variation of Pn from 8:00 to 10:00 continually was decreasing when the seedlings treated at T2.Different temperature made the maximum net photosynthetic rate (Pn) obviously different, the Pn iunder the CK treatment is 2.26 times as high as the T2 treatment, the Pn in the T1 treatment is 1.14 times to the T2 treatment,and the average SUE of CK,T1,T2 were 7.06%, 5.13%, 0.41%.5.The micro-habitat afforestation was one of the most efficient ways to solve afforestation of S. chinensis in Jinsha River dry-hot valley areas.During the dry season, the fruit set percentage could be greatly improved by irrigating.The plant seed production was 6 times higher than those unirigated.