Study On The Characteristics Of Light Distribution In High Density Planting Orchard Of Ziziphus Jujuba Mill. Around The Tarim Basin Oasis Belt

Ziziphus jujuba Mill. had the advantages of easy cultivation, early fruit, ric h in nutrients, light demander, drought resistance, cold resistance and salt resistance properties. From the "Silk Road" in the Western Han Dynasty, Ziziphus jujuba Mill. was gradually planted in Xinjiang, initially formied some special varieties of Ziziphus jujuba Mill., such as Kashi, Hetian and Akesu. Due to deterioration in ventilation and light conditions in recent years, the cultivation and management strength of the high density planting orchard of Ziziphus jujuba Mill. increased, the plant diseases and insect pests added and the quality of Ziziphus jujuba Mill.deter iorated. Therefore the research of light distribution characteristics had become an urgent problem to be solved. Experiments were conducted with Ziziphus jujuba Mill. in plant and in population.Canopy structure characteristic parameters, photosynthetic fluorescence characteristics in plant were measured for analyzing tree growth and light distribution in different part of the canopy. Canopy structure characteristic parameters in population were measured in order to analyze the light distribution and fruit quality. The main research results were as follows.Season change of leaf area index(LAI) of Ziziphus jujuba Mill.Cv.‘Junzao’ and Ziziphus jujuba Mill. Cv. ‘Huizao’ showed similar "Double peak" form, and the peak appeared in full blooming stage and fruit enlargement stage respectively. Light transmittance(Tr) was in contrast.Photosynthetic active radiation(PAR) and light transmittance of Ziziphus jujuba Mill. in plant had the same trend. The horizontal distribution, peripheral,central and bore had no significant difference in relative PAR. The vertical distribution, there was signif icant difference between upper, middle and lower. The three dimensional model indicated that the closer it was from the trunk, the lower relative PAR.was.The trend of photosynthetic parameters were basically the same. The net photosynthetic rate was slightly different in horizontal distribution. Net photosynthetic rate and transpiration rate were gradually increased with the lower of canopy height in vertical distribution.The trend of fluorescence characteristic parameters were basically alike. Maximum light energy conversion rate of bore was higer than other parts in horizontal distribution. Maximum light energy conversion rate of canopyⅠwas lower than canopyⅡand canopyⅢ.Research showed that light resistance of lower near the canopy base was relatively poor.Leaf area index of Ziziphus jujuba Mill.in population increased first and then decreased. The mean tilt angle of row space pattern was obviously better than planting distance pattern. Light transmittance of planting distance pattern was 0.159~0.423,while it was 0.172~0.288 of row space pattern.The law of season change in relative PAR of planting distance.and row space pattern were the same, fell first and rose slightly then.When planting distance range in 1.5m~2.0m and row space range in 2.5m~4.0m, light transmission was better, the yield was higher, soluble sugar content rose markedly and titrable acidity reduced.