The Effect Of Drought Stess On10Different Provenances Mexican Cypress

Mexican cypress (Cupressus lusitanica), also known as fast-growing cypress, evergreen trees.Regarded as the promising high resistance vegetation, the research on the drought resistance ofMexico Bo provided a theoretical basis of its planting and introduction in dry conditions.The results showed that:1. Under water stress, the Mexican cypress seedlings had a series of phenomena, like needlesgather to the center, the newborn coniferous weaker than the old coniferous, coniferous coloryellow, newborn branch of lodging and growth arrest, and etc. Under severe drought stress, itwould wilt.2. Compared with the control trees, the root length, average diameter, surface area and volumeof Mexico Bo were significantly reduced in the arid environment, because the soil droughtinhibited the growth of the Mexican cypress root. Mexican cypress roots under drought treatmentgenerated fine roots, instead of a long taproot, which was the reason why there were still signs oflife in the arid environment.3. Under drought stress, the relative conductivity of Mexico Bo was rising, and it reached themaximum late in the experiment. The relative water content of leaves and water saturation deficitof downward and upward trend showed that the arid environment affected the accumulation ofleaf water. Chlorophyll a, chlorophyll b and total chlorophyll had decreased, to some extent,reducing the photosynthetic capacity of leaves.4. For the influence of drought stress, content of Malondialdehyde had increased in varyingdegrees, while Peroxidase activity under drought stress changed insignificantly, but basically stillhigher than the control. The soluble sugar, soluble protein and praline, as osmotic adjustmentsubstances of the Mexico Bo had similar changes. With the treatment time, the soluble sugarconcentration and soluble protein content increased first and then had a downward trend. And thepralines content had different levels of accumulation.5. Through a comprehensive evaluation of the16physiological and biochemical indexes inexperiments, using principal component analysis and the membership function method, the thesiscalculated the order of the10kinds of Mexican cypress provenances of drought tolerance shouldbe: D9,D5,D3,D10,D8,D7,D6,D1,D4,D2.