Effect Of Elevated Temperature And Drought Stress On The Growth And Fruit Quality Of Lycium Bararum

As the "greenhouse " increased the average global surface temperatures, the global precipitation patterns has changged. Which has been affecting plant growth and physiology.We use Lycium barbarum seedlings to the following controlled conditions:open-top chambers to simulate different temperature conditions (ambient temperature, AT; elevated temperature, ET=AT+2.5-3.7℃); a combination of three different soil water contents (control group, Wl, approximately 70%-75% of maximum soil water content; moderate drought stress, W2, approximately 50%-55% of maximum soil water content; and severe drought stress, W3, approximately 35%-40% of maximum soil water content). We then studied the effects of elevated temperature and drought stress on vegetative growth, assimilate distribution, fruit quality etc of L. barbarum. Our results showed that:1、There has significant different effect for the interaction of temperature and soil water treatments on net seedling height growth (P=0.0016). While the net seedling height growth of elevates temperature treatment was increased by 17.29% compared to ambient temperature treatment. Therefore, soil drought stress reduced the seedling height net growth, net seedling root-collar growth, area of fresh leaf ect. Thus, higher temperatures medlar promoted the growth of L. barbarum seedlings, however,the drought stress inhibit it’s growth. Temperatures exacerbate the effects of drought stress on the growth of L. barbarum seedlings.2、There has significant different effect for the interaction of temperature and soil water treatments on root biomass (P=0.0001). Elevated temperature and soil drought stress increased roots biomass and ratio of root and shoot,which reduced total biomass. With the increasing degree of drought stress and time duration, total biomass decreased. elevated temperature has significant different effect on the biomass of L. barbarum.While the total biomass of elevates temperature treatment was reduced by 13.65% compared to ambient temperature treatment. Temperatures slow down the effects of drought stress on biomass of L. barbarum seedlings.3、Elevated temperature and soil drought stress reduced Photosynthesis, With increasing degree of drought stress, the net photosynthetic rate (Pn) decreased significantly.The net photosynthetic rate of elevates temperature treatment was reduced by 22.74%compared to ambient temperature treatment.As temperatures rise, the transpiration rate significantly increased, However, drought stress reduced the the transpiration rate. Temperatures slow down the effects of drought stress on the photosynthesis in L. barbarum.4、Elevated temperature and soil drought stress increases the initial fluorescence (Fo) and andnone-photochemical quenching coefficient (NPQ).When elevated temperature and drought stress treatment for 60 days, the initial fluorescence of elevates temperature treatment was increased by 9.85% compared to ambient temperature treatment. When it was treatment for 90 days, the average maximum photochemical efficiency of PSII of elevates temperature treatment was reduced by 1.12% compared to ambient temperature treatment. With the increasing degree of drought stress, the maxinalquantum yield, potential activity of PS II and photochemicalquenching coefficientwas significantly decreased. Temperatures increase the effects of drought stress on maxinalquantum yield.5、Elevated temperature and soil drought stress decreased hundred-grain fresh weight and hundred-grain dry weight of fruit appearance quality. There has significant different effect for the interaction of temperature and soil water treatments on yield (P=0.0072). Under ambient temperature treatments, the yield of severe drought treatment was 51.71% compared to control group, but the average yield of elevates temperature treatment was 51.39% of ambient temperature treatment. Elevated temperature and soil drought stress reduced yield of L. barbarum.6、Elevated temperature and soil drought stress decreased carotenoids of L.barbarum, however increased autumn fruit flavonoids content. The average polysaccharide of moderate drought treatment and severe drought treatment was 103.43% and 94.11% respectively of control group. These results indicated that Moderate drought stress is beneficial to the accumulation of polysaccharide of Lycium barbarum.7、With the degree of drought stress increase, the sucrose content of Lycium barbarum in fruit and leaf showed a trend of increase after drop. Elevated temperature and drought stress decreased sucrose contentin root and stem. Meanwhile, after treatment for 120 days, the average sucrose content in leaf of elevates temperature treatments was 94.56% of ambient temperature treatment.8、Elevated temperature increased phosphorus content in leaves of Lycium barbarum, These results indicated that elevated temperature is beneficial to the absorption of phosphorus in the soil of Lycium barbarum. L. barbarum by increasing potassium content to enhance the ability to withstand drought,when it is treated in drought stress and high temperature.