| Elaeagnus oxycarpa Schlecht. is a kind of important economical and ecological tree, which has strong compatibility to stress, such as drought, salt, storm wind and desertification. One- year- old seedling of Elaeagnus oxycarpa Schlecht. was used in this experiment as material, experiment has two part; (1) natural drought stress : soil relative water content is 70%(CK),60%,50%,40%,30%,20%,10%,5%; (2) control drought stress : soil relative water content is T1:70~75%(CK),T2:50~55%,T3:35~40% and T4:15~20%, other, exogenous silicon and abscisic acid were used to T1(CK),T3 and T4, control drought stress treated about 10, 20, 30 days. The article studied about the change of plant growth, photosynthesis characteristic parameters, chlorophyll fluorescence parameters, osmotic adjustments and antioxidant enzymes activity of Elaeagnus oxycarpa Schlecht. seedlings under natural and control drought stress, and the response of Elaeagnus oxycarpa Schlecht. seedlings to exogenous silicon and abscisic acid. Main results as follows:1. Under natural drought, during soil relative water content was 70% to 40%, root activity, net photosynthesis rate and photosynthesis pigment content of Elaeagnus oxycarpa Schlecht. seedling were maximum, cell membrane permeability decreased, the leaf color was changed to dark green and plant growth strongly; during soil relative water content was 40% to 20%, root activity, net photosynthesis rate and antioxidant enzyme activity started to decline, cell membrane permeability increased, but all of these keep to the level is no significantly difference with control; when the soil relative water content is under 20%, net photosynthesis rate, root activity, antioxidant enzymes activity were decreased, cell membrane permeability and praline content were rapidly increasd, most of leaf started to dry and yellow, although the Elaeagnus oxycarpa Schlecht seedling was injured, to a certain extant, the Elaeagnus oxycarpa Schlecht. seedling is still live, and the permanent wilting coefficient of Elaeagnus oxycarpa Schlecht. seedling is 4.3%.2. Under control drought stress, submain stem's relative growth rate of Elaeagnus oxycarpa Schlecht. seedling is higher than main stem, among them T2 treatment seedling is keeping highest relative growth rate in all treatment. After used exogenous silicon, the relative growth rate of T3 treatment was increased, and the relative growth rate of T4 treatment was significantly increased after used exogenous abscisic acid. The results show that, using of exogenous silicon will accelerate the plant crown growth all treatment, and using of abscisic acid will accelerate plant root growth and increase root-crown rate.3. Under different drought stress, the photosynthesis pigment content and net photosynthesis rate of Elaeagnus oxycarpa Schlecht. seedlings showed increase→decrease tendency. Among them T2 treatment's photosynthesis pigment content and net photosynthesis rate was keeping high level because of compensatory effect of light drought. T1 and T2 treatment seedlings'net photosynthesis rate shows singlepeak tendency, T3 and T4 treatment seedlings'net photosynthesis rate shows doublepeak tendency.4. When drought treatment 20 days, with decreasing of soil relative water content, the chlorophyll florescence parameters showed increase→decrease tendency, among them T2 and T3 treatment's were better than other treatments, photochemistry quantum efficiency (Fv/Fm) of every treatment is T1=0.791,T2=0.819,T3=0.822,T4=0.761, all of them was in normal range (0.75-0.85). Chlorophyll florescence dynamic curves shows that, Fv′/Fm′,ΦPSⅡ, ETR, qP, qN of the T2 treatment was better than other treatments.5. With the longering of drought stress time, The MDA contentsand POD activities all of treatment decreased gradually, SOD activities order is 30days >10days >20days, the osmotic adjustments content increased.t.In a word, the Elaeagnus oxycarpa Schlecht. seedlings was in light drought(SWRC≥40%), under natural drought, have net photosynthesis rate and photosynthesis pigment content, strong antioxidant enzymes activity, and the plant growth is healthy and strong. All of physiology and biochemistry index is batter than other treatments, and plant growth is healthy and strong. Therefrom, the Elaeagnus oxycarpa Schlecht. seedlings has drought resistance capacity, and fit to culture light drought soil is 50% relative water content. The study results show that, exogenous silicon will diminish the injureing of Elaeagnus oxycarpa Schlecht. seedlings is at T3 drought stress, and exogenous abscisic acid have good effect to T3 and T4.
|
PDF Full Text Request