Physiological And Morphological Responses Of Prunus Davidiana And P. Sibiria Seedlings To Fertilization And Water Stress

Seedling growth, leaf photosynthesis, root absorption activity, root morphology, biomass allocation etc. of Prunus davidiana and P. sibirica which grew under different high temperature, fertilization and water stress environment was systematically studied in field in the paper. Results showed as follows:1. Light -saturated net photosynthetic rate, water utilization efficiency (WUE) of leaves of the seedlings was increase with fertilization and irrigation and the capacity of drought resistance was strengthened remarkably with fertilization and the most intensive effective factor was irrigation rather than fertilization.P. sibirica had stronger activities of recovering growth and its relative height growth rate and relative collar-diamete growth rate was 5.65%～20.39% and 4.33%～13.97% higher than the other. The leaf photosynthesis of the two species was also influnced obviously by temperature. The results supported the evidence that the leaf photosynthesis of P. davidiana had better resistance to high temperature than that of P. sibirica.2. The relative height growth rate and relative collar-diamete growth rate of P. davidiana and P. sibirica was promoted by proper fertilization. Leaf photosynthesis and WUE of P. davidiana and P. sibirica was increased with apparent quantum yield (the varation range of increase of P. davidiana was 52.94% and that of P. sibirica was 42.86% ), light saturation point, and with decrease of light compensate point and transpiration rate.However,excessive application of fertilization could reduce light saturation point and increase light compensate point. This resulted in limitation of leaf photosynthesis to these two species and decrease in WUE and relative collar-diameter growth rate. Irrigation also could obviously stimulate the relative growths. And irrigation was the dominated factor to promote the relative growth of seedlings3. The root length, root surface area and root volume in different diameter was effectively inceased for P. davidiana and P. sibirica seedlings by irrigation and the proper fertilization. And total root length, total root surface, total root volume, total absorbable area, active absorption area and water and nutrient uptake ability for root of the two species was also increased with irrigation and the proper application of fertilization. Furthermore, the effect of irrigation was stronger than fertilization. The ability of ion absorption was not remarkably different between P. davidiana seedings and P. sibirica Seedlings.4. The water potential of twig for P. sibirica seedlings and P. davidian seedlings were increased continuously with decrease of irrigation and were reduced with increase of fertilization.