Studies On Effects Of Drought Stress On Seedling Growth And Leaf Color Change Of Acer×freemanii ’Autumn Blaze’ Seedling

We set 4 levels of drought stress treatment for one-year-old American maple (Acer×freemanii’Autumn Blaze’) improved cutting seedlings, they are 35%the soil field capacity(severe drought),50%(moderate drought),65%(light drought),80%(control group) to research the effects of different water treatment on seedling growth and leaf color change of American maple with potting experiment method.Analysising by comparing the different conditions of drought stress treatment plant growth, substance content of osmoregulation, the photosynthetic characteristics, leaf pigment content and L*,△A a*, △b* value and other indicators, to understand the water requirement of the plant growth and the influence of moisture condition in leaf color changes of red maple seedlings, to provide a reference and guidance for the red maple cultivation of scientific water management. The main results of the research are as follows:1.Drought stress affect on American red maple seedlings’growth and biomass allocation deeply. The plant stem in each group don’t appear the differences.The indicators between the control group and the soil moisture content 65%of the soil field capacity don’t have significant differences in plant height, root fresh and dry weight, ratio of root and stem, leaf area in the upper(the 1-2 leaf from top) and central(the 5-6 leaf from top); The growth of the seedlings is inhibited when the soil moisture content 50%of the soil field capacity; The growth of the seedlings is seriously inhibited when the soil moisture content 35%of the soil field capacity. The indicators between the control group and the soil moisture content 35%of the soil field capacity have significant differences except the stem fresh and dry weight, the total dry weight, the leaf area in the upper(the 1-2 leaf from top). The root fresh weight, the the leaf area in central(the 5-6 leaf from top) and the leaf area in the lower(the 9-10 leaf from top) is lower than the control 29.97%,32.66%,39.90%.2.MDA and soluble sugar in the leaf of the American maple seedlings under drought stress are increased allow with the prolonged treatment under soil drought stress. Finally the soluble sugar in the plant which is under moderate drought stress is the most. The content of praline in the plant which is under the control group is essentially unchanged. Except the control group, The content of praline in plants under other treatment is multiplied.3.The values of Fv/Fm and Fm of the American maple seedlings under drought stress are increased allow with the prolonged treatment under soil drought stress, the values of Fo are reduced. The Pn, Gs and Tr of the American maple seedlings under drought stress are reduced allow with the prolonged treatment under soil drought stress, the Ci is increased first and then reduced. The plants have been suffered severe drought stress in 35th day. The Amax and LSP are increased with the increasing of soil water in the intensity of light response curves, but the LCP is reduced. The Pn and LSP in the leaf of plants is higher than the severe drought group 50.90%and 50.93%. The LSP in the the control group is 41.94%below the severe drought group.4.In the late period of the leaves change color, the plants have the phenomenon of striking root in the control group, the moderate drought group and the mild drought group. Before the phenomenon of striking root, the total chlorophyll content shows a trend of decline, the contents of chlorophyll a/b decrease, the content of anthocyanin present the rising trend. Variation trend of the ratio of anthocyanin content to total chlorophyll is slowly rising first and then rapidly rising, the ratio of the largest is the control group, is 2880. The anthocyanin is the most in the the moderate drought group, so as the L*-value and the △a*-value. On the other hand, the contents of soluble sugar and the anthocyanin has correlation of significant or extremely significant at different times.5.The red maple seedlings is sensitive to the moisture, soil moisture content have certain influence on the red maple seedlings growth, the stress inhibits the growth of plants. In the period of leaf color change, appropriate drought stress is conducive to the expression of red maple seedlings leaf color.