The Influence Of Vallisneria Natans Growth Under Water Gradient/Light Intensity

An indoor pot experiment was carried out using Vallisneria natans which with same size and young shoots to explore the effects of light intensity and water gradient on growth of young shoots and physiological features of the plants, then to figure out the response of physiological features and morphological indexes to stress and find out the favorable light and water gradient which was favorable for the recovery of V.natans population and also beneficial to population biomass, underwater turf formation and the restoration of aquatic ecosystem. Result show:(1)The effect of water gradient on the content of chlorophyll a is very significant( P<0.01). Otherwise, the content of the chlorophyll a was increased with the increasing water gradient, the decreased. Chlorophyll b has the consistent trend with the chlorophyll a, but the change of chlorophyll b amplitude is relatively small, the maximum amplitude of between adjacent treatment group was 0.06mg? g-1. The trend of Chlorophyll a + b is consistent with the chlorophyll a, carotene does not change significantly with the depth of the water. However, as the light intensity decreasing and weakening, the chlorophyll a, chlorophyll b,chlorophyll a + b, carotene shows significant downtrend.(2)The V. Natans under different water gradient and light intensity, POD and SOD showed an significant downward trending in different water gradients, with the increasing water gradient, the enzyme defense system of plants has been suffered a certain damage, but in the low light stress, as the light intensity weakening, plant protection system of enzyme showed an reaction to the low light. The activity of POD and SOD increased to meet the stress. But the MDA was decreased with the decreasing light intensity and increasing water gradient and Plants of soluble protein at the water gradient of 150 cm dropped to 4.59 mg/g, because of the protein hydrolysis lead to soluble protein content decreased. But under different light intensity the soluble protein has not a obvious trend. It means the environmental stresses may have exceed the limit tolerance in plants.(3)The root activity showed a significant correlated with water depth gradient(P?0.05). But the biomass of the ground and underground have a decreasing trend with the increasing water gradient. Eventually, at the water gradient of 150 cm, both biomass reached the lowest number, followed by 15.69g?3.81 g individually and the root-shoot ratio, rose to 0.26%(150 cm) from 0.09%( 60 cm).(4)The plant height, leaf width, leaf amount of V.natans was decreased with thelow light intensity, as well as the shrinking of clonal ramet amount. The three indexes showed a same trend in different water depth gradient, but mainly the old plant growth condition was affected obviously, the amount of the new plant leaf increased.On the contrary, the height of the old plant and leaf amount both decreased compared with the new plant.