| Under water stress, the experiment studied the effect of three polymers(Kehan98, Heijinzi, Stocksorb 400k) on the physio-biochemical changes(active oxygen metabolism, water metabolism, growth) of pine seedlings(Pinw.s taeda, P. eliottii), and on the resistence to Sphaeropsis sapinea of P. eliottii after inoculation. Meanwhile the properties of water-absorption and water-retention of three polymers were researched in lab and field experiments. The control experiment against S. sapinea was conducted in P. taeda treated with different medicine, including Zenchanbao, salicylic acid, Na2B4O7 10H2O and Fulaixi. The results are as follows:1 Three polymers absorbed water quickly and did not decomposed easily after becoming gelatinous. Water purity degree affected the water-absorption ability. The water is more pure, the water-absorption magnification is higher. The order of the water-absorption ability of three polymers in two types of water is: distilled water > running water. With the increasing solution concentration, the water-absorption ability declined markedly. When the concentration of solution was above 0.5%, the water-absorption ability did not show further. The influence of Ca2+ was higher than K+. When the pH of solution was either higher or lower than 7, water-absorption ability declined. In three polymers, Kehan98 showed best performance, Heijinzi is next and Stocksorb 400k last.2 Three polymers can reduce effectively the soil water evaporation, making soil maintain much amount of water in longer period contrary to the control. Among them, Kehan98 is better. The experiments in either field or lab both indicated that the application of polymers could increase soil moisture content, enhance the moisture-preserved capacity of treated soil. When being treatd with polymers, the soil bulk density declined with the decrement of 3.9%-13.8 %; but the soil air porosity increased with the increment of 52.7 %-63.8 %; the total soil porosity improved markedly, and the increment could up to 95.7%; but the soil capillary porosity had a little increase. Obviously, the application of polymers to soil was a good method to improve the physical characteristics of soil.3 In the Loblolly pine potted experiment, the application of polymers could obviously alleviate the damage to pine seedlings caused by water stress. Compared with the control, RWC and contents of MDA and free proline of the polymer-treated pine seedlings under water stress, all were obviously lower, but activities of SOD and POD were higher in whole variety process. Among them, Kehan98 polymer show better performance than the other two polymers. Afterinoculatin, the pine seedlings without polymer treatment all died because of S. sapinea infections or water deficit, but those treated with polymers only have slightly damage.4 Under water stress, the application of Kehan98 polymer could markedly reduce the degree of water stress and heighten water potential of stem with an increment of 0.27 MPa ~0.87MPa; and promote the growth of the seedlings of P. taeda, as a result of significant increasing plant height(4.8%~17.9%), stem width(8.2%~29.2%), the root length(l.l%~30.8%), dry material weght of root (10.2%~75.7%), and dry material weght of stem and leaves (8.8%~66.9%).5 In the control experiment, Fulaixi show good resistence to S. sapinea, the incidence of desease is very low. But ZenchanBao, salicylic acid and Na2B4O7 10H2O all had no control effects on die-back of pines. |
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