| As far as broadly arid and semiarid areas in the north of China is concerned, it is a principal factor cf water shorten to affect seedlings survival and growth. So developing water-saving and increasing utilization efficiency of water is an important problem of sustainable forest. Application of Super Absorbent Polymer (SAP) is an important technical to hold water and fight drought. In this paper, three types of SAP were offered as materials by"Lvbao" company of Xining, Qinghai. First, holding-water capability and their effects on the soil physics character were studied. Second, the effect of SAP on seedling growth and physiological function were studied by using glasshouse potted plant. Third, SAP application proportion, application effect, cost and benefit of SAP were studied with field section experiment in Chongli county and Kangbao county, on dam of Hebei. The study intended to provide theory direction and offer gist for establishing country standard on SAP. The results were as follows:(1) SAP absorbent ability was negative correlation with the ion concentration in the solution and SAP was gelatinous form after absorbing water. Regardless in any solution, the time of the small grain was the tallest, especially in distilled water, the numbers it could amount to 386 times. On the other hand, the absorbent velocity of small grain SAP was the tallest and water-holding ability was the strongest in outdoor condition. Under the same condition, the small grain could absorb water 80 percent of itself with 33 minutes. Under the nudity condition, SAP of the full-absorbent water could hold water over 5 days indoor and 2 days outdoor. Through the measurement, SAP could absorb water 27 times or above again and again, the use life was longer.(2) After SAP was applied in soil, the mixed soil weight by volume was lowed remarkably, and with dosage increasing and the soil weight by volume was lowed more and more, bulge ratio of soil mixed with SAP was increased too. SAP could regulate the soil temperature; difference in daily temperature of soil mixed with SAP was smaller. The effect of SAP on soil PH value was smaller, and SAP could restrain evaporation of soil water. Water in mixed soil would diffuse to dry soil around. The distance was 2 times as much as CK. The rigidity of mixed soil was smaller than that of CK. Almost retentive water of mixed soil was efficiency (0~1.5MPa). Roots numbers, radicel stem thick, biomass and root hat ratio of Populus langfangensisW. and P.tricuspidata were higher than that of CK. SAP could delay decreasingwater potential and increasing membrane lipid permeability. With increasing of water stress, net photosynthesis (Pn), stomata resistance (Rs) and transpirement (TRN) were increased. For SAP adjusting function, the treat decreased or increased was slow; the small grain SAP difference was significant difference through square analysis. The relation between plant potential and soil potential were changed by SAP, and with increasing of water stress, soil potential was decreased very slowly, the time of plant efficiency water was increasing. So, the users of SAP were not feared tree's root and SAP strive for water. The relation of plant water potential, Relative Electric Conductivity Rate (RECR) and soil water content of Populus langfangensisW was imitated with index equation, but that of Rtricuspidata was periodical.(3) Surviving rate of forestation was increased beyond 90 percent, and conservation ratio was between 70 percent~90 percent by using of SAP. SAP could offer water to seedlings continuously when they were short of water. Seedlings' side root number, side root long, biomass, root dry weight and root hat rate were 1.4-9 times as much as CK. When SAP was used to forest, not the more SAP, the better the result was, but had a certain adaptive proportion. Results of forestation with power SAP 1.0 percent and small grain SAP lOg were better than others at Chongli County, but big grain SAP 3kg at Kangbao county.(4) Forestation cost with SAP is higher than that of the conventional plant... |
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