Study On The Agricultural Properties Of Water-Retaining Agent And Its Application In Cucumber And Chinese Cabbage Cultivation

Water-retaining agent(WRA)is a chemical product to save water and fight drought. It has such advantages as wide use, low expense and quick effect that it can be used in agriculture. The starch water-retaining agent, an ecological safe water-saving product, is a kind of natural macromolecule polymer. It is famous for its high capacity and speed of water-absorption and low cost, but it also has some disadvantages such as short use time, poor stability and weak salt tolerance. So it is worth to research the application characteristics of starch water-retaining agent in agriculture. The water requirement in vegetable cultivation is great especially in fruit vegetables and leaf vegetables. So water-retaining agent has important value in vegetables cultivation. However, little research on the field is reported, and many problems still exist in the application.In this thesis, the properties of water-retaining agent and its application in vegetables are studied. Using cucumber and Chinese cabbage as the material, we studies the growth, yield and quality characteristic, hoping to provide theoretic basis for the practical use. The results are as follows:1. Different water-retaining agents have different physical, chemical and agricultural application properties. The results showed that the pH value decreased a little when the concentration of water-retaining agent raised. When the pH of solution was between 6.0 and 8.0, the water-absorbing capacity was almost not affected. The starch water-retaining agent has higher water-absorbing speed than the polyacrylate water-retaining agent. But all of the 3 water-retaining agents reached the saturation point in 60 minutes. The water absorptivity of the polyacrylate water-retaining agent was higher than the starch and its absorptivity in distilled water was 620.40 and the starch water-retaining agent about 400. The water absorptivity of the water-retaining agent was highe in distilled water than in tap water and ground water. The absorptivity decreased more in nutrient solution. The urea nutritent had little effect, but the ion of Ca, Mg affected serieous. Howerver, fertilizers of KH₂PO₄, NH₄H₂PO₄, (NH₄)₂SO₄. K₂SO₄ and (NH₄)₂HPO₄ were between the two types.