Study On Water Retaining Agent Characteristics And Its Application In Tomato Seedling

4 kinds of crosslinked polyacrylamide water retaining agent from Beijing Hanlimiao New Technology Limited Company was used as the experimental material to study. The water absorption, water release and macronutrient absorption performance of different specifications of water retaining agent in different concentrationsolution was studied to do the screening test of water retention agent. Fertilizer and water conservation screened out the best performance of water retaining agent, added to the nursery, tomato varieties ‘pink champion’plug seedlings as test materials were tested. The physical and chemical properties of the substrates, nutrient content, the growth and physiological variations and photosynthetic fluorescence indicators of tomato seedlings are studied to filter out the appropriate dosage of water retention agent. The experiment is designed to get the best substrate suitable for summer and winter two seasons of tomato seedling in this region and the most appropriate dosage of water retention agent, which provides a theoretical basis and agricultural methods for tomato plug-seedlings. The main results are as follows :1. 4 kinds of water retaining agent were soaked in different concentration solution,with the increasing concentration, water absorption multiples, water absorption rate and repeated water absorption multiples showed decreasing trend; Water release rate in the first 36 h became more and more big, and smaller and smaller between 48 h and 60 h. The adsorption of N, P elements were increased at first and then decreased trend, K elements showed continual increasing trend. Small and medium diameter(0.4~2.8mm)water retaining agent′s water absorption multiples, water absorption rate and repeated water absorption multiples were significantly affected by solution concentration; The larger particle size, the greater water release rate, and the adsorption of N, P and K elements were increased first and then decreased with the time. Medium diameter(1.6~2.8 mm)B specifications of selected water retaining agent showed better characteristics in water absorption, water release and macronutrient absorption than that of other specifications of water retaining agent.2. Adopted by the Shandong Agricultural University research base(Tai’an) produced nursery substrate. Water retaining agent(B specifications, diameter of 1.6 ~ 2.8mm) added the amount set CK 0%, T1 0.05%, T2 0.1%, T3 0.15%, T4 0.2%(Water retaining agent anddried matrix ratio) a total of five processing, tomato varieties ‘pink championship’ as test material plug seedling.The results showed that added a certain amount of water retaining agent, which can effectively improved the quality of water storage fee-based capacity, reduce the number of irrigation, and promoted the growth of tomato seedlings, increased the amount of dry matter accumulation, improve physiological activity; But the dosage of water retaining agent is too high, inhibiting the growth of tomato seedlings. Summer tomato seedling nursery,the appropriate amount of water retaining agent was 0.1%; Winter tomato seedling nursery,the appropriate amount of water retaining agent was 0.15%.