Studies On The Resistance-induced Seed Coating Agents Of Rice And Their Effects

This thesis includes three parts: in the first part, the suitable resistance-induced agents and their appropriate concentrations were determined by means of studying the effects of 3 kinds of cold resistant agents and their formulations in 3 gradient concentration on rice seedlings under chilling stress. The biological effects of the resistance-induced seed coating agents on rice and their application effects compared with other seed coating agents were studied in the second part. In the third part, the influences of 2 kinds of resistance-induced seed coating agents on 5 items of physiological and biochemical indexes, such as root vigor, chlorophyll content, proline content, peroxidase(POD), catalase(CAT) and superoxide dismutase(SOD) activities and malondialdehyde(MDA) content, etc., were studied systematically under chilling stress in growth chamber and fields by using rice varieties Jinyou974 and Xiangzaoxian31 as materials. The main results are as follows:1. The suitable concentrations of YKJ and SNC(Sodium nitro complex) were 2000mg/L and 1000mg/l, respectively in application. Mixture of 1000 mg/L SNC and 2000 mg/L YKJ promoted the growth and cold resistant efficiency of rice seedlings effectively.2. The resistance-induced agents, YKJ and YKJ+SNC selected in the experiment filled the film-forming compound competently. Testing results showed that the physical and chemical properties of the 2 kinds of resistance-induced seed coating agents accorded with the enterprise standard Q/OUHN010-2000.3. The resistant frequency of 2 rice varieties coated with YKJZYJ seed coating agent against 14 kinds of blast isolates usually seen in Hunan were 75%～93.75%, 25.5～31.25 percentages more that than of CK, which revealed that the inducing resistance were broad spectrum; The effects of inducing resistance were 74.81%~80.57%, in which the hybrid rice was superior to the conventional rice.In the experiment of direct seeding of 3 early-rice varieties coated with 3 kinds of seed coating agents, HET, YKJ and YKJZYJ, adult seedling rate, seedling qualities and cold resistance were obviously enhanced, and rotten seedling rate was obviously decreased. Adult seedling rate increased by 10～11.6 percentages, plant damage rate decreased by 53.9～63.7 percentages and yield increased by 8.2%～17.6%. The effect of YKJZYJ was the best among three kinds of seed coating agents tested.Applying under conventional condition, the total effect of YKJZYJ was superior to the effects of seed coating agents applied in production such as Jiangsu Huanong and Sichuan Hongzhongzi produced in China and Shileshi imported from Switzerland.4. Under normal condition, the 2 kinds of resistance-indueced seed coating agents raised obviously the root vigour, the contents of chlorophyll, free praline as well as the activities of peroxidase (POD), catalase(CAT) and superoxide dismutase (SOD), decreased the content of malondialdehyde(MDA), which laid a physiological foundation for raising vigorous seedlings and increasing the seedling's suitability to reverse environments.Under chilling stress, the cold resistant seed coating agents maintained a rather high level of root vigour and chlorophyll content, which guaranteed keeping seedlings a normal nutrient absorption, higher photosynthetic power and normal growth and strengthening the resistance to reverse environments. The cold resistant seed coating agents accelerated the growth of seedlings; the membrance system was protected by enhancing large accumulation of proline, which laid a physiological foundation for strengthening the cold resistance of seedlings. The resistance-induecd seed coating agents reduced the decline of COD, CAT, POD activities, kept a low level of free oxygenic radical, decreased the accumulation of MDA, which ensured the physiological and biochemical metabolism conducted as usual. As a result, the plants were prevented from cold damage.