Studies On The Effects And Physical Bases Of Chemical Control Of Plant Growth And Root Tuber Differentiation And Starch Accumulation Of Cassava

Guangxi is main province planting cassava in China , in which the area of cassava is between 230 and 280 thousand hectares each year , which is 60 percent of the area of cassava in all the country. Cassava is a starch crop of which the product harvested is the root tubers. How to promote the root tubers differentiating and developing and the sarch accumulating is a problem that people always try to study and solve.The effects and physical bases of chemical control of plant growth and root tuber differentiation and starch accumulation of cassava were studied in this experiment, of which three varieties of cassava (SCI24, GR911 and GR891 ) and five plant growth regulators(Homobrassinolide,Rapebrassinolide,Multi-Effect-Age-nt, Ethrel and Multi-Effect-Triazole ) were used as material. The results were reported as follows: (1) It was shown that the rates of sucking water, the activities of amylase, ascorbic acid oxidase, polyphenol oxidase and catalase, the soluble sugar contents andthe rates of, germinating of seed-stems which were soaked with Homobrassinolide, Rapebrassinolide and Multi-Effect-Agent were higher than those of with water ; (2) It was also shown that soaking the seed-stem and spraying the leaves of cassava with Homobrassinoli Rapebrassinolide and Multi-Effect-Agent can increase the nitrate reductases activity, root activities , chlorophyll content and photosynthetic intensity of cassava leaves;(3)Soaking the seed-stems and spraying the leaves of cassava with Homobrassinolide Rapebrassinolide and Multi-Effect-Agent can promote root tubers differntating and the root tuber numbers of plant treated with Homobrassinolide, Rapebrassinolide and Multi-Effect-Agent were more than those of with water; (4) It was found that soaking the seed-stems and spraying the leaves of cassava with Homobrassinolide in early stage and spraying the leaves with Ethrel and Multi-Effect-Triazole in the middle and late stage of cassava growth can promote photosynthate transporting from the stems and leaves to the roots so that can promote root tubers growing and increase starch accumulating in the root tubers,and the lengths,diameters and weights of root tuberand the starch contents in the root tuber were higher than those of with water; (5) The results also showed that when the seed-stems and the leaves of cassava were treated with Homobrassinolide in early stage of cassava growth and with Ethrel and Multi-Effect-Triazole in the middle and late stage ,the activities of starch synthetase, ADP glucose pyrophosphorylase and UDP glucose pyrophosphorylase were higher than those of other treats; (6) Soaking the seed-stems and spraying the leaves of cassava with Homobrassinolide in early stage and the leaves with Ethrel and Multi-Effect-Triazole in the middle and late stage can evidently increase the activity of peroxidase; (7) The economic characters of cassava evidently improved and the yield and starch content of root tubers notably increased when the seed-stems and the leaves were treated with Homobrassinolide in early stage of cassava growth and with Ethrel and Multi-Effect-Triazole in the middle and late stage.It was found first in this experiment that not only the amylase activities , the soluble sugar contents and the rates of germination of seed-stems and the activities of ascorbic acidoxidase , polyphenol oxidase and catalase of the seedlings but also the root tuber differentiations evidently increased with soaking the seed-stems of cassava with Homobrassinolide, Rapebrassinolide and Multi-Effect-Agent, and the nitrate reductases activities, the root activities, chlorophyll content and photosynthetic intensity of cassava leaves notably increased with spraying the plant with Homobrassinolide, Rapebrassinolide and Multi-Effect-Agent. It was also found first in this experiment that the activities of starch synthetase, ADP glucose pyrophosphorylase and UDP glucose pyrophosphorylase and the starch contents of root tuber with spraying the leaves with Ethel and Multi-Effect-Triazole in the middle and late s...