Cmparision Of Physiologic And Biochemical Characteristics Between The Three Timber Laxtex Clones And RRIM 600

Physiologic and Biochemical experiments in lab combining with the observes in fields were used during the studies on the comparision of the physiologic and biochemical characteristics relating to the growth and development of the three timber latex clones and RRIM600. The timber latex clones Haiken 525 Haiken 523 Haiken 501 and RRIM600 were cultivated in the different fields , they were at the different growth phase. Net Photosynthetic rate (Pn), Transpiration (E) and water utilization efficiency (WUE) of the four species' leaves were measured under tropical field condition with the CID-301PS's opening system by controlling the leafs PAR and temperature with the additional attachement. Chlorophyll content was measured referring to the methold of the Arnon's. In vivo assay nitrate reductase activity was measured in young fully expended leaves. IAA and GA1-3 were measured by using ELISA .The results showed that difference among the clones were various in the changing light intensity among different young trees, there was the same increasing tendency in the Pn- PAR curve , E-PAR curve and Wue-PAR curve of the different species , but difference among the species was various, Haiken 501 and RRIM600 adapted to the intensity light more easily than the other two species, the four sepecies showed higher Water utilization efficiency (WUE) under the median light, there were no inevitable connections between chlorophyll contents and Pn among the different species, When the trees were younger, the photosynthetic rate of the leaf was higher. In those species higher nitrate inducing reducatase activity can be measured under special conditions, light and nitrate phosphate buffer can promote the activity of the nitrate reducatase, intensity light can inhibit the inducing reducatase activity comparing with fitting weak light, there was higher inducing reducatase activity in the fitting weak light-exposed leaves than in the dark-exposed leaves when induced for the same time, the reductase activity among the species were different under different conditions, they reacted to the light differently. There was no variation in the content of IAA and GA1-3 in the shoot and bark of the trees among theclones. But IAA and GA1-3 act as an important role in regulating the growth and development of the shoot stem unit of the rubber tree. As the girth of the fielding species, Haiken 525 and Haiken 523 grew faster than RRIM600, but Haiken 501 grew slower than RRIM600. The young RRIM600 nursery stock grew faster than the Timber clones, but the Timber clones had some better ecological characteristics, they had the bigger leaf area than RRIM600, contented more chlorophyll than RRIM600.