Studies On Methods To Select Rubber Rootstock Material Under High-osmosis Stress

Drought is an important limited-factor to growth and yield of rubber tree (Hevea brasiliensis). It is one of effectual means to resist drought for rubber tree to select drought-resistance planting material. At present, planting materials are basically budding in production. The rootstock is the important part of budding. Therefore, it is very important to enhance the ability of drought-resistance of rubber budding trees to improve the abilities of drought-resistance of rootstock.This experiment adopts artificial simulation research approaches, namely using the standardized moisture stress conditions with hypertonic solution to immerge rubber tree seeds during germination to elementarily select out some rubber seedlings, which could stand the high-osmosis stress. The germination characteristic of the rubber tree seed under high-osmosis stress was observed and the phenomena of growth and dynamic changes of physiology and biochemistry were determined and analysed, and then its ability of drought-resistance was valued. And some of rubber seedlings were selected by this way for the experiment to compare the ability of drought-resistance of rubber rootstock in future. The preliminary results of study were shown as follows.1. It was essential to use fresh rubber seeds for selection the seedling, which could stand high-osmosis stress.2. There were obvious effects on the germination characteristics of rubber seeds under of the treatment high-osmosis stress. The germination rate of rubberseeds declined along with the concentration of NaCl solution, osmotic stress increased. But the effect was irregular on the germination rate of the treatment with Mannitol and PEG6000 solution, the other hypertonic solutions.3. Some rubber seedlings standing high-osmotic stresses could be selected out by using the hypertonic solution.4. There were some significant differences in the physiological and biochemical characteristics and growth and development of rubber seedlings between that selected by hypertonic solution and water or germinated in sandy forcing bed.5. The ability of drought-resistance of the seedlings selected under high-osmosis stress could be valued by synthetically appraisable method. The results of synthetical appraisement shown that tht seedling selected by PEG (15%, 7ds) treatment gained a higher X (U) value, meaning its ability of drought-resistance was relatively higher than others selected by other treatments in general.