| It has been found that calcium and its signal transductious system widely mediate the growth and development of plant, which is one of the active research areas in current biology. There is also a close relation ship between calcium and peanut growth and development. It has been known that embryo abortion or less filled pods could occur and so the yield would fall by a big margin because of deficient calcium in soil. This is a general problem existed in peanut production areas in the red and yellow soil region of south China. In order to know the physiological mechanism of embryo abortion in peanut, water culture was carried out to control the concentration of calcium ion. A number of physiological items in peanut development were measured quite systematically, comparision was made for these items between peanut plants growing in different levels of calcium ion, and meanwhile, modal and structure change of embryos between abortion and development were also observed. In addition, the peanut development differences between water culture and field experiment were compared. The results are summarized as following.1. Peanut was influenced widely by calcium. In field experiment, leaves of peanut was influenced gently, but pods were influenced badly by calcium. Lacking of calcium caused changes of photosynthetic product and ill-filled pods and empty pods increased, which significantly lowered the yield. However, both vegetative growth and development of pods in water culture were influenced seriously. Under calcium deficiency stress, stem were thin and weak, branches were few and yield was low.2. Peanut plant's physiological metabolism was affected by calcium. Under calcium deficiency stress, Chi contend photosynthesis rate and content of soluble sugar -, starch and protein decreased. Antioxidants system was destroyed with peroxidase activity and catalase activity decreasing, content of malondialdehyde(MDA) and permeability of plasma membrane of leaves increasing, which resulted in plants getting old easily. Under calcium deficiency stress, amylase activity also decreased which can influence carbohydrate movement.3. Root vigour during all peanut life rose first, then declined. Root vigour i2calcium deficiency decreased. Sprouting root declined and root blacken easily.4. Pod modal development of calcium deficiency(10mg.L-1) and calcium sufficient(100mg. L-1) were observed and found that the modal change of abortive embryos started from 6 days after pegging and the embryos shrinked and dried in 18 days. Lacking of calcium, the embryo cell shape changed, cell wall degraded and disappeared. These are the mechanism of embryo abortion.5. Discussion and analysis were made concerning the differences of plant growth and development between field experiment and water culture with different calcium treatment, and the physiologic mechanism for them was explained. The results obtained would increased the understanding physiology basis for peanut pod development regulated by calcium, which could offer reference for peanut production and further research on the question. |
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