Studies on the Nutritional Peculiarities of Halophytes with Special Reference to their Agricultural Use

点击翻译按钮获取中文摘要

The study has done under the threemajor research items.1) Collection and water culture of salt tolerant plants: Native plants growing in the abandoned salt farm and the salt accumulated soil of Thailand, Mangrove forest of Ishigaki Island were sampled and analyzed their mineral composition. Some of them were water cultured and water culture method for Atriplex gmelini (halophytic dicotyledon), Phragmites comunis (euryhaline monocotyledon) and Bruguiera gymnorrhiza (mangrove tree) were established.2) Mechanism of salt tolerance and nutritional peculiarities of halophytes: Atriplex gmelini took up a large amount of Na from the medium and accumulated it in vacuoles. In the cytoplasm, Na concentration was not so high but betain was sccumulated. Thus Atriplex produced the osmotic pressure inside the cell to cope with the high salt concentration in the medium. In the case of Phragmites cumunis however, excessive uptake of Na was suppressed metabolically. Phragmites did not decrease K/Na rati … More o in the cell so much as Atriplex did when the Na concentration in the medium increased. The K requirement of K dependent pyruvate kinase activity was not different between Atriplex and Phragmites. But co-existence of betaine which accumulate in Atriplex cell under high Na concentration media lowered the K requirement of pyruvate kinase of Atriplex. Atriplex had a tolerancy for high concentration of B(boron) in the medium and it seemed one of the physiological characteristics of halophytes which adapted to sea water contained high B.3) Effect of salt on the fertility of the soil: Among the factors of soil fertility, nitrogen is most important. So the effects of salt on the mineralization of organic nitrogen(ammonification), nitrification and symbiotic nitrogen fixation were examined. NaCl equivalent to sea water did not decrease the rate of ammonification so much, but severely suppressed nitrification. The effect of Nacl on the symbiotic nitrogen fixation showed through the effect on the growth of the host plants and depended on the salt tolerance of Legumes. Less