Study On Salt Tolerance Of 8 Alfalfa Varieties

Salt injury is the main factor of restricting and deciding alfalfa plant everywhere. It is also a big problem that the world agriculture confronts. According to a survey, soil-salinization erosion run riot over 6% of the world's land. Salt injury threats 20% of the agricultural irrigation inordinately. Our country has about 3.46×107hm2 of all kinds of the saline and alkaline land. Arable land accounts for 6×106hm2 of the saline and alkaline land. The study of salt tolerance of plant was imperative. Utilize salt-resistant and salt-tolerant plant is an economic and effective measure to the reclamation of saline and alkaline land. Alfalfa is higher salt-tolerant forage. It can be grown on the mild saline and alkaline land. There are relative big distinctions of salt tolerance among alfalfa varieties. To improve salt tolerance of alfalfa, select and cultivate salt-tolerant alfalfa varieties, on one hand can improve saline and alkaline land and raise the utilization rate of saline and alkaline land, on the other hand increase the supply of high quality protein feed, thus the development of animal husbandry of these saline and alkaline areas can be improved to some extent.Salt tolerance of 8 alfalfa varieties was investigated in this study. The germination rate, the single fresh weight ,the root length and the seedling height as well as the free proline content of 8 alfalfa varieties under different NaCl concentrations(0, 50mmol/L,85mmol/L,120mmol/L,170mmol/L in agar medium) were studied in vitro. Salt tolerance features were comprehensively assessed. The results indicated that lower concentration of NaCl(50mmol/L)promoted germination and growth of alfalfa; However germination rate and growth of alfalfa were restrained prominently with the increase of NaCl contents(85mmol/L,120mmol/L,170mmol/L).The relative germination, the relative single fresh weight ,the relative root length and the relative height decreased significantly with the increase of NaCl concentration, while the free proline content increased significantly. According to the results of integrated evaluation, the sort and score of the salt tolerance of seeds of 8 varieties were"God Empress"(3.095)>"Ameristand201"(2.467)>"Sandity"(2.379)>"Algonquin"(2.369)>"Baoding"(2.077)>"Zhongmu No.1"(1.474)>"Aohan"(0.885)>"WL-232"(0.310)."God Empress"is the most salt-tolerant alfalfa variety, and is suitable for planting in the high saline-alkali soi; while"Aohan"and"WL-232"are the least salt-tolerant alfalfa varieties, we should avoid planting them in the high saline-alkali soil.Furthermore, using Semi-quantity RT-PCR, the differential expression of MsP5CS2 gene of 8 alfalfa varieties was studied under 170mmol/LNaCl concentration. As a result, there are relative big distinctions of salt tolerance among alfalfa varieties was further illustrated at molecular level. Alfalfa varieties have the genetic potential of raising their salt tolerance by genetic engineering. From this it can be seen that the expression of this gene can be served as an index to measure the salt tolerance of alfalfa, and can supply molecular basis of salt tolerance on looking for molecular marker of salt-tolerant breeding.