| Cultivated soybean is an important crop for human and domestic animal nutrition due to its high contents of proteins and fatty acids. It is estimated that about69%of the world’s dietary proteins and30%of the world’s edible oils are from soybean. Soybean is also the main economic crops in our country, which is widely cultivated in China. Soil salinization has become more and more serious because of the changing global climate, population growth and unreasonable use of chemical fertilizers. The increase of soil salinity will reduce the height of soybean plant and leaf area and restrain nitrogen fixation. It will also reduce the protein content in grain, affect seed quality, seriously affect the growth and yield of soybean. At present, the saline soil area in our country is about3.5×107hm2, this is equivalent to30%of the total arable land. In addition, due to unreasonable irrigation, industrial pollution and other reasons, secondary saline land area is expanding year by year.Cultivated soybean(Glycine max)was chosen as our experimental materials. Two neutral salts were mixed at a1:1molar ratio of NaCl:Na2SO4and applied to the saline stress. Similarly, two alkaline salts were mixed at a1:1molar ratio of NaHCO3to Na2CO3and applied to the alkaline stress. Determine the germination rate, germination potential, germination index and germination characteristics in the process of soybean germination, the main anion and cation in root and leaf, low molecular weight sugars content such as sucrose, maltose, fructose and mannitol. Analysis the germination parameters under different types salt stress and the relationship between ion of dynamic balance and the small molecule sugar content. Ion in the process of soybean germination under salt stress of dynamic balance and the influence of the soluble sugar content, and their mutual restriction relation research, not only to provide a scientific basis for soybean breeding new breakthrough, at the same time as the theoretical basis for the breeding of salt resistant soybean.The results showed that under different types of salt stress, cultivated soybean seed germination rate, germination potential, germination index, vigor index, root length, root and leaf dry weight and water content are associated with the increase of stress concentration were showing a significantly reduced trends. The germination and growth parameters under alkaline salt stress injuries are more obvious than that under neutral salt stress, show a bigger difference between two kinds of salt stress on germination characteristics of soybean. With alkaline salt concentration increased, the contention of B3+, K+, Mg2+, Ca2+and C2O42-in root increased significantly, it means that under alkaline salt stress soybean root accumulation B3+, K+, Mg2+, Ca2+and C2O42-to alleviate the damage of alkaline salt. While under neutral salt stress, B3+, K+, Mg2+, Ca2+and C2O42-contention in root were no accumulation phenomenon. With the increase of the two kinds of salt concentration, the ions contribution of B3+, K+, Mg2+, Ca2+and C2O42-in the cotyledons and root increase significantly, Ca2+、P3+、K+Mg2+、NO3-、H2PO4-、C2O42-、reduce significantly. Under the neutral salt stress, the ions contribution rate of Ca2+, Mg2+and C2O42-have no significantly changes, while under alkaline salt stress, the contribution rate of Ca2+, Mg2+and C2O42-increases significantly, this suggests that Ca2+, Mg2+and C2O42-play a bigger role in remitting the alkaline salt stress.Correlation coefficient analysis showed that, compared with Na/K and Na/Ca, Na/(Ca+K) was more closely with soybean seed germination parameters, Can be a better parameter to measure the damage of the from salt to cultivated soybean. Under the neutral salt stress, the content of Ca2+,B3+,Fe2+,Mn2+,Zn2+,C2O42-,NO3-in root have the positively related parameters with germination parameters, while under alkaline salt stress, the content of K+,Ca2+,B3+,Cu2+,Fe2+,Mg2+,Mn2+,Mo2+,P3+,C2O42-in root have the negative related parameters with germination parameters.compared with neutral salt stress, The correlation coefficient of each ion and germination parameters alkaline salt stresshave a significant difference under alkaline salt stress, shows that the high pH of alkaline salt damage by causing more serious ion rate imbalance, which have greater inhibition on the germination of seeds.The experimental of soluble sugar results showed that, under neutral salt stress and low concentration of alkaline salt stress, the content of sucrose, maltose, fructose, mannitol and raffinose all showed the tendency of increase in cotyledon, but under high concentration of alkaline salt stress, sucrose, glucose, mannitol content showed a trend of decrease, shows that a high concentration of alkaline salt stress caused the flocculant of cultivated soybean metabolism disorderly, is beyond the scope of its osmotic adjustment, and cause more damage to seeds. Under neutral salt stress, proportion of soluble total sugar of fructose and sorbitol in root increased significantly. Under alkaline salt stress, sucrose and sorbitol in root accounts for a higher proportion of soluble total sugar, shows that under different types of under salt stress sorbitol were involved in the osmotic regulation in the soybean root. At the same time, the experimental results showed that under neutral salt stress, fructose as the main osmotic regulation substances, and alkaline under salt stress, glucose as the main osmotic regulation substances. Compared with neutral salt stress, alkaline salt stress increases high pH damage on plant. the high pH damage mainly by disrupting plant ion balance, make the plant changes the distribution of anion and cation interfere with the normal physiological metabolism, lead to the produce more damage to plant growth and metabolism.This research for resistance to salt ion group provides quantitative parameters of cultivated soybean, preliminary discussion of soluble sugar content lay the theoretical foundation for the study of glucose metabolism group. |
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