Research On Growth And Photosynthetic Characteristics Of Glycine Gracilis Seedlings Under Diffient Types Saline Stresses

The semi-wild soybean （Glycine gracilis） is wild soybean （Glycine soja） to cultivatedsoybean （Glycine max） in the process of evolution of intermediate type. In this paper, weattempt to discuss different types of salt stress on semi-wild soybean seedling growth andphotosynthetic characteristics. Revealing the physiological stress adaptation mechanisms forsemi-wild soybean seedling under salt stress. Providing a theoretical basis for the use ofsemi-wild soybean cultivation.In this paper, semi-wild soybean was used as experimental materials; studied on diffienttype of saline stress treatment effect on the growth and photosynthetic characteristics. After5days of Stress treatments, the photosynthetic physiological parameters: photosyntheticpigment content, photosynthetic rate, light response curve, diurnal variation of CO₂responsecurve, photosynthetic product were measured; The physiological parameters: plant height（cm）, root length （cm）, relative growth rate and moisture content were measured after6daysof stress treatment.Experimental results showed that: At Growth areas, the low concentrations of twodifferent kinds of salt stress could promote root length, plant height and relative growth rateincreases, but the high concentration of the two kinds of salt stress inhibited root length, plantheight and relative growth rate. On Photosynthetic characteristics: the inhibition effect for saltand low concentrations of alkaline salts to the total photosynthetic pigments and chlorophyllwas not obvious, it promoted the accumulation of carotenoids and increases the value ofchlorophyll a/b. High concentrations of alkaline salts could significantly inhibit the synthesiseof total photosynthetic pigment, chlorophyll and carotenoid, and it could reduce the value ofchlorophyll a/b. Maximum net photosynthetic rate and apparent quantum efficiency had nosignificant difference compared with the control group with stress concentration of saltincreased; In alkaline salt stress, the maximum net photosynthetic rate showed a trend ofincreasing at the beginning, then decreasing later. The light compensation point wasnegatively correlated with salt stress intensity and positively correlated with alkaline saltstress intensity. With the increasing of two kinds salt stress concentration, light saturationpoint generally showed a trend of increasing at the beginning, then decreasing later. In saltstress treatment, with the increasing of salt stress concentration, the R_esp, V_cmax, J_<sub>maxand V_TPUshowed a trend of increasing at first, and then decreasing; With the increasing of stressconcentration, the A_satdid not show a certain trend. In alkaline salt stress, with the stressconcentration increasing, A_sat, R_esp, V_cmax, J_<sub>maxand V_TPUshowed a trend of downwardgradually.We can get the following conclusions through the analysis of this paper:First, the effect of inhibition was defferent in high concentration of different salt stressfor emi-wild soybean seedling on growth. Second, in different types of salt stress, the net photosynthetic rate of semi-wild soybeandecreased for different reasons. In salt stress, it was affected by non-stomatal factors; inalkaline salt stress, it was the joint action of stomatal factors, the decline in photosyntheticpigment content and carbohydrate feedback inhibition.Third, the semi-wild soybean showed a certain flexibility in low stress concentration ofthe two different types of salt.