The Clone Early Selection Of Xanthoceras Sorbifolia Bunge And The Response Of Seedlings To Salinity-alkalinity Stress

Xanthoceras sorbifolia Bunge is important woody of grain and oil resources, but the biggest problem at present is not achieved of improved varieties, early clone selection is the basis of thoroughbred change. The study of Xanthoceras sorbifolia Bunge saline-alkali capacity to identify possible realization of the right matching tree, and expand salinity threaten regional of X. sorbifolia planting area. The early selection and seedling salt tolerance aspects of X. sorbifolia were studied, the results can provide a theoretical basis to early selection and determine the appropriate area to under cultivation.In this early selection,62 clones of Xanthoceras sorbifolia Bunge were studied, viewed from the photosynthetic parameters and morphological indicators. By analysis the principal component indexes, then clustering PCA sorting and correlation test, selected indicators which stand for photosynthetic parameters and morphological representative in early clones’ selection.Through the research and analysis, we considering the maximum net photosynthetic rate (Pn) and water use efficiency (WUE) as photosynthetic characteristics in early selection of Xanthoceras sorbifolia Bunge. We find that the clones of JL57 JL58 JL59 DN01 LX65 YP77 A099 AZ09 AZ11 YP29 JL51 JL52 KX23 KX/LS02 YQ67 JL53 JL55 DX82 DX88, YQ66 YQ71 TZO2 TZ03 DX84 are high Pn type; and the clones of AZ12 JX25 YQ66 YQ71 TZO2 TZ03 JL57 JL58 JL59 DN01 LX65 YP77 A099 AZ09 AZ11 YP29 JL51 JL52 KX23 KX/LS02 YQ67 JL53 JL55 DX82 DX88 are the high WUE type.Through the research and analysis, we considering the basal diameter and length of the year-old branches as morphological indicators in early selection of Xanthoceras sorbifolia Bunge. We find that the clones of AZ11 DN38 DX88 JL52 JL53 JL57 JL58 JL59 JX23 JX51 JX52 KX21 KX23 LF01 LX01 WX03 XX40 YH06 YH07 YP29 YP76 YQ72 A409 A109 A326 are long shoots type; and the clones of AZ11 DN38 DX88 JL52 JL53 JL57 JL58 JL59 JX23 JX51 JX52 KX21 KX23 LF01 LX01 WX03 XX40 YH06 YH07 YP29 YP76 YQ72 A409 A109 A326 KX/YT16 are sturdy typeThe study screened out 9 clones which are DX88 JL51 JL52 JL57 JL58 JL59 YP29 KX23 AZ11 as excellent choice on both of morphological and photosynthetic. These clones can be observed as the focus of the early selection object.Seeds and seedlings is a prerequisite for the development of plant colonization and seedling sensitive to the external environment. This study focuses on the subject of seeds and seedlings of Xanthoceras sorbifolia Bunge, this study designed 0.2%,0.5%,0.8% three kinds of salt gradient, salt stress A (NaCl: Na2SO4= 9:1), alkali stress B (NaHCO3:Na2CO3= 9:1) and alkaline stress C (A:B= 1:1) and alkaline stress F (A:B= 9:1) in response to four salinity stress. By observation and measuremen to the growth and development of Xanthoceras sorbifolia Bunge, and analysis photosynthesis, water potential, root hydraulic conductivity, biomass, soluble sugar and non-structural carbohydrates, as well as nitrogen and phosphorus and other related physiological and biochemical indexes. And research response characteristics and adaptation limit of Xanthoceras sorbifolia Bunge under different stress, in order to provide a theoretical basis for the plant in saline cultivation and propagation. The conclusions of study are as follows:(1) The germination rate of Xanthoceras sorbifolia Bunge under alkali stress (B) higher than the control, and the greater of alkali stress, the higher the germination rate,0.8B stress is 131.71%, a significant difference (P<0.05). It may probably due to the stress undermined the seed testa structure to promote seed germination. Other stress conditions, mild (0.2%) of stress seed germination rate than the control, under moderate and severe stress, seed germination rate serious decline, in which 0.8A seed germination is the lowest under all stress, only 14.63% in control, the difference was significant.(2) Under different saline-alkali stress, the leaf length, width, height, biomass of Xanthoceras sorbifolia Bunge, were lower than CK, mild stress has no significant difference. In moderate and severe stress they decreased significantly (P<0.05). The diameter of Xanthoceras sorbifolia Bunge in mild and moderate stress were higher than controls, indicating that within a certain range of stress, salinity stress can promote stem thickening. The stem-leaf ratio and root-shoot ratio were less than the control, concentration increases, both significantly decreased (P<0.05); and in other stress conditions stem-leaf ratio and root-shoot ratio are in under mild or moderate conditions than the control, under certain stress conditions affected biomass allocation.(3) The salinity stress influenced the seedlings of Xanthoceras sorbifolia Bunge of maximum net photosynthetic rate (Pn) and stomatal conductance (Gs) are significant difference. The seedlings under 0.8B and 0.8C stress are all died when measuring photosynthesis. Pn under different stress conditions than the control significantly decreased (P<0.05),0.5B and 0.5C,0.8A and 0.8F are negative. Under mild stress, stomatal conductance sorbifolia seedlings decreased significantly at 0.2A stress, other conditions were significantly higher than the control; under moderate and severe conditions are significantly lower than the control. Plants use light and gas exchange is severely limited.(4) Under duress, soluble sugars can be used as organic permeate by plant, making adjustments. Resulting that the content of soluble sugar increased in sensitive parts of the plant. Non-structural carbon carbohydrate (NSC), after the plant under duress and soluble sugar converted into each other, carry out osmotic adjustment, can be used as energy source for plants to supplement energy deficiency. Xanthoceras sorbifolia Bunge seedlings under mild or moderate salinity stress, the root, stem soluble sugar content and non-structural carbon were higher than the controls. In severe stress soluble sugar content;0.8B,0.8F handling, roots and leaves soluble sugar content were higher than the control,0.8A,0.8C process root ■ soluble sugar content was significantly higher than the control. Severe stress in the root and leaves NSC levels were lower than the control.(5)In salinity stress seedling, root,tem and leaf of nitrogen and phosphorus under different stress conditions were higher than the control. And in moderate or severe stress show significant differences, which may be due to stress conditions to inhibit the growth of plants, cause an increase in the relative content of nitrogen and phosphorus in plants.Study found that under mild degree of stress, growth conditions and physiological and biochemical Xanthoceras sorbifolia Bunge seedlings have not been significant inhibition, but moderate stress Bunge following growth restriction, decreased photosynthesis, water potential and root hydraulic conductivity decreases, soluble sugar content increased, the normal growth of plants is limited, under moderate stress, the stronger the alkaline salt, various morphological and physiological indicators of plant is limited more significant. Under severe stress, the seedlings of various alkali treatments were not normally survive, a large number of deaths were found in the study..