Screening Of Kidney Bean Cultivars For Saline-alkaline Tolerance And Study Of Physiological And Biochemical Response Mechanism

To increase and stabilize the yield of crops in low middle yield field with abiotic stress limitation,in this study,aiming at restrictive factors for the growth of crops in soda saline-alkali soil regions and secondary salinized farmland,42 kidney bean varieties were chose,and NaHCO₃of 7 concentrations from 25 mmol·L^-1to 175 mmol·L^-1was used,to screen salt alkaline tolerance of kidney bean at seedling stage.Salt alkaline tolerant variety Heiyundou(HYD)and salt alkaline sensitive variety Japanese White(JW)were used as materials.Germination characteristics of kidney bean and salt tolerant mechanism of seedlings were compared and studied under NaCl and NaHCO₃stress.Main results were as follows:1.Identification and screening of different kidney bean cultivars for salt alkaline tolerance during seedling stageAccording to comprehensive evaluation of 42 kidney bean varieties at seedling stage based on salt alkaline tolerance coefficient,principal component analysis,membership function and clustering analysis,dry weight per plant,overground fresh weight,root length,underground water content and underground fresh weight could be used as main identification indexes for kidney bean at seedling stage.HYD was salt alkaline tolerant variety,and JW was salt alkaline sensitive variety.100mmol·L^-1NaHCO₃could be used as proper salt alkaline concentration for the salt alkaline tolerance identification of kidney bean at seedling stage.2.The effects of salt alkaline stress on seeds germination of kidney beanNaCl and NaHCO₃treatment prolonged the time of seeds germinating and that of half seeds sprouting,declined sprouting speed and seed vigor index,and made epicotyls and roots grow more slowly.The inhibitory effect strengthened with the strengthening of the stress.Salt alkaline treatment increased electric conductivity of two kidney bean varieties and decreased amylase activity.3.The effects of salt alkaline stress on antioxidation system of kidney bean seedlingsThe results of experiments on antioxidation enzyme of seedlings of kidney beans showed that the stresses of salt alkaline to roots were stronger than to leaves,meanwhile,the stress of NaHCO₃was stronger than that of NaCl.Those experiments indicated that HYD had stronger salt alkaline tolerance which could maintain stronger antioxidation ability under the stresses of NaCl and NaHCO₃.4.The effects of salt alkaline stress on photosynthentic characteristics of kidney bean seedlings.Although part of seedlings could survive under salt alkaline stress,yet photosynthentic characteristic of them was restrained to different extent.In terms of chlorophyll fluorescence characteristics,Fv/Fm was restrained,Under low-concentration treatment,Fv/Fm of two kidney bean varieties was promoted.The change amplitude of Fv/Fm of salt alkaline sensitive varieties was larger than that of salt alkaline tolerant varieties.5.The effects of salt alkaline stress on osmoregulation and ion balance of kidney bean seedlings.Soluble sugar and soluble protein of two kidney bean varieties were not used as osmoregulation substance,but might could be consumed as energy resource at early stage of NaCl and NaHCO₃stress.With the increasing of the stress concentration and the elongation of stress time,soluble sugar and soluble protein were gradually transformed into osmoregulation substance to regulate leaf micro-environment.Roots had stronger capacity of storing Na⁺to decrease the transportation of Na⁺to leaves.K⁺content and K⁺/Na⁺of roots and leaves of two varieties were somewhat reduced,the decline range of JW was higher than that of HYD.