Identification And Evaluation Of Salt Tolerance Correlated Traits In Seedling Stage Of Gossypium Hirsutum

Cotton is an important cash crop,and is also a pioneer crop cultivating in saline soil.Planting cotton in saline soil is an important direction of cotton industrial structure adjustment in China.In order to develop cotton planting in saline soil,it is necessary to breed salt-tolerant cotton varieties.And the identification and evaluation of salt tolerance correlated traits are the basis of breeding cotton salt tolerant varieties.Some research shown that seedling stage is the key period in response to salt stress in cotton,and the identification and evaluation salt tolerance correlated traits of seedling stage have potential application value for breeding cotton salt-tolerant varieties.Root and leaves are the most important tissues in response to salt stress at seedling stage.Under salt stress,the phenotype of root would be change to improve adaptability and to reduce the degree of injury.And excessive salt was stored in the old leaves,resulting in leaf wilting,even the process of plant salt secretion could be happened through the shedding of the old leaves.In our previously study,the salt tolerance identification of 419 upland cotton core collections was operated under 0.3% Na Cl stress.But,it was not reported that the correlation analysis between the traits of root and leaf and the salt tolerance grade of seedling stage in cotton under salt stress.Combining with the situation of breeding cotton varieties in non-saline-alkali field,three root tissue traits(total root length,root surface area,root volume)and six leaf tissue traits(first true leaf area,first true leaf length,first true leaf width,the second true leaf area,the second true leaf length and the second true leaf width)of trefoil stage were identified and evaluated in 419 upland cotton core collections in this study under normal condition.And the correlation analysis between identified nine traits with salt tolerance grade was carried out in order to identify new correlated traits of salt tolerance at seedling stage.The main results were as follows:1.The results of significantly different of traits and distinct categories were obtained in 419 upland cotton core collections based on three root tissues traits and six leaf tissues traits of the trifoliate stage.2.The correlation analysis showed that the second true leaf area and the second true leaf length were positively correlated with salt tolerance grade in the third leaf stageof 419 upland cotton core collections.The root traits(total root length,root surface area,root volume)in trefoil stage were not correlated with salt tolerance grade.3.The further clustering analysis and evaluation were operated in 419 upland cotton core collections based on the second true leaf area,the second true leaf length and salt tolerance grade.The results showed that all germplasms were divided into four categories when the threshold was 6.66.And the group II included 160 materials,which were high resistance materials and salt resistant materials.4.The mean value of the second true leaf area and the second true leaf length among different groups were significantly different.5.Eight high resistance materials(70 Xuan 24,Jiumian 2,Dai Zhimian 15,Jin 7,Esha 28,Judian Township Miao Hua,Lijiang County,Beijing 432 and E 4396)were selected in this study.Above all,the second true leaf area and the second true leaf length of three-leaf stage were significant positively correlation with salt tolerance grade of seedling stage in 419 upland cotton core collection.The three root traits(total root length,root surface area,root volume)were not correlated with salt tolerance grade at seedling stage.