Screening and Identification of Sorghum Cultivars for Salinity Tolerance During Germination

【Objective】The objective of the current study was to explore the response of 35 different sorghum cultivars to alkali stress,and screen them for suitability for growing in alkaline soil and provide some guidance for their management under alkali stress.【Method】Mixed alkali were used(NaHCO3﹕Na2CO3 with the mole ratio of 9﹕1) to simulate the typical alkali stress environment.The 35 sorghum cultivars were treated with 25 mmol.L-1 solution or distilled water and incubated in Petri dishes for 10 days at humidity of 60%,light/dark of 12 h/12 h,illumination of 34 μmol.m-2.s-1 and 28℃/25℃ of day/night during germination.The germination force was measured on the fourth day and the germination percentage,leaf length,root length,leaf fresh weight,root fresh weight,leaf dry weight,root dry weight and remaining seed dry weight were measured on the tenth day.Through the fuzzy mathematics method of membership function,principal component analysis(PCA) and clustering analysis(CA),the alkali resistance of different sorghum cultivars were evaluated.【Result】The PCA results showed that root length,germination index and leaf dry weight were the most significant factors and are recommended as the main indexes for identifing alkali tolerance of sorghum at germination.The cultivars were ranked based on the membership function,and three groups on alkali tolerance were sorted from the 35 sorghum cultivars according to the CA.The analysis showed that seven of the 35 cultivars were strongly tolerant of alkaline conditions,e.g.Siza25,that twenty-two were had medium tolerance,e.g.Jiza 319 and Chiza 28,and that six were sensitive,e.g.Longza 9.【Conclusion】Principal component analysis showed that root length,germination index and leaf dry weight were the most significant factors and these are recommended as the main indexes to identify alkali tolerance of sorghum at germination,and in plant breeding and evaluation projects should be supported by CA and membership function to provide rigorous assessment of cultivars tolerance of alkalinity.