AN IDENTIFICATION OF DROUGHT TOLERANT GENOTYPES IN VIRGINIA TOBACCOS.M. Sadeghi and H. Samizadeh, E. Amiri, M Ashouri and N. Mohammadian
Drought stress is one of the most important a biotic stress which suffer damages on tobacco production in many countries including Iran. Thus, investigating of drought tolerance genotypes is the important goal in tobacco breeding projects in Iran. For the reason, five Virginian tobacco genotypes and their hybrids were evaluated in a RCBD with three replications in two different environments (water stress and normal irrigation) In the present investigation, some tolerance indices were studies in five Virginia of tobacco together ten their hybrids (fifteen genotypes). The materials were evaluated in two different experiments using a RCBD with three replications in two environments (water stress and normal irrigation) in the Tirtash and Rasht tobacco research station during 2006 and 2007. Based on the dry leaf yield potential (YP) and yield stability (YS), some quantitative criteria of drought resistance such as: mean productivity (MP), tolerance index (TOL), geometric mean productivity (GMP), harmonic mean (Harm), Stress susceptibility index (SSI) figured out. High significance differences were observed among genotypes for all indices and for potential and stress yields, indicating the existence of genetic variation and possibility of selection for drought resistance. Correlation analysis among indices, potential and stress dry leaf yield indicated that were MP, GMP and STI the most suitable criteria for screening tobacco genotypes. Multivariate biplot indicated that k394 ×NC89, NC55 and NC89 ×Coker347 in Tirtash and CC27 and Coker254×VE1 in Rasht have highest yield and they have tolerance to drought stress. Distribution of the genotypes in the biplot space indicated the presence of genetic diversity among the genotypes for drought stress.
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