Study of relationship between tobacco leaf yield and its components using Path analysis under Normal moisture and drought stress

In order to study the relationship between dry leaf yield and some important characteristics of tobacco under drought stress and optimal conditions, 15 hybrid of tobacco, including 10 Iranian hybrids and 5 introduced hybrids from other countries were evaluated in two separate experiments (drought stress and normal) in a randomized complete block design with three replications, at the Research Center of Rasht, Iran, during 2008-2009. Results showed that under normal condition, there was positive and significant correlation between dry leaf yield and days to start flowering, flowering period, stem diameter and leaf area index, but dry leaf yield had negative and significant correlation with stem height. Under drought conditions, there was positive and significant correlation between green leaf yield and days to start flowering, leaf width and leaf area index, while there was no significant correlation between dry leaf yield and other traits. Path analysis of the correlation between dry leaf yield (as dependent variable) and other traits (as independent variables) showed that under non-stress conditions, days to start flowering, leaf length and stem diameter had direct effects on dry leaf yield, while under drought conditions, number of leaf, leaf width and days to start flowering had direct and positive effects. On drought stress conditions, the correlation between days to start flowering and green leaf yield was resulted from indirect effect of number of leaves per plant. To select for tobacco high quality leaves, we can select the best plants indirectly by using of days to start flowering, stem diameter and leaf length under normal water conditions and the number of leaves and leaf width under drought stress conditions.