Sequential path analysis for determining interrelationships between yield and related traits in tobacco (Nicotiana tabacum L.) under normal and abiotic stress conditions

Abstract

In the present work the relationships between yield and its related traits were investigated in tobacco genotypes under normal and abiotic stress conditions (Orobanche aegyptiaca weed) at Urmia Tobacco Research Centre, Iran, during 2006-2009 cropping seasons. The experimental design was a randomized complete block design (RCBD) with three replications in each condition every year. Analysis of variance revealed extent genetic variability among the genotypes for most of the traits studied. In comparison with normal condition, the mean value of studied traits decreased in stress condition. LAI and FD showed the maximum and minimum diminution in the mean values under stress condition compared to normal one so known as more sensitive and more tolerant traits, respectively. Based on CV values, the traits FD and DLYP showed the minimum and maximum variation among traits in both normal and stress conditions. Correlation analysis revealed significant and positive correlations between DLYP with all studied traits in both normal and stress conditions. Path analysis detected the traits including biomass, APDW and DWR as the first-order variables at normal condition and biomass, APDW, DWR and harvest index as the first-order variables under abiotic stress condition. Based on results, the traits such as biomass, APDW, DWR detected as more important factors in both conditions can be used in tobacco breeding programs for increasing yield. Abbreviation: aerial part fresh weight without leaves weight (APFW), aerial part dry weight without leaves weight (APDW), biomass (BIO), coefficient of variation (CV), dry weight of root (DWR), flowering date (FD), fresh weight of leaf (FWL), fresh weight of root (FWR), harvest index (HI), leaf area index (LAI), dry leaf yield per plant (DLYP), number of leaf (NL), plant height (PH), randomized complete block design (RCBD), standard deviation (Std).