Heterotic Studies in Flue-Cured Tobacco across Environments

This research was conducted to determine heterosis for various agronomic and biochemical traits in Flue Cured Virginia tobacco. Seven tobacco varieties/lines, ‘NC606’, ‘K399’, ‘Spt G 126’, ‘Spt G 28’, ‘KHG21’, ‘KHG22’ and ‘KHG24’ with contrasting traits were crossed in all possible combinations to generate 7 x 7 diallel crosses. In 2008 and 2009, all F1 hybrids along with their parent cultivars were planted in randomized complete block (RCB) design with four replicates at Tobacco Research Station Mardan (plain) and Tobacco Research Substation Mansehra (hilly). Data for all traits were analysed in pooled analysis and individual environments. Heterosis over better parent was determined for all traits across environments. Heterobeltiosis estimates reflected both positive and negative values, suggesting additive as well as non-additive gene actions in the expression of traits. Performance of hybrids was environment-specific. However, heterobeltiosis estimates ranged between -7.9 and 25.90 for leaf area, -6.76 and 130.8 for number of cured leaves kg^-1, -10.8 and 17.1 for yield, -16.0 and 9.94 for grade index, -10.4 and 68.66 for nicotine and -26.89 and 31.25 for reducing sugar, respectively. The current study identified KHG24/Spt G 28; KHG21/NC606 and Spt G 126/ KHG24 as best crosses for yield while KHG22/KHG21 was the only best cross for grade index.