Despite the progress, improved determinate (dt/dt) lines of sesame are still low yielding. Further improvement may be achieved by crossing locally adapted indeterminate cultivars with desirable determinates from a broad-based composite population. In order to test this hypothesis, 43 F2 base populations from these kinds of crosses were generated and a distinct variability among populations was observed for seed yield and other traits. A 20% positive selection for number of capsules as the most yield-related component was applied to the pairs of determinate and indeterminate segregating in each population. Although seed yield per plant, number of capsules per plant and number of seeds per capsule were lower in determinates than indeterminates, these gaps were closed in certain crosses sharing certain 'dt/dt' parents. Despite the fact that the plants were short, days to flowering (in F2) and days to maturity took longer in determinates. The effect of selection was not apparent in increasing mean of progeny population in F3 for the character under selection but the determinate group had the highest coefficient of variation (CV) as a basis for further genetic gain. It was concluded that composite populations with suitable genetic backgrounds were valuable sources of 'dt/dt' segregants; recurrent breeding efforts and the modification of farming systems are all necessary in order to adopt novel characteristics like determinacy.
展开▼
