Simultaneous improvement of yield and fibre quality in upland cotton (Gossypium hirsutum)

Two sets of generations of single tester analysis developed during the rainy seasons of 1999 and 2000 from crosses of 17 genetically diverse upland cotton (Gossypium hirsutum L.) genotypes with 'LH 900' in Set I and 'LH 1832' in Set II, were grown in 2 trials in randomized complete block design with 3 replications during the rainy season of 2001 and evaluated for characters related to yield, fibre quality, earliness and plant type. The differences in the magnitude of additive and dominance components as estimated by single tester analysis in Set I and Set 11 and, in means of different generations in both the sets indicated an improvement of seed-cotton yield (51.00 g from 35.89 g) and fibre quality characters in 'LH 1832' compared to 'LH 900'. While fibre length increased (29.13 mm from 25.30 mm) in the strain 'LH 1832' but there was decrease in ginning outturn (30.33% from 35.06%) compared to 'LH 900', which was the major constraint in the improvement of 'LH 900'. The simplified triple test cross analysis indicated that a part of additive genetic variation was utilized for most of the characters as additive genetic component estimated from this analysis was lower than that of Set I and Set 11 as estimated by single tester analysis. On the basis of estimates of gene effects from analysis of generation means and high F-1 performance coupled with low inbreeding depression, 3 crosses, ie 'LH 1832' x 'RS 2013', 'LH 1832' x 'CIM 435' and 'LH 1832' x 'LH 1980', were selected for further improvement having good potential to further improve yield and fibre quality but no single cross was ideal to combine these characters with short height, early maturity and higher ginning outturn. A new base Population from intercrosses of desirable segregants from these 3 crosses may thus be developed to identify desirable recombinants with high yield potential and fibre length combining the plant type and maturity of 'LH 900'.