VARIABILITY AND CHARACTER ASSOCIATIONS FOR VEGETATIVE AND GRAIN FILLING PERIODS IN F2 POPULATIONS OF MACARONI WHEAT (Triticum durum Desf.)

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Date
2004-05
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JAU, JUNAGADH
Abstract
Wheat is one of the important food grains and the durations of vegetative growth and grain filling is believed to be yield determining traits in this crop. To know the extent of variability for these traits and their associations with other agronomic traits particularly in segregating populations of durum wheat, this study was undertaken. Eight F2 populations along with their seven parents were grown in randomized block design with four replications at the Instructional Farm, College of Agriculture, Junagadh during Rabi 2002-03. Observations on fourteen characters were recorded. The results indicated that the differences among the entries found significant across the crosses for all the characters. Positive transgressive segregations in the F2 populations as arised in the Cross 2 and 4 for the characters like grain filling period, grain filling index, grains per spike, 100-grain weight, grain yield per plant and harvest index should be exploited to select for individual superior to the parents. The estimates of GCV, PCV, heritability and genetic advance were low in all the crosses for days to ear emergence, days to maturity, vegetative period, grain filling period, grain filling index, spikelets per spike and 100-grain weight, implying that these characters are largely under the control of nonadditive gene action and selection would be ineffective. On the other hand, grains per spike, grain yield per plant and harvest index with moderate to high heritability and genetic advance showed moderate to high GCV in most crosses, suggesting that additive gene action should have played a major role to explain these characters and more attention should be paid to these traits. Correlation studies revealed significant positive associations among days to ear emergence, days to maturity and vegetative period in all the crosses. Higher grain filling index was usually associated with earliness, shorter vegetative period and longer grain filling period. In such circumstances, selection for earliness in early generations and longer grain filling period through indirect selection of grain filling index in later generations would be better scheme for developing early genotypes with longer grain filling period. However, failure to identify an associations of vegetative and grain filling periods with grain yield per plant indicated that selection for an optimal durations of vegetative and grain filling periods to improve grain yield would not seem to be a deserving objective for durum wheat especially in our conditions and breeding efforts should be concentrated on other characters related to grain yield.
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