Genetic variation and interrelationships of agronomic characters in landraces of bread wheat from southeastern Iran |
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Authors: | M Moghaddam B Ehdaie JG Waines |
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Institution: | (1) Department of Agronomy, Tabriz University, Tabriz, Iran;(2) Department of Botany and Plant Sciences, University of California, Riverside, CA, 92521-0124, U.S.A |
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Abstract: | There is renewed interest in wheat landraces as important sources of genetic variation for agronomic characters. Fifty-three
pure lines of bread wheat (Triticum aestivum L.) derived from seven landraces collected from southeastern Iran were used to
estimate genetic variation and heritability for 13 developmental and quantitative characters. Path-analysis was used to partition
the genetic correlations between grain yield and six grain yield-related traits. Mean values of landraces were also compared
with three improved cultivars from California and Iran. Genotypic differences among the landraces and among the pure lines
collected from the landraces were highly significant for all characters considered. Compared with the modern cultivars, the
landrace genotypes were, on average, later in days to heading and taller than the cultivars but had lower values for number
of grains per spike, 1000-grain weight, grain yield and harvest index. Some landrace genotypes were similar to the modern
cultivars for grain yield. Moderate to high genetic variation was displayed by number of grains per spike, number of spikes
per plant, 1000-grain weight, and harvest index. The heritability estimates ranged from 59% for grain yield to 99% for days
to anthesis. Expected genetic advance (as % of the mean) was ≈34% for number of spikes per plant, number of grains per spike,
and 1000-grain weight. Days to heading and to anthesis correlated positively with number of spikes per plant, shoot biomass,
and straw biomass but negatively with number of grains per spike and harvest index. The strong direct effect of number of
spikes per plant on grain yield was completely counterbalanced by its indirect negative effects via number of grains per spike
and 1000-grain weight. Number of grains per spike and 1000-grain weight were positively correlated with grain yield, and they
had large direct effects. These two characters, however, were negatively correlated and exhibited a substantial counterbalance
effect via one another and via number of spikes per plant. The landraces could be improved by intercrossing the promising
genotypes identified in this study, with simultaneous selection for earliness, fewer number of spikes per plant, greater number
of grains per spike and heavier grains. For further improvement, crossing programs between the landraces and introduced germplasm
may be necessary.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | Triticum aestivum L bread wheat landraces genetic variation path-analysis yield and yield components selection Iran |
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