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Wheat breeding: VIII. Associations of grain yield with other agronomic characteristics in crosses involving different sources of dwarfism in wheat

Standard height cultivar C-3 was crossed with the semi-dwarf cultivar Siete Cerros and the dwarf cultivars Tordo, Vican-71 and Olesen. Parents, F1's, F2's and reciprocal back-crosses were tested for grain yield, plant height, number of spikes per plant, number of spikelets per spike, number of grains per spike, number of grains per spikelet, 100-grain-weight, spike length, in a experiment carried out at Itararé Experimental Station, State of São Paulo, Brazil. All data was determined on an individual plant basis. Broad sense heritability estimates for number of spikelets per spike and plant height were 0.533 and 0.525, respectively. The values for spike length, number of grains per spike and spikelet, 100-grain-weight and number of spikes per plant showed variation between 0.339 and 0.473. Broad sense heritability for grain yield was low and equal to 0.255. Narrow sense heritability estimates for all characteristics under study except for number of spikes per plant showed that great part of the total genetic variation found in the studied populations was associated with additive gene action. The correlations between grain yield and all the other characteristics were positive and significant at 1% level probability, for all the populations under study, except for the correlations between grain yield and number of spikelets per spike for the populations C-3 x Siete Cerros and C-3 x Vican-71, between grain yield and 100-grain-weight for the population C-3 x Siete Cerros, between grains yield and number of grains per spikelet for the populations C-3 x Siete Cerros, C-3 x Tordo and C-3 x Olesen, which showed to be positive and significant only at the 5% probability level.


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