Performance of upland rice families selected from segregant populations

Abstract

The objective of this research was to analyze the agronomic performance of rice (Oryza sativa L.) families selected from divergent populations evaluated under different sowing times and locations in 1996/97. The source populations for the families were CNA x 5496, CNA x 6001, CNA x 6063 and CNA x 6102. A hundred families from each cross (population) were evaluated and submitted to five common treatments, which originated a three-replicate 20x20 lattice, grown at two locations, Lavras and Patos de Minas in 1997/98. In the next year (1998/99), the ten best and the ten worst-performing families from each population were again evaluated to confirm the superiority of families selected from the CNA x 5496 and CNA x 6001 populations. A 9x9 lattice with three replications experimental design was used. The two populations selected as the most promising in 1996/97 yielded the best families upon selection. Therefore, in a similar breeding program, it would be advantageous to carry out a high number of crosses, originating a great number of segregant populations, and to select the best ones, concentrating efforts on the evaluation of families extracted from superior populations. Such results confirm the efficiency of selection of source populations for family extraction. KEY WORDS:Oryza sativa, breeding, yield.maize (Pinto, 1996) were conducted under field conditions, which revealed the need to evaluate a large number of families within each population, especially if character heritability is low.

Genetic progress after cycles of upland rice recurrent selection

“…Thus, the dominance variance ( ) was confirmed as having a negligible influence compared to the additive variance ( ). This result corroborated with Santos et al (2002), who similarly argued that the dominance variance had a minimal impact on trait because the magnitude of the coefficient associated with this parameter was low, i.e., equal to (Cockerham, 1963). Among the cycles, there was considerable variation in PS in traits under the two assumptions.…”

Study of the interaction genotypes x environments in the selection process of upland rice

“…A few researches exist that evaluate the best planting dates for different cultivars (Morais et al 1989). Santos (2002) studied the effect of the interaction of segregant populations versus environments on the choice of superior populations in a breeding program. The greater emphasis has been given to the identification of more stable genotypes as they perform in regional trials of strains and cultivars under competition (Morais et al 1981, Morais et al 1982.…”

Seleção em Feijão-Caupi Visando Obtenção de Linhagens Extraprecoces

“…No que se refere às estimativas de herdabilidade realizada e ganho realizado com a seleção, Santos et al (2002) trabalhando com o desempenho de progênies de arroz, obtiveram estimativas de herdabilidade realizada para o caráter produção, superiores às obtidas nesse traballho. Já Frey;Horner (1955), comparando os ganhos reais e preditos em cevada, obtiveram estimativas de 14,4% para produção.…”