Seleção recorrente na população CNA9 de arroz de terras altas para tolerância e responsividade ao fósforo
Carregando...
Data
2015-02-12
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
The upland rice has a high potential for expansion in the Brazilian savannahs region, where
soils have limiting factors to yields, such as low phosphorus (P) availability. Considering
the costs and the natural reserves scarcity, a suitable alternative is to explore the genetic
resources to develop cultivars with P deficiency tolerance and P-use efficiency. Given the
polygenic inheritance of these traits, a strategy is to concentrate the favorable alleles
gradually through recurrent selection. The objectives of this study were to estimate genetic
and phenotypic parameters, and evaluate progenies from CNA9/3/1 recurrent selection
population of upland rice for the tolerance to P deficiency in the soil. In 2011/12 crop year,
in Santo Antônio de Goiás-GO and Sinop-MT, two contrasting trials were conducted within
each location: low and high P-level determined by the clay content of the soil, and without
discrimination of other crop practices. The simple square lattice design 14 x 14 was adopted,
with 189 S0:2 progenies and seven checks, with plots consisted of four 3-m-long rows. Grain
yield (GY, in kg ha-1), plant height (PH, cm) and days-to-flowering (DF, in days) were
evaluated. The individual variance analysis by location and by P-level were obtained, well
as their phenotypic, genetic and environmental correlations. Only for PG, genetic and
phenotypic parameters were estimated from joint analysis of variance within each P-level,
and involving locations and P-levels. Estimates of the expected response to selection were
obtained for the two P-levels, considering the direct, indirect and general selection criteria,
and also the Harmonic Mean of Relative Performance (𝑀𝐻𝑃𝑅) and Tolerance Index (𝐼𝑇) of
the genotypes identified as efficient and responsive from a graphic dispersion of adjusted
means. The overall average of the GY was reduced significantly in 27% for P deficiency in
the soil and the genetic variance among S0:2 progenies (𝜎̂𝑝
2) was narrowed in 63%. Highly
significant diferences (p≤0.01) were observed among progenies, demonstrating the presence
of sufficient genetic variability for GY, in this population, to obtain genetic progress in both
P-levels. The progenies showed performance significantly (p≤0.01) below the of checks and
also a significant interaction (p≤0.01) with locations, in both P-levels. The genotype x Plevel
interaction was significant (p≤0.01) and the phenotypic correlation (√R2) between Plevels
was low (0.44). In this sense, the expected response to selection demonstrated that
progenies must be evaluated in P-deficient environments to obtain effective genetic gain in
this environment. The genetic correlations between traits were significant (p≤0.01) and are
favorable for the selection of genotypes with tolerance to P deficiency, short plant height
and early cycle. However, there is a greater difficulty in increasing the yield potencial, since
there the genetic correlation between this trait and PH was significant (p≤0.01) and positive
(𝑟𝐺= 0.385). From the graphic dispersion of S0:2 progeny means have been identified 57
efficient and responsive to the presence of P in the soil, and for the selection within this
group, the 𝑀𝐻𝑃𝑅 was more appropriate than 𝐼𝑇, because considering simultaneously these
two attributes.
Descrição
Citação
VIDOTTI, M. S. Seleção recorrente na população CNA9 de arroz de terras altas para tolerância e responsividade ao fósforo. 2015. 118 f. Dissertação (Mestrado em Genética e Melhoramento de Plantas) - Universidade Federal de Goiás, Goiânia, 2015.