Genetic correlation between traits in the ESALQ-PB1 maize population divergently selected for tassel size and ear height

Austeclínio Lopes Farias Neto,José Branco De Miranda Filho

doi:10.1590/s0103-90162001000100018

Austeclínio Lopes Farias Neto, José Branco De Miranda Filho

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https://doi.org/10.1590/s0103-90162001000100018

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Abstract

Full-sib and selfed (S1) progenies were obtained from sub-populations of ESALQ-PB1, divergently selected for tassel size (T+ and T-) and ear height (E+ and E-), and used for estimating genetic and phenotypic correlation coefficients between traits. The analyzed traits were: EW- total ear weight (g/plant), PH- plant height (cm), EH- ear height (cm), TB- tassel branch number and TL- tassel length. The highest genetic (rG) and phenotypic (rF) correlation was observed for the combination PH x EH, as expected, with average of 0.800 and 0.778, respectively over sub-populations and locations. It is apparent that divergent selection for tassel size did not affect greatly the correlation between PH and EH in the full sib progenies, but in the inbred progenies the correlation was smaller in the sub-population selected for larger tassels. Genetic correlation between PH and EH with tassel traits was always positive but ranged from 0.020 to 0.668 in Piracicaba and from 0.06 to 0.309 in Rio Verde. Genetic correlation between PH and EH with yield (EW) also was positive in the range of 0.087 to 0.503. EH showed higher correlation with EW in relation to PH x EW and differences were larger in the sub-populations divergently selected for ear height. Correlation between tassel traits with other traits was positive in most of instances and a lack of consistency was observed among sub-populations. Generally the coefficients of genetic and phenotypic correlation differed substantially from the estimates in the base population ESALQ-PB1 before divergent selection for tassel size and ear placement. Divergent selection affected the correlation between traits under unpredicted and varying magnitudes.

Highlights

Maize (Zea mays L.) is, among the cultivated species, one that has undergone a fantastic improvement in yield through artificial selection (Hallauer & Miranda Filho, 1995)
Intentionally or not, changes have occurred in tassel size for a better utilization of photosynthates (Mock & Pearce, 1975)
In most breeding programs the strategy is based on selection for several traits simultaneously and, knowledge on the genetic association between traits is inevitably useful for the establishment of selection criteria

Summary

Introduction

Maize (Zea mays L.) is, among the cultivated species, one that has undergone a fantastic improvement in yield through artificial selection (Hallauer & Miranda Filho, 1995). Attention has been given to plant architecture toward a better efficiency in the utilization of solar energy and photosynthetic capacity (Donald, 1968; Wittner, 1974; Paterniani, 1974, 1981; Miranda Filho, 1974; Sampaio, 1986). The association between traits is an important aspect to deal with in breeding programs, because genetic change in a given trait may change positively or negatively other traits (Vencovsky & Barriga, 1992). The basic causes of genetic correlation are pleiotropy, and linkage disequilibrium (Falconer, 1964; Vencovsky, 1978; Hallauer & Miranda Filho, 1995)

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