Abstract
ABSTRACT: The aim of this study was to use quantile regression (QR) to characterize the effect of the adaptability parameter throughout the distribution of the productivity variable on black bean cultivars launched by different national research institutes (research centers) over the last 50 years. For this purpose, 40 cultivars developed by Brazilian genetic improvement programs between 1959 and 2013 were used. Initially, QR models were adjusted considering three quantiles (τ = 0.2, 0.5 and 0.8). Subsequently, with the confidence intervals, quantile models τ = 0.2 and 0.8 (QR0.2 and QR0.8) showed differences regarding the parameter of adaptability and average productivity. Finally, by grouping the cultivars into one of the two groups defined from QR0.2 and QR0.8, it was reported that the younger cultivars were associated to the quantile τ = 0.8, i.e., those with higher yields and more responsive conditions indicating that genetic improvement over the last 50 years resulted in an increase in both the productivity and the adaptability of cultivars.
Highlights
INTRODUCTIONBrazil is the world’s largest producer and consumer of beans (Phaseolusvulgaris L.) and reached 3.39 million tons in the 2016/2017 harvest (CONAB, 2017).Genetic improvement has contributed significantly to this production (or productivity) growth over the last decades
Brazil is the world’s largest producer and consumer of beans (Phaseolusvulgaris L.) and reached 3.39 million tons in the 2016/2017 harvest (CONAB, 2017).Genetic improvement has contributed significantly to this production growth over the last decades.In a genetic improvement program, when the objective is to recommend genotypes for cultivation, it is necessary to consider the interaction between genotype and environment (GxE)
Aiming to evaluate the increase in productivity and the adaptation and predictability of black bean cultivars, BARILI et al (2015) estimated the average grain yield as well as the adaptability and phenotypic stability parameters of genotypes developed by the main Brazilian genetic improvement programs between 1959 and 2013
Summary
Brazil is the world’s largest producer and consumer of beans (Phaseolusvulgaris L.) and reached 3.39 million tons in the 2016/2017 harvest (CONAB, 2017).Genetic improvement has contributed significantly to this production (or productivity) growth over the last decades. Aiming to evaluate the increase in productivity and the adaptation and predictability of black bean cultivars, BARILI et al (2015) estimated the average grain yield as well as the adaptability and phenotypic stability parameters of genotypes developed by the main Brazilian genetic improvement programs between 1959 and 2013. V.49, n.3, researchers, genetic improvement programs have contributed to an increase of productivity as new cultivars are recommended Interesting, such studies evaluate the adaptability in average terms, i.e., the correlation between environmental variation (X) and phenotypic response (Y) is explained by conditional expectation E(Y|X). In view of the above mentioned, the present study aimed to characterize the adaptability of black bean cultivars recommended by different national research institutes over the last 50 years (from 1959 to 2013), according to the distribution of the observed values of grain yield, from of the quantile regression analysis (QR)
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