Estimates of Genetic Parameters and Selection Gains to Scab Resistance in Sour Passion Fruit

Abstract

-Passion fruit stands out as one of the most cultivated fruits in Brazil. As the culture expanded, an increase in phytosanitary problems was observed. Fungal diseases like scab are among phytosanitary problems. The aim of this study was to quantify scab intensity on leaves, and to estimate genetic parameters and selection gains to scab resistance in sour passion fruit full related families (FRF). Two experiments were conducted to evaluate the reaction of FRF, the first period from January to April (environment 1) and the second from May to August 2014 (environment 2). Experiments were conducted in greenhouse. Randomized block design for both experiments with FRF in two seasons was used, with three plants per plot and three repetitions. The evaluated characteristics were: score within 42 days after inoculation (DAI), area under the disease progress curve of severity (AUDPCS) and incidence (AUDPCI). Individual and joint variance trait analyses were carried out, estimating genetic parameters and gains per direct and indirect selection. Heritability estimates in a broad sense were higher than 89.9% for all traits in the individual and joint analysis. Selection gains were high for the evaluated traits in both environments and the greatest genetic progress was obtained by the direct selection in each feature. Of FRF selected, 92% and 36% were classified as moderate for environments 1 and 2, respectively. The highest gains in direct and indirect selection were obtained for AUDPCS in the individual analyses of environments and in the joint analysis. FRF 68, 46, 66, 75, 47, 51, 52, 54 and 77 were moderately resistant, which allows their use in a scab resistance breeding program. Index terms: Passiflora edulis, Cladosporium herbarum, breeding. ESTIMATIVAS DE PARÂMETROS GENÉTICOS E GANHOS DE SELEÇÃO DA RESISTÊNCIA DO MARACUJAZEIRO-AZEDO À VERRUGOSERESUMO -O maracujá destaca-se como uma das frutíferas mais cultivadas no Brasil. Com a expansão da cultura, houve aumento dos problemas fitossanitários. Dentre os problemas fitossanitários, estão as doenças fúngicas, como a verrugose. Objetivou-se, neste trabalho, quantificar a intensidade da verrugose nas folhas, estimar parâmetros genéticos e o ganho de seleção da resistência à verrugose em famílias de irmãos completos (FICs) de maracujazeiro-azedo. Foram realizados dois experimentos para avaliar a reação das FIC, sendo o primeiro no período de janeiro a abril (ambiente 1) e o segundo de maio a agosto de 2014 (ambiente 2). Os experimentos foram conduzidos em ambiente protegido. Utilizou-se o delineamento de blocos casualizados para os dois experimentos, com as FICs em duas épocas, contendo três plantas por parcela e três repetições. As características avaliadas foram: nota aos 42 dias após a inoculação (DAI), área abaixo da curva de progresso da severidade (AACPS) e da incidência (AACPI) da verrugose. Foram realizadas análises de variância individual e conjunta das características, estimados os parâmetros genéticos e os ganhos por seleção direta e indireta. As estimati...