Genetic parameters and line selection of Cucurbita pepo based on selection indices

Igor Forigo Beloti,Fernando Cezar Juliatti,Gabriel Mascarenhas Maciel,Daniel Bonifácio Oliveira Cardoso,Rafael Resende Finzi

doi:10.14393/bj-v36n0a2020-53607

Igor Forigo Beloti, Fernando Cezar Juliatti + Show 3 more

Open Access

https://doi.org/10.14393/bj-v36n0a2020-53607

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Abstract

In the improvement of pumpkins, the selection based on one or a few characters of interest tends to be less efficient, leading to a superior product only compared to the few characters selected. To maximize the simultaneous selection of multiple characteristics of interest, selection indexes are used to obtain a numerical value resulting from the combination of the characters on which the simultaneous selection is to be practiced. The objective of this study was to determine genetic parameters and the most appropriate selection indexes in strains of Summer squash (C. pepo). Statistical analyzes were performed based on 65 genotypes belonging to the vegetable germplasm bank of the Federal University of Uberlândia. The variables analyzed were: leaf area index, precocity, SPAD index, productivity. plant-1, number of fruits. Plant-1, leaf temperature, NDVI index and NDRE index. The indexes were used: Smith (1936) and Hazel (1943), the sum of “Ranks” by Mulamba and Mock (1978), and Willians (1962). The selection methodologies selected ten individuals (15% of the genotypes). The values found for h² (%) ranged from 36.92% (SPAD) to 59.65% (cycle). The values obtained in the CVg / CVe quotient were below 1, varying from 0.18 for leaf temperature to 0.70 for the cycle, with the other variables close to 0.5. The CVg genetic variation coefficient (%) was also low, ranging from 1.84% for leaf temperature to 30.94% for productivity. The greatest gains obtained with direct and indirect selection were for the characters productivity (35.92%), NDRE (33.04%), number of fruits (28.93%) and leaf area index (22.72%). The Mulamba and Mock (1978) index showed the highest total selection gain value, providing a balanced distribution of selection gains, choosing the genotypes: 8, 31, 34, 38, 42, 64, 65, 66, 67 and 68.

Highlights

Summer squash (C. pepo L.) is a vegetable of great socioeconomic importance, especially for family farming in several countries
A plant breeding program depends on the existence of genetic variability, because through hybridizations it is possible to obtain individuals that gather favorable alleles of characteristics of interest (MATSUO; CRUZ; SEDYAMA, 2020)
Sixty-five C. pepo genotypes were obtained in the fifth generation (Table 1), through prior selection based on desirable fruit characteristics such as shape and color, number of male and female flowers, leaf temperature and SPAD index

Summary

Introduction

Summer squash (C. pepo L.) is a vegetable of great socioeconomic importance, especially for family farming in several countries It belongs to the family Cucurbitaceae, with wide genetic variability, composed of more than 80 genera and 800 species of plants (FORMISANO et al, 2012). The selection based on one or a few characters proves to be inadequate, leading to a superior final genotype only in relation to the few characters selected. It is a complex process, since the characters of agronomic importance are quantitative in nature, generally correlated with each other and, in most cases, of low heritability (NOGUEIRA et al, 2012; LEITE et al, 2016)

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