Selection of watermelon starting material by adaptability for breeding for suitability for intensive and organic growing technologies

Abstract

Purpose and Objectives. To select watermelon starting materials by major productive indicators (yield, average marketable fruit weight) for the breeding of genotypes suitable for intensive and organic cultivation technologies.

Materials and Methods. Collection watermelon accessions were studied: 101 cultivars and lines from 9 countries. Cv. ‘Maks Plus’ (Ukraine) was taken as the control accession. The following parameters were determined: Sg_i – genotype’s stability, b_i – regression coefficient of the genotype's response to changing conditions (plasticity), GBV_i – genotype’s breeding value. Plants were grown by traditional technology in the Forest-Steppe of Ukraine (DSTU 3805-98, 1998; DSTU 5045:2008, 2008). Watermelon plants were fertilized and protected in compliance with scientific and practical recommendations. The study was conducted in accordance with routine methods of breeding. Kilchevskiy & Khotylyova’s method, 1997 was used to estimate the genotypes’ stability parameters. The coefficient of environmental plasticity (b_i) was calculated by Eberhart & Russel algorithm, 1966. Data were statistically and mathematically processed in Statistica 6.

Results and Discussion. The adaptive potential of the watermelon collection was evaluated for the following characteristics: total and marketable yields and average marketable fruit weight. The following parameters were determined: b_i - coefficient of regression of the genotype’s response to changes in conditions (plasticity), Sgi – genotype’s stability, and GBV_i – genotype’s breeding value of the watermelon collection. We established the amplitudes and ranges of variation of the yield indicators. By the coefficient of environmental plasticity b_i, the collection watermelon accessions were grouped as showing low, medium or high environmental plasticity for different traits. The collection accessions were categorized as follows: 1 - intensive genotypes with enhanced responses to growing conditions; 2 - with medium environmental plasticity; 3 - highly plastic, which slightly respond to changes in growing conditions. For breeding for various traits, we identified accessions of practical value in terms of stability parameters and genotype’s breeding value (GBV_i) for intensive and organic cultivation technologies. Taking into account the environmental variability parameters in collection watermelon accessions to be used in the breeding of cultivars and hybrids suitable for intensive technologies, we selected accessions with enhanced responses to changing growing conditions, which also consistently yielded sufficiently high. As to the yield constituents (productive traits), 5 breeding-valuable accessions were selected by the "total yield" trait, 6 – by the "marketable yield" trait, and 1 – by the "average fruit weight" trait. Analysis of the environmental variability parameters in the watermelon collection to be used as starting materials in the breeding of genotypes suitable for organic cultivation enabled us to select a number of accessions by productive traits: 6 breeding-valuable accessions were distinguished due to the "total yield" trait, 4 – due to the "marketable yield" trait, and 6 - due to the "average fruit weight" trait. The selected accessions optimally responded to year’s conditions and were relatively stable in terms of high levels of expression of these traits under in changing growing conditions.

Conclusions. For the breeding of genotypes suitable for intensive technologies, accessions with enhanced responses to changing growing conditions were selected; at the same time, they maintained a sufficiently high stability of yields. The breeding-valuable accessions were selected by yield constituents: 5 - by the "total yield" trait; 6 – by the "marketable yield" trait; and 1 – by the "average fruit weight" trait.

Analysis of the environmental variability parameters in the watermelon collection to be used as starting materials in the breeding of genotypes suitable for organic cultivation enabled us to select a number of accessions: 6 – by the "total yield" trait; 4 – by the "marketable yield" trait; and 6 - by the characteristic "average fruit weight" trait. The selected accessions optimally responded to changing conditions of cultivation and showed relatively stable and strong expression of these traits.