Expansion of the genotypic variability in watermelon by physical mutagenesis

Abstract

Purpose. Studies have been conducted on 18 promising watermelon genotypes to expand the genotypic variability of watermelon by induced mutagenesis.

Materials and methods. Air-dried seeds were irradiated with a closed ⁶⁰Co γ-source «Doslidnyk» (Department of Molecular and Medical Biophysics, Faculty of Radiophysics, Biomedical Electronics and Computer Systems, V.N. Karazin Kharkiv National University of MES of Ukraine).

Results and discussion. Each of the most informative breeding traits was statistically analyzed for their expression patterns and levels by variants of mutagenic treatment (different doses - 150 Gy, 200 Gy, and 250 Gy) in each of the 18 genotypes. The patterns of influence of the irradiation doses on plant growth and development have been determined, both in individual genotypes and for the whole sample. It has been found that γ-irradiation had a depressing effect in the majority of genotypes (late maturation, long or short stems, altered order of the 1^st female flower formation, extended phases of the growing period). Genotypes and their groups (clusters), in which expression of traits is opposite (alternative), have been identified. Sources of economically valuable traits have been identified, and the following effective doses of γ-irradiation have been established for genotypes (clusters): 4 genotypes of cluster 4 γ-irradiated at 250 Gy ‑ in breeding for yield capacity; 2 genotypes of cluster 3 γ-irradiated at 150 ‑ 250 Gy – in breeding for marketability; 3 genotypes of clusters 3 γ-irradiated at 150, 200 or 250 Gy – in breeding for large fruits: 1 genotype of cluster 5 γ-irradiated at 150, 200 or 250 Gy – in breeding for late maturation; 2 genotypes of cluster 3 γ-irradiated at 200 or 250 Gy and 5 genotypes of cluster 5 γ-irradiated at 150 or 200 Gy– in breeding for early maturation; 3 genotypes of cluster 3 γ-irradiated at 200 or 250 Gy and 7 genotypes of cluster 5 γ-irradiated at 150, 200 and especially 250 Gy – in breeding for long stems; and 1 genotype of cluster 1 γ-irradiated at 150, 200 or 250 Gy – in breeding for short stems