Improving genetic variation, shelf-life and functional properties in Dioscorea esculenta (Lour) burk using recurrent irradiation

Abstract

Ionising radiation has become an effective tool to generate novel genetic variation and reduce postharvest losses in roots and tuber crops. The present study investigated the effect of gamma irradiation and re-irradiation on growth and yield characters, shelf-life and functional characteristics of Dioscorea esculenta. Tubers of two accessions SO89021 and TA97166 were irradiated at 10, 20, or 30 Gy. The M₁V₁ population was replanted to produce the M₁V₂ population and the tubers harvested were re-irradiated at 30 or 40 Gy to induce sufficient genetic variation. At 12 months, M₂V₁ tubers were cured for two weeks before determination of proximate composition, physicochemical and functional properties. For the shelf-life study, selected tubers from M₂V₁ were re-irradiated at 0, 80, 100, or 120 Gy and monitored for rots, sprouts, and weight loss for 14 weeks. Initial irradiation at 0–30 Gy did not have a significant effect on the morphological traits of the plants. However, re-irradiation at 40 Gy decreased plant height, number of leaves, tuber weight, and length compared to the controls. The decrease in tubers in accession TA97166 resulted in a significant increase (p ≤ 0.05) in tuber weight and width at 40 Gy. Similarly, starch content, solubility, and swelling power of the flour decreased with increasing irradiation dose. Gamma irradiation significantly (p ≤ 0.05) affected the gelatinization viscosity, maximum viscosity and breakdown viscosity. This study demonstrated that gamma irradiation can improve tuber size and some functional properties of D. esculenta.