Standardization of suitable Gamma irradiation doses 60 Co for mutagenesis in strawberry (Fragaria × annanasa Duch) cv. Chandler

Abstract

The process of mutation breeding for strawberry varieties entailed subjecting runner sections to irradiation, specifically utilizing three unique dosages of 60Co-gamma rays. The present study was carried out at Lovely Professional University, wherein strawberry runners belonging to the cv. Chandler were subjected to varying dosages of acute gamma radiation. The irradiation therapy was conducted at Punjab Agriculture University using the 60Co source. Different concentrations, namely 20 Gy, 30 Gy, 40 Gy, and 0 Gy, were administered at a consistent dosage rate of 1.52 Gy per minute. The physiological effects arising from irradiation were evaluated by the LD50 analysis, which was measured 30 days post-transplantation, serving as a benchmark for three distinct levels of irradiation dosages. The highest mortality rate was recorded in the group exposed to the maximal dosage of irradiation, which was 40 Gy. In addition to the control group, it was noted that the irradiated dose of 20Gy yielded the greatest plant height, fruit length, and diameter, while the lowest results were obtained from the 40 Gy treatment. Furthermore, the 20 Gy dose exhibited the largest leaf area index, number of leaves, and chlorophyll levels, whereas the 40 Gy treatment yielded the lowest outcomes. The occurrence of early flower bud formation was documented at a dose of 30 Gy, while late flower bud formation was observed at a dose of 20 Gy. Additionally, early flowering was noted at a dose of 40 Gy, with late flowering occurring at a dose of 20 Gy. Furthermore, early fruit set was found at a dose of 40 Gy, while late fruit set was observed at a dose of 20 Gy. In our observation of yield, we recorded the largest number of buds, flowers, and fruits at a radiation dose of 20 Gy. Conversely, we noticed a lesser number of buds with a radiation dose of 40 Gy. The results indicate that the maximum values for primary secondary root length and root number were recorded in the 30 Gy treatment, while the lowest values were observed in the 40 Gy treatment. Additionally, a greater number of deformed fruit and leaves were observed in the 40 Gy treatment of gamma irradiation dose. These findings would be beneficial in future endeavours aimed at producing potential mutants in the strawberry plant.