Potato Sprout Inhibition and Tuber Quality after Post Harvest Treatment with Gamma Irradiation on Different Dates

Storage of potatoes is very important because fresh potatoes are available only for a few months in a year. Thus, any treatment such as irradiation that controls sprout growth and extends shelf life of potatoes could be beneficial. In this study, potato sprout inhibition and tuber quality after treatment with various levels of Gamma Irradiation (0, 50, 100 and 150 Gy) on different dates (10, 30 and 50 days after harvest) were studied during prolonged storage at 8 and 16°C using tubers of Agria variety. A factorial experiment based on a randomized split plot design with three replications was carried out. There was minimum sprout development (4.83±0.01 g/3kg tuber) in tubers from early irradiation date (10 days after harvest). This study indicated that early irradiation and higher irradiation levels significantly decreased sprouting, percent weight loss and specific gravity of tubers. The loss of ascorbic acid and the contents of reducing and nonreducing sugars significantly increased by delay in irradiation whereas the content of sugars and ascorbic acid level decreased by irradiation. The loss of firmness became clearer during five months storage in non-irradiated tubers. Higher storage temperature (16°C) caused greater loss of ascorbic acid (20.34%). In other words, tubers stored at 16°C showed greater metabolic changes as indicated by sprouting, weight loss, and changes in sugars and ascorbic acid contents. The 50 Gy irradiation treatment on the 10th day after harvest resulted in complete sprout inhibition of tubers at 8°C storage and 150 Gy dose while inhibiting sprouting at 16°C, caused greater loss of ascorbic acid. Tubers irradiated with later after harvest were subject to greater loss of ascorbic acid in response to higher doses of irradiation and higher storage temperature. Consequently, to reduce undesirable changes in Agria potato tubers, delay in irradiation and storage at high temperature are not recommended.