Sprout development of seed potato tuber after different storage conditions

Sprout growth and development of 'Fraser' seed potato tubers were quantified after a period of 'Early storage (5-16 weeks from crop defoliation) of tubers in the 'ground', 'shed' or 'cooler' (storage at approximately 4°C) in mid-Canterbury, New Zealand. 'Late' storage treatments exposed the tubers to either one or three months further warm-up prior to planting (mid-October). The seed potato tubers stored at the lowest temperature ('cooler') required 760±17.2°C days (°Cd)(T b=0°C) to sprout compared with 1,614 °Cd for 'shed' and 1,791 °Cd for 'ground' stored potatoes. The number of major sprouts on a tuber and the number of nodes formed on the main sprout were both affected by the 'Late' storage treatment. Tubers with three months warm up produced fewer sprouts (approximately 3.5) with more nodes (approximately 5.0) and longer sprouts than those warmed up for one month. There was an inverse relationship between dominant sprout number and warm up duration, with fewer dominant sprouts from a longer warm up duration. These results show that storage treatments can be used to manipulate vegetative development in tubers in anticipation of planting