The effects of the date of defoliation of the seed potato crop and the storage temperature of the seed on subsequent growth: 2. Field growth

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Abstract
Summary: Six experiments carried out over 3 years investigated the effects of the date of defoliation of the seed potato crop and the storage temperature of the seed on the growth of the subsequent ware crop.Defoliation of the seed crop in July tended to reduce foliage dry weight particularly at later harvests, and in two experiments in 1974 affected the tuber yield. In one of these experiments defoliation in July resulted in a lower yield than from defoliation in August, while in the other experiment it significantly reduced the bulking rate of the ware crop and gave a lower yield of King Edward at the final harvest. Storage of the seed tubers at low temperature (2–3 °C) tended to increase the amount of foliage produced but only in two out of six experiments was there any effect of storage temperature on yield; in both storage at low temperature gave the lowest yield.There was a significant relationship between the effect of storage temperature on tuber yield and its effect on the time to emergence of 50% of the plants. It is suggested that in these experiments a combination of late planting and weather conditions before emergence reduced the effect of storage temperature on the time to 50% crop emergence and therefore reduced its effect on tuber yield.In 1973 when there was a large effect of storage temperature on yield, there was a significant relationship between the tuber yield of the ware crop and the physiological age of the seed measured as accumulated day degrees above 0 °C from dormancy break to planting.