The effect of cultural and environmental factors on potato seed tuber morphology and subsequent sprout and stem development

Seed crops of the variety Estima were grown in each of 2 years using two pl anting dates. two harvest dates. two plant densities and two irrigation reg imes to product seed tubers which had experienced different cultural and en vironmental conditions. The effects of these treatments on tuber characteri stics, sprout production and stem development in the ware crop were then de termined in subsequent experiments using storage regimes of 3 and 10 degree sC. Time of planting the seed crop affected numbers of eyes, sprouts acid a bove ground stems in the subsequent ware crop because environmental conditi ons around the time of tuber initiation appeared to alter tuber shape. Cool er. wetter conditions in the 7 days after tuber initiation were associated with tubers which were longer, heavier and had more eyes, sprouts and above ground stems. In contrast, the time of harvesting the seed crop did not af fect tuber shape or numbers of above ground stems acid there was no interac tion with tuber size. The density of the seed crop had no effect on any cha racter measured and irrigation well after tuber initiation did not affect t uber shape, numbers of sprouts or numbers of stems. Seed production treatme nts, which resulted in earlier dormancy break. were associated with tubers that produced more sprouts and above ground stems. in contrast to the conve ntional understanding of apical dominance. Storage at 3 degreesC gave fewer sprouts, a lower proportion of eyes with sprouts and fewer stems than stor age at 10 degreesC. The major effects on stem production appear to result f rom environmental conditions at the time of tuber initiation of the seed cr op and sprouting temperature.