Effects of temperature and photoperiod on early growth and final number of tubers in potato (Solanum tuberosum L)

A phytotron experiment with all combinations of two photoperiod (12 or 18 h) and four temperature (18/12. 22/16, 26/20 or 30/24 degrees C; 12 h/12 h) treatments was carried out to analyse quantitative effects on early tuber growth, dry-matter partitioning and number of tubers of two cultivars. Higher temperatures and longer photoperiod delayed the onset of expolinear tuber growth and the onset of linear tuber bulking. Higher temperatures also gave lower absolute tuber growth rates. Photoperiod did not affect absolute tuber growth rate at lower temperatures. Higher temperature and longer photoperiod gave lower relative rates of partitioning of dry matter to the tubers. Differences between treatments in numbers of tubers initiated were inconsistent. This quantitative analysis of the effects of temperature and photoperiod on characteristics of tuber growth should prove useful in potato modelling.