TEMPERATURE ACCUMULATION AND PHYSIOLOGICAL AGING OF SEED POTATO-TUBERS

Tubers of cv. Maris Bard were allowed to accumulate different numbers of day-degrees early, late or continuously throughout the seed storage period. Sprout growth, time of emergence, development of early canopy cover and early tuber yield were increased more by late temperature a ccumulation than by increasing the number of day-degrees experienced f rom 250 up to a maximum of 700-degrees-C days. The relative physiologi cal age of seed, as indicated by the subsequent rate of early crop gro wth, was poorly related to the number of day-degrees accumulated. The implications for the quantification of seed physiological age are disc ussed.