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Seed length integrates heat accumulation and can be used to predict harvest date of Prunus persica

Day, K. R., DeJong, T. M.
Acta horticulturae 2017 no.1177 pp. 203-208
Prunus persica, cultivars, flowering, growing season, harvest date, heat, heat sums, nectarines, prediction, ripening
Harvest date of many fruit species is primarily determined by heat accumulation during the early portion of the fruit developmental period. Our prior work with several Prunus species has demonstrated that growing degree hour accumulation during the first 30 days following full bloom can be used to estimate harvest maturity. In this trial we studied seed length during four growing seasons of two nectarine cultivars, one ripening in May and the other in June. Seed length was highly correlated with heat accululation, and growing degree hours between full bloom and 10 mm. During this period seed length provided a better fit for predicting harvest date than did degree days. However, during the period from 10 mm seed length to harvest maturity, the number of days was a better predictor of the duration until harvest maturity than was heat accumulation.