M.D. Whiting, M.R. Salazar, G. Hoogenboom
An accurate prediction and potential forecast of flowering for tree fruit crops could improve the efficiency of many critical orchard operations. Further, bloom phenology models might be useful for predicting the potential impact of climate change on their flowering time and duration. Our study was conducted to improve the understanding of bloom phenology for apple and sweet cherry. Individual flowers on the first day of anthesis were labeled. Replicate limbs or trees, respectively, were assessed daily. For 2009 and 2010, flowering of two sweet cherry genotypes, ‘Kordia’ and ‘Sweetheart’, was evaluated in Tasmania, Australia, as well as two apple genotypes, ‘Gala’ and ‘Fuji’, in Washington, USA. The cumulative percentage of open flowers per branch/tree, for each observation date, was assessed as a function of both time and thermal time using 4.5°C as a base temperature. A logistic equation was used to fit the data. Among the cherry genotypes, ‘Sweetheart’ exhibited the most concentrated flowering, defined as the number of flowers that opened per node/day, and the fastest rate of appearance. The thermal time at which the rate of the percentage of open flowers was at its maximum (peak bloom) was 43 and 106 GDD for ‘Sweetheart’ and ‘Kordia’, respectively. For apple, ‘Fuji’ exhibited a delay in flowering compared to ‘Gala’. In 2009, the estimated RMSE was low for both genotypes, e.g., 0.8%, compared to 2010 when it was 0.3% for ‘Gala’ and 0.6% for ‘Fuji’. For both genotypes and years, the d index was 0.99, indicating a strong agreement between the observed number of flowers and the predicted value. From these preliminary assessments, there was variability in model parameters as a function of year and genotype. There is, therefore, a need to further advance the development of these models as more experimental data sets become available.
Whiting, M.D., Salazar, M.R. and Hoogenboom, G. (2015). DEVELOPMENT OF BLOOM PHENOLOGY MODELS FOR TREE FRUITS. Acta Hortic. 1068, 107-112
DOI: 10.17660/ActaHortic.2015.1068.12
bloom phenology, apple, sweet cherry, flowering, decision support system

Acta Horticulturae