Phenological response to the climate change of oil-bearing rose under subtropical conditions of the southern coast of the Crimea

Temperature is a critical cue for most rose species and some cultivars to bloom as they have an obligate vernalization requirement for flowering. Optimization of rose flower yield requires the ability to predict the response of plants to various environmental conditions, particularly air temperature. The aim of the present study was analyzed the quantitative response for the beginning of oil-bearing rose blossom to temperature. Three phenological models were examined with respect to their suitability to estimate possible shifts in the timing terms blossom of oil-bearing rose due to climate change. One of the approach was pure forcing model (F) and the remaining two models were combined parallel and sequential chilling-forcing (CF) models. The starting date of temperature accumulation, base temperature and the forcing requirements were optimized on the basis of observed data. The starting date of the models was set to 1 November (CF) and 1 January (F). Phenological observations and temperature data in the period 1968-2017 were used to fit these models. Root mean square errors (RMSE) between modeled and observed oil-bearing rose blossom data varied from 4.9 to 6.2 days. The percentages of variance explained by the flowering models were mean from 62 to 89%. The present study showed that the beginning of rose's blossom has moved forward since 1968 due to climate change slightly (average 2-3 days) however average air temperature during flowering since 2000 increased by 0.9 degrees. This study was funded by a research grant Nº 14-50-00079 of the Russian Science Foundation.