Modeling approach for cold hardiness estimation on cherries

Abstract

Plants go through a physiological process of cold hardening to limit the damage, caused by low temperatures at the end of fall and winter. Under a variable climate, plants may be less or more cold hardened and hence more or less susceptible to the effects of an unexpected temperature drop. Seasonal patterns were estimated for three cherry cultivars that vary in freezing tolerance. Measures were taken during fall, winter and early spring for four consecutive seasons. The objective of the study was to develop an empirical dynamic cold hardiness model applicable to three cherry cultivars. The data used to develop the model came from cold hardiness measurements collected for cherry bud hardiness of Bing, Chelan, and Sweetheart during four consecutive seasons (2012–2015) consolidated from the 1st of October through April 30th per each season. Three quantitative lethal temperatures LT10, LT50 and LT90 of bud freezing were estimated from fitted sigmoid curves using a logistic function. Correlations and auto-correlations between lethal observed temperatures and air temperatures (maximum, minimum and average) were calculated. A nonlinear model then was fitted including the lethal temperature of the two days prior to freezing, the accumulative day for the studied period and the maximum temperature. Equation coefficients of cultivar-specific models were determined for each cultivar. Cold hardiness predictions were compared to actual observations for each cultivar and the confidence limits and uncertainty were derived. The model allowed for comparisons of cold hardening and de-hardening between the studied cultivars and between seasons. The information generated by the model can be valuable for frost protection management.