Influence of temperature accumulation on phenology of apple under Kashmir conditions
1Division of Fruit Science, SKUAST-K, Shalimar, Kashmir, India. 2Division of Soil Science, SKUAST-K, Shalimar, India. 3Division of Basic Sciences and Humanities, SKUAST-K, Shalimar, Kashmir, India. 4IBPR, SKUAST-K, Shalimar, Kashmir, India. 5Division of Vegetable Science, SKUAST-K, Shalimar, Kashmir, India. Corresponding e-mail: Baizasidiqi@gmail.com
DOI: https://doi.org/10.37855/jah.2026.v28i02.60
Temperature is a major driver of phenological development in apple under temperate conditions. The present study was conducted to evaluate to study the influence of temperature accumulation on the phenological stages as well as derive the relationship between accumulated growing degree days (GDD) and phenological progression in apple cv. Gala Redlum under Kashmir conditions using three years of field observations (2023-2025). Growing degree days (GDD) were calculated from 1 January of each year to the date of occurrence of each phenological stage using a base temperature (Tbase) of 4°C. Nine phenological stages were recorded and expressed as day of year (DOY) and accumulated growing degree days (GDD). Variation in the timing of phenological stage appearance (DOY) was observed across years; with advanced development in 2023 and 2024 and delayed development in 2025. However, the accumulated GDD for the appearance of each phenological stage remained within a relatively narrow range across three years, indicating that thermal time is a useful indicator of phenological progression. The results suggest that GDD-based phenology forecasting in apple can be used to optimise the timing of orchard operations such as spraying, thinning, irrigation, pollination management, and frost protection. Additional validation across cultivars, locations and other environmental variables is needed to improve the applicability of GDD-based phenology models.
