Figure 1: Sample abbreviations, their collection intervals, comparative conditions and accumulated chilling units (CUs) during winter dormancy.

The developmental stages in sequential phenological events were compared in six comparative conditions viz: dormant bud and silver tip (STL-vs-DBL; STH-vs-DBH), silver tip and green tip (GTL-vs-STL; GTH-vs-STH) and green tip and initial fruit set (FSL-vs-GTL; FSH-vs-GTH), under respective low (L) and high (H) chill conditions. The remaining four comparative conditions include comparison of similar developmental stage under differential chilling conditions viz: dormant bud (DBL-vs-DBH), silver tip (STL-vs-STH), green tip (GTL-vs-GTH) and fruit set (FSL-vs-FSH), considering high chill as control condition. The Utah model was used to calculate the accumulated CUs. The accumulated CUs under both locations indicate that apple buds accumulate more CUs under high chill condition as compared to low chill condition. The high chill and low chill conditions are represented by Palchan and Seobag, respectively.