A study on growth dynamics, heat accumulation and phenological stages under subtropical conditions: optimizing litchi cultivation

Abstract

Aim

Litchi (Litchi chinensis) is a commercially valuable subtropical fruit, and understanding its phenology is crucial for optimizing orchard management and improving fruit production. This study investigates the phenological development of litchi cv. Dehradun under the subtropical climate of Himachal Pradesh, using the extended BBCH (Biologische Bundesanstalt, Bundessortenamt, and Chemische Industrie) scale.

Methods

Studies conducted from 2021 to 2023, focuses on key growth stages such as bud break, leaf and shoot development, inflorescence emergence, flowering, fruit development, and maturity. Heat unit accumulation, measured through growing degree days (GDD), was tracked at each stage to provide a detailed phenological profile.

Results

The study identifies 74 distinct secondary growth stages, offering precise descriptions of each phenophase. Results show that temperature plays a critical role in determining the success of flowering and fruit set, with deviations impacting flowering intensity and fruit quality. The phenological data derived from the BBCH scale has been suggested as a guide to the litchi growers in optimizing irrigation schedules, pest control, and the use of plant growth regulators (PGRs) to enhance fruit quality and yield.

Conclusions

This study provides a framework for sustainable litchi cultivation by aligning agricultural practices with the crop’s developmental needs according to the growing degree days, minimizing input costs and environmental impact.