Effect of thermal summation on harvest maturity of Citrus aurantifolia Swingle 'Local'

S.D. Samaradiwakara, W.A.H. Champa, J.P. Eeswara
It is important to identify the optimum harvest maturity to manage fruit quality and postharvest life to ensure market and consumer demand. The effect of thermal summation on acid lime (Citrus aurantifolia Swingle) fruit growth has not widely been studied. This study was conducted to evaluate fruit growth by means of maturation curves and quantified accumulation of growing degree days required for harvest maturity, under low country dry zone (DL1b: temperature 30-35°C, rainfall <1750 mm year‑1, elevation 0-300 m a.m.s.l.) conditions in Sri Lanka. During the peak season, fruit-lets at the diameter of 4-5 mm were tagged, assuming the fruit set. Thereafter, fruits were harvested at 14-day intervals until fruits showed 100% yellowness in situ and days after fruit set (DAFS) was counted. Rapid increase in fruit weight, length and diameter were observed from 28 to 70 DAFS and slowed thereafter up to 147 DAFS. Maximum weight, length and diameter of 51.0 g, 4.9 cm and 4.6 cm, respectively, were recorded at 147 DAFS. Juice content was increased by 30.0% from 56 to 147 DAFS and reduced marginally thereafter. Fruit peel thickness declined at a reducing rate and remained constant until 100% in situ yellowing. Considering 12.8°C as the lower base temperature, the thermal sum for fruit growth and maturation of 'local' acid lime ranged from 2,326 to 2,444 growing degree days.
Samaradiwakara, S.D., Champa, W.A.H. and Eeswara, J.P. (2020). Effect of thermal summation on harvest maturity of Citrus aurantifolia Swingle 'Local'. Acta Hortic. 1278, 53-58
DOI: 10.17660/ActaHortic.2020.1278.8
acid lime, fruit growth, harvest maturity, quality

Acta Horticulturae