Effect of weather on panicle development, flower morphogenesis and fruit set in litchi cv. Shahi

This study aims to evaluate the effects of weather on panicle development, flower morphology and fruit set in litchi cv. Shahi. Meteorological data from 2017 to 2018 were documented and panicles were tagged in order to follow the dates of the onset of several floral phenological stages, such as flower bud initiation, panicle emergence, flower opening, fruit set, pulp development, colour break, and fruit maturity. To ascertain the relationship between crop and weather as well as the relationship between temperature and the quantity of female flowers and the sex ratio, statistical analysis was conducted using the two-year combined weather and crop records. Temperature in 2018 during the first flowering phase was lower (Tmax: 17.1 °C and Tmin: 8.4 °C) than in 2017 (Tmax: 21.49 °C and Tmin: 9.50 °C). Low temperatures encouraged the formation of healthy panicles with a higher proportion of female flowers (7.82%), guaranteeing a respectable final fruit set (4.53%) at harvest. The highest yield (83.45 kg/ha) was recorded in the year 2018 as compared to the year 2017 (64.28 kg/ha). Fruit set peaked first and then started to decline at fruit maturity due to a sudden increase in temperature soon after fruit set, which caused a loss of moisture and eventually fruit drop. Thus, lower temperature during floral bud differentiation endured strong panicle development which carried out more female flower and fruit set resulted in the higher yield.