Temperatures above 20°C reduce flowering in lychee (Litchi chinensisSonn.)

Abstract

SummaryFlowering in lychee (Litchi chinesis Sonn.) is promoted by low temperatures, but the critical level and duration of chilling required for successful induction are not known. The effects of maxima/minima of 15°/5°, 20°/5°, 20°/10°, 20°/15°, 25°/10°, 25°/15°, 25°/20° or 30°/20°C on vegetative growth and flowering of cvs Kwai May Pink and Casino were investigated. In a second experiment, plants of cv. Wai Chee were given 0, 2, 4, 6, 8,10 or 31 weeks of induction at 15°C before transfer to non-inductive conditions at 30°/20°C. In a third experiment, cv. Wai Chee was grown at 15°C and given 0, 1, 2 or 8 h above 20°C (0, 2, 4 or 15 h above 15°C) per 24 h. In Experiment 1 with cv. Kwai May Pink, there was vegetative growth at 25°/20°C and 30°/20°C, a mixture of vegetative growth and flowering at 25°/10° and 25°/15°C, and flowering at lower temperatures. Cv. Casino responded similarly, except that there was no growth or flowering at 25°/10°C and 25°/ 15°C. For both cultivars, nearly all branches flowered a...