Giberellic acid and flower bud development in loquat (Eriobotrya japonica Lindl.)

The application of gibberellic acid (GA3) to the whole loquat tree from mid-May to early June and fromearly August to the onset of flowering, significantly reduced the number of premature flowering shootsper current shoot and per m3 of canopy, and so reduced the total number of panicles per m3 of canopy.The number of vegetative shoots per m3 of canopy was also significantly reduced by applying GA3. Theresponse depended on the concentration applied and produced optimal results at 50mg l− 1.Differences inthe number of flowers per panicle and leaves per shootwere not significantlymodified by the treatment.Nevertheless, GA3 applied directly to the developing apex near to flower differentiation reduced thenumber of flowers per panicle by 25–35% and without modifying the morphological characteristics ofthe panicle. Results suggest that less sprouting of lateral buds was largely responsible for the reductionin flowering intensity caused by GA3. Best treatments reduced thinning costs (60%, approximately) ofpremature flowering shoots, slightly increased fruit diameter and significantly improved fruit colour andjuice quality, thus advancing harvest date.