Effect of pollination, fruit thinning and gibberellic acid application on 'Fuyu' kaki fruit development.

摘要

'Fuyu' kaki (Diospyros kaki L. f.) usually experiences heavy fruit drop between anthesis and fruit veraison under climatic conditions of the Moroccan Sais plain. This can be caused either by non satisfactory pollination or bad weather conditions during fruit development. This work aimed at studying the effects of pollination, fruit thinning and gibberellic acid application on fruit drop and development. Seven treatments are compared according to a completely randomized block design. Trees are eight years old, grafted onto Diospyros lotus and 'solaxe' trained. The compared treatments are pollinated trees (P), non pollinated trees (NP), trees thinned to 2 to 3 fruits per shoot (E), trees sprayed with 25 ppm GA₃ either at flowering onset (25DF), at mid-flowering (25PF) or end flowering (25FF) and open pollinated, non thinned and GA₃ unsprayed trees (T0). Controlled parameters are current year shoot growth, fruit drop, fruit diameter, yield, fruit juice pH, titrable acidity and degrees Brix and fruit seediness. Pollination reduced fruit drop, improved fruit diameter and yielded nearly one current year vegetative growth flush. Hand thinning reduced fruit yield but made it possible to obtain fruits with profitable size and weight in comparison to non thinned trees. Moreover, it induced more current year vegetative growth. GA₃ application induced an early increase in fruit diameter, reduced fruit drop and improved final fruit yield and weight.