Temperate Fuits Production in the Tropics: A Review on Apples in Kenya

Abstract

Temperate zone fruit crops undergo bud dormancy which can be described as a mechanism for avoiding the exposure of tender flowers and leaves to low winter temperatures. In Kenya, apple growing is mostly hampered by inadequate chilling that causes the plants to have prolonged dormancy leading to poor flowering and consequently low yield. Although the chilling requirements are obligatory, under subtropical and especially tropical conditions avoidance is possible. To achieve this, it is necessary to select cultivars with low chilling requirements. This has proven effective in Zimbabwe with cultivar Matsu which is grown without a need for artificial breaking of dormancy. In Kenya like Zimbabwe, low chilling requiring cultivars such as Anna have been grown successfully. However, for cultivars with high chilling requirements, there is need to apply artificial techniques/methods to enhance bud break. Some of the cultural techniques used are: defoliation after harvesting and bending of the shoots holizontally. Defoliation after harvesting has particularly been used successfully in the island of Java in Indonesia and it enables two crops to be grown per year. Root chilling of rootstock has also been found to enhance bud break of the shoot. In addition, chemicals like KNO3, mineral oil and thiourea (TU) have been found to be effective in breaking bud dormancy in Kenya. This paper is reviewing the challenges encountered in growing apples in the tropics and Kenya in particular and the progress that has made in addressing them.