Incidence of Jelly Seed Disorder in ‘Tommy Atkins’ and ‘Van Dyke’ Mangoes as Affected by Agro-Ecological Conditions in Kenya

Abstract

Jelly seed disorder is one of the major problems in mango production in Kenya as well as other mango producing countries in the world. This problem manifests itself through breakdown of tissues around the seed of the  affected fruits resulting in unmarketable fruits. Although the exact cause of jelly seed in mango is unknown, some reports indicate that the condition could be due to imbalance related to Ca, Mg, N and K supply to the fruit. To establish the extent of this problem in Kenya, a study was conducted in 2013 in three major mango producing counties located in different agro-ecological zones namely Embu, Murang’a and Meru. Three farms with homogenous trees of “Tommy Atkins” and “Van Dyke” mangoes were randomly selected per county. Soil and mango leaf analysis were carried out to determine the nutrient status. Rainfall and temperature data were also recorded during the study period. At harvest time, 50 tree-ripe fruits of each variety were randomly sampled from 25 trees per site and sliced along the endocarp to expose the seed then visually examined and scored for the incidence of jelly seed using Galan Sauco scale. Soil analysis showed that, Meru vertisol and lithosols soils had higher Ca, Mg, K content compared to Murang’a eutric Nitisol soils and Embu ferralic arenosal soils. Similarly, mango leaves and fruits sampled from Meru county had higher Ca, Mg and K contents than those from Murang’a and Embu. Fruits (both varieties) from Embu county showed higher incidents of jelly seed that those from Murang’a and Meru county. Significantly higher jelly seed incidents were reported in ‘Van Dyke’ compared to ‘Tommy Atkins’ mangoes. It can therefore be concluded that incidences of jelly seed depend on the variety as well as  agro-ecological zone where the mangoes are produced.