Impact of loranthaceae infestation in some yield parameters of cultivated grapefruit in Njombe locality (Littoral-Cameroon)

Abstract

Citrus fruits are the most widely grown fruits in the world because of their many medicinal benefits. They are are a source of income for both individual producers and countries. The objective of this study was to assess the impact of mistletoes on grapefruit yield. Experiments carried out in one of the orchards of the IRAD Polyvalent Agricultural Research Station in Njomb-Penja subdivision. Data were sampled on 90 individuals divided in three level of parasitism, on which morpho metrical parameters were taken, and species of mistletoes recorded. Yield parameters such as number of mature fruits, their weight and diameter were taken on each tree during three months. As the results, three species of mistletoes were recorded on grapefruit trees Phragmanthera capitata, Helixanthera mannii and Tapinanthus bangwensis. The infection intensity was 8.9±4.9 tufts/tree. Weakly parasitized trees showed a greater number of mature fruits, weight and fruit diameter than moderately parasitized trees and heavily parasitzed trees. Negative significantly correlation between number of fruits and their weight have been found respectively on moderately parasitized trees (p= 0.002) and heavily parasitized trees (p= 0.000). The impact ratio was greater on heavily parasitized trees (IR= 2.42) and lower on weakily parasitized trees (IR= 0.48). Linear regression showed the increase of impact ratio with the number of mistletoes tufts. The Impact Threshold calculted on the regression line was 7 tufts per tree. Depper studies must be carry on the mistletoes-host plant to understand well their relationship.