Further development of the mango growth model. 1. The effect of pruning to different structural forms on the yield and carbohydrate reserves of the mango tree. 2. Determination of total tree mass without excavation.
Walt M. van der, Davie S. J., Stassen P. J. C.
Author Affiliation: Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit 1200, South Africa.
Inligtingsbulletin - Instituut vir Tropiese en Subtropiese Gewasse : 10-16
Abstract : As part of the development of a mango tree growth model, a study was carried out to determine the effect of pruning to different structural forms on seasonal starch reserve patterns. Five-year-old mango cv. Sensation trees were pruned in May 1994 to central leader, open vase or palmette forms. Further corrective pruning was conducted in Mar. 1995. Two trees of each of the different forms and 3 unpruned control trees were sampled by excavation every second month starting in June 1995. Roots and main stem xylem samples were analysed for starch and the results were correlated with the phenological stages of the tree. Differences in starch reserves were observed between pruned and control trees, and these differences were supported by photosynthesis measurements. It was concluded that pruning had a positive effect on carbohydrate production, delayed flowering and increased its synchrony without affecting yield or fruit size. The results from the control trees were used to determine the relationships between main stem circumference, canopy volume, canopy radius and total tree height on the one hand and above ground mass, root mass and total tree mass on the other. A very good correlation was found between stem circumference and total mass as well as between total height and total mass. The correlation between crown height and total mass was also good. Using stepwise regression, equations were formulated for above ground mass, root mass and total mass, making it possible to determine the mass of a tree non-destructively, although these equations are only valid for young, bearing trees.