The effects of paclobutrazol on the vegetative growth, reproductive development, total nonstructural carbohydrate of the shoots, and nutrient mobilisation to the leaves of 'Tommy Atkins' mango (Mangifera indica) trees grown in the Rift Valley of Ethiopia were evaluated during the 2002/03 season. The trees used were characterised by excessive vegetative growth, erratic flowering, and fruiting with declining productivity that validated the evaluation of paclobutrazol. Uniform trees were selected for a randomised complete block design experiment with two methods (soil and spraying) and four rates of paclobutrazol (0, 2.75, 5.50, 8.25 g a.i. per tree) in factorial combinations. There were three blocks and three trees per plot for each treatment. The results showed that application of paclobutrazol at rates of 5.50 and 8.25 g a.i. per tree both as a soil drench and spray applications were effective in suppressing vegetative growth compared with the control. Consequently, the trees from these treatments had higher total non-structural carbohydrate in their shoots before flowering. Compared with the control, trees treated with paclobutrazol had higher results for percentages of shoots flowering, number of panicles produced, percentages of hermaphrodite flowers, yield as well as quality of the fruit. Applications of paclobutrazol did not affect the leaf macronutrient content levels analysed (N, P, K, and Ca), and with the exception of manganese, the micronutrient (Cu, Zn, and Fe) levels of the treated tree's leaves were significantly higher than the control.

The effects of potassium nitrate and paclobutrazol on flowering and vegetative growth of 'Tommy Atkins' and 'Keitt' mango (Mangifera indica) were studied for various periods in inductive and non-inductive temperature regimes. The experiment was done at the University of Pretoria experimental farm in a temperature-regulated cabinet on 2-year-old potted 'Tommy Atkins' and 'Keitt' mango cultivars. 'Keitt' was more sensitive towards low temperature floral induction than 'Tommy Atkins'. For both cultivars, the trend for the interaction of duration and cultivar revealed the possible floral induction complementation effect of PBZ after the trees stayed only 15 days at the inductive temperature (10/15°C). Paclobutrazol also significantly reduced vegetative growth and number of days required for visible inflorescence emergence in both cultivars. Potassium nitrate promoted the initiation of buds for vegetative growth in non-inductive temperature conditions and reproductive growth in inductive conditions. The minimum inductive period at 10/15°C (12 h light/12 h dark) required for "complete" floral induction and development was found to be 35 days for both cultivars. Surpassing the inductive (cold) period showed adverse effects on normal development of the reproductive parts and also delayed inflorescence emergence.

The effect of different kinds of pruning treatments was studied on Keitt and Tommy Atkins cultivars over two seasons. The trial was conducted at Bavaria Estate, around Hoedspruit area, Northern province of South Africa (latitude: 24o25'S; longitude: 30 54'E; elevation: 600m). With regard to inflorescence development, panicle pruning (during full bloom) at the point of apical bud attachment proved to induce re-flower, more rapid fruit development and more fruit per panicle than the other panicle pruning treatments. Renewal (early in the season when fruit were on the tree) as well as post harvest pruning (especially for early cultivars) treatments were also observed to effect a well-synchronized inflorescence development and adequate number of productive inflorescences per season. Post harvest pruning treatments produced a significantly higher result for the vegetative growth parameters in both cultivars while the control trees showed the lower result. Pertaining to yield, the trend showed that, promising increment could be expected after the second season (with vigilant management of the trees) especially from panicle pruning at apical bud attachment and shoot pruning treatments on 'Tommy Atkins'. 'Keitt' was found to be not responsive to the pruning treatments applied for various parameters observed.

The effects of 7 pruning treatments were studied in 2 mango cultivars (‘Keitt’ and ‘Tommy Atkins’) in the Hoedspruit region of the Northern Province of South Africa. Trees that received panicle pruning (during full bloom) treatment at the point of attachment were observed to be induced for synchronised re-flowering, and also attained early fruit set and more fruit per panicle than the other panicle pruning treatments. Trees on which renewal pruning (early in the season when fruits were on the tree) as well as postharvest pruning treatments were applied, have been observed for development of adequate number of productive inflorescences per season in an early-maturing cultivar, Tommy Atkins. Postharvest pruning treatments also resulted in significant increase of postharvest vegetative growth in both cultivars. Promising improvement in yield could be expected after the second season from panicle pruning in Tommy Atkins. The fruit quality, especially with regard to total soluble solids (TSS), was also greatly improved due to the applications of renewal and postharvest pruning treatments. Inflorescence removal together with apical whorl of leaves subtending the inflorescence had adverse effects for the various parameters studied in both cultivars.

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Different fruit thinning methods were tested on 'Sensation' mango trees over two seasons in a trial conducted in Northern Province, South Africa. The objective of the study was to select the best thinning intensity and method based on different parameters. Thinning was carried out in October prior to the occurrence of excessive natural fruit drop. When fruits were thinned to one and two fruits per panicle, fruit number, weight and yield per tree at harvest were all increased. When 50 % of the panicles were thinned there was an increase in the fruit retention potential of the trees as well as in the size and quality of the fruit produced. Large fruits were, however, prone to certain physiological problems. Chemical thinning with Corasil.E produced very small fruits with an increased percentage of 'mules' (fruit without seed). Trees subjected to severe thinning intensities showed earlier recovery of starch reserves and better vegetative growth than the control.