Bud Development, Flowering, and Fertilization of Moringa oleifera Lam. (Horseradish Tree) Grown in South Africa

Moringa oleifera is becoming increasingly popular as an industrial crop due to its multitude of useful attributes as water purifier, nutritional supplement and biofuel feedstock. Given its tolerance to sub-optimal growing conditions, most of the current and anticipated cultivation areas are in medium to low rainfall areas. This study aimed to assess the effect of various irrigation levels had on floral initiation, flowering and fruit set. Three treatments namely, a 900mm (900IT), 600mm (600IT), and 300mm (300IT) per annum irrigation treatment were administered through drip irrigation, simulating three total annual rainfall amounts. Individual inflorescences from each treatment were tagged during floral initiation and monitored throughout until fruit set. Flower bud initiation was 65.3% higher at the 300IT and 4.6% higher at 600IT compared to the 900IT. Fruit set however, was 22.0% lower for the 300IT and 4.4% lower for 600IT, compared to the 900IT. Floral abortion, reduced pollen viability, as well as moisture stress in the style were contributing factors to the reduction in fruiting/yield observed at the 300IT. Moderate water stress prior to floral initiation could stimulate flower initiation, this should however be followed by sufficient irrigation to ensure good pollination, fruit set, and yield.