Papaya, being a fast and continuously growing tree, has the potential of producing fruits throughout most months of the year under good management. Therefore, an abundant supply of nutrients at regular intervals for good growth and production of good quality fruit is critical. It is good practice to lime soils before growing papaya since a soil pH of 6.0 to 6.5 is universally considered as optimum for papaya growth and yield performance. For most tropical soils, 3 to 4 tonnes per hectare of lime are required. Well-limed papaya trees come to bearing earlier with higher yields of marketable fruits.

During the early stages, an adequate supply of nitrogen and phosphorus should be provided to ensure good vegetative growth. At fruiting, the level of potassium should be raised considerably to improve fruit quality (e.g. richer flesh colour, sweeter and firmer fruit). At the same time, the level of phosphorus should be reduced to maintain large fruit size. For nitrogen , the levels do not change throughout the vegetative and fruiting stages. However, excessive nitrogenous fertilisers, especially organic fertilisers, should be avoided since this would promote sex reversal of hermaphrodite flowers to females that may result in misshapen fruits.

Diversity of soil types, climatic conditions and practices makes it necessary to develop recommendations for specific areas, based on soil and foliar analyses. In Malaysia 50 – 100 g/tree of 15:15:15 formulation is given monthly till trees are four-months old, after which 180 g/tree of 12:12:17:2 formulation is given monthly. On top of the recommended rates of inorganic fertilizer, chicken dung, Palm Oil Mill Effluent ( POME ) or other organic fertilizers are supplemented at regular intervals. This supplement should be limited to about 2 kg per tree at four-month intervals since high application of organic manure induces excessive vegetative growth and a concomitant reduction in yield and fruit quality.

Boron deficiency is an important consideration in papaya growing, especially when cultivated on sandy soil. In young vegetative plants, the young leaves become brittle and claw-like. At fruiting stage, the symptoms are confined to fruits that become malformed with rough or ‘bumpy' surfaces (Plate 1). Affected plants are dwarfed and fruit set is severely reduced while affected fruits tend to be seedless, poorly developed or absent, and ripening uneven with low sugar content. Boron deficiency can be treated with soil application of 5-10 g borax per tree or foliar spray with 0.25% borax solution.

FERTILISER APPLICATION

* At half-yearly intervals 2 kg per plant Organic Matter is applied.
TSP1 = Triple Super Phosphate

Borax fertiliser (1-5 gm/plant) should be added if boron deficiency symptoms appear.