Cocoa: Shade and Light

Although cocoa seedlings can be grown in the absence of shade (Cunningham & Burridge, 1960; Lee & Garot, 1971; and Lee, 1978), in most cases, it is usually very difficult to achieve a satisfactory cocoa plantation in Malaysia under fully exposed condition.

Inadequate shade and subsequent moisture stress retards the growth of young cocoa. In extreme cases, 30-50% casualties have been reported. Over-exposure also results in cocoa jorquetting at very low heights thus impeding field access/operations. Another problem excessive light is increased attach by leaf eating insects, particularly cockchafer beetles. Over-exposure also creates problem in weed control.

Over the other hand, excessively shaded mature cocoa produces very poor yields.

The light requirement of cocoa has been extensively reviewed by Owusu (1978). Young cocoa plants grow best at about 30%-60% light, the light requirement of individual leaves on a plant for photosynthesis being met by 3-30% full sunlight.

Harun & Kamariah (1983) reported that for nursery seedlings, the optimal shade regime is 80% shade initially and gradually reduced to 55% shade from the 4^th month onwards.

Murray (1954) reported that best yield was achieved at 50% light without manuring and at 75% light with manuring in Trinidad. Khoo & Chew (1978) noted that the yield of the underplanted cocoa increased linearly with the rate of coconut thinning.

The requirements for light vary between environments and also with the age of the cocoa plants. In general, young cocoa plants require more shade than those with well developed and self-shading canopy. Cocoa grown on fertile soils located in areas with little moisture stress also requires less shade.

For good results, shade regimes must be adjusted to suit the stage of growth of cocoa, soil fertility as well as the environmental conditions.

A suggested shade regimes suitable for Malaysian conditions is given in Table 4.

Table 4 : Suggested % shade levels for cocoa

Age (mths)	High Management Standards (And soil fertility)				Moderate Management Standards (And soil fertility)
	Moisture stress expected				Moisture stress expected
	Negligible	Slight	Moderate	Severe	Negligible	Slight	Moderate	Severe
Year 1 (0-12)	30-40	50	50-70	50-70	30-50	50	50-70	70
Year 2 (13-24)	30	30-40	50	50	30	40-50	50	50-70
Year 3 (25-36)	20	20-30	30	40	20	30	40	50
Year 4 (37-48)	20	20	20-30	30	20	30	40	40
Year 5 (49-60)	10-20	20	20	25-30	20	20	25	30
Year 5+ (61+)	10	10-20	20	25-30	10-20	20	25	30

 

N.B. : These are expected theoretical % shade levels for best establishment, growth and yields under each condition. Practical considerations, in particular damage from retained initial overhead shadewhich is poisoned out after the first year, however make it necessary often to modify these levels. Other management practices are than implemented to offset the setback from the less than optional shade conditions.

Reference 
Ooi L.H. and Chew P.S. 1985. Some important agronomic and agricultural practices in cocoa estates. TDMB Plantation Management Seminar, Kuala Trengganu

Note: The full list of references quoted in this article is available from the above paper.