Jayarama and M. Violet D' Souza

Coffee can be cultivated under shade or without shade depending upon the environmental conditions and cultural practices. In countries like Brazil, where the temperature does not exceed 24°C to 30°C, the intensity of daylight is low, the rainfall is well spread over through out the year without having long gap between two rainfalls, no shade is provided for coffee. Whereas, in the countries where high light intensity, high temperature and prolonged drought exist, coffee is cultivated under shade and the best example for this category is India. The coffee growing regions in South India receive rainfall which is influenced either by south-west monsoon or north-east monsoon or both, followed by a long dry spell of 90 to 180 days. Therefore, the coffee plants experience fluctuating weather conditions like continuous wetness; heavy winds, prolonged drought and dry periods. Despite these favorable and unfavorable conditions, the coffee has been cultivated for more than 100 years with economically viable yields and here lies the importance of shade in Indian coffee plantations. In India growing coffee under shade is blessing -in- disguise. Two economically most important coffee species, Arabica and Robusta have a natural adaptation to shade.

Shade is more essential to Arabica coffee for the reasons that high light intensity, high temperature and i low soil moisture affect the growth by reducing the leaf area, net photosynthesis and extension growth and also induce over-bearing and 'Die-back' which refers to the death of young tertiary branches. Arabica coffee is very sensitive to high light intensity and high temperature resulting in the early senescence of leaves and defoliation. Shade trees can provide conducive environment for coffee cultivation in India but with proper management. Shade trees have positive effects on microclimate and soil biological properties which are the key to long term sustainability of coffee eco system.

Why Shade

Under tropical conditions as in South India, shade is very much essential to prevent over-bearing, suppress weed growth, reduce the intensity of sunlight and temperature, combat drought effects, to maintain the moisture levels in tissues and to protect the coffee plants from low temperature, wind velocities and damage caused by hail stone. Adequate shade improves soil fertility by way of returning large amounts of leaf litter to the underneath soil, nitrogen fixation and retains soil moisture. Shade limits the incidence of pest such as white stem borer and leaf rust disease in Arabica coffee. The incidence of white stem borer, which can cause death of plants, will be more in arabica coffee grown under less shaded condition. Similarly the incidence of leaf rust will be more in Arabica coffee grown in open condition compared to shaded condition. Heavy incidence of leaf rust results in defoliation, which is found to be a predisposing factor for stem borer build up. The shade was also found to improve the coffee quality.

Shade trees are therefore recommended as a protective measure when environmental conditions can be difficult for coffee, particularly in areas which are exposed to high temperature, long drought, heavy rain fall and chances of hail.

Two Tier Shade Canopy

In India for all the reasons mentioned above two tiers of shade canopy is recommended especially for Arabica coffee. Dadap (Erythrina lithosperma) has to be planted for the lower shade canopy at closer spacing initially along with coffee in new clearings and the population of Dadap can be thinned out later based on the requirement.

For better establishment of dadap, soil drenching of 1 or 2 litres of Hormonol solution (200m1 of HORMONOL per 200 litres of water) could be given around the dadap stake immediately after planting. Three to four weeks later, 25 grams of super phosphate per dadap stake could be applied to the soil for boosting the growth. The branches of dadaps have to be lopped once or twice in a year to regulate the light requirements. The lopping of dadap is advocated immediately after the on set of monsoon. However, dadap,s do not come up very easily in marginal soils and hence glyricidia can, be planted in such areas as lower canopy shade.

The exotic species of Grevillea robust (Silver oak) can be grown in coffee plantation as a shade tree (however, now a days in some of the plantations, silver oak is the major shade, may be to train large number of pepper vines and for timber value as well as they establish easily and develop faster). Initially, it can be planted with a spacing of 6 m X 6 m and later it can be thinned out based on light requirement. However, providing monoculture shade of Silver oak for Arabica coffee has to be curbed, since it does not provide the required shade. Further, the fall off silver oak leaves covering the coffee plants during the monsoon period lead to the high incidence of black rot. The fallen leaves will also take longer period to decompose. For these reasons the number of Silver oak trees could be at minimum for Arabica plantations.

The permanent shade trees such as Ficus spp, Albizzia spp, Terminalia sps, Artoarpus integrifolia (Jack fruit) and other jungle trees can be planted at a distance of 12 m to 14 m apart as top shade canopy. The mixed shade canopy is always found to be very advantageous in maintaining the higher productivity due to recycling of nutrients from the shade litter. Wherever replanting programme is undertaken in the timber extracted fields, planting of Indigofera and Maesopsis eminii could be opted along with the Dadap and Glyricidia, since these trees will be very quick in achieving the required shade pattern.

All trees can provide shade but some are planted with well defined objectives to provide shade. The shade trees should have the following desirable characteristics:

i) Rapid growth
ii) Constant leaf growth which persist during the dry periods
iii) Resistant to wind
iv) A deeply embedded root system that will not compete with coffee plants
v) Not to be a potential host for pest and diseases affecting coffee trees
vi) Leguminous or the trees which give filtered sunlight.

Shade Management for Arabica coffee

Arabica coffee requires 50-60% of filtered shade for maintaining good consistent crop yield. The canopy of permanent shade trees has to be regulated by undertaking the operations such as shade lopping, shade thinning and shade lifting depending upon the necessity and requirement to maintain optimum shade for the coffee plants.

Types of shade regulation:

· Shade thinning: Removal of tiny branches of the shade trees on alternate years without damaging the coffee. If the operation is undertaken irregularly by allowing branches to grow thick, this operation can cause damage to coffee plants on account of fall of thick branches.

· Shade lifting / Whiskering: The shade canopy has to be lifted to 10 to 14 m (z35'-45') above the coffee by chopping of lower hanging/ smaller branches every year wherever it is necessary.

· Shade topping to be carried out depending upon on need for minimizing the vertical growth, since this will affect the timber value.

Time of shade regulation:

· The arabica plantations of higher elevations (3700' and above), which are having two-tier shade canopy of dadap (lower canopy) and permanent shade trees (upper shade canopy), the shade regulation could be under taken during the month of February or March.

· In the absence of lower canopy shade (Dadap), it is advisable to undertake shade regulation during the last week of May or June in the area, which is influenced by the South-West Monsoon predominantly and during the month of July for the North-East monsoon conditions. This will also help- in minimizing the incidence of white stem borer (WSB) during March to May months. But, one should not be under the total assumption that maintenance or non maintenance of proper shade alone can be the sole criteria for the incidence of white stem borer. incidence is low and the plantations maintained lower canopy shade of dadap.

· Dadap lopping should be under taken immediately after the on set of monsoon and all the stakes . could be finely chopped and returned to the field along with the leaf compliments or could be used for temporary shade rising.

· Timber extraction in arabica fields could be done only after establishing the shade by planting shade trees well in advance of 2 to 3 years in the area, where the removal of shade trees is proposed.

Important Points to be remembered

· Maintenance of monoculture shade i.e., Silver oak has to be discouraged. It will not help for maintenance of micro-climatic conditions; it accelerates the white stem borer incidence and leaf rust and koleroga problems in arabica coffee.

· Two-tier or two level of shade canopy with indigenous mixed shade trees is a must to reduce the white stem borer incidence and also for the maintenance of consistent productivity.

· Every year lifting of lower shade tree branches should be carried out regularly for maintenance of the optimum shade.

equisetifolia or Silver oak could be planted closely in zig-zag manner as a shield belt for reducing the exposure to evening sun.

· Ficus sps especially Ficus glomerata should be planted in arabica, plantations, as Ficus sps keep the micro climate conducive for coffee and also provide lot of leaf litter, which will improve the soil fertility and conserve the soil moisture.

· It is not advisable to train Pepper vines in all the shade trees. The number of vines could be restricted to around 40 vines per acre of arabica coffee, as more number of vines increases the level of shade and finally reduces the crop yield.

· Wherever the temporary shade tree such as dadap's establishment is a problem, the alternative fast growing temporary shade trees i.e., Gliricidia sp., Indigofera tasmania and Mesopsis sps could be planted.

· Under multiple cropping systems, depending upon the shade level the permanent shade trees could be maintained.

· Shade management also has influence on the hydrological and pedological values. For example coffee grown under no shade suffers from water stress. Growing shade trees help in conserving top soil and soil nutrient dynamics.

· If the soil moisture is adequate due to rainfall during the month of December and January, shade regulation could be under taken during February and March provided the white stem borer

· The blocks or estates exposed to western aspect should have high shade canopy of 60 to 70% and also the lower branches of shade trees should be maintained on the boarder rows and also Casuarina

· Under Indian conditions, if proper recommended shade densities are maintained, they can contribute around 10 metric tones of organic matter per hectare which help in increasing the nutrient status of the soil as well as cation-exchange capacity of the soils. Leaf litter cover in the estates can also contribute to some extent, the top soil run off.

· As per the literature survey few interesting points have emerged when we grow coffee at different altitudes in relation to shade level and they are:

At lower altitudes, un-shaded coffee production decreases in response to increasing heat stress while at higher altitudes; it decreases due to low temperatures and also due to wind damage. Under such conditions shade trees can reduce the microclimatic stress to the coffee plants by shading at lower altitudes and providing wind protection at higher altitudes. As a result shade trees can tend to increase coffee production when compared to un-shaded fields.

· Nutritional stress and foliar deficiencies generally will be more pronounced in un-shaded coffee and hence maximum care and cultivation aspects are required to nurture coffee under direct sun for higher productivity when plants age especially.

Shade for RobustA coffee

Robusta coffee also requires shade especially for the un-irrigated field on account of its susceptibility to drought, although it has tolerance to high light intensity and temperature to some extent.

Time of shade regulation

· Normally the shade regulation could be done after the crop harvest and before undertaking light pruning of irrigated robusta coffee.

· Shade regulation has to be done only after the receipt of 4 to 5" rainfall (100 to 125mm) for the un-irrigated robusta coffee.

Effects of High Shade

The coffee plant requires shade during dry weather period to protect themselves from adverse micro and macro climatic conditions. During monsoon months the shade should be at minimum by lopping the dadap and regulating the permanent shade canopy to allow the full daylight to fall on the plants. The heavy shade during this period increases the disease incidence of black rot, stalk rot etc. and also cause premature fruit drop due to prolonged wet conditions. Further, high shade induces excessive vegetative growth and less induction of flower buds. Production of more black beans was also observed under high shaded conditions. Hence, shade regulation during premonsoon period is very much essential for improving the productivity of coffee. On the other hand, by cushioning the impact of atmospheric conditions, shade has a positive effect, particularly when leguminous shade trees are used because they enrich the soil with organic matter and nitrogen

Shade can play vital role for maintaining long term coffee productivity, for conserving soils, moisture and biodiversity and even improving coffee quality. The shade grown coffee enjoys the advantages of reduced plant exhaustion, extended crop life, reduced fruit drops, lower nutritional requirements, enhanced soil health and fertility, sustained production, greener environment, sustained production, lower soil erosion, lower water requirements and reduced pest and disease occurrence.

References

The use of Shade in Coffee, cocoa and Tea: Horticultural Abstracts, Commonwealth Bereau of Horticulture and plantation crops, 1975, Vol.45, and No.12 by R. W. Willey

The effects of artificial shading on the growth growth characteristics of arabica an d robusta coffee:

J.AppLEcol, 1967, Vol 4 Page 291308 by Huxley,P.A

Biodegradable organic matters as potential sources of coffee nutrition in coffee plantations in India,

Indian Coffee, 1996, LVX, No.1-2, page 3-8 by Jayarama, C.S.Krishnappa Naik, R.P.Ananda Alwar and R.Naidu

Shade in coffee culture, 1901, USDA Bulletin 25,USDA, Washington. DC by O.F. Cook

Coffee growing, processing, sustainable production, book edited by jeanNicolas Wintgens, WileyVCH Verlag GmbH& Co.kGaA,2004

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