Plant Smilde, 1985). Foliar diagnosis will provide a

Plant analysis gives a direct indication of the
nutritional status of the plant and may show a strong correlation with yields
(Ahn, 1993; Foster and Prabowo, 2002). Plant chemical analysis may be another
helpful tool in establishing fertilizer requirements. The plant’s nutritional
status is the net effect of variables related to soil, plant, climate, and
management (Ahn, 1993).

In perennials, nutrient deficiencies can be
detected through plant (usually leaves are used) in the analysis and corrected
before they have an effect on production (Ahn, 1993; Smilde, 1985). Foliar
diagnosis will provide a better understanding on the nutrient uptake and the
it’s proper interpretation will help in providing idea about the plant nutrient
status.

Cocoa
(Theobroma cacao L.) is a
preferentially alogamous tropical woody species formerly in the Sterculiaceae
family (Cuatrecasas, 1964) and reclassified in the Malvaceae family (Alverson et al., 1999) which originates from the
tropical rainforests of the Americas. Cocoa is grown almost exclusively within
10°N and 10°S of the equator; predominantly grown in the tropical areas of
central and south America, Asia and Africa (Marita et al., 2001). Here, the
climate is warm and humid and thus suitable for growing cocoa (Hartemink and
Donald, 2005).

 It is considered one of the most important
perennial crop in the planet, Global annual production of cocoa currently
exceeds 4 million tons. However, while global demand for sustainable cocoa is
growing annually by 2 to 3 %, while Africa still contributes about 72% of the global
supply (ICCO, 2015). Cocoa is a major source of export earnings for many
producing countries; mostly it is commercially exploited for seed output mainly
for chocolate manufacturing and consumed in Western Europe and the United
States (ICCO, 2012, 2015). However, derivatives and by products of cocoa can
also be transformed in cosmetics, beverages, jellies, ice creams.

Around
80–90% of global cocoa production occurs on smallholder farms, by about 5–6
million cocoa farmers worldwide (WCF, 2014). Estimated at Ghana is around 400
kg/ha (Aneani and Ofori-Frimpong, 2013) while potential yield at modeled is 5000
kg/ha under rainfed conditions (Zuidema et al., 2005)

As
cocoa is a perennial in nature, the duration of its productive life should also
be taken into consideration when assessing productivity. Trees come into
bearing after 2–6 years depending on the variety and location (Wessel, 1971;
Wood and Lass, 1985). To
achieve high productivity, cocoa requires a soil abundant in nutrients (Wessel,
1971). Although nutrients have different functions in the development of the
tree (e.g., canopy formation, flowering, pod production), all nutrient deficiencies
will ultimately lead to decreased yields. It is hypothesized that pod
production is fundamentally determined by the available nutrients in the tree
at different stages from flower initiation to pod maturity (Hutcheon, 1976).
Soil nutrient levels have declined and can no longer support productive cocoa
(Appiah et al., 2000). Critical values for leaf nutrient
analysis are referred to for cocoa (Table 14).

Cocoa
production envisages techniques to improve yield through drip and fertigation,
nutritional management. Omotoso (1975) reported
that a crop of 1000kg dry Cocoa beans removed about  20kg N, 41kg P and 10kg K  and where the method of
harvesting  (as in Nigeria) involves the
removal of pod husks from the field, the amount of potassium removed increased
more than five folds.  Nelliat
(1984) concluded that cocoa was a heavy feeder of potassium. A good crop of
cocoa removes as much as 170 kg of K ha-1. Potassium is also the
principal element present in the pods of cocoa (Fassbender et al.,
1985).  Wessel (1971) reported that there is a steady
decline in almost all the nutrients with length of cultivation of cocoa.
Ogunlade and Aikokpodion (2006) reported that phosphorus is grossly inadequate
for optimum cocoa yield in cocoa ecologies of Nigeria. 

Soil nutrients in cocoa plantation are being mined annually via
cocoa harvest (Ogunlade et al.,
2009).  Opeyemi et al, (2005) reported that an effective
use of fertilizer on cocoa would help not only to improve yield but also has
the advantages of profitability, product quality and environmental protection

            In
India, Cocoa was introduced in the early part of 20th century and
now it has become one of the important horticulture crops and where it is
largely confined to southern states, viz., Kerala, Karnataka, Tamil Nadu and
Andhra Pradesh in an area of 78000 ha with total production of 16,050 MT. Tamil
Nadu ranks first with an area of 26,969 ha whereas Andhra Pradesh ranks first
in production. The average productivity of cocoa in Indian is 475 Kg/ha. (DCCD,2017
). It is
cultivated as component crop in arecanut, coconut and oilpalm  plantations, where  large area of cocoa
cultivation is under irrigated coconut condition. However, the productivity is
low which is only 2 kg dry beans tree-1 as against the potential
yield of upto 4 kg tree-1 through improved production techniques.  As the demand for cocoa in India is more (30,000 MT) than the
present supply (12,954 MT), cocoa production needs to be intensified (DCCD,
2011).

Plant analysis has been considered a very practical approach for
diagnosing disorders and formulation fertilizer recommendations (Kelling et al. 2000). Plant analysis, in
conjunction with soil testing, becomes a highly useful tool not only in
diagnosing the nutritional status but also an aid in management decisions for
improving the crop nutrition. Approaches to diagnosing
leaf nutrient status can be estimated by Compositional Nutrient Diagnosis (CND)
(Parent and Dafir, 1992;). For CND, the high-yield subpopulation is selected
from a crop survey database. This technique has been effectively utilized for
the establishment of nutrient norm and for identification of yield limiting
nutrients in fruit crops like banana (Raghupathi
et al, 2002,). With the background, present study was conducted
with the following objectives, To study the present status of nutrients in
cocoa growing enterprises of Puttur region of Karanataka and To develop CND
norms for identification of common yield limiting nutrient