Cashew Nut (Anacardium occidentale L.)
The cashew nut, native to southeastern Brazil, was introduced to India's Malabar Coast in the 16th century primarily for soil conservation. Presently, India cultivates cashew on approximately 1.04 million hectares, yielding around 0.68 million tonnes (as of 2015-16). Despite being a leading exporter of cashew kernels, India still faces a shortage of raw cashew nuts for its processing industries. This is due to East African nations like Mozambique and Tanzania, which now process their nuts domestically, thus reducing exports to India. This shortfall highlights the urgent need to enhance domestic production. The average productivity in India is about 700 kg/ha.
Botanical Description
Cashew belongs to the Anacardiaceae family and is a medium-sized tree, growing between 7 and 13 meters tall. Its leaves are simple, alternate, smooth (glabrous), and leathery in texture.
Flowering
The tree bears a panicle that includes both male and hermaphrodite (bisexual) flowers, a condition known as polygamo-monoecious. While only a small percentage (0.45 to 2.49%) of perfect flowers may be present on a tree, they are generally larger than staminate flowers. Typically, about 85% of the flowers get fertilized, but only 4–6% develop into mature fruits.
Fruit
The cashew fruit consists of two parts: the apple and the nut. The cashew apple is a swollen pedicel and not a true fruit. The true fruit is the nut, which matures from green to ash-gray in color. As it ripens, the apple enlarges and turns yellow, red, or a combination of both. The nut contains a thick, oil-rich pericarp surrounding a kidney-shaped seed. The seed is covered by a thin brownish skin and contains a white edible kernel. The nuts vary in size, weight (3–20g), and shelling percentage (15%–30%).
Climate and Soil Requirements
Cashew thrives in tropical climates and can be grown in almost any soil type up to an elevation of 700 meters above sea level. However, it performs best in red sandy loam and coastal sandy soils. It requires a minimum annual rainfall of 600 mm and prefers full sunlight over shaded conditions.
Propagation
Since cashew is predominantly cross-pollinated, propagation via seeds is discouraged except for raising rootstock. Seeds generally germinate within 15–20 days. Vegetative propagation techniques include grafting, layering, and budding. Among these, softwood grafting is widely practiced. In this method, 30–40-day-old seedlings with 1–2 leaf pairs are used. Grafting is done 15–20 cm above the ground using the soft shoot portion. Epicotyl grafting and air layering are also practiced in certain areas.
Top Working in Cashew
Due to poor and inconsistent yields from seedling-origin plantations, top working with superior clones is recommended. These rejuvenated trees, benefiting from mature root systems, start producing up to 4 kg of nuts per tree from the second year, with further increases over time.
Input Requirements
- Plant population: 155 trees/ha (spacing 8 m x 8 m)
- FYM/Compost: 2.5 tonnes/ha
- Fertilizer dose per plant (g):
| Year | May-June | Sept-October | ||||
|---|---|---|---|---|---|---|
| N | P2O5 | K2O | N | P2O5 | K2O | |
| I | 50 | 40 | -- | 50 | 40 | -- |
| II | 100 | 40 | 30 | 100 | 40 | 30 |
| III | 200 | 60 | 60 | 200 | 60 | 60 |
| IV | 250 | 60 | 60 | 250 | 60 | 60 |
Harvesting and Processing
Cashew nuts are harvested once fully mature and are sun-dried for 2–3 days before storage. The primary harvesting period in India is from March to May. Processing involves several steps: moisture conditioning, roasting, shelling, drying, peeling, grading, and packing.
- Moisture Conditioning: Sprinkling water to attain 15–25% moisture content.
- Roasting: Two methods are commonly used:
- Drum Roasting: Offers higher shelling rates and better kernel quality but results in CNSL loss.
- Oil Bath Roasting: Heats shells in cashew nut shell liquid to extract oil while roasting.
- Shelling: Typically done manually using sharp tools to extract the kernel.
- Drying: Post-shelling, kernels are dried for 6–12 hours.
- Peeling: Removing the thin seed coat manually.
- Grading & Packing: Final steps before marketing the product.
Yield and Economic Life
Cashew trees begin to bear fruit from the 3rd or 4th year and reach full productivity by the 10th year. Their economic lifespan is around 50 years. A good tree yields 10–15 kg of raw nuts annually after maturity. Trees producing more than 8 kg after 12 years are considered productive.