Tamil Nadu State is situated at the South-eastern extremity of the Indian peninsula bounded on the North by Karnataka and Andhra Pradesh, in the east by Bay of Bengal, in the South by Indian Ocean and in the West by Kerala State. It has a coastal line of 1076 km and a land boundary of 1200 km. It lies between 8 5 and 13 35 at Northern Latitude and 76 15 and 80 20 of Eastern Longitude with an area of 1,30,058 sq. km. (50,154.7 sq.miles)
The State is divided broadly into two natural division ie., (a) the coastal plains and (b) the hilly western areas. It is further divided into coromandal plains comprising the districts of Kancheepuram, Tiruvellore, Cuddalore, Villupuram and Vellore, Thiruvannamalai and alluvial plains of Cauvery delta extending over Thanjavur, Nagapattinam Thiruvarur and part of Trichy and dry southern plains in Madurai, Ramanathapuram, Sivaganaga, Virudunagar, Tuticorin and Tirunelveli districts. It also extends a littloe in Western Ghats in Kanayakumari district. The Western Ghats averaging 3000 to 8000 height runs along the western part withthe hill group of Nilgiris and Anamalais on either side of it. Palani hills,Varashanad and Andipatti ranges are the major off-shoots of Ghats. The other prominent hills comprise of Javadhu, Shervarayan, Kalrayans and Pachai Malais. These ranges continue south of river Cauvery. A plateau is found between these hills and the Western Ghats with an average elevation of 1000 feet raising west-ward. The highest peak Doddapettah in the Nilgiris is 8650 above M.S.L.
Western Ghats forms a complete watershed and no river passes through them. The main streams i.e., Paraliyar, Vattasery Phazhayar etc., are of limited length and fall in the Arabian sea. All other rivers are east-flowing rivers. The Eastern Ghats are not a complete watershed and as a results the river pass through them at places, notable among them is the river Cauvery. The main river of tamil Nadu are Cauvery (with tributaries of Bhavani, Amaravathi, Noyyal) Vaigai, Tamaraparani, Palar, Ponniyar and Vellar.
The climate of Tamil Nadu is basically tropical. Due to its proximity to the sea, the summer is less hot and winter is less cold. In plains, the maximum daily temperature is 44.4 C and the minimun daily temperature is 11.8 C. In hill station maximum temperature is 25.5 C and minimum temperature is 4.4 c. The state is exposed to both South West and North East monsoon.
The seven agro climatic zones viz., Western, Southern, North Eastern, North Western, Delta, High Rainfall, and Hilly and Tribal zones posses conductive climatic condition coupled with monsoon rains.
Agroclimatic zones of Tamil Nadu
||North Eastern zone
||North Western zone
||High Rainfall zone
||Hilly and Tribal zone
The special feature of climatic condition in Tamil Nadu is that the four seasons are not distinct and over lap with immediate next season. In the plains there is no winter seasons and in the hills summer is not severe allowing continuous production of horticultural crops in the state.
The summer (March May) overlaps into windy seasons (June August) which overlaps into rainy seasons (September November). The rainy season overlaps into winter (December February) which in turn overlaps into summer season. There are areas with temperate climate (above 2000 m), subtropical climate (1000-2000 m), humid tropical climate 500- 1000 m and tropical climate (upto 500 m) to accommodate all possible types of horticultural crops.
These overlapping seasons have made possible grapes to grow round the year, vegetables and spices in all possible crop rotation and systems of planting. Nearness to the equator and the presence of long stretch of western Ghats, discontinuous eastern Ghats and presence of hill and hillocks in the plains help moderation of climate to ensure the required heat unit and degree-days for growing different kinds of horticultural crops.
Broad classification of Horticultural crops
Horticultural crops are classified in to six categories viz. Fruit Crops, Vegetable Crops ,Spices and Condiments, Plantation Crops, Flower Crops and Medicinal and Aromatic Plants.
Fruit Crops depending upon the climatic preference are classified as:
Tropical and Sub-Tropical Fruit crops like Banana, Mango, Citrus, Grapes, Guava, Sapota, Papaya, Ber, Pomegranate, Fig, Custard apple, Pineapple, Mangosteen, Amla, Phalsa, Avocado, etc.
Fruit Crops which come up well under cool temperature and high altitudes are known as temperature fruits. In Tamil Nadu hilly areas, the commonly grown temperate Fruit Crops are Apple, Peach, Plums, Pear, Persimmons etc.
Out of about 8.90 lakhs ha. of Horticulture Crops in Tamil Nadu crops account for 26%.
In Tamil Nadu major vegetable crops are Tapiaco, Onion, Tomato, Brinjal, Potato, Lablab, Drumstick, etc.
Out of about 8.90 lakhs ha. of Horticulture Crops in Tamil Nadu, Vegetable crops are grown in 2.34 lakhs ha. accounting for 22%.
Spices & Condiments
Spices & Condiments form a very important group of horticulture crops from the point of view of high income generation and foreign exchange earnings through exports. Spices & Condiments are grown in 1.30 lakhs ha. in Tamil Nadu which is around 18% of Horticulture Crops. The important spices crops are Chillies, Pepper, Turmeric, Tamarind, Cardamom, Cloves, etc.,
Plantation Crops are location specific. They cannot be raised at every place. They generally come up well at higher elevation where in there is an ample rainfall and high humidity. Plantation Crops are ideally taken up on hill slops or in valleys. The important Plantation Crops grown in Tamil Nadu are Tea, Coffee, Rubber, Cahew, etc. About 2.37 lakhs. Of Plantation Crops are grown in Tamil nadu which account for 27% total horticulture crops grown in the state.
The major area under domestic flower in Tamil Nadu is with traditional flowers like Jasmine, Crossandra, Tuberose, Chrysanthemum, etc. With its varying climatic conditions in the hill ranges and plain, Tamil Nadu offer good scope for the production of different varieties of flower crops.
Flower crops are grown in 0.25 lakhs ha. in Tamil Nadu out of 8.90 lakhs ha. of Horticulture Crops.
Medicinal & Aromatic Plants
Medicinal & Aromatic Plants are grown in about 0.06 lakh ha. in Tamil Nadu and there is vast scope for increasing the area in the coming years due to potential export value of Medicinal & Aromatic Plants. The important Medicinal & Aromatic Plants are grown in Tamil Nadu are lemon grass, senna, etc.