Dr. YOGESH SUMTHANE (Ph.D.), Mob. 8806217979
Casuarina was introduced into mainland India in 1868 to meet increasing fuelwood demand by the then Collector of Kanara in the Bombay Presidency. It now occupies a sizeable area in South India because of its ability to grow in a wide range of soil and climatic conditions including moisture and nutrient-limited plantation sites A surging terrible for high-density plantations (10000 stems per ha) and responds well to irrigation and nutrient application. Casuarina cultivation techniques are simple and not labour intensive and hence cost-effective.
Area and extent of cultivation :
Although Casuarina is cultivated throughout South India, plantations are concentrated in the coastal areas of Andhra Pradesh, Orissa, Puducherry, and Tamil Nadu which account for about 80% of total plantations. It is estimated that about 500,000 ha are planted with Casuarina in the above States. Growing Casuarina is also steadily increasing in inland areas where it is not traditionally grown. Shortage of farm labour, insufficient water availability for agriculture, non-remunerative prices for farm produce, and the growing tendency of absentee farming are the major reasons for farmers shifting to Casuarina cultivation. The increasing demand for Casuarina wood and steady rise in its price during the last 5 years have also made it a cash crop with assured returns in a short span of 3 to 5 years.
Botanical characteristics :
The botanical name of the casuarina species grown in India is Casuarina equisetifolia. It belongs to the family Casuarinaceae which includes about 90 species naturally distributed in Australia, South East Asia, and Pacific Islands. Casuarina equisetifolia is an evergreen tree with a straight stem and a conical crown made up of permanent, horizontal branches containing deciduous needlelike branchlets (a modified stem called cladode). Leaves arise in a whorl in each node, and are fused along the next internode, and become free at the next node with teeth-like tips. The bark is smooth in young trees and may become fissured in older ones.
In India, trees are dioecious in nature, i.e. male and female flowers are produced in different individuals. Normally male and female trees have equal distribution but a small percentage of trees produce both the sexes in the same tree which are called monoecious trees. Pollination is effected by wind. The entire inflorescence develops into an infructescence commonly called as ‘cone’ or ‘fruit’ in about 3-4 months. Each fruit has 30 to 40 seeds. In India casuarina trees generally flower twice a year during June – July and November – December followed by fruit maturation in September – October and February – March respectively.
The method of cultivation varies in different areas but some of the basic features like high density planting (1×1 m spacing) and short rotation period (3 to 4 years in irrigated and 4 to 6 years in dry lands) are common in all places. The following is the generalized description of cultivation practices for casuarina.
Nursery techniques :
Casuarina is predominantly planted as bare-root seedlings and the nursery is raised in two stages. The first stage is called primary nursery which is from seed sowing to production of 1-2 months old seedlings. The second stage is known as secondary nursery which involves transplanting of seedlings from primary nursery and growing them for the next 3 to 4 months. Nursery activities should start 4-5 months ahead of the field planting date if bare-root seedlings are used and 3-4 months before if containerized (polybag/root trainer) plants are preferred. The nursery area should be well lit throughout the day and devoid of any shade from nearby trees or buildings. In general, the surroundings of the nursery should be kept weed-free to avoid attracting insects and pathogens.
Sowing of seeds :
Casuarina seeds are small and a kilogram has around 6 lakh seeds, but about half of them may actually be immature seeds which usually do not germinate. Germination is generally around 30% and up to 100,000 seedlings are obtained from a kg of seed depending upon source of seed and nursery efficiency.
Seeds are sown in raised sand beds (called ‘mother beds’) of the size 10 x 1 meter. Generally, no pretreatment is necessary for casuarina seeds. In each bed, about 250 g of seeds are evenly spread by mixing with fine sand. A thin layer of sand is applied over the seeds. The sand bed is covered with rice straw to prevent the washing off of seeds while watering. Water is provided through a rose can or a sprayer. A suitable repellent is applied along the periphery of the bed to prevent ants from removing the seeds.
Germination and transplanting :
Seeds start germinating from the 5th day and the straw is removed on the 7th day. They are grown in the mother beds for the next 4 to 6 weeks. The beds have to be kept moist by watering through rose can once or twice a day but water stagnation should be avoided to prevent fungal diseases.
After 4 to 6 weeks when the seedlings attain 8 to 10 centimetres height they are transferred either to a secondary bed or polythene bags. Secondary beds are also of the same size as the mother beds but in addition to sand, farm manure and soil (2:1:1) are also added to increase nutrient availability and water holding capacity. They can be watered either through rose can or flood irrigation depending upon the size of the nursery. But water stagnation should be avoided.
Seedlings pricked from primary beds are transplanted to the secondary beds a approximately 4 cm apart. Though it is a common practice to plant more than one seedling per planting point, it is strongly recommended to plant only one plant in a point to raise vigorous and healthy seedlings. Seedlings are grown in the secondary beds for 3 months to obtain a height of 30 to 45 cm and a collar diameter of 3 to 5 mm.
Growing seedlings in polybags and root trainers is better than bare root seedlings especially for planting in rainfed areas. Seedlings raised in containers establish well in plantations and record vigorous growth in the first year. Polybags (size: 15 x 8 cm) filled with a potting mixture of sand, farm manure and soil in a ratio of 2:1:1 are suitable for raising casuarina seedlings. Seedlings may attain plantable size within 2 months but can be maintained for another 4 to 6 months if planting is delayed.
Vegetative propagation :
Outstanding casuarina trees can be propagated by rooting of young shoots (‘sprigs’). Such plants produce uniform superior growth in plantations. Sprigs collected from selected trees are trimmed to 8-10 cm length (Fig. 5) and washed in a 5% solution of fungicide like Bavistin”. The lower portion of the shoot is treated with a rooting hormone.
Indole butyric acid (commercial name: Seradix BTM). The treated cuttings are placed in root trainers containing vermiculite or composted coir pith and kept in mist chamber or propagation chambers made of polythene sheets. Rooting occurs in 15 to 20 days and then transplanted into polybags or root trainers and grown in the same way as seedlings.
Box 2. Fact File on Casuarina
Biological nitrogen fixation : Symbiotic nitrogen fixation through Frankia: 40-60 kg per hectare per vea Wood Properties
|Physical properties||Mechanical Properties||Pulping traits|
|Wood density (4 years age) : Irrigated : 698 kg m3 Rainfed : 703 kg m3 Moisture content : 47-67 % Calorific value : 0.3% 5000 kcal kg2 Bark : 2-3 mm (8-10% of woody biomass)||Static bending, centre loading : Equivalent fibre stress at elastic limit : 373 kg cm2 Modulus of elasticity (1000 kg cm): 114 Impact – max, drop 23 kg hammer: 124 cm2 Max : compressive strength parallel to grain : 115 kg cm2 Hardness : side : 677 kg Shear – max. shearing strength parallel to grain : 115 kg cm2 Tension perpendicular to grain: Radial : 37 kg cm2 Tangential : 44 kg cm2||Lignin : 29% Holocellulose : 69% Pentasons : 16% Ash : 0.3% Fibre length : 1036 Fibre wall thickness 5.3u|
Durability and resistance to Insects
Moderately durable when exposed to weather, Susceptible to ambrosia beetles but resistant to powder-post beetles and dry-wood termites. Susceptible to subterranean termites. Susceptible to marine borers even after treatment with creosote/diesel oil.