Exercise 8

Exercise 8: Cultivation and Nursery Practices for Leucaena
    Nursery and planting of Leucaena leucocephala Lam.
    Botanical name : Leucaena leucocephala Lam.
    Common name : Subabul, Ipil-ipil
    Family : Leguminosae

    8.1
    Fig.1. Leucaena leucocephala
    Description:-
    • It is a large evergreen shrub or a small tree
    • It has feathery leaves, spreading and light crown
    • Bark is brownish and leaves are bipinnate
    • More than 800 species and these are broadly classified in four types
      • The Hawaiian type
      • The Salvador type
      • The peru type
      • Cunningham type
    Distribution:-
    • It is native to Mexico, Gauntemala, Honduras and El Salvador
    • Grown in many Oceanic countries Philippines, India, Indonesia, Srilanka, Papua New Guinea, Malaysia, Hawaii, Fiji, Northern America, East and West Africa and the Caribbean Islands for various purpose soil conservation, fuel and fodder etc
    • In India, planted in Andhra Pradesh, Karnataka, Tamil Nadu, Himachal Pradesh etc.
    Site Factor:-
    Climate
    • Temperature : Maximum 45°C
    • Rainfall : 600-1700mm
    • Altitude : up to 1000 m
    Soil
    • It is found to grow on diverse type of soils
    • It grows only on neutral to alkaline soils but low tolerance for acidic soils
    • Soils with low pH level give lower increments and yields
    • At 6.8 pH 50% reduction and at 6.3 pH 80% reduction in increment and yield
    • Exhibit good growth on coral and limestone outcroppings
    • Best growth is obtained on deep fertile soils with adequate moisture and abundant supply of nutrients
    Phenology
    • It is evergreen tree; frost or prolonged drought may, however, result in defoliation and such affected plants bring back to life with the return of favourable conditions.
    • The flowers are small, white and are arranged in globose heads, about 1-2 cm in diameter and often in pairs.
    • The flowers are usually self-pollinated.
    • A cluster of thin, flat, almost straight pods is soon formed from each flower head.
    • The pods develop quickly and soon attain full size.
    • The young pods are green and translucent and mature pods are reddish brown and hard.
    • The pods mature in about 3-4 months after pollination.
    • Each pod contains 15-30 seeds. Mature seeds are flat, shiny brown and have waxy seed coat.
    • The pods split along the edges dehiscing the seed.
    Silvicultural characters
    • It produces a long tap-root and hence utilizes deep soil water
    • It is fire retardant and fire tolerant plant
    • It is fairly drought resistant
    • It can withstand prolonged drought and severe flooding
    • It is frost tender
    • The seedlings are highly vulnerable to browsing
    • It is good coppice
    • It is an aggressive colonizer
    Regeneration
    Natural:-
    • In natural conditions, seed germinates after it has been soaked in water
    • Germination is epigeous
    • Sufficient light, moisture, freedom from tall weeds and thick shade are necessary for germination and seedling development
    • Symbiotic association of Leucaena root system with effective strains of Rhizobium bacterium or with vesicular arbuscular mycorrhizal fungi (VAM) is essential for successful establishment, growth and development of the species in any place
    Artificial:-
    • It can easily raised either by direct sowing or by planting out seedlings raised in the nursery
    • Stem cuttings treated with auxins, roots throughout the year, maximum rooting is obtained (80%) with IAA 100ppm in January, followed by IBA 100ppm February.
    Seed collection and storage:-
    • Ripe pods are collected before they open to scatter seeds on the ground
    • The pods are stirred and the seed is collected, winnowed and dried before storage
    • Seed yields vary from 50-2000 Kg/ha
    • The seeds remain viable for 20 years without any infestation if refrigerated
    • Seeds weigh 20000-26000 per Kg
    • Seeds should be treated with malathion or metoxychlor or with systemic fungicide as it is liable to be attacked by insects and fungi
    Pre-sowing treatment:-
    • Seeds have hard waxy seed coat which is impervious to water hence need pre-sowing treatment to ensure uniform germination
    • Mechanical scarification done by putting seed in a rotating drum lined with sand paper or knicked mechanically by knife or scissors
    • Acid treatment- Immerse seeds in concentrated H2SO4 or HCl for 15 minutes, washing and drying seeds before used for sowing
    • Seeds treated with hot water (80%) for 3-4 minutes gives about 80% germination
    • Seed inoculation with rhizobium or and with VAM is needed as it enhances the nodulation and biomass production
    Direct sowing:-
    • It can be raised by direct sowing when weeds, ants, rodents are kept under check; seed viability is high and plenty of seed is available
    • Seeds can be sown by hand, seed drills and by hand jabbers
    • Seed may be sown in fire burnt and cleared strips or in dug up patches or in lines
    • Seeds should not be placed deeper than 1-2cm as seeds sown deeper exhibit emergence problems
    • The seed rate for line or patch sowing is about 10-20Kg/ha
    • For timber production spacing should be 3 m × 3 m or 5 m × 5 m
    • Sowing should be done in moist soil preferably in the beginning
    • Germination occurs in 6-8 days and about 70% germination is expected
    • Seedlings can be raised in pots, small soil filled plastic bags or peat pellets or bamboo baskets and transplanted to the field when they are nodulated and about 15-30cm
    • For raising bare root plants, a raised seed bed of well drained and fertile soil is prepared on cement or impermeable floor
    • The soil should have pH near neutral
    • Scarified and inoculated seeds are sown in lines spaced 25 cm apart and at a distance of 5 cm between seed to seed
    • Seeds are sown about 1.2-1.5 cm deep
    • For container raised seedlings, the pre-rooted seed is sown in 22 cm × 10 cm polythene tubes which are filled with soil mixture having compost in 2:1 ratio
    • Sowing is done in March-April
    • Shifting of polythene bags is also necessary as the taproots of seedlings develop very fast
    Planting technique:-
    • It is done in the month of July-August at the onset of monsoon in the pre-dug pit of 30cm3
    • Nursery raised seedlings in containers or with ball of the Earth may be planted out
    • Pruning of lower branches is helpful in areas of low and erratic rainfall
    • Long tap root should be pruned to a length 12-15 cm
    • Dense plantation (1m × 1m) produce relatively small trees in 4 years of about 15 cm diameter, height of 12-15cm and wood weight per tree of about 25Kg
    • Regular weeding is necessary as its seedlings are slow growing in the beginning, get shaded and suppressed by weeds
    • The use of paraquat weedicide 4-5 days after sowing has been effective in controlling weeds
    • For timber production planting spacement is about 10m × 2m with later thinning to 10m × 4m and 10m × 6m
    • For firewood production planting spacement is about 1m × 2m and for forage production a much narrower 75cm apart furrows at 10cm for dibbling of seed is adopted
      • It is used for fuelwood
      • It is used for charcoal making
      • It suitable for making unbleached and bleached kraft pulp for wrapping and writing paper
      • The wood is used in parquet flooring
      • Pole can be used as fence posts or rafters for small houses
      • It is promising forage crop

Last modified: Friday, 19 October 2012, 4:55 AM