Exercise 7

Exercise 7: Cultivation and Nursery Practices for Robinia
    Robinia pseudoacacia Linn.
    Common Name: Robinia, Black locust

    7.1
    Fig.1. Robinia pseudoacacia tree
    Botanical name: Robinia pseudoacacia Linn.
    Common name: Black Locust
    Family: Leguminosae
    Sub family: Papillinioideae
    Description:-
    • It is a medium sized thorny, deciduous tree
    • Full grown trees have rough brown dark grey longitudinally furrowed bark
    • The young shoots are smooth, purplish brown, armed without triangular spines in pairs, which persist for some years
    Distribution:-
    • It is native to North America, from where it has been introduced to France, Hungary, Belgium, Southern Russia, Italy and Balkan states
    • In India it was first introduced in Himachal Pradesh in 1890 and later to Jammu and Kashmir in 1919
    • In has performed well in outer Himalayas between 1800-3000m and in the inner Himalayas at elevations as low as 1050m in Himachal Pradesh
    Site factors:-
    Climate:
    • Temperature - Maximum 29.4°C Minimum -3.8°C
    • Rainfall - 700-1750 mm
    • Altitude - 1500-2000 m
    Soil:
    • It grows on wide variety of soils
    • Favors lime-derived soils having pH between 4.6 and 8.2
    • It is a versatile colonizer
    • For best growth it requires a deep, rich gravelly, well drained loamy soils and avoids wet, heavy and stiff soils
    • Excessively dry soils and soils with slow drainage are not suitable for its growth
    Phenology:-
    • Leaf fall - September-November
    • Leaf renewal - March-April
    • Flowering - April-May
    • Fruiting - June-July
    • Fruit ripening - September-October
    Silvicultural characters:
    • It is strong light demander
    • It is intolerant of competition
    • It is frost hardy
    • Young seedlings suffers from frost injury in first season
    • Mature trees are drought hardy
    • The tree is wind firm under ordinary wind velocity
    • It coppices freely
    • Root suckers produced abundantly from its superficial roots which run up to 12 or 15m from the parent tree
    • Root suckers are produced after an age of 3 to 4 years
    Regeneration:-
    Natural:
    • Seedling regeneration is absent in plantations
    • Root suckers and coppice shoots
    • Seeds falling on fresh, moist mineral soil before the winter snow, germinate in spring and seedlings may establish
    Artificial:
    • The species can be propagated by planting out nursery raised seedlings
    • Direct sowing does not useful
    Seed collection and storage:
    • Abundant seed produce every 1-2 years
    • The tree starts seeding at an early age of about 2-3years and commercial quantities of seed are available from the age of 8years onwards
    • The ripened pod should be collected from October to December
    • One kilogram contains 60000 to 80000 seeds
    • Pods dried in the sun, thrashed and winnowed to obtain clean seed.
    • About 35 to 77 seeds weigh one gram
    • The seed can be stored for one year in airtight containers at room temperature without any appreciable loss in viability
    • The seed requires pre-sowing treatment which may consist of immersion in H2SO4 or dipping in hot water or soaking in cold water.
    • The treatment of the seed with either H2SO4 or HNO3 or hydrogen peroxide for two minutes is reported to injure the seed (Chandra and Sharma, 1976).
    • Hot water treatment, which is normally adopted, consists of soaking the seed in cooling boiled water for 2 to 5 minutes and allowed to soak at room temperature for 8 to 10 hours (Muthoo and Kango, 1965; Chandra and Sharma, 1976).
    • Soaking of seed in water at room temperature for about 24 hours has been found to be satisfactory.
    • Sowing is done in the nursery beds in lines about 20 cm apart.
    • The spacing between the seeds in the lines is about 5 cm, and the depth of sowing is about 1.5 cm.
    • Sowing is normally done in March in irrigated nurseries.
    • Late sowings done in June-July normally give poor results as the seedlings suffer from damping off as a result of monsoon rains at the time of germination.
    • In Kashmir valley where spring rains are good, March-April sowing may suffer from damping off and the sowing done in May gives better results (Muthoo and Kango, 1965).
    • Under rain-fed conditions, the sowings are done in September as the seedlings raised from sowings done in July or August may suffer from damping off.
    • Germination starts in about 7 days and takes about 10 days to complete.
    • The seedlings are transplanted into the nursery beds in the following January-February and are grown in transplant beds for one year.
    • A germination percentage of about 70-85 can be expected for the seed treated to soften the seed coat before sowing
    • Weeding is necessary to protect the young seedlings from being smothered by weeds The seedlings are thinned out to a spacing of about 10 cm between lines, when these have attained an average height of 5 cm.
    Planting technique:
    • The plants from March sowings become fit for planting the following December-January when they attain height of 1-2 m.
    • September sowings do not, however, produce plants of sufficient height in the following winter and they become plantable during the next winter.
    • Planting out is done in pits of 30 cm3 dug in advance.
    • Spacing adopted is generally 2.5×2.5 m for compact block planting and about 4 m for line planting around agricultural field.
    • A spacing of 2×2 m is adopted for comparatively poorer sites.
    • Bush cutting is done at the time of planting.
    • Naked root plants are planted out. Sometimes root suckers are also used for planting
    • The taproot is cut and the lateral roots are pruned so as to accommodate the root system of the plants in 30 cm3 pits.
    • The plants are bundled and the roots wrapped in gunny bags during transport.
    • Care is taken to ensure that the roots are not injured during planting.
    • The plantation areas are closed to grazing, to protect the plants against browsing.
    Economic importance:-
    • Black locust is valued for leaf-fodder, timber and as honey bee flora.
    • The trees are very heavily lopped for fodder as the leaves are rich in crude protein, calcium and phosphorus.
    • Crude protein, phosphorus and tannin contents decrease while crude fibre, total ash and calcium contents increase as the leaves mature.
    • The palatability of the leaves is good and it improves as the tannin content decreases with the maturity of leaves.
    • Total digestible nutrients in the case of leaves lopped in September-October were higher than those of leaves lopped in June-July.
    • Late (September-October) feeding of leaves is better than feeding them in the early part of the year.

Last modified: Friday, 19 October 2012, 5:16 AM