MULBERRY CULTIVATION (CONT…2) – BUD AND METHODS OF BREAKING DORMANCY IN BUDS

Bud: In mulberry, generally one bud is found in the axial of a leaf. Sometimes two more independent buds on either side of the main bud are also found.

Causes for dormancy in bud: Earlier physiologists were of the opinion that low, temperature, nitrogen deficiency, inactivation of enzymes due to excessive accumulation of carbohydrate; photoperiodism etc. might be responsible for dormancy.

METHODS OF BREAKING DORMANCY IN BUDS:

Mechanical: Sometimes even under tropical climate, during winter period, the buds do not sprout quicily.

Chilling treatment: Gururajan (1962) reported the success of breaking dormancy in buds of Morus nigra by subjecting them to a low temperature of 0 to 6⁰C.

Chemical treatment: Iwata (1970) reported the effect of chemicals such as methyl cap rate on the sprouting of mulberry buds and retardation of growth of mulberry plants. Mulberry plants grown were sprayed by aqueous emulsion of methyl cap rate in summer with varying concentrations ranging from 0.01 M to 0.2 M.

Leaves: The size of mulberry leaf varies in different species and varieties. Varieties like Kanva‑2 are characterized by large leaves and varieties like "Mysore 'Local" bear only small leaves. The leaf size is an important character taken into consideration in selecting high yielding varieties.

Inflorescence: The inflorescence of mulberry is a CATKIN with its characteristic pendent or drooping peduncle, bearing unisexual flowers.

Male catkin: The male catkin is usually longer than the female catkin measuring 2.5 to 5 cm long.

Female Catkin: The female catkin is axillary, sometimes occurs in clusters.

Flower: The flowers of mulberry are small, usually sessile or infrequently shortly pedicillate, regular and unisexual.

Male flower: The male flower consists of four perianth leaves arranged in two whorls with imbricate aestivation.

Female flower: The female flower consists of four perianth leaves arranged in the same manner as in the male flower.

Pollination: Since the flowers of mulberry are unisexual, only cross pollination takes place.

Seed: Typical tree whose seeds are to be used for propagation by sexual means is select d from which dark purple colored ripe fruits are collected. These fruits are kept for one day for softening the pulp taking necessary precautions to prevent the pulp from rotting. The next day, these fruits are transferred to a trough containing water. Then by constant kneading of the fruits the seeds become squeezed out of the pulp. The water is decanted and the seeds are taken out, dried and stored under dry conditions.

Structure of seed: Mulberry seed is oval in shape with a nearly flat surface at the micropylar region.

Polyembryonic seed: Rare occurrence of seeds giving rise to two identical seedlings has been reported. Such seedlings were thought to be polyploids. Generally embryo is developed only from the egg cell in the ovule. Sometimes embryos may be formed from nucellar tissues also.

Storage of seed: Mulberry seeds may be viable for a few weeks or may be at the most for three months beyond that they may not be viable.