Training Manual Development Of Cultivars And Seed ... - icrisat

suggested that pollen with a moisture level of 7.5% can be stored in a plastic zip lock bag tor 185 days
at -73°C, remaining 1 0 0 % viable.
Fertilization and Grain Formation
After pollination, the stigmas dry up in 24 h. Seed-set can be seen in the panicle about a week after
fertilization (Burton and Powell 1968). There is a gradual increase in the dry mass of grains from the milk
to dough stage, reaching maximum at maturity. Physiological maturity of the grain is indicated by the
appearance of a black layer just above the hylar region on the abgerminal side of the grain opposite the
embryo (Fussel and Pearson 1978). At physiological maturity, the seed contains 3 0 % moisture.
There are large variations in seed shape (Fig. 8) — obovate, oblanceolate, cuneiform, pyriform,
pyramidal, elliptical, hexagonal or globular — size, and color. The grain mass varies from 3 to 5 g 1000' 1
seeds for small-seeded genotypes and 10 to 12 g 1000 -1 seeds for bold-seeded genotypes. The seeds
are yellow, white, light brown or gray.
Grain Structure
The pearl millet grain is a caryopsis with three main parts: pericarp, endosperm, and germ (Fig. 9). The
pericarp contains three layers of tissues: epicarp, mesocarp, and endocarp. The term bran refers to the
pericarp, the seed coat, and the aleurone layer of the seed. The endosperm contains simple starch
granules and protein bodies. The germ contains about 2 5 % lipids, 2 0 % protein, and phytin, vitamins, and
enzymes. The germ of pearl millet constitutes about 1 7 % of the total seed mass (Rooney and
McDonough 1987).
Factors Influencing Flowering and Seed Formation
Photoperiod and temperature affect flowering in pearl millet. Some genotypes fail to flower when the day
length exceeds 12 h. Many genotypes flower under long day length conditions (16 h photoperiod), but
flowering takes place earlier under short-day conditions (Burton 1965).
Increasing the temperature up to 32°C and providing an appropriate photoperiod reduces the
number of days from sowing to flowering (Hellmars and Burton 1972).
Drought may hasten flowering in some genotypes but delay it in others. A combination of high
temperature and drought affect pollen viability, stigma receptivity, and seed-setting.