Studies on Dormancy and Germination of Seed in Finger Millet (Eleusine coracana) : I. Effect of light, temperature, and their interaction on germination

Abstract

Finger millet is a cereal that is extensively cultivated in Africa and India. Recently, finger millet has been grown as a fodder crop in central and southern lowland of Japan. Although only a few reports had been published on evolution, morphological variation and characteristics of cultivars, information on dormancy and germination of seed of cultivars had been meager and unsatisfactory. The present investigations were undertaken to elucidate effects of light, temperature, and their interaction on germination in relation to seed dormancy-awakening in cultivars originated from Africa, India, and Japan. The results obtained were as follows; 1) The seeds of tested cultivars, when stored at room temperature for about seven months, showed the wide range of variation in degree of dormancy. The seed of cultivar which inherits deep dormancy character, as Yukijirushi, could not germinate under any light and temperature condition, while the seed of cultivar which inherits shallow dormancy hcaracter showed full germination over a wide range of temperature. High temperature (30℃) and prolonged period of storage were effective for dormancy breaking. 2) The temperature range for germination was very wide, being from 10℃ to 30℃, even at early stage of dormancy-awakening. When seed dormancy was broken up, full germination occurred at any temperature regardless of light condition. 3) The tested cultivars were classified into the following three types, based on the response to temperature in germination in light at an early stage of dormancy-awakening. Type I: The germination percentage was high at 30℃ and germination at 30℃ was inhibited by dark condition. Iya (Japanese cultivar) belongs to this type. Type II: The germination percentage was high at 15℃ and germination at 15℃ was inhibited by dark condition. The cultivars of this type are African ones. Type III: The germination percentage was high at both 15℃ and 30℃ and germination at 15℃ and 30℃ was inhibited by dark condition. The cultivars of this type are Indian ones. 4) In all the cultivars tested, the light-inhibited germination occurred at 10℃. The dark period for three to five days immediately after seed soaking was necessary to induce germination at 10℃ in dark. Germination at 10℃ was inhibited when a brief interruption of light was applied during the dark period. The light break was most effective when at about the second or third day from start of seed soaking immediately followed by dark condition.