Germination Characteristics of Tropical Grasses and Legumes

Abstract

In order to gain a better understanding of the seed germination characteristics of tropical grasses and legumes, preliminary studies were carried out at Pakchong Forage Crop Station, Thailand, over two years from April, 1972 to April 1974. The main results of the experiments were as follows: 1. In using six species of grasses and seven species of legumes, observations were made on the process of dormancy awakening in seeds stored at room temperature. The results indicated that these species could be classified into the following three groups with respect to germination rate and percentage. (1) High germination percentage, with high germination rate: sorghum, blue panic, columbusgrass, dolichos, centrosema. (2) Low germination percentage, yet high germination rate: Alabang X, green panic, Guineagrass (1971 harvest), alfalfa. (3) Low germination percentage, with low germination rate: Guineagrass (1972 harvest), leucaena, Townsville stylo. 2. By means of scarification of the seed coat, it was found that the main cause of seed dormancy in legumes was due to the hard seed coat. With respect to the process of dormancy awakening, species of legumes could be classified into four groups. (1) Absence of dormancy: dolichos. (2) Gradually and continuously broken dormancy: Townsville stylo and centrosema. (3) Repeatedly broken dormancy at short intervals: leucaena and alfalfa. (4) Repeatedly broken dormancy at relatively long intervals: siratro and perennial soybean. 3. High-temperature pretreatment (hot water, 80℃) increased both germination rate and germination percentage of dormant legume Townsville stylo seeds. Low-temperature pretreatment was also effective in breaking dormancy in legumes ; the lower the temperature, the higher the germination rate and percentage. In grass seeds, the effect of low-temperature pretreatment was relatively small and even uncertain compared with legume seeds.