Germination and seedling emergence of soybean seeds having cracked seedcoats.

Abstract

The seeds having cracked seedcoats (the cracked seeds) are not only regarded as an inferior quality in an exterior view but also tended to cause lower seedling emergence. However, since the cracked seeds seem generally to occur among bigger seeds, it is suggested the possibility to bring the better seedling emergence by elaborating the cultural methods. Soybean seed, cultivar Enrei, was used in a series of experiments. The experiments related with seedling emergence were carried out on the field nursery beds in natural conditions or on beds in glasshouse, and ones related with germination were done on filter paper folded up in V-shape. The results obtained are summarized as follows : (1) The seeds having uncracked seedcoats (the uncracked seeds) emerged, but the cracked seeds did not (Table 1) under natural conditions in much rainy days (Fig. 1, Oct.9-25). (2) Significance (p=0.05) in percentages of seedling emergence by sowing uncracked seeds, cracked seeds, and germinated seeds developed from cracked and uncracked seeds, under adequate sprinkling water in glasshouse, was not recognized. But 92% seedling emergence by sowing germinated seeds developed from cracked seeds was a slightly higher than the other treatments (Table 2). (3) Percentages of seedling emergence by sowing germinated seeds developed from uncracked seeds and from cracked seeds were about 90%, but ones by sowing ungerminated seeds were very low (Table 3) under natural conditions in continuous much rainy days (Fig. 1, Oct. 31-Nov. 14). (4) Percentage of germination by seeding the cracked seeds was a little higher than that by seeding the uncracked ones. That was progressed to be higher by pasting Himosab (one of the granular rosins which is able to absorb water rapidly) with starch paste on a part of hilum (Fig. 3). (5) Elongation of each part in the seed was measured by changing the seeding directions. The longest elongation in length was found in case of seeding the cracked seeds and the second one in case of submerging hilum and micropyle of seed in water (Fig. 4). Supposing from the above results, the following cultural methods are persuaded to bring the better seedling emergence in case of using the cracked seeds. 1) The cracked seeds are sown at adequate soil moisture in the field. 2) Germinated seeds developed from the cracked seeds are used. 3) Transplanting seedlings which are developed from cracked seeds under adequate sprinkling water on the beds in glasshouse are used.