PHYSIOLOGICAL-CHARACTERISTICS ASSOCIATED WITH WATER IMBIBITION BY CALOPOGONIUM MUCUNOIDES DESV SEEDS

The relationships between physiological quality and water imbibition i n seed samples of Calopogonium mucunoides, a tropical forage legume, w ere investigated. Seed quality was evaluated by the germination and te trazolium tests. Water absorption was expressed in terms of percentage of imbibed (swollen) seeds observed after one, two, three, five and s even hours of imbibition. The imbibition test consisted of placing see d samples in contact with moist blotter in closed plastic boxes, at 30 degrees C. Water absorption by the seed samples occurred at rates cha racteristic to each individual seed lot. As the imbibition period prog ressed within the range of 1-7 hours, differences among the lot sample s accentuated. Particularly after 2-3 hours, they tended to reach dist inct levels by which the lot samples could be distinguished from one a nother. The sample's hard seed content determined the upper limit of t hose levels. Imbibition rates were associated with the physiological q uality of the seeds; low quality seeds were the first to imbibe. The p ercentages of imbibed seeds and the parameters derived from tests of s eed quality were similarly ranked by the Tukey's test. Periods of thre e and four hours of imbibition presented the greatest potential for di stinguishing between seed lots differing in physiological quality. The concept of using the imbibition characteristics of seed samples of on e variety to develop simple tests for estimating and comparing their p hysiological quality has enough potential to warrant further research.