Physiological and Biochemical Variations in Seed Germination of Cowpea (Vigna unguiculata L. Walp) Cultivars

摘要

Germination, coefficient of velocity of germination (CVG), lipid and sugar compositions were determined in whole ungerminated seed of three cowpea cultivars. The cultivars were chosen for biochemical characteristics based on seed germination and coefficient of velocity of germination tests. Texas cream 40 was able to germinate at very high and low temperatures. Black Crowder demonstrated acceptable germination at high temperatures but negatively affected at low temperature. Mississippi Purple obtained low germination percent and CVG at all temperatures studied. The main sugars present in cowpea seed are sucrose, raffinose and stachyose. Sugar contents were affected by cultivar. Sugar compositions were higher in the cultivars with high percent germination and reduced in the cultivar with lower percent germination suggesting the use of sugar for seed germination process. The most abundant fatty acids in cowpea seed were palmitic acid [CH_3(CH_2)_(14)COOH; (16:0)], palmitoleic acid [CH_3(CH_2)_5CH = CH(CH_2)_7COOH; (16:1)], stearic acid [CH_3(CH_2)_(16)COOH; (18:0)], oleic acid [CH_3(CH_2)_7CH = CH(CH_2)_7COOH; (18:1)], linoleic acid [CH_3(CH_2)_4CH = CHCH_2CH = CHCH2(CH_2)_6COOH; (18:2)], linolenic acid [CH_3CH_2CH = CHCH_2CH = CHCH_2CH = CH(CH_2)_7COOH; (18:3)] and arachidic acid [CH_3(CH_2)_(18)COOH; (20:0)]. The result shows that the long-chain fatty acid appears to be important in the cowpea seed germination process. Thus, the information provided by this research will facilitate future plant physiological and genetic studies of cowpea cultivars.