Changes in carbohydrate and nitrogen fractions during germination of fenugreek (Trigonellafoenum-graecum L.) seeds presoaked in GA3, growing under different osmotic potentials

Abstract

Changes in carbohydrate and nitrogen fractions during seed germination of fenugreek under water stress and GA^ treatment were investigated. The germination percentage was reduced with the decrease in the osmotic potential of seed media, reaching its lower value at -0.8 MPa. Sucrose was accumulated considerably which could have had a major contribution in the total carbohydrate, while monosaccharides showed a substantial reduction and polysaccharides demonstrated no consistent pattern of changes due to water stress. The response of total nitrogen was variable; it increased considerably in -0.1 and -0.3 MPa osmotic potential, then dropped sharply at -0.5 and -0.8 MPa. Similar behavior was found in TSN(Total Soluble Nitrogen), whereas protein-N changed only slightly and proline was accumulated substantially by decreasing the osmotic potential of the seed media. Although GA, application had no any promotive influence on seed germination under water stress, it caused considerable changes in carbohydrate fractions in the growing seedlings. For example, monosaccharides were reduced, sucrose was accumulated and polysaccharides were degraded in hormone treatment as compared to water treatment. Nitrogen constituents, on the other hand, showed no clear responses to GAi treatment. The possible metabolic roles of all these fractions in the growing seedlings due to water stress were discussed.