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The Effect Of Gibberellins On Seeds Germination Of Seed Germination

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Abstract
Faster and uniform germination of seed as well as establishment of vigourous crop is of paramount importance in direct-seeded rice crop, which in turn depends on seed germination and vigour per se. Rice being an albuminous seed, it is hypothesized that galactomannan hydrolysing enzymes (viz., β-mannanase, β-mannosidase and α-galactosidase) play important role in loosening of the embryo-surrounding tissue viz., endosperm, which in turn governs the speed of germination. The study was an assessment of this hypothesis, on ten rice genotypes comprising of five early germinating (which have taken less than 30 hours for radicle emergence) and five late germinating (which have taken more than 44 hours for radicle emergence) genotypes. The effect of gibberellins (GA) and Abscisic acid (ABA) on enzyme activity was also subsequently evaluated. The activities of β-mannanase, β-mannosidase and α-galactosidase were present in dry and germinating rice seeds and increased during germination. GA could promote the activities of all the three enzymes that reduced the time taken by the germinating seed to reach the stage of lemma rupture and radicle emergence. On the other hand, ABA had an antagonistic effect on the activities of these enzymes and enhanced the time taken by the germinating seed to reach the stage of radicle emergence. However, no changes were observed with respect to time taken for lemma rupture, which corroborate that lemma rupture could be due to expansion of

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