Studies On Seed Vigor And Hard-seededness Of Indigofera Amblyantha And Lespedeza Bicolor

Difficulties were existed extensively in germination and vigor test on legume seeds because of their high percentage of hard seeds, so screening out the exact physiological index to test and the effective methods to improve the germination and seeds vigor of legume seeds were of great importance for quality evaluation of legume seeds. Experiments were conduct on the seeds of Indigofera amblyantha and Lespedeza bicolor to (1) partially reveal the relationship between hardness of seeds and their vigor; (2) select effective treatments to break the hard seeds coat thus improve legume seeds germination; (3) develop the simple, exact test regulations of vigor test for legume seeds.Germination test showed that up to 90% of hard seeds in newly harvested seeds lots could germinate under normal conditions after their coat were broken; effectiveness of accelerated aging on the hard seeds rate were negligible. No remarkable difference in germination and vigor index were existed between aging and un-aging hard seeds.Effectiveness of different treatments to break the hard coat of were evaluated in our experiment to screen out the effective methods which could be applied in field conditions to improve the field emergence. Results showed that eroding in 85% (W/V) sulfuric acid for 15~35min for the seeds of Indigofera amblyantha, 25min for Lespedeza bicolor was of most effective to break the hard seeds coat while maintain reasonable germination rate, compared with soaking in water, desiccating at 70℃ or 140℃, freezing in liquid nitrogen.Under 25℃, the vigor of normal seeds and coat broken hard seeds (by mechanical method) of Indigofera amblyantha and Lespedeza bicolor were increased gradually after soaking in water for 1~5 and 1-3 days, respectively, (depending on their rate of imbibition seed) , the vigor of coat-broken hard seeds were higher than that of normal seeds.Taking the germination rate as standard, remarkable correlation were existed between seed vigor and germination index, vitality index, relative electric conductivity of plasma membrane, activity of acidic phosphor-esterase, thus could be effective index of seeds lots quality with same hard seeds rate, but not the soluble carbohydrates in soaking water, and dehydrogenase. Otherwise, the activity of superoxide dismutase (SOD), peroxidase (POD), and content of malondialdehyde (MDA) could be taken as referenced index to evaluate the vitality of legume seeds.Our results suggested that: the coats of hard seeds could protect the seed from injury, thus maintain relatively higher vitality and vigor; the vigor of hard seeds could be tested solely as the complementarity in the evaluation of legume seeds quality.