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Accueil du site → Doctorat → États-Unis → 1975 → SOME PHYSIOLOGICAL AND PHYSICAL CHANGES EXHIBITED BY SEEDS OF LEHMANN LOVEGRASS (ERAGROSTIS LEHMANNIANA NEES.) WITH PRE-SOWING SEED TREATMENTS OF MOISTENING AND DRYING

University of Arizona (1975)

SOME PHYSIOLOGICAL AND PHYSICAL CHANGES EXHIBITED BY SEEDS OF LEHMANN LOVEGRASS (ERAGROSTIS LEHMANNIANA NEES.) WITH PRE-SOWING SEED TREATMENTS OF MOISTENING AND DRYING

HAFERKAMP, MARSHALL ROY

Titre : SOME PHYSIOLOGICAL AND PHYSICAL CHANGES EXHIBITED BY SEEDS OF LEHMANN LOVEGRASS (ERAGROSTIS LEHMANNIANA NEES.) WITH PRE-SOWING SEED TREATMENTS OF MOISTENING AND DRYING

Auteur : HAFERKAMP, MARSHALL ROY

Université de soutenance : University of Arizona 1975

Grade : Doctor of Philosophy (PhD) 1975

Résumé
Seeds of Lehmann lovegrass (Eragrostis lehmannlana Nees.) were treated with pre-sowing seed treatments of moistening, oven drying, or mechanical scarification. Seeds were imbibed in water at 24 C (24w), in a water saturated atmosphere at 24 C (24v), or with water at 10 C (lOw). Oven drying (OD) at 70 C for 24 hr was an individual treatment or followed one of the 24v or lOw treatments. Seeds were scarified in a modified Forsberg seed cleaner. Control seeds were air dry with no treatment.
Treated seeds were imbibed for 24 and 48 hr in the 24w environment, and germination percentages were determined. The 24v and lOw treatments of varying durations, applied alone or in combination with OD, OD and scarification increased germination percentage. The 24v or lOw treatments were as effective when applied for 24 hr and combined with OD as when applied for 48 or 72 hr with OD. Physiological development was measured after 0, 6, 18, 31, 48, and 60 hr imbibition in 24w, 24v, or lOw environments. Contents of ATP, ADP, alcohol soluble sugars, and starch ; rate of respiration ; and alphaamylase activity were measured. Sixty percent of the 24w seeds germinated by 60 hr imbibition. As water content increased in the 24w seeds, contents of ATP, ADP, and rate of respiration increased. The content of alcohol soluble sugars decreased from 1.88% to 1.20% during the initial 31 hr, but increased to 3.03% in the following 29 hr. The increase was accompanied by a decrease in starch content and an increase in alpha-amylase activity. The 24v and lOw seeds, after 60 hr imbibition, attained physiological development comparable to 24w seeds at 0 to 6 hr and 6 to 18 hr imbibition, respectively.
The ATP content and germination percentage, after 9 and 24 hr imbibition, respectively, in the 24w environment were compared for seeds treated with one of seven treatments. Scarified, OD , 24v + 0D, lOw + 0D, 24v, and lOw seeds contained more ATP after 9 hr and germinated significantly better after 24 hr than control seeds. Content of ATP was highest in scarified, 24v + OD, and lOw + OD seeds, and intermediate in OD, 24v, and lOw seeds. Germination percentage was greatest for scarified, OD, 24v + OD, and lOw + OD seeds and intermediate for 24v and lOw seeds. Physical changes in the seed coat were investigated by viewing seeds with a scanning electron microscope, determining water content of treated seeds after 6 and 18 hr imbibition in the 24w environment, and determining germination percentage for treated seeds after 37 hr imbibition in atmospheres of 21, 10, or 5% oxygen. Properties of the seed coat appeared to be affected by scarification, OD, and moistening plus OD. The gelatinous seed coat appeared to be torn during the lOw + OD treatment and loosened in the OD and 24v + OD treatments. Scarified, OD, 24v + OD, and lOw + OD seeds contained the most water after 6 hr imbibition in the 24w environment, but OD and lOw + OD seeds contained the most by 18 hr. Germination percentages were significantly higher for scarified, OD, 24v + OD, and lOw + OD seeds than for control seeds in atmospheres of 21, 10, or 5% oxygen. In 21% oxygen, scarified seeds germinated best while in the 10 and 5% oxygen, OD seeds germinated best. Germination percentages under all treatments decreased from the 21% oxygen to the 5% oxygen atmosphere, but control, OD, and 24v + OD seeds germinated better in 10% oxygen than in 21% oxygen. Germination percentage was about the same in both atmospheres for scarified seeds but was decreased in the 10% oxygen for lOw + OD seeds.

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