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Accueil du site → Doctorat → États-Unis → 1972 → SEED DORMANCY OF SIDEOATS GRAMAGRASS, BOUTELOUA CURTIPENDULA (MICHX.) TORR.

University of Arizona (1972)

SEED DORMANCY OF SIDEOATS GRAMAGRASS, BOUTELOUA CURTIPENDULA (MICHX.) TORR.

Major, Roger Lee

Titre : SEED DORMANCY OF SIDEOATS GRAMAGRASS, BOUTELOUA CURTIPENDULA (MICHX.) TORR.

Auteur : Major, Roger Lee

Université de soutenance : University of Arizona

Grade : Doctor of Philosophy (PhD) 1972

Résumé
The objectives of this study were to determine the pattern, duration, and causes of seed dormancy in sideoats gramagrass. Investigations were pursued to identify and characterize seed dormancy and to relate seed dormancy characteristics to stand establishment under natural conditions. Germination experiments were conducted in a laboratory germinator on five relatively dormant and five relatively nondormant seed sources. The germination pro cedure for all experiments was standard except the factor under evaluation was varied. Post-harvest dormancy was present in all sources, but disappeared after four to six months dry storage following harvest. Long-term dormancy persisted for five years in the relatively dormant seed, with no decrease in viability. Long-term dormancy was almost completely removed by removing the lemmas, paleas, and glumes from the caryopses. Post-harvest dormancy was evidently due to factors within the caryopses, while long-term dormancy was conditioned primarily by the spikelet appendages enclosing the caryopsis. Germination in soil, alternating moisture condi tions, enriched-oxygen atmosphere, and sodium hypochlorite treatment were effective in breaking dormancy. Prechilling, light treatments, leaching with water, sodium carbonate, and hydrogen peroxide were less effective in relieving dormancy. Characteristics associated with seed dormancy included 30% less caryopsis weight, a low molecular-weight protein, apomixis, and coumarin-like compounds in the spikelet appendages. The mechanism of seed dormancy appeared to involve interactions among low seed weight, impermeable seedcoats, and the presence of inhibitory materials. The emphasis of these investigations was directed toward the potential advantages of seed dormancy in range land and stand establishment. The determination of the relationship between seed dormancy and field establishment would allow the development of selection criteria asso ciated with desirable seed dormancy characteristics.

Mots clés : Side-oats grama. ; Dormancy in plants. ; Seeds.

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