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Accueil du site → Doctorat → États-Unis → 2006 → Physiological and morphological characteristics associated with drought resistance mechanisms in bentgrass species

Rutgers The State University of New Jersey - New Brunswick (2006)

Physiological and morphological characteristics associated with drought resistance mechanisms in bentgrass species

DaCosta, Michelle

Titre : Physiological and morphological characteristics associated with drought resistance mechanisms in bentgrass species

Auteur : DaCosta, Michelle

Université de soutenance : Rutgers The State University of New Jersey - New Brunswick

Grade : Doctor of Philosophy (PhD) 2006

Résumé
The availability of water is a major factor limiting distribution, growth, and productivity of cool-season turfgrass species. Insight into the physiological mechanisms that impart drought tolerance to turfgrasses will aid in the identification of important characteristics that can serve as selection criteria for improved stress tolerance, and also improve management strategies for the maintenance of high quality turfgrasses in water-limiting environments. Bentgrasses (Agrostis spp.) are primarily utilized for high maintenance, close-cut turf for golf course tees, greens, and fairways in cool, humid climatic regions of the United States. Even though their use has increased, bentgrass species are among the least studied cool-season grasses in terms of drought tolerance. Relatively little is known of their water use requirements, relative drought tolerance, and mechanisms of drought adaptation. Therefore, the objectives for this research were to determine bentgrass species variability in drought resistance and to evaluate the physiological and morphological mechanisms associated with drought resistance in bentgrass species. Major strategies for drought resistance in plant species, including changes in water use, carbohydrate metabolism, the antioxidant defense response, and hormonal regulation were evaluated. Velvet bentgrass (A. canina L.) exhibited the highest turfgrass quality under drought stress and least sensitivity to drought stress. Creeping bentgrass (A. stolonifera L.) exhibited intermediate drought performance among the three species, and colonial bentgrass ( A. capillaris L.) generally declined the most rapidly in response to drought stress. The better turf performance of velvet bentgrass was associated with higher water use efficiency, greater capacity for osmotic adjustment, prolonged maintenance of the antioxidant defense response, and low accumulation of abscisic acid. When soil water was replenished following drought stress, colonial bentgrass exhibited greater recovery from drought stress compared to both creeping and velvet bentgrasses. Greater recuperative ability of colonial bentgrass was associated with greater allocation of carbohydrate reserves to storage organs such as stems as well as more rapid recovery of hormone balance to pre-stress levels. Taken together, these studies indicated that bentgrass species varied in drought persistence and recuperative potential. Selecting for the combination of traits associated with both strategies could greatly improve turfgrass growth and survival in water-limiting environments.

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