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Accueil du site → Doctorat → États-Unis → 2016 → Drought physiology of beans : dissection of drought response mechanisms in soybean (Glycine max), tepary (Phaseolus acutifolius), lima (P. lunatus) and common bean (P. vulgaris

University of California Davis (2016)

Drought physiology of beans : dissection of drought response mechanisms in soybean (Glycine max), tepary (Phaseolus acutifolius), lima (P. lunatus) and common bean (P. vulgaris

Medina, Viviana

Titre : Drought physiology of beans : dissection of drought response mechanisms in soybean (Glycine max), tepary (Phaseolus acutifolius), lima (P. lunatus) and common bean (P. vulgaris)

Auteur : Medina, Viviana.

Université de soutenance : University of California Davis

Grade : Doctor of Philosophy (PhD) 2016

Résumé
Global warming’s expected harsher and more extreme weather patterns will severely affect agriculture. As a matter of food security, agriculture needs to adapt to these warmer, drier conditions. The main purpose of this dissertation was to find target traits that breeders can use to select for greater drought resilience and tolerance specifically for soybean (Glycine max), tepary (Phaseolus acutifolius), lima (P. lunatus) and common bean (P. vulgaris). The initial step was to define drought and a hierarchy of drought adaptation mechanisms and appropriate experiments (Gilbert and Medina 2016). Physiological traits such as stomatal closure under high VPD, heat tolerance, and photosynthetic damage repair were assessed under field ((Chapter 1 and 3) (Medina and Gilbert 2015) or outdoors under high-light/ high-heat (conditions of Chapter 2). While species and genotype differences were apparent, the species were not considerably different, and plants successfully avoided photosynthetic damage. While physiological traits were important for tolerance, we found limited genetic variation for use in breeding programs. The new experimental protocols developed in this work allowed greater differentiation of traits than in the past (Chapter 2), explaining why this study found limited differences in comparison to past studies that had less physiological control of stress and soil water deficit. In the field, phenology differences and variations towards allocation of biomass to reproduction appeared to have the greatest influence on drought productivity (Chapter 3). Future breeding programs in Phaseolus species should thus further focus on phenology and reproductive allocation differences rather than physiology differences. The four species of leguminous crops studied here showed considerable ability to withstand soil water deficit and had sufficient physiological damage avoidance mechanisms to be effective under drought, but differed significantly more in their reproductive success under drought conditions.

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Page publiée le 20 septembre 2017