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Accueil du site → Master → Etats Unis → 2016 → PARENTAL EFFECTS AND PROVISIONING UNDER DROUGHT AND PHOSPHORUS STRESS IN COMMON BEAN

Pennsylviana State University (2016)

PARENTAL EFFECTS AND PROVISIONING UNDER DROUGHT AND PHOSPHORUS STRESS IN COMMON BEAN

Lorts, Claire Madeline

Titre : PARENTAL EFFECTS AND PROVISIONING UNDER DROUGHT AND PHOSPHORUS STRESS IN COMMON BEAN

Auteur : Lorts, Claire Madeline

Université de soutenance  : Pennsylviana State University

Grade : Master of Science (MS) 2016

Résumé partiel
Low soil fertility and drought are primary constraints in common bean (Phaseolus vulgaris) production in low input agricultural systems, and a threat to food security in many developing nations. Common bean genotypes tolerant to drought or low phosphorus conditions have been identified, and root traits associated with tolerance to such stress have been examined. The utility of these root traits in tolerant genotypes is usually tested using seed from a well-watered and high-nutrient parental environment. However, many farmers in developing nations collect seed for the next year’s crop from parent plants grown in low phosphorus and/or drought conditions. Thus, it is important to understand how progeny from a stressed parental environment perform under similar stressful conditions. This study investigates the impact of a low phosphorus and/or drought parental environment on progeny seed and root traits. To test whether differences in progeny seed and root traits from stressed parental environments could be explained by differences in parental provisioning of seeds during seed development, we also examined seed and root traits in seeds from different pod positions (stylar versus peduncular) and pod developmental times on the parent plant. Greenhouse, field, and seedling experiments were used to evaluate seed, seedling, and mature root traits in progeny from stressed and non-stressed parental conditions. In parental drought studies, progeny from drought stressed parents had lower individual seed weight, lower basal root number (BRN) in both seedlings and plants at growth stage R2, and lighter total seedling dry weight, shorter seedling basal roots, shorter lateral roots borne on seedling tap roots. The length and density of root hairs borne on seedling tap and basal roots also differed between progeny from parental drought and well-watered environments. At growth stage R2 progeny from parental drought had a smaller basal root diameter, lighter shoot dry weight, fewer shoot-borne roots, and fewer dominant shoot-borne roots. In parental phosphorus (P) studies, progeny from a low P parental environment had lower individual seed P content, fewer shoot-borne roots at R2, and greater BRWN at R2. In studies comparing root traits between seeds from the peduncular (closest to the petiole) versus stylar (farthest from the petiole) positions in the pod, and between seeds from early versus late developing pods, seeds from the peduncular position in the pod at growth stage R2 had lower individual seed weight, lower BRN, lighter root dry weight, smaller tap root diameter, and fewer lateral roots borne on basal roots. In all studies, responses to parental effects varied across genotypes. Seed and seedling root traits had greater consistency across genotypes compared to mature root traits, whereas stronger genotypic effects were seen in mature root traits. Seeds and seedlings showed more consistency in parental effects across genotypes likely due to the exposure to fewer environmental factors, resulting in less variability among measured traits.

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Page publiée le 4 juin 2021