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North Carolina State University (2013)

Peanut Genetic Variation for Recovery from Severe Soil Drying and Low Epidermal Conductance as a Drought Tolerance Trait

Rosas-Anderson, Pablo Jose

Titre : Peanut Genetic Variation for Recovery from Severe Soil Drying and Low Epidermal Conductance as a Drought Tolerance Trait

Auteur : Rosas-Anderson, Pablo Jose

Université de soutenance : North Carolina State University

Grade : Master of Science (2013)

Résumé
Peanut (Arachis hypogaea L.) is an important food crop that is often grown in areas prone to intermittent drought. After drought is relieved, plant recovery from soil drying is an important factor for continued productivity. This thesis sought to identify genotypic variation for transpiration recovery and leaf maintenance in peanut and identify traits responsible for superior plant recovery from soil drying. In the first study, two greenhouse experiments were conducted to evaluate the transpiration recovery of 18 peanut genotypes subjected to a well-defined level of water-deficit stress before being re-watered. In addition, a visual rating scale was used to evaluate the maintenance of leaves during severe water deficit stress one day after re-watering ; where a rating of 1.0 indicated that plants had greater than 80% dead leaves and 5.0 meant that there was minimal leaf damage. A subsequent field experiment was conducted to verify the results of plant recovery observed in the greenhouse. Considerable genotypic variation for transpiration recovery from soil drying and leaf maintenance was found. Four genotypes with both superior transpiration recovery and leaf maintenance were identified : TMV 2, ICGV 86388, PI 497579, and N05006. These genotypes had transpiration ratios of at least 0.5 by the second day after re-watering and a visual rating of at least 4 or higher in almost all cases.
In the second study, two greenhouse experiments and a field experiment were conducted to identify genetic variation for epidermal conductance (EC) in peanut. In addition, the effect of water-deficit stress on peanut EC and the association of two leaf anatomical traits with EC were investigated in the field. Genetic variation for EC in peanut was found among genotypes evaluated in the greenhouse and the field. Results indicated that water-deficit stress did not affect the EC of peanut. Neither stomatal density nor specific leaf weight were associated with peanut EC. TMV 2 and PI 298639 had the least EC in the first greenhouse experiment with 1.72 and 1.71 mmol m-2 s-1, respectively. In the second greenhouse experiment VA 98R had the least EC of 2.16 mmol m-2 s-1. In the Field, SPT 06 07 had the least or second least EC and Bailey consistently had low EC throughout all measurements. When results from the first and second study are considered together, low EC was in part responsible for higher leaf retention and consequently better recovery in TMV 2, SPT 06-07, PI 298639 and to some extent, Bailey.

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Page publiée le 21 septembre 2013, mise à jour le 2 janvier 2018