Xylem Anatomical Study in Diverse Capsicum sp. Accessions, Implication to Drought Tolerance

Drought is a limiting factor for plant survival and food production. Plants have developed various strategies in response to this stress. The immediate response to drought is the closure of the stomata. However, it prevents the transpiration and the photosynthesis. From the point of view of crops, it is interesting the ability of the plants to keep photosynthesizing under drought. Leaf water content is affected by the difference among leaf and soil water potentials (Ψ leaf-Ψ h) and by the xylem-speciϐic hydraulic conductivity (Ks). It has been hypothesized that the number and diameter of the xylem vessels would affect the drought tolerance. In this experiment the inϐluence of the xylem anatomy in the tolerance to water stress of three Capsicum sp accessions: Bol 58, Piquillo, Chimayo was studied. Plants were grown in plastic pots ϐilled with soil:sand mixture in a glasshouse at UPV, during spring season. Two different treatments were used in the assay: normal irrigation and restricted irrigation (50 % less irrigated than the control). Three and a half months after transplantation plants were harvested; roots, stems and fruits were weighted. Portions of the stem bases were ϐixed in FPA and rehydrated for the analysis of the xylem total area. Material was sectioned with a freezing microtome and dyed with phloroglucinol. Vessel element area wa