Influence of germination date on Dioon edule (Zamiaceae) seedling tolerance to water stress
2014
Yañez-Espinosa, L. ((Universidad Autonoma de San Luis Potosi, San Luis Potosi, S.L.P (Mexico). Instituto de Investigacion de Zonas Deserticas), (Universidad Autonoma de San Luis Potosi, San Luis Potosi, S.L.P (Mexico). Programas Multidisciplinarios de Posgrado en Ciencias Ambientales)) | Flores, J. | Rodriguez Millan, P.S. | Rubio Mendez, G.
Dioon edule seedling mortality is mostly attributed to dehydration by prolonged drought, even when they present xeromorphic characteristics like the adult plants. The effect of germination date (GD) and soil water deficit on seedling tolerance to water stress was assessed. The seedlings germinated and grown from mature seeds every month from December to April GD were selected to evaluate the leaf area, photosynthetic pigment content, crassulacean acid metabolism (CAM) activity, stomatal conductance (gs) and leaflet anatomy at soil water potential (psis) of 0.0 MPa (day 1), -0.1 MPa (day 40), -1.0 MPa (day 90), -1.5 MPa (day 130), and a control (0.0 MPa at day 130) to recognize differences due to leaf development. The seedlings shifted from Csub(3) to CAM cycling when exposed to water stress at psis of -1.0 MPa, like adult plants. The March-April GD seedlings with undeveloped sclerified hypodermis and stomata, presented reduced leaf area, lower Chlorophyll a/b ratio, higher CAM activity and midday partial stomatal closure when reached psis of -1.0 MPa. These have higher probability of dehydration during severe drought (February-April) than those of the December-February GD with similar psis. Plants used for restoration purposes must have full leaf development to increase the survival.
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