title: Influence of germination date on Dioon edule (Zamiaceae) seedling tolerance to water stress.
abstract: 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 (Ψs) 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 C3 to CAM cycling when exposed to water stress at Ψs 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 Ψs of -1.0 MPa. These have higher probability of dehydration during severe drought (February-April) than those of the December-February GD with similar Ψs. Plants used for restoration purposes must have full leaf development to increase the survival.
authors: Instituto de Investigación de Zonas Desérticas, Universidad Autónoma de San Luis Potosí, Altair 200, Col. del Llano, San Luis Potosí, S.L.P, 78377, Mexico, lyaneze@uaslp.mx.
authors: Laura
authors: L
authors: Yáñez-Espinosa
authors: Joel
authors: J
authors: Flores
authors: Paulina S
authors: PS
authors: Rodríguez Millán
authors: Gabriel
authors: G
authors: Rubio Méndez
mesh_terms: D000222:Adaptation, Physiological; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D003681:Dehydration; D018525:Germination; D010788:Photosynthesis; D054046:Plant Stomata / Q000502:physiology / Q000648:ultrastructure; D036226:Seedlings / Q000502:physiology*; D012987:Soil; D013997:Time Factors; D014867:Water; D032481:Zamiaceae / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology*
chemical_list: D012987:Soil; D014867:Water; D002734:Chlorophyll; D002338:Carotenoids; C037184:chlorophyll b; D000077194:Chlorophyll A