Water relations for sun and shade leaves of four mediterranean evergreen sclerophylls

The water relations, stomatal conductance, size, chlorophyll and proline content have been measured in sun and shade leaves of four evergreen sclerophyll species, throuthout the year. It was found that there were no major differences in water status of the two leaf types. However, in young expanding shade leaves, higher stomatal conductance, turgor, chlorophyll and proline content leves was significantly larger. Plastochron ratios of the two leaf types in the four species were similar, indicating a synchronized gorwth rate related to seasonal rhythemicity. It is suggested that different mechanisms have been operating in the response of the two leaf-types to microclimatic conditions: an avoidance by sun leaves and tolerance by shade leaves. © 1991 Oxford University Press

Water relations for sun and shade leaves of four mediterranean evergreen sclerophylls

The water relations, stomatal conductance, size, chlorophyll and proline content have been measured in sun and shade leaves of four evergreen sclerophyll species, throuthout the year. It was found that there were no major differences in water status of the two leaf types. However, in young expanding shade leaves, higher stomatal conductance, turgor, chlorophyll and proline content leves was significantly larger. Plastochron ratios of the two leaf types in the four species were similar, indicating a synchronized gorwth rate related to seasonal rhythemicity. It is suggested that different mechanisms have been operating in the response of the two leaf-types to microclimatic conditions: an avoidance by sun leaves and tolerance by shade leaves. © 1991 Oxford University Press

Seasonal changes of carbohydrates, lipids and nitrogen content in sun and shade leaves from four mediterranean evergreen sclerophylls

Annual fluctuations of starch, soluble sugars, nitrogen, proteins, lipids and energy-content of storage substances were determined and compared in sun and shade leaves from four evergreen sclerophyll species: Arbutus unedo, Olea europaea, Pistacia lentiscus and Quercus coccifera. Sun leaves of P. lentiscus and Q. coccifera contained higher amounts of starch compared to shade leaves; in A. unedo and O. europaea reciprocal results were obtained. The seasonal trends of soluble sugar content differed among species. Nitrogen content was high in young expanding leaves and decreased considerably during the growth period. Sun leaves contained higher amounts of proteins and lower amounts of soluble nitrogen when compared with shade leaves. The total lipid content was greater in sun leaves of P. lentiscus and Q. coccifera, whereas shade leaves of A. unedo and O. europaea contained higher amounts of total lipids at the beginning of the growing season. It is likely that these various accumulations in sun and shade leaves of these evergreen sclerophylls represent a species-specific response. © 1994

Seasonal trends in energy contents and storage substances of the mediterranean species Dittrichia viscosa and Thymelaea tartonraira

The annual fluctuations of soluble sugars, lipids, starch and nitrogen content were determined in leaves, stems and roots of Dittrichia viscosa and Thymelaea tartonraira. The energy content of storage substances was calculated. Soluble sugars increased in all parts of both species during the summer while starch and total lipids decreased. The annual variations of lipids, total and protein-nitrogen and the energy content of storage substances differed between the leaves of the two species. In contrast, starch and soluble sugars showed similar annual fluctuations in the leaves of both species. During the periods of growth foliar nitrogen concentration was correlated with foliar soluble sugar and starch concentrations, but relationships varied with time and between species. The differences in leaf lifespan between species affected only the leaf storage contents and not the stem and root contents. A sink storage system may be functioning between stems and roots of both examined species