Tropical canopy tree species can be classified into two types by their heterobaric and homobaric leaves. We studied the relation between both leaf types and their water use, together with the morphological characteristics of leaves and xylem, in 23 canopy species in a tropical rain forest. The maximum rates of photosynthesis and transpiration were significantly higher in heterobaric leaf species, which also underwent larger diurnal variations of leaf water potential compared to homobaric leaf species. The vessel diameter was significantly larger and the stomatal pore index (SPI) was significantly higher in heterobaric than that in homobaric leaf species. There was a significant positive correlation between the vessel diameter, SPI, and maximum transpiration rates in all the studied species of both leaf types. However, there was no significant difference in other properties, such as leaf water-use efficiency, leaf mass per area, leaf nitrogen content, and leaf δ13C between heterobaric and homobaric leaf species. Our results indicate that leaf and xylem morphological differences between heterobaric and homobaric leaf species are closely related to leaf water-use characteristics, even in the same habitat: heterobaric leaf species achieved a high carbon gain with large water use under strong light conditions, whereas homobaric leaf species can maintain a high leaf water potential even at midday as a result of low water use in the canopy environment., Y. Inoue, T. Kenzo, A. Tanaka-Oda, A. Yoneyama, T. Ichie., and Obsahuje bibliografii
Measurements of reflectance in visible and near-infrared spectral regions were made on detached leaves of two crop species of different leaf morphology, structure, and water content (peanut and wheat) throughout progressive desiccation. Relative water content (RWC) was well correlated with water index (WI) but even better with the ratio of WI and normalized difference vegetation index. RWC was also significantly correlated with structural independent pigment index indicative of carotenoids/chlorophyll ratio. New indication is thus provided to assess leaf water content and apply simple and fast radiometric techniques for plant water stress management. and J. Peñuelas, Y. Inoue.