The objective of this study was to evaluate the response of the giant reed (Arundo donax L.) to drought stress at early stages, as well as to determine the effects of limited soil water availability on plant growth, gas exchange, and water-use efficiency. Plantlets of a commercial clone were grown in a greenhouse under two water treatments: at 100% of field capacity and progressive drought for 66 days (until 20% of field capacity). Soil water content, leaf elongation rate, plant water consumption, and gas-exchange parameters were measured throughout the experiment. Total plant biomass, leaf water, and osmotic potential were determined at the end of the experiment. Plant growth and leaf gas-exchange parameters were significantly affected by soil water availability, but only when it was below 40% of field capacity. At early stages, Arundo donax showed drought stress acclimation due to leaf plasticity, stomatal regulation, and osmotic adjustment., A. Romero-Munar, E. Baraza, J. Cifre, C. Achir, J. Gulías., and Obsahuje bibliografii
Seedling recruitment is a critical developmental stage in regeneration of plant populations under Mediterranean conditions that strongly depends on water availability. Seed mass and relative growth rate (RGR) may affect the early establishment of seedlings through different physiological processes. Here, we examined the effects of the seed mass and carbon balance on seedling growth under two water regimes in Rhamnus alaternus L. and Rhamnus ludovici-salvatoris, two Mediterranean shrubs, showing a different ability to recruit seedlings. Plant water consumption and biomass accumulation (ΔB) were measured during three periods of the growth in order to estimate water use efficiency (WUE), RGR, and its components. Additionally, net photosynthesis and leaf, stem, and root respiration were measured in plants grown in pots well watered and under progressive drought. Rhamnus alaternus showed the higher seed mass, ΔB, and plant WUE than that of R. ludovici-salvatoris in all periods and water regimes. The higher RGR of R. alaternus was observed during the first and the second period, but the reverse trend was registered during the third period as a consequence of the higher initial biomass of R. alaternus. Also, R. alaternus showed a higher specific leaf area and estimated carbon balance than that of R. ludovicisalvatoris. The observed differences in ΔB, estimated carbon balance, seed mass, and WUE between both species could explain their different distribution and ability to recruit seedlings under natural conditions., H. El Aou-Ouad, I. Florez-Sarasa, M. Ribas-Carbó, J. Flexas, H. Medrano, J. Gulías., and Obsahuje seznam literatury