Effects of fertilization and water stress on Eucalyptus camaldulensis seedlings.

This study examined the responses of Eucalyptus camaldulensis seedlings to water stress and fertilization. To assess the effects of fertilization on osmotic adjustment underwater stress conditions, 4-month-old E. camaldulensis plants were raised in pots and fertilized with either nitrogen (2 g of urea) or phosphorus (12 g of triple superphosphate). The soil was watered to attain one of the two conditions: field capacity and osmotic potential. Solute accumulation increased under the influence of P fertilizer in well-watered conditions, which indicates better performance under water stress. However, under waterstress conditions, control plants increased dry mass allocation to leaves but decreased allocation to roots. Water use efficiency, i.e. the grams of water transpired per gram of dry mass accumulated, was not altered by fertilization or water stress. N-fertilized plants increased allocation to roots and maintained allocation to leaves under water-stress conditions in comparison with control plants. They were not affected by water stress as much as l'-fertilized plants. Osmotic adjustmentwas observed only in P- ertilized and control'plants. Osmotic adjustment in water-stressed plants was associated with increased stomatal conductance. Water stress strategies were altered by fertilization and water availability.