Effect of water stress conditioning on morphology, physiology and field performance of Pinus halepensis Mill. seedlings

Five-month-old Pinus halepensis Mill. seedlings were subjected to 4 irrigation treatments for 8 weeks. After the treatments, morphological and physiological attributes assessed included height, diameter, dry weight, water relations parameters, and determination of N, P, K, soluble carbohydrates, and starch concentrations. The remaining seedlings were field planted. Survival and height growth were recorded for four growing seasons after planting. The most significant effect of irrigation was on morphology. Increased irrigation lead to seedlings with significantly higher height, root collar diameter and shoot and root biomass. Starch and soluble carbohydrate concentrations were also affected by irrigation. However, parameters derived from pressure-volume curves were not significantly different among treatments, nor were N, P, and K concentrations. There were no differences among treatments for survival in the field, which was highly related to summer rainfall. In comparison, absolute and relative height growth showed some significant but minor differences among treatments.