The effects of irrigation and dry farming on growth indices of yarrow (Achillea millefolium L.) in Karaj

In order to study the effects of irrigation and dry farming condition on growth indices of yarrow (Achillea millefolium L.) an experiment was carried out in Alborz Research Center during 2005-2006. In the first year after planting, the plants viability investigated in dry farming condition and growth physiological indices were determined. In the second year, the treatments were irrigated based on total accumulated evaporation from class A pan namely at the rate of 30 mm (mild stress), 60 mm (medium stress), 90 mm (severe stress), full irrigation (no stress) and no irrigation (control). For each treatment, the soil moisture content was measured by weighting method (daily) before and after applying irrigation treatments. The amount of water requires for each treatment was measured by water meter.In the second year, the growth physiological indices were also determined. The results showed that, at the first year, dry matter cumulated to 2250 GDD then reduced during growth. In second year, the plants with no irrigation were died. In other treatments, by increasing soil moisture from severe to medium, the dry mater cumulative and Leaf area index increased. In all of the stress treatments, decreasing in plant growth was observed in 3000 GDD. The results showed that, mild water stress had highest performance than other treatments.