Effect of Deficit Irrigation at Different Growth Stages on Yield and Yield Components of Two Safflower Cultivars

In order to evaluate the effect of water deficit at different growth stages on yield and yield components of two cultivars of safflower, a study was conducted during 2009 and 2010 growing seasons at Research Farm of College of Agriculture, Shiraz University, Shiraz, Iran. The treatments were cultivar at two levels (Sina and Local Isfahan) as the main factor, irrigation regime at four levels (40, 60, 80 and 100% of field capacity (FC)) as sub factor and time of applying deficit irrigation at two levels (vegetative and reproductive stages) as sub-sub factor. The results showed that the highest and lowest seed yield was recorded for Sina (3085 kg/ha) and Local Isfahan (2757 kg/ha) cultivars, respectively. Applying deficit irrigation at reproductive stage caused a 14.3% increase in yield, irrespective of the cultivar. The highest and lowest seed yields were obtained by applying deficit irrigation at reproductive and vegetative stages, respectively. Based on the results, the optimum seed yield (5100 kg/ha) can be achieved by applying 80% FC deficit irrigation at reproductive growth stage of Sina cultivar. In general, the seed yield decreased with reducing irrigation water amount at any growth stage. This reduction was significant at vegetative and reproductive stages of Sina cultivar, from 100 to 80% FC and from 80 to 60% FC, respectively. For Local Isfahan cultivar, the reduction was significant at both growth stages, from 100 to 80% FC.