Effects of plant density and water stress on growth characteristics, yield and oil content of Coriander (Coriandrum sativum L.)

To achieve the appropriate growth rate and yield in water stress condition, an optimal plant density is of great importance. In order to evaluate the effect of irrigation regimes and plant density on growth characteristics, yield, and oil content of coriander (Coriandrum sativum L.), an experiment was conducted at the research farm of the Agriculture and Natural Resources Campus, Kermanshah, Iran, during 2012-2013. The study was performed in a split plot arrangement based on a randomized complete block design (RCBD) with three replications. The main plots were irrigation regimes (1- no irrigation (rainfed), 2- one time irrigation at stem elongation stage, 3- two times irrigation at stem elongation flowering stages and 4- three times irrigation at stem elongation flowering seed formation stages), and the sub-plots were plant density (10, 30, 50 and 70 plants.m-2). The results of analysis of variance showed that the effect of irrigation regimes and plant density were significant for biomass, grain yield, number of grains per umbel, and 1000-grain weight. The highest biomass yield was obtained for two times irrigation at stem elongation flowering stages with 50 plants.m-2. Three times irrigation at stem elongation flowering seed formation stages with 30 plants.m-2 led to the highest grain yield. The irrigation regimes had the highest effect on the number of seeds per umbel (45% increase compared to rainfed conditions); however, plant density had the highest effect on the number of umbels per plant (44.7% decreases at a density of 10 compared to 70 plants.m-2). In this experiment, the oil content was not affected by treatments. Generally, this study showed that coriander had appropriate performance at rainfed condition, and the grain yield increased to 16% with increasing of irrigation interval.