Effect of irrigation interval, Nitrogen fertilizer rate and plant density on morphological traits, yield and water use efficiency of Fenugreek (Trigonella foenum-graecum L.)

In order to study the effect of irrigation interval, Nitrogen (N) fertilization and plant density on yield and yield components of fenugreek (Trigonella foenum-graecum L.), a split-split-plot experiment was conducted in Darmian, Iran in Spring 2010 based on a randomized complete block design with three replications. The main plots were irrigation interval at two levels of 5 and 10 days. The sub-plots were N fertilization at three rates of 0, 75 and 150 kg N.ha-1 from urea source and the sub-sub-plots were plant density at three levels of 22, 33 and 66 plants.m-2. According to the results of analysis of variance, irrigation interval significantly affected traits of pod length and water use efficiency (WUE) for seed and biomass production. In addition, main branch number per plant, pod length, seed yield, chlorophyll index and WUE for seed and biomass production, were significantly affected by nitrogen rate and plant density had significant effect on main branch number per plant and ring diameter. Means comparison showed that as irrigation interval was increased from 5 to 10 days, pod length decreased 8.7%, but WUE for seed and biomass production increased 40.5 and 47.5%, respectively. Also, as N rate was increased from 0 to 150 kg N.ha-1, main branch number per plant, pod length, seed yield, chlorophyll index and WUE for seed and biomass production increased by 23.5, 26.4, 23.2, 67.1, 72.3 and 71.5%, respectively. Moreover, with increasing of density from 22 to 66 plant. m-2, branch number per plant and ring diameter decrased 7.9 and 11.2%, respectively. In total, given the results of the study and the importance of water saving, it is recommended to use irrigation interval of 10 days with the application of 150 kg N.ha-1 and density of 66 plants.m-2 for the cultivation of fenugreek in Darmian, Iran.