Effect of application of zeolite and nitrogen fertilization on growth, seed yield and water productivity of fenugreek (Trigonella foenum-graecum L.) under drought stress conditions

To study the effects of drought stress, nitrogen fertilization and zeolite on some morphological, phenological and agronomic traits of fenugreek, a split factorial experiment was laid out in randomized complete block design with three replications in 2014 and 2015 growing seasons at research field of Tarbiat Modares University, Tehran, Iran. Five irrigation regimes (non drought stress; mild drought stress during the vegetative and reproductive stages, respectively; severe drought stress during the vegetative and reproductive stages, respectively) were randomized in main plots. Subplots were six factorial combinations of three nitrogen fertilization levels (untreated plots, vermicompost fertilizer at a rate of 2.7 ton.ha-1 and Urea fertilizer at rate of 11 kg.ha-1) and two zeolite levels (0 and 9 ton.ha-1). Results showed that in both growing seasons, drought stress significantly decreased all traits in comparision with control, and vermicompost fertilizer and zeolite reduced the negative effects of dought stress. The highest seed yield was obtained in non-water stress with vermicompost (903.1 kg.ha-1) and application of zeolite and vermicompost (568. 09 kg.ha-1). In the first growing season, grain yield declined by 24% and 76% with increasing deficit water stress in vegetative and reproductive stages, respectively.In the second growing season, these decreases were 31% and 54%, respectively. It was concluded that application of vermicompost and zeolite extended the duration of availability of water and nitrogen and led to increase seed yield and its component as well as water productivity in fenugreek.