Effect of Deficit Water Stress on Some Growth Indices and Yield of Fenugreek (Trigonella foenum-graecum L.) in Response to the Zeolite and Nitrogen Fertilizer

This study was conducted to investigate the effects of water deficit stress, nitrogen fertilizer and zeolite on growth parameters, biomass and seed yield of fenugreek. A split factorial experiment based on a randomized complete block design with three replications was conducted at the Research Field of Tarbiat Modares University in 2014 and 2015. Five irrigation regimes (unstressed, mild stresses during the vegetative and reproductive stages, respectively; severe stresses during the vegetative and reproductive stages, respectively) were randomized to the main plots. Subplots consisted of six treatments of a factorial combination of three levels of nitrogen fertilizations (untreated plots, vermicompost fertilizer at a rate of 2.7 t.ha-1 and nitrogen chemical fertilizer at a rate of 11 kg.ha-1) and two rates of zeolite (0 and 9 t.ha-1). In both years, increasing severity of water deficiet stresses reduced leaf area index, crop growth rate, plant height, biological and seed yield of fenugreek; Thus, severe water deficit stress at the reproductive stage without fertilizer and zeolite (with the least amount of biological and grain yield) compared with that of control, caused 60.96 and 48.09 percent reduction in biological yield and 80.18 and 75.62 percent reduction in grain yield, in both years, respectively. Application of nitrogen fertilizer, especially vermicompost, resulted in a significant increase in the leaf area index, crop growth rate of fenugreek in various stages of development, thereby increased biological and grain yield in different irrigation regimes. In various irrigation regimes, higher leaf area index, crop growth rate and finally more yield produced with application of vermicompost or zeolite