The effect of different amounts of nitrogen and water deficits tension on yield, yield components and some physiological indicators in spring barley

The effect of nitrogen consumption on yield, yield components and contributor metabolites of spring barley under water deficits conditions as a factorial experiment was conducted based on completely randomized design with three replications in greenhouse conditions in 2012. Experiment factors including water deficit tension in three levels 35%, 60% and 85% field capacity and nitrogen consumption at three levels 40, 80 and 120 kilogram per hectare nitrogen fertilizer (urea source 46 percentage). In this research length and stem weight, specific weight of stem, harvest index, 100- grain weight, grain yield, soluble sugar and the amount of proline were measured. The results showed when the plant is exposed to water deficit tension, the length and stem weight, specific weight of stem, harvest index, 100-grain weight, grain yield decrease significantly and proline amount and soluble sugar increase significantly. Among the fertilizer treatments the highest grain yield and yield components was obtained by consuming of 120 kilogram nitrogen per hectare. Nitrogen with ameliorate the tension effect caused significant increasing the amount of traits related to yield and significant reduction of metabolites of compatibility. The correlation results showed 100- grain weight had the highest positive and significant correlation (r = 0.944, α =%1) with grain yield. In other words, decrease of dry matter production under water deficit tension, will affect plant reproductive development. Also, the proline showed the lowest correlation with grain yield (α=%5, r= -0.875). It seems that the more carbon allocation in the structure of metabolites of compatibility, such as proline can cause growth reduction. So the more synthesis of proline due to water deficit tension may be one of the reduction factors in yield.