Variation in efficiency of nitrogen, phosphorus and potassium in some crop and weeds of Gramineae family

In the recent years, the study of genotypic variation in terms of efficiency of mineral nutrient has attracted the attention of researchers worldwide. Hence, to investigate the variation in the nitrogen (N), phosphorus (P) and potassium (K) use efficiency in 6 important crop and weed species (durum wheat, common barley, naked barley, triticale, wild oat and canary grass), a pot experiment was conducted as a factorial arrangement in a completely randomized design with three replications in Gorgan University of Agricultural Sciences during 2016-17 growing season. This experiment was carried out under unfertilized and fertilized at optimum rate conditions. Concentrations of elements and dry matter were measured in stem elongation, anthesis and physiological maturity. The results of variance analysis showed a significant effect of experimental factors on efficiency (dry matter to nutrient content ratio), nutrient efficiency ratio (dry matter in control to fertilized treatment ratio) and nutrient harvest index (nutrient content in grain to total dry matter ratio). There was no significant interaction between experimental factors for the traits studied in three stages. The results also showed a significant decrease in traits as a result of fertilizer application. According to the results, evaluation of nutrients efficiency in early stages of growth is not sufficient for comparison or screening of genotypes and should be done in more advanced stages, especially maturity. Also, considering the substantial variation among studied genotypes in terms of nutrient efficiency, more detailed studies on genotypic variation seems to be useful for identifying traits related to mineral nutrient efficiency.