Variations in phosphorus concentration, accumulation and partitioning in some of crop and weed species of Poaceae family

Phosphorus (P) after nitrogen is the most important nutrient limiting the yield of crops especially in acidic and alkaline soils. Extensive studies indicate considerable genetic variation in the efficiency of uptake and utilization of phosphorus which is related to concentration, accumulation and allocation of phosphorus to different parts of the plant. The use of this diversity in order to increase the growth and yield of crops, as well as to reduce the need for phosphorus fertilizers, especially in low-phosphorous soils, has attracted the attention of researchers in recent years. In addition, accurate information on this issue can be used in the efficient management of mineral nutrition of crops. Therefore, the present study was conducted to investigate the variations in concentration, accumulation and allocation of P to different parts of the plant in some important crops and weeds species of the Poaceae family. This experiment was conducted in a completely randomized design with a factorial arrangement with three replications in Gorgan University of Agricultural Sciences using a low (4.85 mg / kg) available P soil during 2016-17 growing season. In this pot study, 6 crop and weed species of Poaceae family including durum wheat, common barley, naked barley, triticale, wild oat and canary grass were studied under two conditions of non-consumption and use of fertilizer as amount as recommended. In the physiological maturity, P concentration in different parts of plants separately, and P accumulation and allocation coefficients were calculated using P concentration and dry weight of the organs. The results of analysis of variance showed that the effect of genotype, fertilization and their interactions on the amount of accumulated P in all parts of the plant and total plant were significant. The average of P content of the whole plant in the studied species indicates an increase of 4.2 times the amount of P absorbed by fertilizer application. In fertilization conditions, the lowest P content in plant parts and total plant was observed in two weed species, while under non- fertilization conditions, there was no significant difference between species in the plant parts. Alterations in P content in the studied species were due to changes in its determinant components, i.e. the amount of dry matter and P concentration. Although, both the amount of dry matter and P concentration in all parts of the plant significantly (P = 0.01) were influenced by the factors of the experiment, and in most of the cases, their interactions, the amount of alterations in the dry matter and as a result , its contribution to changes in the P content was more than the P concentration. The average of P content allocated to grain in all species was 54.3%, in the crop species was 64.1 and in the two weed species was 34.7, which shows a much higher allocation of P to the grains in the crop species. This study showed that the accumulation of P, followed by P concentration and P allocation coefficients to different parts of the plant in physiological maturity stage were influenced by fertilization and genotype and the interactions of these two factors. Further alterations in P accumulation can be attributed to its dependence on variations in dry matter and P concentrations. The obtained results showed a small variation of the studied species in terms of P accumulation in low available P conditions compared to the conditions of fertilizer application as amount as recommended which is a sign of the similarity of these species in terms of tolerance to P deficiency as well as different response of species to P fertilizer application.