Genotypic variation in P efficiency of selected Iranian cereals in greenhouse experiment

A factorial completely randomized block design experiment with three replications was carried out in greenhouse to evaluate cereal genotypic variation in phosphorus (P) acquisition and utilization efficiency in a calcareous soil with low available P (4.6 mg P kg-1 soil) and high total P (1260 mg P kg-1 soil). Treatments consisted of eight bread wheat (Triticum aestivum L.), three durum wheat (Triticum durum L.), three barley (Hordeum vulgare L.), one rye (Secale cereale L.), one oat (Avena sativa L.) and one triticale (X Triticosecale L.) genotypes at two levels of P fertilizer (0 and 84 mg P kg-1 soil).  Genotypes showed significant differences in chlorophyll meter reading, number of tillers, shoot P concentration and content (the total amount of P per shoot in pot), and shoot dry weight (SDW). Phosphorus efficiency (relative shoot dry weight) significantly differed among genotypes and ranged from 0.42 for barley (genotype M-80-16) to 0.97 for bread wheat Azadi. Shoot P concentration increased significantly from 1.9 to 4.7 mg g-1 DW and shoot P content from 13.2 to 46.1 mg P pot-1 by applying P. With no P supply (P0), durum wheat Yavarus with 20.1 mg P pot-1 and barley line M-80-16 with 5.8 mg P pot-1 had the highest and lowest P content, respectively. Bread wheat Azadi (0.45) and durum wheat Yavarus (0.43) had the highest relative P content; therefore, they were efficient in P acquisition. Oat produced the highest dry weight per unit of P taken up and hence was efficient in P utilization. There was no correlation between P efficiency and shoot P concentration of genotypes (r= 0.12), but the relationship between P efficiency and shoot P content (total amount of shoot P per pot) was highly significant (r= 0.66**), suggesting that shoot P content is a reliable parameter in screening cereal genotypes during vegetative growth.