N, P and K Uptake in Bread Wheat 'Pavon 76' and Its 1RS Translocation Lines.

Increased grain yield observed in short-arm of rye chromosome one (1RS) translocation lines in bread wheat may be due to their larger root system and consequently greater uptake of water and nutrients. We investigated uptake of N, P and K in green-revolution spring bread wheat (Triticum aestivum L.) Pavon 76 and its 3 translocation lines: Pavon 1RS.1AL, Pavon 1RS.1BL, and Pavon 1RS.1DL. The 1RS arm came from Petkus rye (Secale cereale L.) via winter wheat ‘Kavkaz’. These four near-isogenic lines were grown at optimum and low levels of nutrients in 80 cm sand-tube experiments in an unheated, cooled glasshouse over two years. Plants received the same amount of irrigation solution. First- and second-degree interactions involving genotype were relatively small. Thus, genotypic performance averaged across years and nutrient levels are reported. Plant height was taller in Pavon 76, but mean number of spikes, shallow and deep root weight, and grain yield per plant was greater in the translocation lines. Mean root biomass in translocations was greater than Pavon 76 by 35% (3.4 vs. 4.6 g/plant). N content and P content in the plant and grains was greater in translocation lines by 11%. K content in genotypes behaved similarly, but in grains it was greater in translocations by 15%. The amount of N in the leachate during tillering and early grain filling was greater for Pavon 76 than for translocation lines; 673 vs. 577 mg and 407 vs. 311 mg, respectively. These results indicate the larger root system of Pavon 1RS translocation lines may increase nutrient uptake and consequently increase grain yield and grain protein content in wheat while reducing residual N in the drain water. Increasing root size of CIMMYT wheat 2 to 3 times (certainly possible) might increase fertilizer uptake by 33% to 66%.