Root Mass and Yield Variation in the Spring Bread Wheat Cultivar Pavon 76 and Its Wheat-Rye Translocations 1RS.1AL, 1RS.1BL &1RS.1DL in Organic and Synthetic Nitrogen Fertilizer Systems.

Breeding efforts to improve the wheat (Triticum aestivum.L.) root system have involved wheat-rye (Secale cereale.L.) translocations that use the short arm of the rye chromosome 1R (1RS). Rye chromosome 1(1RS) translocations derived from “Kavkaz” winter wheat, in ”Pavon76” spring wheat back ground have been reported to improve agronomic characteristics  and confer disease resistance qualities. We evaluated root growth and yield performance of the spring bread wheat cultivar Pavon 76 and its 1RS translocations 1RS.1AL, 1RS.1BL &1RS.1DL under organic (compost) and synthetic(urea) nitrogen (N ) fertilizer systems in field and pot experiments in 2010 and 2011. Organic and synthetic fertilizers systems were each compared at high and low rates. The 1RS translocations significantly increased root mass per unit volume of soil, with overall means of 420.46g/m³ and 404.15g/m³ for 1RS.1AL and 1RS.1BL respectively compared to  331.88g/m³ from the parent line Pavon 76. Although not significant, higher root mass on average was recorded from the organic compared to the synthetic fertilizer system. Within the organic N system, higher root mass was obtained from the higher organic N rate, while the reverse was true for the synthetic N system, with the lower rate producing more root mass. The mean grain yields were 5.55, 5.45 and 5.42t/ha for 1RS.1DL, 1RS.1BL and 1RS.1AL respectively compared to 5.11 t/ha, for Pavon76. Within fertilizers, highest yields were obtained under the lower synthetic N rate. These results indicate that the rye translocations 1RS.1BL and 1RS.1DL produce high root mass and grain in both organic and synthetic fertilizer systems; thus could be exploited by crop improvement programs targeting the root system to increase nutrient resource utilization.