GRAIN PROTEIN AND GRAIN-YIELD OF TRITORDEUM IN COMPARISON TO WHEAT AND TRITICALE

The new species of cereal x Tritordeum Ascherson et Graebner (Hordeum chilense Roem. et Shultz x Triticum ssp.) has a grain protein concentr ation (GPC) of up to 25%. The relationship between GPC and yield, and the factors responsible for the high GPC of tritordeum were examined a nd compared in field experiments. Three experimental tritordeum lines, two early and a later released (recombined and secondary tritordeums) were compared to wheat (cv. Cajeme) and triticale cultivars (cv. Truj illo). GPC's were 19%-22% for recombined tritordeums, 16% for the seco ndary tritordeum, 12-15% for wheats and 11% for triticale. Grain yield s of the recombined and secondary tridordeum were 17-33% and 45-57% th at of the wheats and triticale, respectively. Reducing grain sink size by spikelet removal resulted in an increased GPC of remaining grains. Considering all species together there were a strong inverse relation ship between GPC and grain yield (GY) per main ear (GPC = 26 - 4.76 In GY; r2= 0.82). In another experiment, frost damage to an early sown t reatment of wheat reduced sink size. Harvest index (HI) of early sown wheat was reduced from 0.45 to 0.19, values comparable to that of trit ordeum. Having similar HI, the GPC of the early sown wheat was the sam e as an early sown tritordeum (around 18%). Data for total N uptake an d the N concentration of plant tissue during the growing season indica ted that enhanced N uptake and remobilisation were not responsible for tritordeum's high GPC. These results suggest that the high GPC of the early lines of tritordeum is a consequence of the small grain yield c oncentrating the grain protein.