The effect of increased soil nitrogen associated with medic ley on the performance of a standard and a semi-dwarf wheat cultivar

Abstract

Two cropping rotations of fallow-wheat and four years of barrel medic (Medicago truncatula) pasture were used to obtain two levels of soil total nitrogen on a grey clay at Longerenong College, Dooen, Victoria. A semi-dwarf cultivar, Mexico 120, and a standard cultivar, Olympic, were then compared at the two levels of soil nitrogen over four years from 1964 to 1967. Mexico 120 outyielded Olympic by 1490 kg ha-1 in 1964 at the higher soil nitrogen level; however, it did not yield any better than Olympic at low soil nitrogen in that year nor at either soil nitrogen level in the other years. Mexico 120 had higher tiller survival, larger grain size, and shorter straw than Olympic in all years. In 1965 and 1966 its harvest index and the percentage of plant nitrogen in the grain responded more to higher soil nitrogen than that of Olympic.