Wild Oat (<i>Avena fatua</i>) Competition with Wheat (<i>Triticum aestivum</i>and<i>T. turgidum durum</i>) for Nitrate

Abstract

Lath-house experiments were conducted to compare the effect of wild oat ( Avena fatua L.) competition on two wheat ( Triticum aestivum L. ‘Anza’ and T. turgidum durum group ‘Mexicali′) genotypes at three nitrate concentrations. Plants were grown to maturity in pots containing 10 wheat or wild oat plants, or mixtures of 10 wheat and 10, 25, or 50 wild oat plants. Nitrate was supplied in 500 ml Hoagland's solution with 1.5, 7.5, or 15.0 mM nitrate, as K and Ca nitrate, every 4 days. When grown without competition, Anza had more above-ground plant weight and grain yield and less whole-plant percent nitrogen than Mexicali. Wild oat competition caused larger reductions in plant weight and grain yield, and smaller reductions in percent nitrogen for Anza than for Mexicali. Wild oat competition reduced the effectiveness of nitrate in increasing plant weight, grain yield, and whole-plant percent nitrogen of wheat.