ABSTRACT
Effect of rapeseed and tall oatgrass on yield of dry peas and the estimation of economic thresholds of control

Jorge Díaz S.1, Nelson Espinoza N.1 y María Graciela Márquez B.1
 

Seed yield losses in dry peas (Pisum sativum L.) cv. Progreta caused by the effect of different plant densities of rapeseed (Brassica napus L.) as volunteer plant (weed) and tall oatgrass (Arrhenatherum elatius (L.) J. et K. Presl: ssp. bulbosus (Willd.) SchOb. et Martens) were estimated. The relationships between seed yield losses and weed density were fitted to a rectangular hyperbola. A seed yield reduction of 2.3% was observed when peas were subjected to rapeseed competition of one plant per m2. Likewise, yield reductions ranging from 8.5 to 33.8% and from 17.7 to 47.7% were observed with 1 to 8 plants oftall oatgrass per m2, during 1991/92 and 1992/93, respectively. These levels of yield losses indicate an economic threshold control at densities of 2 plants per m2 of rapeseed and between 0.2 and 0.4 plants per m2 of tall oatgrass.

Keywords: peas, weed, rapeseed, tall oatgrass, economic threshold.
1 Estación Experimental Carillanca (INlA) , Casilla 58·D, Temuco, Chile.