Interference and economic damage level of turnips in rye

Abstract

Turnip (Raphanus sativus) is one of the weeds that have caused the most quantitative and qualitative losses by infesting winter crops, including rye. Therefore, the objective of this work was to test mathematical models and identify explanatory variables to determine the economic damage level (EDL) of the weed turnip in rye genotypes. Treatments consisted of rye genotypes (BRS Serrano, IPR 89, BRS Progresso, and Crioulo) and turnip densities ranging from 0 to 648 plants m -2 in competition with the crop. Plant density, leaf area, soil cover, and shoot dry matter of the turnip were evaluated 30 days after species emergence. For rye, grain yield, control cost, bag price, and control efficiency were determined. The rectangular hyperbola model was efficient for estimating rye yield loss due to turnip interference. Plant density best fitted the rectangular hyperbola model. BRS Serrano, BRS Progresso, and Crioulo genotypes showed greater competitiveness and higher EDL values (from 2.03 to 4.36 plants m -2 ) in the presence of turnip. The lowest EDL values ranged from 1.31 to 2.19 plants m -2 , for the genotype IPR 89, which showed the lowest competitive ability. EDL values decreased with increasing grain yield, price of a bag of rye, herbicide efficiency, and with decreasing turnip control costs, justifying the use of control measures at lower weed densities. Highlighted Conclusions1. The plant density of ryegrass showed better fit to the rectangular hyperbola. 2. The ryegrass genotypes BRS Serrano, BRS Progresso and Crioulo showed greater competitive ability in the presence of turnips. 3. The rye genotype IPR 89 had the lowest EDL values and the least competitive ability in the presence of turnip.