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Print version ISSN 0100-8358
PAULA, J.M et al. Competition of wheat with ryegrass as a function of application times and nitrogen doses. Planta daninha [online]. 2011, vol.29, n.3, pp. 557-563. ISSN 0100-8358. http://dx.doi.org/10.1590/S0100-83582011000300009.
Wheat productivity potential is limited by competition with weeds, especially considering light, water, and nutrient resources. The objective of this work was to evaluate morphological variables and productivity components in wheat in competition with ryegrass, considering application times and N doses. The first factor evaluated was the competition condition (absence and presence of ryegrass); the second factor was N application times (100% applied at the beginning of tillering; 50% applied at the beginning of tillering and 50% at the beginning of spike differentiation [BSD]; and 100% at BSD); and the third factor was N doses (0, 40, 80, 120 and 160 kg ha-1). The variables evaluated were: leaf area (LA), aerial part dry mass (APDM), number of tillers ( NT), number or stems (NS), N content in the culture(CN), number of grain per spikelet (NGPS), spike grain number (SGN), number of grains per spike (NGS), biological productivity (BP), average weight of 1000 grains (AWG) and grain productivity (P). The results showed that ryegrass competes with wheat for nitrogen reducing FA, APDM, NT, NT, NS, NGPS, CEGN, BP, AWG and P of the culture. N application at the beginning of tillering or fractionated, at the two highest doses, increases FA and MSPA. N dose increase accelerates CN in wheat culture, independent of the presence or absence of the competitor. N application in BSD or increased N dose increase NSPS and SGN.
Keywords : Triticum aestivum; Lolium multiforum; weeds; interference.