Influence of nitrogen on competition between winter cereals and sterile oat

Abstract

Field experiments were carried out in northern Greece during 1994, 1995, and 1996 to study the effect of nitrogen fertilization on competition between sterile oat and wheat, barley, and triticale. Dry weight of all crops was not affected until early March by sterile oats (110 plants m−2), but wheat and triticale dry weight were significantly reduced by sterile oats competition after that time. Grain yield of both wheat and triticale was equally reduced by 61% due to the presence of sterile oats, whereas the reduction for barley grain yield was 9%. Nitrogen fertilization (150 kg N ha−1) slightly increased yield of all crops grown without weed competition compared to the control (0 kg N), whereas the same treatment increased sterile oats dry weight as well as its competitive ability against wheat and triticale. Split application of nitrogen (50 kg N ha−1 before planting and 100 kg N ha−1 in early March) caused a slightly higher increase in sterile oats dry weight compared to the control or one application (150 kg N ha−1) before planting, when grown with wheat and triticale. However, dry weight of sterile oats grown with barley was severely reduced by the interference of the crop. Total nitrogen content of all crop plants grown without sterile oats increased with nitrogen fertilization compared to the control. However, total nitrogen in crop plants grown with sterile oats was reduced compared to the weed-free control; percent reduction was greater in plants grown in plots treated with nitrogen than in the control. These results indicate that barley could be used for limiting sterile oats interference in areas where winter cereals are grown; time of nitrogen application could also be used for a slight reduction of sterile oats competitive ability against wheat or triticale.

Competição de trigo com azevém em função de épocas de aplicação e doses de nitrogênio

“…Resultados na literatura indicam redução na produtividade dos grãos de cereais em competição com plantas daninhas. Para Dhima & Eleftherohorinos (2001), a produtividade dos grãos de trigo, triticale e cevada foi reduzida, na ordem de 61, 62 e 9%, respectivamente, quando em competição com Avena sterilis. O grau de interferência das plantas daninhas em culturas de cereais não depende tão somente da interação de competição com as plantas daninhas, mas também do uso de cultivares com maior ou menor habilidade competitiva e das condições edafoclimáticas da região (Mennan & Zandstra, 2005).…”

“…A adição de 150 kg N ha -1 favorece o aumento na massa seca de trigo, cevada e triticale, quando não competem com plantas daninhas; no entanto, em competição com Avena sterilis, a massa seca dessas culturas apresentou-se menor quando receberam N do que quando não o receberam (Dhima & Eleftherohorinos, 2001).…”

Influência de cultivares de arroz e épocas da adubação nitrogenada nas relações de interferência da cultura com cultivar simulador de infestação de arroz-vermelho

“…Por sua vez, Eberhardt (1998) constatou que a incorporação do N junto às linhas de semeadura aumentou a habilidade competitiva dos cultivares de arroz avaliados, em relação ao arroz-vermelho. Na literatura, diversos trabalhos de pesquisa mencionaram que a época de aplicação do N afeta as relações de competição entre cultura e plantas daninhas (Watkins, 1971;Carlson & Hill, 1986;Dhima & Eleftherohorinos, 2001). Nesse sentido, Watkins (1971) constatou que a aplicação tardia do N produziu maior número de panículas em aveia-silvestre (Avena fatua), a qual concorreu mais intensamente com trigo e cevada, comparada à aplicação precoce.…”

Effect of N fertilizer on the emergence and seedling growth of Eleusine indica in aerobic rice systems

“…Fertilizer application at correct timings and doses are crucial to improve the competitive ability of crop plants against weeds . Addition of fertilizer may reduces crop yield, if it increases weed growth because some weeds capable to capture nutrients more faster than the crops (Kristensen et al, 2008) and in some cases crop can be more efficient and quick in taking up fertilizers than weeds (Dhima and Eleftherohorinos, 2001). Weeds are capable of absorbing nutrients faster and in relatively bigger amounts than crop plants (Blackshaw, 2005), and in the presence of a high weed population density, fertilizer application may stimulate weed growth greatly over the crop growth (Mahajan et al, 2009).…”