Effects of spatial pattern and cultivar on weed control and grain yield in rice at reduced rates of herbicide / Efeitos do padrão espacial e cultivar on controle de plantas daninhas e rendimento de grãos do arroz com taxas reduzidas de herbicida

To evaluate the effects of herbicide rate, cultivar, and spatial pattern on rice grain yield and weed suppression, a field experiment was conducted on a lowland rice field at the Rice Research Station of Tonekabon, north of Iran, in 2011. The experimental design was a split plot-factorial where the whole plot portion was a randomized complete block with three replicates. Main plots were pretilachlor rates (0, 0.5, 1, 1.5, 2 L ha-1 of pretilachlor). The subplots were factorial combinations of two crop spatial patterns (uniform and wide-row planting patterns, 20× 20 and 30 × 13 cm, respectively) and two traditional rice cultivars ('Hashemi' and 'Deylamani'). Regardless of cultivar and spatial pattern, rice grain and biological yields, panicle number per m2, leaf area index, and herbicide efficacy increased, while weed biomass decreased with increasing pretilachlor application rate. Rice grain and biological yields, panicle number per m2, leaf area index, and herbicide efficacy were significantly greater in uniform planting pattern than in wide-row planting pattern when averaged over cultivars and pretilachlor rates. Moreover, uniform planting pattern of rice plants suppressed weeds 39% better than wide-row planting pattern as averaged across pretilchlor rates and cultivars. 'Deylamani' produced grater grain and biological yields, panicle number per m2, leaf area index than 'Hashemi' as averaged across pretilachlor rates and spatial patterns. This experiment illustrated that uniform spatial pattern increased weed suppression, herbicide efficacy, and grain yield.

Para avaliar os efeitos da taxa de herbicida, cultivar e padrão espacial em arroz produção de grãos e supressão de plantas daninhas , um experimento de campo foi realizado em um campo de arroz irrigado na Estação de Pesquisa do Arroz de Tonekabon , norte do Irã, em 2011. O delineamento experimental foi uma fração de lote - fatorial, onde toda a parte de enredo foi em blocos casualizados com três repetições. As parcelas foram as taxas pretilaclor (0, 0.5, 1, 1.5 , 2 L ha-1 de pretilaclor) . As subparcelas foram combinações fatoriais de dois padrões de culturas espaciais (uniformes e padrões de plantio em toda a linha, 20 × 20 e 30 × 13 cm , respectivamente) e duas cultivares de arroz tradicionais (' Hashemi ' e ' Deylamani ') . Independentemente de cultivar e padrão espacial , grãos de arroz e os rendimentos biológicos , número de panículas por m2 , o índice de área foliar e eficácia do herbicida aumentou, enquanto a biomassa de plantas daninhas diminuiu com o aumento da taxa de aplicação pretilaclor . O grão de arroz e os rendimentos biológicos , número de panículas por m2 , o índice de área foliar e eficácia do herbicida foram significativamente maiores no padrão de plantio uniforme do que em toda a linha de plantio padrão quando calculados sobre cultivares e taxas pretilaclor . Além disso, o plantio uniforme padrão de plantas de arroz suprimida ervas daninhas 39% melhor do que em toda a linha de plantio padrão como média entre as taxas de pretilchlor e cultivares . ' Deylamani "produzido grão ralador e os rendimentos biológicos , número de panículas por m2 , índice de área foliar do que" Hashemi ", como média entre as taxas de pretilaclor e padrões espaciais. Este experimento mostrou que padrão espacial uniforme aumento supressão de plantas daninhas , eficácia do herbicida , e rendimento de grãos.

Períodos de interferência de plantas daninhas na cultura do girassol / Periods of weed interference in sunflower culture

A interferência de plantas daninhas na cultura do girassol pode reduzir significativamente a produtividade de aquênios. O objetivo deste trabalho foi determinar o período anterior à interferência e o período total de prevenção à interferência da comunidade infestante sobre a produtividade de aquênios e rendimento de óleo da cultura do girassol. O experimento foi conduzido em campo, no município de Botucatu (SP), no ano agrícola de 2007/2008. O delineamento experimental foi o de blocos casualizados, com quatro repetições. Os tratamentos foram compostos por parcelas constituídas por períodos de controle e de presença de plantas daninhas. Para os períodos de controle, a cultura foi mantida livre das plantas daninhas pelos períodos crescentes de 7, 14, 21, 28, 35, 42, 49 e 110 dias após a emergência (DAE) do girassol. Para os períodos de convivência, a cultura foi mantida na presença da comunidade infestante pelos mesmos períodos. Foram avaliadas as seguintes variáveis: diâmetro de capítulos, produtividade de aquênios, rendimento de óleo de girassol, densidade e matéria seca das plantas daninhas. O período anterior à interferência foi de 35 DAE da cultura para a produtividade de aquênios, sendo que o período total de prevenção à interferência estendeu-se até 24 DAE. Para o rendimento de óleo, o período anterior à interferência foi de 25 DAE, enquanto que o período total de prevenção à interferência prolongou-se por 14 DAE.

The interference of weeds in sunflower cultivation can significantly reduce the productivity of achenes. The objective of this study was to determine the period before interference and total period of interference of the weed community on productivity and achene oil of sunflower cultivation. The experiment was conducted under field conditions in the fieldin Botucatu (SP) in the 2007/2008 agricultural year. The experimental design was a randomized complete block with four replications. The treatments were composed of portions represent periods of control and presence of weeds. For control periods, the culture was kept free of weeds by increasing periods of 7, 14, 21, 28, 35, 42, 49 and 110 days after the emergence (DAE) of sunflower. For periods of coexistence, the culture was maintained in the presence of the weed community for the same periods. We assessed the following variables: diameter of chapters, achene yield, oil yield of sunflower, density and dry matter of weeds and phytosociological indices. The period before the interference was 35 DAE culture to the productivity of achenes, and the total period of interference lasted until 24 DAE. For oil yield, the period before the interference was 25 DAE, whereas the total period of interference lasted for 14 DAE.

Effect of nursery nitrogen application of bare-root Larix olgensis seedlings on growth, nitrogen uptake and initial field performance.

Nursery nitrogen application has been used to improve seedling quality. The technique has received little attention with bare-root seedlings and their subsequent field performance on weed competition sites. Our research objective was to examine responses of one- and two- year-old bare-root Olga Bay larch (Larix olgensis Henry) seedlings to nursery nitrogen supplements and subsequent one-year field performance on a competitive site. The fertilizer levels (kg N ha-1) were 0 (control), 60 (conventional fertilization, 60 C), 120 (additional nitrogen applied two times, 120 L), 180 (additional nitrogen applied three times, 180 L) and N were applied in increments of 30 kg ha-1 at 15-day interval to maintain a base nutrient level. Although pre-planting morphological attributes and nitrogen status of one-year-old (1a) seedlings were more sensitive to 60 C than for two-year-old (2a) seedlings, the conventional application failed to enhance their field survival(15.6% vs 17.8%), relative height growth (89.0% vs 79.6%), and relative diameter growth (17.0% vs 22.9%). The 1a seedlings‘ field survival (15.6% for 0, 17.8% for 60 C) and 2a seedlings‘ relative height growth rate (11.0% for 0, 8.9% for 60 C) were not increased significantly until they were provided the 120 L (survival of 23.3% for 1a, relative height growth rate of 15.0% for 2a). According to pre-planting attributes and field performance, optimum nursery nitrogen application was 120 L for the 2a seedlings and 180 L for 1a seedlings. Except for component nitrogen concentration, pre-planting morphological attributes and component N content for the 2a seedlings were as much 3.3 to 37.7 times that of 1a seedlings. In conclusion, the contrasting survival of poor (15.6%-28.9%) for 1a seedlings and high (84.4%-91.1%) for 2a seedlings indicated that additional nitrogen fertilizer would not equal the benefits of an another year‘s growth in the nursery. Successful reforestation could not be fulfilled by 1a seedlings regardless of their pre-nutrients. An alternative technique for sites with competing vegetation was to apply 120kg N ha-1 in the nursery during July and August on 2a seedlings.