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Weeds in Br11 Rice as Affected by Spacing and Nitrogen

Nur A. Khondaker
RARS, Hathazari, Chittagong

M. A. Gaffar
Department of Agronomy, BAU, Mymensing

A.M. Shamsuddin
Department of Agronomy, BAU, Mymensing

M. H. Mondal
BARI, Joydebpur, Gazipur.

Abstract/ Executive Summary:

Phytosociolgical observation on weeds was made before 1st and 2nd weeding done at 25 and 45 days of transplanting (DT) respectively in BR11 rice grown with five nitrogen levels (0,40,60,80 and I00 kg N/ha) and three spacings (20 X 10 cm, 25x15 cm and 30x20 cm) in a split-plot design during the kharif season of 1986. Nine species of weeds representing six families were found to grow and infest the experimental plots of which five species viz., Scirpus mucronatus, Paspalum distichum, Cyperus iria, Jussiaea decurrens and Fimbristylis milliaceae constituted the bulk (95.90% at 1st weeding and 93. 32% at 2nd weeding) of the weed population. On an average 7. 69 and 4.53 weeds competed with one rice hill at 1st and 2nd weeding, respectively. The nitrogen failed but the spacings showed significant effect on the weed densities, intensity of infestation and dry weight of weeds.

Keywords: Weeds, BR11, Spacing, Nitrogen, Phytosociolgical observation

Location: Bangladesh Agricultural University, Mymensingh

Start Date:

End Date:

Program Area: Pest Management

Commodity: Rice

Objectives:

To observe weeds in BR11 rice at maximum tillering and panicle initiation stages as influenced by spacing and nitrogen levels.

Methodology:

The study was carried out in a medium high land (pH 6.5 and organic matter content 1%) at the Bangladesh Agricultural University, Mymensingh. The experiment was conducted in a split-plot design with nitrogen levels, (0,40,60,80 and 100 kg/ha), in the mainplot and the spacings, (20 x 10 cm, 25 x 15 cm and 30 x 20 cm) in the sub-plots replicated four times. In addition, 60 kg P₂0₅/ha and 40 kg k₂0/ha were applied in the main plots through triple superphosphate and muriate of potash respectively. Transplant aman variety BRII was selected for the experiment. The plots were hand weeded twice, at 25 and 45 days of transplanting. Before each weeding, phytosociological observation on weeds was made. The weeds in each plots were counted species wise together with the number of crop plants from three spots of 1m² area. The intensity of weed infestation and the relative density were calculated following the formula of Mian and Rahman (1968 ); and Shetty and Rao (1979). To assess the weed biomass three weed samples per plot were collected at each weeding and sundried followed by drying in an electric oven at 105⁰C for 24 hours and the weight of each sample was recorded. The data were statistically analysed and the means were separated by LSD.

Source of Information: Bangladesh Agron. J. 1987, 2( I): 46- 52

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Nine species of weeds representing six families were found to grow and infest the experimental plots of which five species viz., Scirpus mucronatus, Pas palum distichum, Cyperus iria, Jussiaea decurrens and Fimbristylis milliaceae constituted the bulk (95.90% at 1st weeding and 93. 32% at 2nd weeding) of the weed population. On an average 7. 69 and 4.53 weeds competed with one rice hill at 1st and 2nd weeding, respectively. The nitrogen failed but the spacings showed significant effect on the weed densities, intensity of infestation and dry weight of weeds.

Knowledge Management: Journal