A field experiment was carried out to study the effect of sowing dates on phenology and accumulated heat units of rapeseed (Brassica campestris L.). Seeds of three varieties (BARI Sarisha-14, BINA Sarisha-5 and BINA Sarisha-6) were sown on four different dates from October to December (S 1 -18 October, S 2 -2 November, S 3 -17 November and S 4 -3 December). The results indicated that the number of days required to attain different phenological stages decreased with delay in sowing. For all the phenological stages, S 1 required higher heat units than that of other sowings. The plants of S 1 used heat more efficiently than S 2 , S 3 and S 4 . At the earlier phenological stages, phenothermal index decreased with delay in sowing, but increased at the later stages.
Context: To analyze the effect of sowing dates and weeding treatments on growth attributes such as total dry matter (TDM), leaf area index (LAI), net assimilation rate (NAR), crop growth rate (CGR), leaf area ratio (LAR) of three rapeseed (Brassica campestris L.). Objectives: The objective of the study was to identify the growth in relation to sowing dates and weed competition and identify the weeding number for better growth of rapeseed. Materials and Methods: This investigation was arranged as factorial experiment based on the split-split plot design with three replications. Four sowing dates were including 18 October (S1), 12 November (S2), 17 November (S3) and 3 December (S4) and three weeding treatments were no weeding (WO), one hand weeding (W1) and two hand weeding (W2) and three varieties viz., BINA Sarisha-5, BINA Sarisha-6 and BARI Sarisha-14 were investigated.
Results:The results showed that, TDM, LAI, CGR, NAR and LAR were affected by sowing date and weeding treatments. The highest TDM, LAI and CGR were obtained in the first sowing and two weedings treatment. The highest NAR was found in S2 plants and W0 treatment. The highest LAR was found in S2 plants and W1 treatment.
Conclusion:The results obtained in this study suggest that the first sowing and two weeding treatments are superior for the production of rapeseed.
A survey was conducted to highlight the weed flora infesting rapeseed in the experimental field of Rajshahi University. Frequency (F), density (D), abundance (A), relative frequency (RF), relative density (RD), relative abundance (RA) and importance value index (IVI %) of weeds were calculated in rapeseed field. The objective of the study was to study the weeds and their quantitative characters. Weed infestation was studied in three rapeseed varieties (BARI Sharisha 14, BINA Sharisha 5 and 6). The weed population was studied using quadrat. The species which had 100% frequency values were Cyperus rotundus, Cynodon dactylon, Ammania baccifera, Echinochloa crusgalli and Leucas lavendulifolia. Other species had 50% or less than 50% frequency values. The highest frequency, density, abundance and importance value index were exhibited by Cyperus rotundus.
J. bio-sci. 26: 01-06, 2018
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