Journal of Research in Weed Science

Abstract A two-year (2017 and 2018) field trials was conducted in the School of Agriculture, Njala University, Sierra Leone, to evaluate weed management practices on weed dynamics and productivity of maize. The experimental trials were laid out in a randomized complete block design (RCBD) with three replications. The treatment combinations comprised of weedy check (Control), two hoe weeding at 4 and 8 weeks after planting (WAP), Double force^® at 4 L ha^-1 plus one hoe weeding at 8 WAP, Gliricidia sepium leaves mulch at 40 kg m^-2 plus one hoe weeding at 8 WAP, weed-free check and Atrazine 500 SC at 3 L ha^-1 plus one hoe weeding at 8 WAP. The results showed that growth and yield physiognomies differ significantly (P<0.05) among weed control practices across both years. The weed-free check treatment recorded the highest growth and yield physiognomies with respect to reduced weed density and increased weed control efficiency followed by herbicidal treatments, while weedy check had the lowest growth and yield attributes across both years. Nonetheless weed-free check required lot of labour force which was not economical to the farmer’s point of judgment. Thus, Double force^® at 4 L ha^-1 plus one hoe weeding at 8 WAP proved to be better in controlling weeds, increasing crop yield and economical compared with other weed management practices. Hence Double force^® at 4 L ha^-1 plus one hoe weeding at 8 WAP was recommended as a pre-emergence herbicide in maize production for effective and environmentally friendly weed control method.

Abstract Growing two or more cultivars of same crop species in mixture reduces intra-specific competition for natural resources and increases competitive ability of crops against weed growth and thus enhances crop yield. The objective of this study was to evaluate the potentiality of growing rice cultivars in mixtures in temporal dimension for minimizing weed pressure and increasing rice yield and to determine the best time of introduction of one cultivar in relation to another cultivar. The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during aman season (July-December) 2017. Two transplanted aman rice cultivars having different plant height and growth duration viz. Binadhan-13 (tall, late- maturing and fine grained aromatic rice cultivar) and BRRI dhan49 (semi-dwarf, mid-maturing and coarse grained rice cultivar) were used in this study. The experiment comprised time of introduction of BRRI dhan49 namely 7 days before Binadhan-13, 7 days after Binadhan-13, same day as Binadhan-13, Binadhan-13 as sole crop, BRRI dhan49 as sole crop and three different weeding regime namely weedy, recommended weeding and weed free. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Both the cultivars showed better growth and higher yield when grown in mixture rather than sole culture. Transplanting of one cultivar before or after another cultivar produced more yield and suppressed weed better than transplanting of two cultivars on the same day. Thus only spatial arrangement produced no advantages over sole culture. Among the weeding regimes, weedy treatment performed the worst, while recommended weeding and weed free treatment performed similarly. Therefore, for better weed suppression and higher production, BRRI dhan49 may be transplanted 7 days before or after Binadhan-13 in 1:1 ratio following recommended weeding.

Abstract To evaluate most economical and efficient weed management practices in dry direct seeded rice, a field experiment was conducted at research block of AFU Rampur, Chitwan during the Kharif 2016 season. The treatments consisted of two establishment practices viz., zero till and conventional tillage and eight weed management practices such as weedy check, weed free, Pendimethalin followed by hand weeding at 20 DAS 1 kg a.i ha^-1, Pendimethalin followed by 2, 4-D ethyl ester at  25 DAS 1 kg a.i ha^-1, pendimethalin followed by bispyribac-Na at 25 DAS at 25 g a.i ha^-1, pendimethalin followed by ethoxysulfuron at 25 DAS 25 g a.i ha-¹, pendimethalin followed by penoxsulam at 25 DAS 25 g a.i ha^-1, pendimethalin followed by (ethoxysulfuron + bispyribac-Na. The experiment was conducted in split plot design with three replications. The result of experiment showed that non-significant difference was notice among the establishment method. However, significant difference was observed in weed management practices in all the traits expect number of weeds m^-2, number of weed species m^-2, and dry weight of broad leaf, narrow leaf and sedges weeds. The higher number of weeds m^-2 was found in weedy check plot which resulted in higher weed infestation at all the stages as compared to other weed management practices. Application of pendimethalin followed by hand weeding at 20 DAS recorded higher weed control efficiency which reflected in higher yield of 4202 kg ha^-1 was recorded under this treatment as compared to weedy check plot (1292.13 kg ha^-1) but rest of the treatments are statistically at par with other weed management practices.

Abstract The experiment was carried out at Umulolo in Okigwe Imo State in 2016 and 2017 seasons. The experiment was laid in randomized complete block design, replicated three times. The treatments were mulching materials (two synthetic materials-polythene sheet, trampoline sheet) while natural or organic materials were 6/ha sawdust and grasses and control treatment (no mulching). Result showed significant difference in all the weed infestation parameters, vegetative growth and yield parameters assessed. In both cropping seasons, the control had significant higher weed density and biomass. Garden egg fruit yield as influenced by different mulching materials was also significantly different (p<0.05) in both cropping seasons. The highest fruit yield; 22.27 and 23.63 t/ha in 2016 and 2017, respectively was from the plot mulched with sawdust. The grasses mulched plot had 21.19 and 22.17 t/ha fruit yield, respectively. The trampoline plot produced 18.77 and 17.18 t/ha fruit, respectively. The least fruit yield was 5.43 and 6.54 t/ha in both cropping seasons in control treatment. The result showed that the plot mulched with sawdust had 7-76% and 6-72% greater fruit yield compared to the other mulching materials in both cropping seasons. The result of indicated that application of grasses and sawdust were more cost effective in weed management and higher economic returns to management compared to trampoline and polythene sheets. Farmers in the study area were advised to mulch their garden egg field during off-season with sawdust. The application of sawdust would reduce weed infestation and also enhances high fruit yield.

Abstract Sustainable agriculture requires the use of environmentally friendly management practices. Mulching is one of the most effective methods that can play a positive role in weed management, improving soil properties as well as increasing crop production. A field experiment was conducted at the research farm of National Maize Research Program (NMRP), Rampur, Chitwan, Nepal during winter season, 2016. The experiment was carried out in single factor randomized completely block design comprising of nine weed management methods with four replications. Data regarding the weed population, weed dry weight, yield attributes and yield were recorded during the study. Different weed management practices showed significant differences on weed dynamics and weed control efficiencies. Black polythene mulch and silver black mulch was found more effective to reduce total weed density and dry weight during whole crop season and remain comparable with other polythene mulch too. The effect of weed management practices observed on weed density and dry weight were reflected on grain yield. The highest grain yield was recorded in silver black plastic mulch (4537.50 kg ha^-1) followed by black plastic mulch (4068.20 kg ha^-1), clear plastic mulch (4065.22 kg ha^-1), green plastic mulch (3834.84 kg ha^-1) and weed free (3222.74 kg ha^-1) which were comparable to each other. At tasseling-silking stage among plastic mulch treatment, the higher moisture conservation observed on the black plastic mulch followed by clear plastic mulch, green plastic mulch and silver black plastic mulch. While comparing of plastic mulch with dead mulch, moisture on dead mulch remain higher than plastic mulch after 90 DAS. Thus, in humid subtropical region of western Chitwan, Rampur, the maize can be successfully cultivated by using different color of polythene mulch.