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Develoment of weed competitive crop cultivars is an attractive low-cost strategy of integrated weed management program that can reduce the heavy dependence of crop cultivation to chemical herbicides. Hence, to evaluate the weed competitiveness Bangladesh Rice Research Institute (BRRI) released selected monsoon rice varieties, a field experiment was conducted during July to December 2018 at the Agronomy Field Laboratory of Bangladesh Agricultural University. Thirty-three rice varieties were grown under season long weedy and weed-free conditions. Plots without rice plants were also maintained to investigate the natural growth of weed in absence of rice. The experiment was conducted following randomized complete block design with three replicates. The results showed that rice varieties varied widely in yielding ability and weed competitiveness. Among rice varieties, BRRI dhan31 allowed the minimum weed growth (32.5 g m-2) while BRRI dhan51 allowed the maximum weed growth (155.3 g m-2). Grain yield ranged between 3.6 t ha-1 (BRRI dhan49) and 7.5 t ha-1 (BR10) under weed-free condition and between 2.2 t ha-1 (BRRI dhan70) and 3.9 t ha-1 (BRRI dhan34) under weedy condition. Weed imposed relative yield loss ranged from 10.2 to 66.9% among the rice varieties. BRRI dhan34 allowed the least yield penalty (10.2%) while BRRI dhan70 had the maximum yield penalty (66.9%) due to competition with weeds. Although BR10 appear as the most productive variety (7.5 t ha-1) its weed imposed relative yield loss was higher (51.3%) than many other varieties with low yield potential. On the other hand, BRRI dhan34 appeared as the most weed competitive variety (only 10.2% relative yield loss) with productivity of 3.9 t ha-1. Considering the yield, BR10 was the best but for weed suppressive ability BRRI dhan34 performed well.

The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during February to June 2017 to study the feasibility of different direct seeded rice based intercropping systems under varying fertilizer management. The experiment was conducted in afactorialrandomized complete block design with three replications. Four leafy vegetables viz., gimakalmi, Indian spinach, red amaranth andjute were intercropped with dry direct seeded boro rice (cv. BRRI dhan28) following three fertilizer dose such as 100, 75 and 125% of recommended fertilizer, and sole rice was also maintained as control. Rice yield was the highest (3.87t ha-1) in sole cropping, and intercroppingresulted insignificant rice yield reduction. Although inintercropping rice yielddecreased, but increased both gross margin and benefit cost ratio (BCR) as compared to rice sole cropping. Among the vegetables, gimakalmi performed the best followed by red amaranth in terms of yield and 125% recommended fertilizer was the best fertilizer dose. Gimakalmi intercropped with rice following 125% recommended fertilizer showed the highest gross return and BCR (2.53). Therefore, vegetables like gimakalmi and red amaranth couldbe recommended as intercrop with dry direct seeded winter rice with 125% recommended fertilizer for better productivity and higher economicreturn. Bangladesh Agron. J. 2019, 22(2): 103-112

An experiment was carried out to study the effect of date of sowing and level of phosphorus on the yield, yield components and seed protein content of faba bean (Vicia faba L.) at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during November 2018 to March 2019 to study the influence of sowing date and phosphorous fertilization on the growth, yield and quality of faba bean (V. faba). Three date of sowing viz. 25 November, 5 December, 15 December and five levels of phosphorus viz., 0, 10, 20, 30, 40 kg P ha-1 were used in this experiment laid out in a randomized complete block design with three replications. At 60 DAS, 25 November sowing fertilized with 40 kg P ha-1 showed significant influence on all characters except dry matter production. Early sowing on 25 November produced the tallest plant (42.95 cm), highest number of branches plant-1 (8.31), number of pods plant-1 (49.87), 1000-seed weight (97.55 g), seed yield (1.21 t ha-1), stover yield (1.98 t ha-1) and seed protein content (31.54%) while the corresponding lowest values were recorded from late sowing on 15 December. The crop fertilized with 40 kg P ha-1 produced the highest number of branches plant-1 (8.33), number of pods plant-1 (49.05), 1000-seed weight (97.40 g), seed yield (1.33 t ha-1), stover yield (2.28 t ha-1) and seed protein content (38.17%) while control treatment (0 kg P ha-1) produced the lowest values of all parameters. In case of interaction, the highest number of pods plant-1 (58.42), seed yield (1.59 t ha-1), stover yield (2.44 t ha-1) and protein content in seeds (39.60) were recorded with 25 November sowing fertilized with 40 kg P ha-1 whereas the lowest seed yield (0.54 t ha-1), stover yield (1.32 t ha-1) and seed protein content (25.90%) were obtained from 15 December sowing along with control treatment. Therefore, early sowing (25 November) with 40 kg P ha-1 appears as the promising combination for higher yield and seed protein content of faba bean.

The study was conducted during winter season (February-June) of 2016 at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh. Fourteen rice varieties namely, BRRI dhan28, BRRI dhan29, BRRI dhan47, BRRI dhan50, BRRI dhan55, BRRI dhan58, BRRI dhan59, BRRI dhan67, Binadhan-5, Binadhan-6, Binadhan-8, Binadhan-10, BRRI hybriddhan3 and Agrodhan14 were grown under weedy and weed- free conditions. Plots with no rice were also maintained to study the natural growth of weed in absence of rice. Primed rice seeds were dry seeded following 25 cm ×15 cm spacing with 5 seeds hill-1 on non-puddled soil. Plots were surface irrigated as and when necessary to maintain aerobic condition (at around field capacity) up to heading stage followed by wet condition from heading to grain filling stage. The results revealed that rice varieties varied widely in yield performance and weed suppressive ability. Among varieties, BRRI dhan59 allowed the minimum weed growth (20.8 g m-2) while Binadhan-5 allowed the maximum weed growth (65.8 g m-2). Grain yield ranged from 2.2 t ha-1 (BRRI dhan55) to 4.67 t ha-1 (Binadhan-5) under weed-free condition and from 0.62 t ha-1 (BRRI dhan55) to 2.48 t ha-1 (BRRI dhan59) under weedy condition. Weed infected relative yield loss ranged from 40.1% to 78.2% among varieties. BRRI dhan59 incurred the least yield penalty (40.1%) while Binadhan-5 performed the best in terms of grain yield (4.67 t ha-1) but its weed inflicted relative yield loss was higher (76.4%) than any other variety with low yield potential. BRRI dhan59, on the other hand, appeared as the most weed competitive variety (only 40.1% relative yield loss) with yield of 4.19 t ha-1. Present study confirms that the varieties tested under study varied widely in terms of weed suppressive ability and yield performance. Considering both yield and weed competitiveness, BRRI dhan59 can be recommended for cultivation following modified aerobic system.

This experiment aimed to study the efficacy of different nitrogen (N) management approaches in winter rice. The experiment consisted of two rice varieties: 1) BRRI (Bangladesh Rice Research Institute) dhan29-an inbred and 2) Dhanigold-a hybrid, and eight N management approaches: 1) BRRI recommended N (control), 2) Soil analysis based N management, 3) N application based on Agro-ecological zone, 4) 20 kg·N·ha-1 at ≤35 SPAD (Silicon photon activate diode) value, 5) 30 kg·N·ha-1 at ≤35 SPAD value, 6) 20 kg·N·ha-1 at ≤3.0 LCC (leaf colour chart) value, 7) 30 kg·N·ha-1 at ≤3.0 LCC value and 8) Urea Super Granule. Between two varieties, hybrid Dhani gold produced higher grain yield (6.67 t·ha-1) than the inbred BRRI dhan29. Application of 20 kg·N·ha-1 at ≤3.0 LCC value gave the highest grain yield (7.10 t·ha-1), whereas the lowest grain yield (5.92 t·ha-1) was found from the SPAD approach with 20 kg·N·ha-1 at ≤35 SPAD value. In case of treatment interaction highest grain yield (7.34 t·ha-1) was found in BRRI dhan29 coupled with 20 kg·N·ha-1 at ≤3.0 LCC value with 18 kg·N·savings·ha-1 over control, maximum gross income (146,800 BDT·ha-1) and net benefit (142,120 BDT·ha-1), which was statistically identical with the grain yield from the interaction of Dhani gold and 30 kg·N·ha-1 at ≤3.0 LCC value but required 42 kg·extra·N·ha-1 (over control). The lowest grain yield (5.19 t·ha-1) was found when Dhanigold was coupled with 30 kg·N·ha-1 at ≤35 SPAD value, while the 20 kg·N·application·ha-1 at ≤35 SPAD value gave moderate yield (6.87 t·ha-1) with considerable higher gross (139,600 BDT·ha-1) and net (136,090 BDT·ha-1) incomes than the control (gross: 121,000 and net: 115,600 BDT·ha-1). The results reveal that 20 kg·N·ha-1 at ≤3.0 LCC value appeared as the promising practice for inbred BRRI dhan29, and 30 kg·N·ha-1 at ≤35 SPAD value for hybrid Dhanigold in terms of yield, N use efficiency and economic benefit of winter rice.

An attempt has been made in this article to accumulate and elucidate the literatures about the allelopathic potentiality of medicinal plants, and its role on the development of bio-herbicides for eco-friendly weed management strategies to conserve bio-diversity and ecological balance. This review paper has been prepared by comprehensive studies of various published research articles, books and proceedings available in the world literature. The farmers of different countries use several weed management techniques in order to minimize the deleterious effect of weeds. Among them most commonly used practice is application of herbicides due to its high efficacy and cost effectiveness, less time-consuming nature, flexibility and easy accessibility, and more rapid out return. Although use of synthetic herbicides in the crop fields has increased the crop production as well as the productivity by reducing the weed infestation, over time it causes a number of environmental hazards. Hence, to avoid these detrimental effects of synthetic herbicide, a lot of efforts have been dedicated by the researchers to search the novel natural plant products mainly allelochemicals and try to apply them as a tool for the development of bio-degradable natural herbicides. This paper intended to reflect the current state of allelopathic medicinal plants and their potentiality to develop eco-friendly and natural product-based herbicides for sustainable agriculture, and to invite further debate on this issue.

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during December 2014 to May 2015 to examine the effect of variety and water management system on the growth and yield performance of boro rice. The experiment consisted of three varieties (cv. BRRI dhan28, BRRI dhan29 and Binadhan-14) and four water management systems (viz. Traditional flooding, non-flooded rice straw mulching, non-flooded water hyacinth mulching and non-flooded no mulching). The experiment was laid out in a split plot design with three replications. Different growth characters, yield and yield contributing characters of boro rice were found to the significantly influenced by variety, water management system and their interactions. At 100 DAT, the highest plant height, maximum number of tillers hill-1, dry matter of shoot hill-1 and dry matter of root hill-1were obtained from BRRI dhan29 and the lowest values were found in Binadhan-14. At 100 DAT, the highest plant height, maximum number of tillers hill-1, dry matter of shoot hill-1 and dry matter of root hill-1 were obtained in non-flooded rice straw mulching treatment and the lowest ones were obtained from non-flooded no mulching treatment. Variety had significant effect on all the crop characters under study except 1000-grain weight. The highest grain yield was obtained from BRRI dhan29 and the lowest value was recorded from Binadhan-14. Water management system was also significantly influenced all crop characters. The highest grain yield was recorded from non-flooded rice straw mulching treatment and the lowest grain yield was found from non-flooded no mulching treatment. The interaction of variety and water management system showed that BRRI dhan29 with non-flooded rice straw mulching resulted in the highest grain yield whereas the lowest yield was observed from the interaction of Binadhan-14 with non-flooded no mulching treatment. The result of the experiment suggests that BRRI dhan29 can be grown economically with non-flooded rice straw mulching treatment.Progressive Agriculture 28 (1): 26-35, 2017

Aerobic rice or dry direct seeded rice is highly vulnerable to weeds because of lack of “head start” over weeds and standing water layer to suppress weeds. The risks of chemical control and the huge cost involvement in mechanical control demand an eco-friendly and cost-effective integrated weed management. Weed competitive rice cultivar may be considered as a viable tool for integrated weed management. In these circumstances, an experiment was designed to evaluate weed competitiveness of some selected winter rice varieties under aerobic soil conditions. The study was conducted during dry season (February to June) 2016 at the Agronomy Field Laboratory and Weed Management Laboratory, Bangladesh Agricultural University, Mymensingh. Fourteen rice varieties namely, BRRI dhan28, BRRI dhan29, BRRI dhan47, BRRI dhan50, BRRI dhan55, BRRI dhan58, BRRI dhan59, BRRI dhan67, Binadhan-5, Binadhan-6, Binadhan-8, Binadhan-10, BRRI hybrid dhan3 and Agrodhan-14 were grown under weedy and weed-free conditions. Plots with no rice were also maintained to observe the natural growth of weed in absence of rice. The experiment was conducted with split-plot design with three replications. Weeding regime was allocated in main plot and rice variety was allocated in sub-plot. Results showed that rice varieties varied widely in their yield performances and weed competitiveness. Among rice varieties, BRRI dhan59 allowed the minimum weed growth (19.2 g m-2) while Binadhan-5 allowed the maximum weed growth (62.8 g m-2). Grain yield ranged from 1.85 t ha-1 (BRRI dhan55) to 3.92 t ha-1 (Binadhan-5) under weed-free condition and between 0.41 t ha-1 (BRRI dhan55) and 2.06 t ha-1 (BRRI dhan59) under weedy condition. Weed inflicted relative yield loss ranged from 43.4% to 82.1% among the varieties. BRRI dhan59 allowed the least yield penalty (43.4%) while Binadhan-5 had the maximum yield penalty (82.1%) due to weed competition. Although Binadhan-5 is the most productive variety (3.92 t ha-1) for aerobic culture but its weed inflicted relative yield loss is higher (82.1%) than many other varieties with low yield potential. On the other hand, BRRI dhan59 appeared as the most weed competitive variety (only 43.4% relative yield loss) with productivity of 3.84 t ha-1. Therefore, weed competitive variety should be considered as a vital tool while designing integrated weed management system for aerobic rice.

On-farm two experiments were carried out at the Fulbaria upazila under Mymensingh district and Agronomy Field Laboratory, Department of Agronomy, Bangladesh Agricultural University (BAU), Mymensingh during the period from November 2011 to March 2012. The experiment comprised ten fields for each of the locations which composed of three weeding regime treatments, namely, unweeded, farmers’ weeded and weed free. The design was randomized complete block with ten replications. Data on weed density, yield contributing characters and yield of wheat were recorded. Except straw yield in Fulbaria all others yield contributing characters were affected significantly due to weeding regime treatment. The highest grain yield was recorded in weed-free treatment compared to farmers weeded and unweeded treatment in Fulbaria. Whereas, in Agronomy Field Laboratory at BAU, the highest grain yield was observed in weed-free treatment which was statistically identical to farmers’ weeded treatment. Five dominant weed species were identified in Fulbaria naimly Cynodon dactylon L. , Cyperus rotundus L. , Alternanthera sessilis L., Polygonum orientale L. and Chenopodium album L. and in Agronomy Field Laboratory at BAU namely Gnaphalium affine L. , Cyperus rotundus L. , Digitaria sanguinalis L., Cynodon dactylon L. and Panicum repens L. Infestation of Cynodon dactylon L. was more in Fulbaria due to control difficulties and Gnaphalium affine L. was more in BAU due to weed seed bank year after year and poor cultural management. So there is scope to increase yield potential of wheat by improving existing weed control practices. Progress. Agric. 2014. 25: 23-30

Till now, herbicide seems to be a cost effective tool from an agronomic view point to control weeds. But long term efficacy and sustainability issues are the driving forces behind the reconsideration of herbicide dependent weed management strategy in rice. This demands reappearance of physical and cultural management options combined with judicious herbicide application in a more comprehensive and integrated way. Keeping those in mind, some agronomic tools along with different manual weeding and herbicides combinations were evaluated for their weed control efficacy in rice under aerobic soil conditions. Combination of competitive variety, higher seeding rate, and seed priming resulted in more competitive cropping system in favor of rice, which was reflected in lower weed pressure, higher weed control efficiency, and better yield. Most of the herbicides exhibited excellent weed control efficiency. Treatments comprising only herbicides required less cost involvement but produced higher net benefit. On the contrary, treatments comprising both herbicide and manual weeding required high cost involvement and thus produced lower net benefit. Therefore, adoption of competitive rice variety, higher seed rate, and seed priming along with spraying different early-postemergence herbicides in rotation at 10 days after seeding (DAS) followed by a manual weeding at 30 DAS may be recommended from sustainability view point.

Peat moss (PM) is the most widely used growing substrate for the pot culture. Due to diminishing availability and increasing price of PM, researchers are looking for viable alternatives for peat as a growth media component for potted plants. A pot study was conducted with a view to investigate the possibility of using spent mushroom waste (SMW) for Kai-lan (Brassica oleraceavar. Alboglabra) production replacing peat moss (PM) in growth media. The treatments evaluated were 100% PM (control), 100% SMW, and mixtures of SMW and PM in different ratios like 1 : 1, 1 : 2, and 2 : 1 (v/v) with/without NPK amendment. The experiment was arranged in a completely randomized design with five replications per treatment. Chemical properties like pH and salinity level (EC) of SMW were within the acceptable range of crop production but, nutrient content, especially nitrogen content was not enough to provide sufficient nutrition to plant for normal growth. Only PM (100%) and SMW and PM mixture in 1 : 1 ratio with NPK amendment performed equally in terms of Kai-lan growth. This study confirms the feasibility of replacing PM by SMW up to a maximum of 50% in the growth media and suggests that NPK supplementation from inorganic sources is to ensure a higher productivity of Kai-lan.

Axonopus compressusis one of the native soft grass species in oil palm in Malaysia which can be used as a cover crop. The competitive ability ofA. compressusto overcomeA. gangeticawas studied using multiple-density, multiple-proportion replacements series under a glasshouse and full sunlight conditions in a poly bag for 10 weeks.A. compressusproduced more dry weight and leaf area when competing againstA. gangeticathan in monoculture at both densities in the full sunlight and at high density in the shade. Moreover, the relative yield and relative crowding coefficients also indicatedA. compressusis a stronger competitor thanA. gangeticaat both densities in the full sunlight and high density in the shade. It seemed thatA. gangeticaplants in the shade did not compete with each other and were more competitive againstA. compressusas could influenceA. compressusheight in the shade. It is concluded that although suppression ofA. gangeticabyA. compressusoccurred under full sunlight, irrespective of plant density, this ability reduced under shade asA. compressusdensity decreased. The result suggests thatA. compressusin high density could be considered as a candidate for cover crops under oil palm canopy.

This study investigated the allelopathic effect ofAxonopus compressuslitter onAsystasia gangeticaandPennisetum polystachion. In experiment 1 the bioassays with 0, 10, 30, and 50 g L−1of aqueousA. compressuslitter leachate were conducted. Experiment 2 was carried out by incorporating 0, 10, 20, 30, 40, and 50 g L−1ofA. compressuslitter leachate into soil. In experiment 3, the fate ofA. compressuslitter leachate phenolics in the soil was investigated.A. compressusleachates did not affect the germination percentage ofA. gangeticaandP. polystachion, but delayed germination ofA. gangeticaseeds and decreased seed germination time ofP. polystachion.A. compressuslitter leachates affected weeds hypocotyl length. Hypocotyl length reductions of 18 and 31% were observed at the highest concentration (50 g L−1) compared to the control inA. gangeticaandP. polystachion, respectively. When concentration ofA. compressuslitter leachate-amended soil increasedA. gangeticaandP. polystachionseedling shoot length, root length, seedling weight and chlorophyll concentration were not affected. The 5-week decomposition study ofA. compressusshowed that the phenolic compounds inA. compressuslitter abruptly decreased about 52% after two weeks and remained steady until the end of the incubation.

Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return.