Dry direct-seeded rice (Oryza sativa L.), a climate-smart and resource-efficient (labor and water) rice production technology is gaining popularity in many parts of Asian countries; however, weeds are the major constraints for its early establishment and optimum productivity. Chemical weed management is effective, rapid, and also decreases weed management costs in dry direct-seeded rice (DSR) system; however, chemical use for weed management have a negative effect on the environment and also have human health hazards. Therefore, integrated weed management (IWM) is the best option for the sustainability of rice production under the DSR system. Improving competitiveness against weeds, weed-competitive rice cultivars, and high seeding rates were found to be the most promising IWM strategies in DSR. In this context, a field study was conducted to evaluate the weed competitiveness of rice cultivars and seeding rates on the performance of aus rice in dry direct-seeded systems in Bangladesh. Three inbred rice cultivars (CV), namely “BRRI dhan26”, “BRRI dhan48”, and “BRRI dhan55”, and one hybrid cultivar, “Arize” were tested in a seeding rate (SR) of 20, 40, and 80 kg ha⁻¹ under two weeding regimes (WR) of weed-free and partially-weedy. Rice grain yield was strongly affected (p < 0.01) by the interactions of WR, CV, and SR. In weed-free conditions, the yield of all three inbred cultivars was increased up to SR of 40 kg ha⁻¹ and for the hybrid cultivar, up to SR of 20 kg ha⁻¹, and with further increment of SR, there was no yield advantage. Conversely, under partially weedy conditions, the yield of three inbred cultivars increased up to SR of 80 kg ha⁻¹; however, for the hybrid cultivar, this increment was up to SR of 40 kg ha⁻¹ and thereafter, no yield gain. In weedy conditions, the higher SR compensates for the yield losses by increasing the competitiveness of rice with weeds. Across SR, the hybrid cultivar had a significantly (p < 0.01) higher weed competitive index (WCI) than all the inbred cultivars and the highest SR always had a higher WCI.

COVID-19 has caused a deep economic impact on the lives of small and marginal farmers due to travel restrictions, market closures, and social distancing requirements. Due to COVID-induced labor scarcity and water shortage in India, direct-seeded rice (DSR) has emerged as a viable alternative to puddled transplanted rice (PTR). However, there was plenty of labor available in Pakistan and Bangladesh for rice cultivation during COVID-19 times. Therefore, both countries did not observe the shift from PTR to DSR. The cost of inputs, such as seed, fertilizer, pesticide, and fuel, was high due to a supply–demand conflict during the COVID-19 pandemic in three countries. Farmers faced weed problems and physical and/or economical non-availability of suitable machinery for DSR cultivation during the COVID-19 pandemic. In the later years of 2022 and 2023 (post-COVID), the area under DSR decreased by 88% in India, while it remained stagnant in Pakistan and Bangladesh.

Cyperus iria is amongst the most threatening weeds of rice in Sri Lanka, India, Pakistan, and the Philippines. Broad knowledge about the ecology and fecundity of C. iria is important for its effective management. Field studies were conducted over two seasons (wet (WS) and dry seasons (DS)) to investigate the influence of C. iria populations (40 and 80 plants m⁻²) on its growth, survival, and fertility, with four emergence times, 3, 15, 30, and 45 d after rice emergence (DARE), during 2013. We postulated that (a) higher plant density of this weed would result in more biomass production and viable seeds per unit area, (b) interference of rice would reduce the biomass production and fecundity of this weed, and (c) delaying weed emergence would lead to downsizing of its percent survival and seed bank enrichment in soil. The results indicated that rice interference decreased C. iria growth and seed production as compared with those of plants established without rice interference. A linear decrease in the percent survival of C. iria without rice and a sigmoid decrease with rice were observed during both seasons. Plant height of C. iria was moderately affected up to 30 DARE, and a significant reduction was observed at 45 DARE. There was a linear relationship between C. iria shoot dry weight and seed number plant ⁻¹, across-weed density, seeding rate of rice, and emergence time. C. iria seed production, 1000-seed weight, and seed yield were greater when seedlings emerged simultaneously with the rice crop (3 DARE) than when they emerged late. Under rice weed interference growth, the production of viable seeds was completely stopped at 45 DARE. The delay in the emergence of C. iria up to 45 DARE was unable to produce seed in both seasons. The results of the current studies advocate that the emergence, weed biomass, and seed production of C. iria can be checked by adopting suitable cultural weed management practices, which can impede the emergence of weed relative to rice. These practices, enabling the respective crops to be more competitive, will foster integrated weed management approaches, thus offering a key role in seed detection to the soil seed reservoir or pool by notorious weeds in the field.

Echinochloa crus-galli (L.) Beauv. is a stronger competitor of rice for resources than other weeds. An adequate knowledge of the biology, ecology and critical period of competition of E. crus-galli with dry-seeded rice (DSR) is fundamental in designing effective, sustainable and integrated weed management programs. Experiments were conducted in the 2013 dry and wet seasons to determine the effect of two E. crus-galli densities (40 and 80 plants m⁻²) emerging at four intervals (2, 15, 30 and 45 d after rice emergence, DARE) with and without rice interference on the growth and biomass accumulation of both rice and weed, and the productivity of rice. The E. crus-galli plant height decreased with the interference of rice plants. The maximum height of 115–130 cm and number of tillers of 477–508 m⁻² in rice plants were recorded when grown alone, and these growth parameters declined to 105–109 cm and 315–352 m⁻², respectively, when rice emerged simultaneously with E. crus-galli. Other rice growth parameters (stem, leaf, panicle and shoot biomass, and leaf area) and grain yield attributes (panicle density, per panicle filled spikelets and grain weight) decreased significantly with increases in E. crus-galli density at the early emergence time. A delay in E. crus-galli emergence from 0 to 45 DARE caused a significant reduction in E. crus-galli biomass, which resulted in less reduction in rice biomass and leaf area index. Rice grain yield, grain weight, and harvest index improved significantly with a delay in weed emergence up to 45 DARE. The highest grain yield was recorded when rice was grown alone (6.8–7.3 t ha⁻¹), which was similar to the yield produced in the plots wherein E. crus-galli sown at 40 plants m⁻² (6.9–7.0 t ha⁻¹) and 80 plants m⁻² (6.4–6.7 t ha⁻¹) emerged at 45 DARE. The lowest grain yield (4.3–4.9 t ha⁻¹) was recorded in the plots wherein E. crus-galli emerged simultaneously with rice. This study established that E. crus-galli emergence at 45 DARE could not cause an economic yield loss because of less biomass accumulation and lower survival rate.

The utilization of vermi-technology to reduce allelopathic effects is a cost-effective, efficient, and environmentally appropriate alternative to traditional chemical and mechanical methods. The current investigation was an effort to obtain vermicompost from C. erectus and its binary combination with soil and farmyard manure (FYM) using E. foetida. The pH, EC, organic carbon, macro and micro-nutrients, CO₂ emission, the average growth rate of the worms, number of worms, number of cocoons, and weight gained by earthworms were analyzed by standard methods. The present study also investigated the effect of produced vermicompost on the growth and yield of mung beans (Vigna radiata L). The maximum reduction in soil pH was observed (6.47) in vermicompost of C. erectus leaves, among other treatments. The highest N (1.86%), P (0.15%), and K (0.41%) contents were found in the vermicompost of C. erectus leaves + FYM. Similarly, the maximum plant height (36.00 cm) was achieved in vermicompost of C. erectus leaves + FYM compared to other treatments. The highest SPAD value was observed (56.37) when the soil was treated with vermicompost (C. erectus leaves + FYM) @ 5 t ha⁻¹, followed by the treatment where vermicompost (C. erectus leaves + soil) @ 8 t ha⁻¹ was applied. The soil amendment of vermicompost (C. erectus leaves + FYM) @ 5 t ha⁻¹ showed competitive results (in terms of the growth and yield parameters of mung beans) compared to other types of vermicompost and C. erectus biomass. This study has the potential to reduce the phytotoxicity of C. erectus biomass and transform it into a potent organic fertilizer through vermicomposting.