The creeping weed, Chrysopogon aciculatus (Retz.) Trin., is widely known for its use as folk medicine, while its phytotoxic potential has not been examined. Therefore, we carried out an investigation into the phytotoxic potential of C. aciculatus to identify phytotoxic substances. C. aciculatus extracts showed inhibitory effects on shoot and root growth of cress, lettuce, rapeseed, and Italian ryegrass. Inhibition was both species‐dependent and concentration‐dependent. Two substances, (9S,10E,12Z)‐9‐hydroxyoctadeca‐10,12‐dienoic acid (9‐HO‐ODDEA) and rhizopycnin A, were isolated using chromatographies and characterized by spectral analysis. 9‐HO‐ODDEA retarded shoot and root growth of cress at concentrations higher than 1.0 and 0.3 mM, respectively, while on cress seedling by rhizopycnin A, the inhibition began from 1.0 mM. The concentrations needed for 50% inhibition of the shoot and root growth of test plants ranged from 1.71–2.31, and 0.71–0.72 mM for 9‐HO‐ODDEA and rhizopycnin A, respectively. These results indicate that these substances may contribute, to a certain extent, to the phytotoxic activity of C. aciculatus.

Weed-competitive rice cultivars, a viable tool for integrated weed management of rice-field weeds, may greatly reduce the weed pressure and excessive dependence on herbicide in controlling weeds. Based on this premise, field experiments were conducted in 2018 and 2019 during the monsoon and winter rice-growing seasons at the Agronomy Field Laboratory of Bangladesh Agricultural University, Bangladesh, to evaluate the weed competitiveness of the selected rice varieties. A total of 42 monsoon and 28 winter rice varieties from Bangladesh were evaluated under “weedy” and “weed-free” conditions in the puddled transplanted system of cultivation. The field experiments were designed with three replications in a randomized complete block design. The results revealed that weed competition greatly reduces the yield of rice, and relative yield loss was 15–68% and 20–50% in monsoon and winter season rice, respectively. The lowest relative yield losses were recorded in monsoon rice from the variety BU dhan 1 (18%) and from the winter rice BRRI hybrid dhan5 (23.7%), which exhibited high weed tolerance. The weed competitive index (WCI) greatly varied among the varieties in both seasons and the monsoon season, ranging from 0.4 to 2.8, and the highest value was recorded from the hybrid variety Dhani Gold followed by BU dhan 1. In winter season rice, the WCI varied 0.25 to 2.4 and the highest value was recorded from the variety BRRI hybrid dhan3, followed by hybrid variety Heera 6. In monsoon rice, hybrid Dhani Gold was the most productive, but BU dhan 1 was the most weed competitive variety. Among the winter-grown varieties, the hybrid Heera 6 was the most productive, and the most weed competitive. Our research confirmed a high degree of variability in weed competitiveness among the 70 Bangladeshi rice varieties tested.

In an experimental investigation, we looked into how different zinc (Zn) and boron (B) dosages affected the production and the amount of oil in mustard. Zn and B treatments, respectively, were separated into four levels: 0, 1, 2, 4, and 0, 0.4, 0.6, and 0.8 kg per hectare. We observed considerable Zn as well as B effects on mustard yield and its oil content. The maximum (1.6 Ton per hectare) and minimum (1.3 T ha⁻¹) seed output, the maximum (1.9 T ha⁻¹) and minimum (1.5 T ha⁻¹) stover production, the maximum (4.9) and minimum (3.99) number branches plant⁻¹, and the longest (114.6 cm) and shortest (87.44 cm) plant height were observed from 4 kg of Zn ha⁻¹ and 0 kg of Zn ha⁻¹, respectively. On the other hand, we discovered that applying 0.8 kg and 0 kg of B ha⁻¹, respectively, resulted in the highest (1.6 T ha⁻¹) and lowest (1.3 T ha⁻¹) seed yield, the highest (1.8 T ha⁻¹) and lowest (1.5 T ha⁻¹) stover yield, the maximum (4.75) and minimum (4.02) number of branches plant⁻¹, and the longest (118.7 cm) and shortest (85.15 cm) plant heights. The maximum seed (1.9 T ha⁻¹) and stover output (2.0 T ha⁻¹), tallest plant (140.9 cm), and most branches per plant⁻¹ (5.47) were obtained when 4 kg of Zn ha⁻¹ was given with 0.8 kg of B ha⁻¹. However, while Zn and B were not applied, the lowest output for all of the crop attributes assessed was observed. As a result, for mustard, 4 kg of Zn ha⁻¹ combined with 0.8 kg of B ha⁻¹ may be advised as an effective approach in terms of seed yield and oil content.

In Bangladesh’s hill regions, where there is less cultivable land, increasing crop output requires efficient land use. Thus, in this challenging farming setting, two crop-based patterns evolved into three or four crop-based patterns. To increase cropping intensity and farmer income by incorporating mustard and mungbean in a rice-based cropping pattern, a field experiment was carried out at Sadar and Panchari Upazila, Khagrachhari during 2017–2018 and 2018–2019. Two years’ mean data (using a block farming approach) showed that the modified pattern had produced a much higher yield through improved management practices. In the improved cropping pattern (Transplant aman (T. aman)–mustard–mungbean–aus rice), a higher rice equivalent yield (16.25 t ha⁻¹) was found due to the inclusion of mustard and mungbean in the existing rice-based cropping patterns T. aman–fallow–boro (9.87 t ha⁻¹) and T. aman–fallow–tomato (9.09 t ha⁻¹). The gross margin from the improved cropping pattern was 448,715 BDT, which was 44.26% higher than the mean gross margin (311,050 BDT) of the two existing cropping patterns. Farmers are interested in growing mustard and mungbean since both can easily cultivated in hilly areas and can yield great economic returns quickly. For the large-scale production of oil and pulse, the T. aman–mustard–mungbean–aus rice cropping pattern might be introduced in the Khagrachhari district of Bangladesh.