BRRI Dhan29 Research Articles

Seed Dormancy and Germination Potential of Coastal Rice Landraces in Bangladesh: Implications for Climate-Resilient Cultivation

The coastal regions of Bangladesh host a rich diversity of Aman rice landraces, which are crucial for local agriculture but are highly vulnerable to natural disasters like cyclones and floods. Specifically, local landraces often experience flooding during grain filling and maturation stages, and sprouts in the field lead to a severe loss of yield. Seed dormancy, which delays germination, is a key trait for escaping sprouting in the field during harvesting. However, there is lack of information on genetic variability in the existing rice landraces grown in the coastal area of Bangladesh. This study evaluated the seed dormancy of 28 local Aman rice landraces, plus four varieties from the Bangladesh Institute of Nuclear Agriculture and Bangladesh Rice Research Institute. Germination tests were conducted under controlled conditions, and an electrical conductivity (EC) test was used to assess seed vigor. The results showed that Bari Mota, Tulsimala, Chinigura, Dishari, and Birindi exhibited the highest dormancy rates, i.e., 100%, 100%, 99%, 99%, and 99%, respectively, while BINA Dhan 10, Nona Bokra, and BINA Dhan 8 had the lowest dormancy rates, with values of 11%, 16%, and 24%, respectively. Priming treatments enhanced germination rates in some varieties; however, others, such as Bari Mota and Tulsimala, remained dormant, underscoring the variability in seed dormancy levels. Compared to non-priming, a significant improvement of germination was recorded in BRRI dhan 41 (85.3% vs. 9%), Motha mota (84% vs. 8%), Lal chikon (74.6% vs. 1%), Sadamota (74.6% vs. 5%), and Bashful (53.3% vs. 3%). Altogether, our results suggest that local landraces are diverse in seed dormancy, and genotypes with high dormancy, such as Bari Mota and Tulsimala, can potentially be grown in the disaster-prone coastal areas. In contrast, these genotypes can be used for future breeding programs. Therefore, this study carries significant implications for rice cultivation in the coastal areas of Bangladesh.

Enhancing Genetic Diversity and Blast Resistance in Rice (Oryza sativa L.) Through Ethyl Methane Sulfonate (EMS) Mutagenesis

ABSTRACTPlant diseases cause significant losses to food crop production with blast being one of the most destructive diseases affecting rice. Breeding for disease resistance is an effective approach for developing varieties that can withstand such diseases, ultimately contributing to stable yields in rice. Besides hybridization, chemical mutagenesis is a potential method of bringing desirable genetic alteration towards disease resistance in seed propagated crops like rice. Therefore, a study was conducted to generate variants employing ethyl methane sulfonate (EMS) mutagenesis, evaluate the resulting mutants for variability and identify genotypes resistant to rice blast disease following a completely randomized design (CRD). Seeds of BRRI dhan28 were mutagenized with LD50 (0.108 M) of EMS to develop 100 mutants. The mutants demonstrated notable variation in all traits assessed. The higher level of phenotypic and genotypic coefficient of variation was assessed together with high heritability as well as genetic advance in percent of mean for filled grains panicle−1, tillers hill−1, grain and straw yield hill−1 and harvest index. Plant height, panicle length, tillers hill−1, branches panicle−1 and grains panicle−1 showed a statistically significant and positive correlation with grain yield. The cluster analysis grouped the mutants into seven main clusters, and the PCA demonstrated 42.96% of total variation for the first two components. Screening of the mutants against leaf blast disease exhibited variable responses from resistant to highly susceptible. A total of 9 mutants were found as resistant and 35 as moderately resistant against blast disease. Seed mutagenesis with EMS is an effective technique for generating variability towards blast resistance in susceptible rice varieties, and the identified resistant genotypes can serve as valuable resources for further research in improving blast resistance in rice.

Effectiveness of pre-emergence herbicides on weed population and yield of boro rice (cv. BRRI dhan58) under different dose

Weed management is crucial for optimal crop performance in rice cultivation. In this respect, an experiment was conducted at the Agronomy Field Laboratory (AFL), Bangladesh Agricultural University (BAU), Mymensingh, from December 2019 to May 2020 and aimed to evaluate the effectiveness of various herbicide treatments on weed management and crop performance in rice cultivation, focusing on the variety BRRI dhan58. The study included a control group and various herbicide treatments: half the recommended dose (RD), RD, and a double dose of pendimethalin, bensulfuron methyl + acetachlor, bensulfuron methyl + bispyribac sodium, pretilachlor, and butachlor. Eleven weed species from six families infested the plots. The results showed that double doses of pre-emergence herbicides resulted in lower weed populations (WP) (m-²), reduced weed dry weight (DW) (gm-2), and higher weed control efficiency (WCE %). The highest weed control efficiencies at 30 DAT were 94.58% for Bensulfuron methyl + Acetachlor and 94.38% for Pretilachlor. The double dose of Bensulfuron methyl + Acetachlor achieved the lowest WP and DW and the highest WCE. Crop performance improved significantly with the double dose of Bensulfuron methyl + Acetachlor, resulting in the highest PH, a more significant number of effective tillers (NET) hill-1, 1000-grain weight (TGW), grain yield (GY), straw yield (SY), biological yield (SY), and harvest index (HI). The second-highest GY was observed with the double dose of Bensulfuron methyl + Bispyribac sodium. The study concluded that the double dose of Bensulfuron methyl + Acetachlor was the most effective weed management strategy, leading to the highest grain yield in boro rice. These findings highlight that using a double dose of Bensulfuron methyl + Acetachlor not only offers superior weed control but also maximizes grain yield, making it the most effective weed management strategy for boro rice cultivation and a practical recommendation for farmers seeking to optimize productivity through targeted herbicide application.

Co-Composted Fecal Sludge Based Integrated Nutrient Management for Sustainable Aman Rice Production

This study was undertaken to judge the efficacy and economic feasibility of cocomposted fecal sludge (CCFS) in increasing growth and productivity of transplant Aman (T. Aman) rice and to optimize CCFS dose for integration with chemical fertilizers to maximize T. Aman rice yield and economic return. This study was consisted of two factors included two T. Aman rice varieties namely, BRRI dhan 49 and Dhanigold; and 10 chemical fertilizer+CCFS combinations such as, recommended dose of synthetic fertilizer (RDF), CCFS @ 5 t ha-1, RDF+CCFS @ 2 t ha-1, RDF+CCFS @ 1.5 t ha-1, RDF+CCFS @ 1 t ha-1, RDF+CCFS @ 0.5 t ha-1, 75% RDF+CCFS @ 2 t ha-1, 75% RDF+CCFS @ 1.5 t ha-1, 75% RDF+CCFS @ 1 t ha-1 and 75% RDF+CCFS @ 0.5 t ha-1. A clear advantage of integrating CCFS with chemical fertilizers to increase rice growth and yield was evident in this study. The highest grain yield was recorded when CCFS @ 2 t ha-1 was integrated with recommended chemical fertilizers, and that was >7% higher than that obtained from the application of only recommended chemical fertilizers. But application of only CCFS @ 5 t ha-1 reduced grain yield by as much as 47%. The highest benefit:cost ratio for BRRI dhan49 and Dhanigold (1.66 and 1.61, respectively) were calculated from recommended chemical fertilizers application closely followed by application of recommended chemical fertilizers+CCFS @ 2 t ha-1 (1.55 and 1.49, respectively). In case of both the varieties, application of only CCFS @ 5 t ha-1 resulted in negative net return and <1 benefit:cost ratio (0.75 and 0.73, respectively for BRRI dhan 49 and Dhanigold) due to poorer yield and higher cost for CCFS. Encouraging findings of this study confirm that CCFS obtained from faecal sludge can be integrated with chemical fertilizers to increase the productivity of T. Aman rice. In terms of grain yield, recommended chemical fertilizers+CCFS @ 2 t ha-1 appeared as the best option, but application of only recommended chemical fertilizers was found a bit more economic than integration. Application of only CCFS without chemical fertilizers was found neither productive nor economic. To conclude, co-compost can be used to supplement chemical fertilizers for in rice cultivation, and thus will contribute to green agriculture by improving soil health and minimizing environmental pollution. It is therefore necessary to conduct multi-location trials for consecutive years on other crops as well to confirm the potentiality of co-compost as a manure to increase crop productivity, and as a soil conditioner for soil health improvement. J. of Sci. and Tech. Res. 6(1): 149-159, 2024

Investigating the impact of oligo-chitosan on the growth dynamics and yield traits of Oryza sativa L. ‘BRRI dhan29’ under subtropical conditions

Investigating the impact of oligo-chitosan on the growth dynamics and yield traits of Oryza sativa L. ‘BRRI dhan29’ under subtropical conditions

Quality aspects of paddy grain and seed dried in HSTU mobile grain and seed dryer integrated with a dual heating system

Proper drying and excellence of dried grain and seed are the key concerns of millers, farmers and seed growers. The performance of a new Hajee Mohammad Danesh Science and Technology University (HSTU) mobile grain and seed dryer (HMD) integrated with dual heating system was assessed regarding the quality of dried seed and grain. The HMD was found to be capable of drying 720±10 kg paddy in a batch and drying period varied between 7 to 8 h at drying air temperatures of 65 oC. Paddy seeds of BRRI Dhan 49 and BRRI Dhan 89 were dried at 40 oC and the drying time required 9 to 10 h and 14 to 16 h in Aman and Boro season, respectively. Head rice yield and milling recovery varied from 59.50±0.16% to 61.61±0.54% and 74.95±0.09% to 75.70±0.59% for paddy dried in HMD. In addition, higher germination percentage (GP) of BRRI Dhan 49 varieties was found in Aman season that ranged from 86% to 88% which was dried in HMD in contrary to GP of paddy seeds dried under the sun. Moreover, higher GP was found from BRRI Dhan 89 varieties dried by HMD in Boro season. Also, the vigor index of HMD dried paddy seeds was more than the sun dried samples in both seasons. In conclusion, HMD integrated with a dual heating system is recommended for using at farm level as an alternative drying process for rapid and efficient handling of high-moisture grain and seed in Bangladesh and other subtropical nations in adverse climate.

Comparative Analysis of Nitrogen Use Efficiency in Boro Rice under Long-term Inorganic and Organic Fertilization Practices

An experiment was conducted during Boro rice in the permanent experimental field of the Department of Soil Science, Bangladesh Agricultural University (BAU), Mymensingh to investigae the long term outcome of manure and fertilizers on the yield and Nitrogen Use Efficiency (NUE) of BRRI dhan29 in floodplain (Subtropical) soil (Aeric Haplaquepts). The experiment was designed in a randomized complete block design with three replications. There were ten treatment combinations viz, control; Nitrogen (N); (Nitrogen Phosphorus) NP; Nitrogen Potassium (NK); Nitrogen Phosphorus Potassium (NPK); Nitrogen Zinc (NZn); Nitrogen Sulphur (NS); Nitrogen Sulphur Zinc (NSZn), Nitrogen Phosphorus Potassium Sulphur Zinc (NPKSZn) and NPK+FYM. The yield contributing characters and yield of BRRI dhan29 significantly increased due to different treatments. Grain and straw yields were highly influenced by the application of nutrients in various combinations. The longest panicle length (25.3 cm), the highest 1000 grain weight (22.7 g), the maximum grain yield (6.29 t ha-1), the highest nitrogen uptake in grain (70.4 kg ha-1) were found for the NPKSZn treatment. Grain yield increased by 24.8%, 85.8%, 40.7%, 68.9%, 29.2%, 33.2%, 107.1%, 28.9% and 78.9% due to N, NP, NK, NPK, NS, NSZn, NPKSZn, NZn and NPK+FYM treatments respectively and the corresponding straw yields attainment by 49.6%, 51.1%, 82.0%, 95.3%, 37.8%, 34.4%, 82.7%, 41.8% and 90.2%. The maximum value of apparent nitrogen use efficiency was obtained with NPKSZn (54.06%) treatment which evidently suggested its resultness for the long term fertilized soil.

Optimization of milling degree for maximizing nutrient retention and yield in milled rice: A study on six common Bangladeshi rice cultivars

Awareness of the nutritional value and health benefits of milled rice is crucial for its role as a staple food. This study explores the impact of different degrees of milling (DOM)—5%, 7%, and 9%—on head rice yield, proximate composition (protein, fat, fiber, and carbohydrates), and mineral content (sodium, magnesium, potassium, iron, calcium) in six rice cultivars: BRRI Dhan 28, 29, 36, 90, 51, and Bogura Katari. Our findings reveal that head rice yield decreases significantly, by 3% to 8%, when DOM is increased from 5% to 7% or 9%. Increasing the DOM also led to pronounced losses of protein (15% to 25%), fat (40% to 70%), and fiber (15% to 40%), while carbohydrate content increased. Additionally, substantial reductions in mineral content were observed at 9% DOM. Notably, consuming rice milled at 5% DOM can meet significant portions of daily nutrient requirements: 50% of protein, 10% of fiber, 20% of fat, 10% of sodium, 80% of magnesium, 35% of potassium, 100% of iron, and 30% of calcium, based on a per capita consumption of 400 g per day. This research highlights the importance of optimizing DOM between 5% and 7% to enhance head rice yield and maximize nutrient retention.

Bacterial endophyte Pseudomonas mosselii PR5 improves growth, nutrient accumulation, and yield of rice (Oryza sativa L.) through various application methods

BackgroundPseudomonas spp. have drawn considerable attention due to their rhizospheric abundance and exceptional plant growth-promoting attributes. However, more research is needed on the optimal application methods of Pseudomonas mosselii for rice growth, nutrient accumulation, and yield improvement. This research explored the application of the endophytic bacterium P. mosselii PR5 on rice cultivar BRRI dhan29 with four treatments: control, seedling priming, root drenching, and bacterial cell-free culture (CFC) foliar application.ResultsPR5 led to better rice growth, improved nutrient acquisition, and higher yields compared to the control, regardless of the application method used. The highest results in fresh weight of root (146.93 g/pot), shoot (758.98 g/pot), and flag leaf (7.88 g/pot), dry weight of root (42.16 g/pot), shoot (97.32 g/pot), and flag leaf (2.69 g/pot), and grains/panicle (224.67), were obtained from seedling priming treatment, whereas root drenching resulted in maximum plant height (105.67 cm), root length (49.0 cm), tillers/pot (23.7), and panicles/pot (17.67). In all three application methods, rice grain yield per pot was higher in PR5 inoculated treatments, compared to the control. The amount of P, Mg and Zn in the shoot and N, P, Ca, Mg and Si content in the flag leaf was significantly increased along with effective suppression of naturally occurring blast disease in bacterial CFC foliar application, validated by multivariate analysis.ConclusionOur results indicated that rice seedlings priming with PR5 improved rice growth, yield and nutrient uptake, whereas CFC foliar application significantly increased the concentration of most nutrients in the rice plant and suppressed the naturally occurring rice blast disease. This research highlights the significant potential of P. mosselii PR5 in enhancing rice growth, yield, and nutrient uptake, particularly through seedling priming and CFC foliar application methods.

Presumption of Herbicide Resistant Weeds and Yield of Boro Rice as Influenced by Pre- and Post-emergence Herbicides

In Bangladesh, weed infestation is a leading problem in rice cultivation and the sole dependency on post-emergence herbicides is ineffective. Therefore, a field experiment was carried out at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh from December 2021 to May 2022. The study was done to determine the relative effectiveness of different pre-emergence herbicides and to presume the herbicide-resistant weeds and yield of boro rice as influenced by pre-and post-emergence herbicides. Four rice varieties: BAU dhan3 (V1), BRRI dhan28 (V2), BRRI dhan81 (V3), BRRI dhan96 (V4) and six herbicide managements: Control (H1), Hand Weeding at 30 DAT (H2), Bensulfuron methyl @ 980 g ha-1 (H3), Pretilachlor @ 2 L ha-1 (H4), Carfentrazon ethyl @ 208 mL ha-1 (H5), Ethoxisulfuron @ 200 g ha-1 (H6) were used in a randomized complete block design (RCBD) with three replications. The most dominant weed species in the experimental plots were Echinochloa crussgalli, Scirpus mucronatus, Monochoria hastata, Enhydra fluctuans and Oxalis europaea. This study found Ethoxisulfuron (H6) and Carfentrazon ethyl (H5) were the most effective weed management treatments for weed suppression and grain yield at twice the recommended doses. In this study, the highest grain yield (5.40 t ha-1), straw yield (6.80 t ha-1) and biological yield (12.20 t ha-1) were obtained from BRRI dhan81 (V3) with hand weeding (H2) and highest harvest index (45.60%) were obtained from BAU dhan3 (V1) with Pretilachlor (H4). Therefore, this result is useful for farmers at field level cultivation of boro rice.

Pyramiding of multiple resistant genes of blast and bacterial blight diseases in the background of rice (Oryza sativa) mega variety BRRI dhan29

Blast and bacterial blight (BB) are the two major rice diseases in the world including Bangladesh. In this study, BB resistance genes (Xa21 and xa13) and blast resistance (Pi9 and Pb1) genes were pyramided into a mega variety, BRRI dhan29 through marker-assisted backcross breeding. IRBB58 was used as a BB-resistant donor and Pi9-US2, and Pb1-US2 were used as blast-resistant donors. Backcross was done between BRRI dhan29 and donor parents to develop BC3F1 population and then selfing was done to develop BC3F6 population. BC3F2 population was genotyped and phenotyped for segregation analysis and BC3F6 was evaluated for genotyping, phenotyping and morphological traits and yields. Chi-square analysis of BC3F2 data revealed that blast and BB resistance followed the single gene mendelian fashion (1:2:1 and 3:1). Two to four gene combinations were found in the advanced lines of the BC3F6 population. The yield of the advanced lines ranged from 6.42 (t ha−1) to 9.5 (t ha−1) and they showed resistant against blast and BB with mean disease scores ranging from 0.67 to 2.33 and 0.33–2.33, respectively. Finally, eight lines having four genes (xa13, Xa21, Pi9 and Pb1) were selected for multilocational (five locations) trials for yield performance and disease reaction. Mean yield data of eight advanced lines of all locations were varied from 6.48±0.15–8.38±0.11 t ha−1 and all the lines showed resistant reactions against blast (score 0.53–1) and BB (score 0.6–0.87) disease. The highest yield was found in BR (Path) 13800-BC3–224–12 (G28, 8.38±0.11 t ha−1) followed by BR (Path) 13800-BC3–134–252 (G26, 8.28±0.08 t ha−1) and BR (Path) 13800-BC3–136–115 (G12, 8.24±0.07 t ha−1). Pyramided advanced lines of this study could be released as BB and blast-resistant varieties or could be utilized as donor parents in resistant breeding.

Allelopathic Effects of Residues of Fimbristylis dichotoma Along with Manures and Fertilizers on the Weed Growth in Boro Rice

Currently, the rice-growing system seeks a biological solution to reduce the negative impacts of chemical herbicides because it is heavily reliant on these for weed control. This is where allelopathy comes in; it's a potential substitute for conventional weed management strategies in rice cultivation by making use of allelopathic plant residues. In the study we used Fimbristylis dichotoma residues with several organic sources of nutrient to measure the integrated effect of manures, fertilizers, and Fimbristylis dichotoma residues on weed growth in boro rice field. Two rice varieties viz., BRRI dhan29 and BRRI dhan89; and six treatments total viz., Control (T1), Residues @ 3 t ha-1 + Recommended doses of inorganic fertilizers (T2), Residues @ 3 t ha-1 + Tricho-compost @5 t ha-1 (T3), Residues @ 3 t ha-1 + Tricho-compost @1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers (T4), Residues @ 3 t ha-1 + Tricho-compost @2.5 t ha-1 + 50% less than recommended doses of inorganic fertilizers (T5) and Residues @ 3 t ha-1 + Tricho-compost @3.75 t ha-1 + 75% less than recommended doses of inorganic fertilizers (T6) were taken. In the experiment, at 25 DAT (days after transplanting), BRRI dhan89 had the highest weed density (35.0) when no residue was applied, and BRRI dhan29 had the lowest (18.00) when 3 t ha-1 F. dichotoma residue with Tricho-compost @ 1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers were applied. At 55 DAT, BRRI dhan89 had the highest weed density (19.66) when no residue was administered, and the lowest (10.66) when 3 t ha-1 F. dichotoma residue was applied along with Tricho-compost @ 1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers. When it came to dry weight, at 25 DAT, BRRI dhan89 had the highest weed dry weight (3.76 g) when no residue was applied, and BRRI dhan29 had the lowest (1.72 g) when 3 t ha-1 F. dichotoma residue with Tricho-compost @1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers were applied. At 55 DAT, BRRI dhan89 had the highest weed dry weight (2.29 g) when no residue was sprayed, and the lowest (1.46 g) when 3 t ha-1 F. dichotoma residue with Tricho-compost @ 1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers were applied. The study's findings suggest that applying F. dichotoma residue and incorporating Tricho-compost @ 1.5 t ha-1 + 25% less than the recommended amounts of inorganic fertilizers may be able to suppress the growth of weeds and could a package in biological weed control strategy.

Regulation of eating quality, sensory aroma and 2-acetyl-1-pyrroline biosynthesis in fragrant rice through foliage application of aromatic compounds

The experiment was conducted at the research area of Sher-e-Bangla Agricultural University from 15 June 2022, to 25 November 2022 (Aman season) to evaluate the impact of aromatic compound application on fragrant rice. The experiment included two factors: factor 1 comprised four rice varieties (BRRI dhan34, BRRI dhan70, BRRI dhan80, and Tulshimala), and factor 2 comprised application of four aromatic compounds (L-proline, α-ketoglutaric acid, γ-aminobutyric acid, and sodium selenite). A randomized complete block design was employed with three replications. Results revealed significant effects of aromatic compound applications and/or rice varieties on grain eating qualities, sensory aroma and 2-acetyl-1-pyrroline, which were superior in Tulshimala and BRRI dhan34. α-Ketoglutaric acid and sodium selenite application improved water uptake ratio, amylose and amylopectin content, alkali spreading value, gel consistency, protein content, sensory aroma score, and kernel stickiness and tenderness of fragrant rice. Moreover, α-ketoglutaric acid application led to enhanced 2-acetyl-1-pyrroline content in Tulshimala and BRRI dhan34. Several eating quality and fragrance parameters were found either positively or negatively correlated. Apparent amylose content exhibited a negative correlation with stickiness of kernel. Sensory aroma and grain 2-AP content were also positively correlated.

Study of Genetic Diversity of Aromatic Rice Genotypes Using Random Amplified Polymorphic DNA Markers

The study of genetic variation in aromatic rice is necessary for enhancing and preserving its genetic makeup. In this study, we amplified four Random Amplified Polymorphic DNA (RAPD) markers from the genomes of 11 different aromatic rice genotypes in order to evaluate the genetic variation and relatedness in aromatic rice. The genotypes were collected from different sources- five of which were obtained from the Bangladesh Rice Research Institute, one from the Bangladesh Institute of Nuclear Agriculture, and the remaining five were local genotypes. In RAPD profiling, twenty-seven of the thirty-six bands that were generated by the four primers were polymorphic, resulting in an estimated average polymorphism of 47.22 percent. The average value of the polymorphic information content was 0.309 with a range from 0.165 to 0.456, indicating that the primers were effective to detect genetic diversity between the genotypes. The genetic diversity and Shannon information index across all of the genotypes and primers were 0.176 and 0.260, respectively, which indicated that there was a certain amount of genetic variation in the studied aromatic rice genotypes. Kalizira and Binadhan-9 genotypes had the smallest genetic distance (0.057), while it was the highest (0.406) between the BRRI dhan 34 and BRRI dhan 50. The genotype pairs BRRI dhan 38 vs BRRI dhan 34, BRRI dhan 38 and Kalizira, and Zirakatari and Kalizira had also a higher level (0.365) of genetic distances. The genotypes were grouped into two main clusters in the UPGMA dendrogram. Cluster I included five genotypes: BRRI dhan 34, Basmoti, Atashail, Kalizira, and Binadhan-9. Cluster II included remaining six genotypes: BR5, BRRI dhan 38, BRRI dhan 50, Uknimodhu, BRRI dhan 37, and Zirakatari. Documentation of the genetic variation and relatedness among the aromatic rice genotypes under this investigation could be useful for future research into the development of aromatic rice and related fields. J Bangladesh Agril Univ 22(3): 277-284, 2024

Influence of Grass Pea Residues Extract on Weed Control Efficacy and Performance of Boro Rice

The agriculture sector is constantly adopting environmentally friendly and sustainable methods to reduce the harmful effects of herbicides on crop production. In this respect, an experiment was conducted at the Agronomy Field Laboratory (AFL), Bangladesh Agricultural University (BAU), Mymensingh to assess the allelopathic effects of grass pea crop residues on weed suppression and the growth performance of Boro rice from December 2021 to May 2022. The experiment consisted of four cultivars of Boro rice i.e. BAU dhan3, BRRI dhan28, BRRI dhan81, BRRI dhan96 along with four different treatments of weed control viz. no extract and no weeding (control), hot water extract of Grass pea residues as pre-emergence application at 3 DAT (days after transplanting), hot water extract of Grass pea residues as pre-emergence application at 3 DAT+ post- emergence at 10 DAT, hand weeding 3 times at 15, 30 and 45 DAT. The highest weed growth was noticed when no extract was added and the lowest was found when three times hand weeding was performed. The highest number of effective tillers (NET) hill-1, number of spikelets panicle-1 (NSP) and grain yield (GY), straw yield (SY) and biological yield (BY) were recorded from the rice variety BAU dhan3. The highest NET hill-1, NSP, 1000-grain weight (TGW), GY, SY and BY were recorded from three hand weeding which was followed by hot water extract of grass pea as pre-emergence application at 3 DAT+ post-emergence application at 10 DAT. From the interaction it is observed that the highest NET hill-1, NSP, SY and BY were obtained from BAU dhan3 with three hand weeding which was followed by BAU dhan3 with hot water extract of grass pea as pre-emergence application at 3 DAT+ post-emergence application at 10 DAT. The findings of this study reveal that hand weeding, followed by the application of grass pea crop residues, effectively suppresses weed growth. Our research suggested leveraging the allelopathy-weed inverse relationship to address weed problems. This approach holds significant promise for weed management in the twenty-first century. J Bangladesh Agril Univ 22(3):360-368, 2024

Allelopathic effects of leaves extract of parthenium hysterophorus l. On seed germination of three Rice varieties

This study investigates the allelopathic effects of Parthenium hysterophorus L. leaf and root extracts on the germination and growth of three rice varieties (Hira dhan, BRRI dhan-28, and BRRI dhan-29) in Bangladesh. Leaf and root extracts of P. hysterophorus were prepared at different concentrations and applied to rice seeds in a controlled environment. Results showed that low concentrations of the extracts inhibited seed germination and growth, with significant differences among rice varieties (p < 0.05). Hira dhan exhibited the most sensitivity, with germination rates as low as 42.86% under high extract concentrations. In contrast, BRRI dhan-29 showed a stimulatory effect, particularly at low concentrations. The shoot and root lengths of Hira dhan and BRRI dhan-29 were significantly inhibited at higher concentrations, while BRRI dhan-28 demonstrated growth stimulation. The fresh and dry weights of roots and shoots varied significantly among the varieties with the greatest inhibitory effect observed in BRRI dhan-29. These findings align with previous studies, suggesting that allelochemicals in P. hysterophorus, such as parthenin and phenolic acids, play a critical role in inhibiting rice growth. The study emphasizes the need for further research on allelopathic interactions and suggests that controlling P. hysterophorus at the crop emergence stage could mitigate its suppressive effects on rice growth. Bangladesh J. Bot. 53(3): 411-421, 2024 (September)

Phylogenetic analyses and pathogenic diversity of Meloidogyne graminicola of rice (cv. BRRI Dhan28) from different agro-ecological zones of Bangladesh

Rice root-knot caused by Meloidogyne graminicola is a major yield-limiting factor in all rice growing countries around the world, which is often ignored in Bangladesh due to its subtle and obscure above ground symptoms. The current study proposes a comprehensive diagnosis of rice root-knot nematode at the molecular level and analyzes the pathogenic diversity of M. graminicola population of different AEZs. Rice seedlings of a popular variety (BRRI Dhan28) showing galls in the roots were collected from thirty Agro-Ecological-Zones (AEZs) of Bangladesh. For molecular identification, nuclear DNA was collected from single second-stage juvenile and internal transcribed spacer (ITS) was used as a universal primer. Molecular identification and phylogenetic analyses revealed that all nematode populations of galled rice seedlings from different locations belong to M. graminicola. The nematode populations constitute six phylogenetic clades. Nematode population of phylogenetic clade II showed the highest no. of galls (178 ± 1.67), although galling index was higher and similar in clade I, clade-II, clade-III and clade-VI. The highest percent reduction in both vegetative and yield-contributing traits were recorded in clade-II. A negative correlation was found in galling incidence and all growth and yield parameters. Comparative hatching of M. graminicola from different locations reveals that the pathogenicity of M. graminicola depends on the genetic variability of the nematode population, but not on the hatched juveniles. It might be concluded that the rice root-knot nematodes (M. graminicola) are prevalent in all agro-ecological zones of Bangladesh, despite the most pathogenic groups being frequent in AEZ- 1, 6, 7, 10, 18, 19, 21 and appropriate management initiatives are therefore crucial for maximizing rice yield.

Effect of Golden Dock (Rumex maritimus) Residues on Weed Growth Performance of Boro Rice (cv. BRRI dhan58 and BRRI dhan74)

Allelopathy plays an important role in weed control and crop productivity. We evaluated the effect of the residues of Rumex maritimus on the growth performance of boro rice comprising two cultivars i.e., BRRI dhan58 and BRRI dhan74 and four rates of R. maritimus residues treatment such as 0, 1.0, 2.0, 3.0 t/ha and a farmers practice. The experiment was laid out in a randomized complete block design (RCBD) with three replications. We identified four weed species (Panikachu, Shama, Shusni, Chesra) belonging to four families. Dry weight of Shama, Shusni, Chesra except Panikachu were significantly affected by variety. The highest Shama dry weight (6.61 g/0.0625 m2) was found in BRRI dhan74 and the lowest weed population (5.81 g/0.0625 m2) was obtained in BRRI dhan58 at 1% level of probability and also the highest Chesra dry weight (5.58 g/0.0625 m2) was found in BRRI dhan74 and the lowest weed population (4.89g/0.0625 m2) was obtained in BRRI dhan58 at 1% level of probability. The highest Shusni dry weight (5.11 g/0.0625 m2) was found in BRRI dhan58 and the lowest weed population (5.00 g/0.0625 m2) was obtained in BRRI dhan74 at a 1% level of probability. Weed density and dry weight were also significantly affected by variety and residue treatment. Results of this study indicate that R. maritimus residues showed the potential to inhibit weed growth of boro rice. Therefore, R. maritimus residues might be used as an alternative way for weed management in effective and sustainable crop production.

Combined hot water extract of lentil and grass pea increase weed control efficiency and yield of boro rice

The agriculture sector is continuously adopting environmentally friendly and sustainable methods to reduce the harmful effects of herbicides on crop production. In this context, an experiment was conducted at the Agronomy Field Laboratory (AFL), Bangladesh Agricultural University (BAU), Mymensingh, from December 2021 to May 2022, to investigate the effect of combined hot water extracts of lentil and grass peas (ELG) on weed control efficiency and yield performance of boro rice. The experiment involved four varieties of boro rice (BAU dhan3, BRRI dhan28, BRRI dhan81, and BRRI dhan96) and four treatments of crop residues. For most weed species, varieties and crop residue extracts significantly impacted weed population (WP) and weed dry weight (DW). The highest numbers of effective tillers (NET) hill-1, numbers of spikelets panicle-1 (NSP), 1000-grain weight (TGW), grain yield (GY), and straw yield (SY) were observed in the three-times hand weeding treatment. This was followed by the combination of hot water ELG applied as a pre-emergence treatment three days after transplanting and post-emergence ten days after transplanting, with the lowest values found in the no-extract treatment. Considering interaction effects, the highest GY (7.07 t ha-1) and SY (8.23 t ha-1) were observed with hand weeding combined with the variety BAU dhan3. The results of this study indicated that hand weeding, followed by the combined application ELG crop residue, showed potential activity to suppress WP and significantly affected the yield of boro rice.

Yield performance of aromatic fine rice as influenced by nitrogen fertilization and weed control techniques

Nitrogen fertilization and weed management is the major concern to yield maximization of rice. The study was conducted to assess the influence of nitrogen and weed control to yield improvement of aromatic rice BRRI dhan34. The experiment included three nitrogen levels viz. 50, 100 and 150 kg N ha-1 as well as three weeding schedules viz. one hand weeding at 15 days after transplanting (DAT), two hand weeding at 15 and 30 DAT and three hand weeding at 15, 30 and 45 DAT. The experiment was conducted with randomized complete block design. The findings demonstrated important correlations between weeding techniques, nitrogen levels and yield components. When the crop was fertilized with 50 kg N ha-1 the highest numbers of total tillers hill-1 (8.53), effective tillers hill-1 (7.51), grains panicle-1 (128.0) and grain yield (3.97 t ha-1) were resulted. Regarding weeding practices, two manual weeding carried out at 15 and 30 DAT reported the highest numbers of effective tillers hill-1 (7.62), grains panicle-1 (128.1) and grain yield (4.10 t ha-1). The highest effective tillers hill-1 (8.33), the most grains panicle-1 (129.8), the grain yield (4.36 t ha-1) and straw yield (6.40 t ha-1) were found in two hand weeding at 15 and 30 DAT combined with 50 kg N ha-1 and the lowest grain yield (3.53 t ha-1) was obtained from one hand weeding given at 15 DAT along with 150 kg N ha-1. Therefore, the study demonstrated that BRRI dhan34 can be fertilized with 50 kg N ha-1 along with two hand weeding at 15 and 30 DAT to obtained higher yield.