Aman Season Research Articles

Impact of supplemental irrigation and organic manure on growth and yield performance of rice variety BRRI dhan103 under terminal drought condition in Aman season

BRRI dhan103 is a transplanting Aman (T. Aman) rice variety that demands sufficient organic manure and supplemental irrigation to ensure successful production. Seven treatments, viz., T1= rainfed control; T2= one supplemental irrigation at 80 days after transplanting (DAT); T3= two supplemental irrigations at 70 and 80 DAT; T4= additional 5 t ha-1 poultry compost under rainfed condition; T5= additional 10 t ha-1 poultry compost under rainfed condition; T6= additional 2.5 t ha-1 biochar under rainfed condition; and T7= additional 5 t ha-1 biochar under rainfed condition, were evaluated against BRRI dhan103 to assess the impact of supplemental irrigation and manuring under terminal drought conditions. It was revealed that supplemental irrigation and manuring significantly improved all growth parameters and yield attributes compared to the rainfed control. Notably, T5 treatment provided its greatest performance statistically in respect of SPAD value (36.13), root dry weight (12.43 g), number of tillers hill-1 (13.22), panicle length (28.87 cm), panicles hill-1 at harvest (9.13), total spikelet (194.53), spikelet panicle-1 (197.63), filled spikelet panicle-1 (197.63), thousand grain weight (33.78 g), grain weight panicle-1 (28.70 g), grain yield hill-1 (31.97 g), and above-ground biological yield (3043.35 g m-2). The highest tiller hill-1 at harvest (9.53) was achieved when an additional 10 t ha-1 of poultry compost was applied under rainfed conditions. This study suggested that additional 10 t ha-1 poultry compost under rainfed conditions performed best to enhance the growth and yield of BRRI dhan103.

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.

Integrated Manure and Fertilizer Application: A Pathway to Enhanced Rice Yield and Soil Health

A research study was carried out in the Soil Science field laboratory of Bangladesh Agricultural University, Mymensingh during the Aman season of 2021 to examine the effect of various manure and fertilizer combinations for optimizing the growth and yield of rice. The experiment employed a Randomized Complete Block Design (RCBD) with 3 replications across eight treatments. The treatment combinations were: T­1 (Control), T2 (100% Recommended Fertilizer Dose (RFD)), T3 (75% RFD + Cowdung (CD) @ 5 t ha-1), T4 (75% RFD + Poultry manure (PM) @ 3 t ha-1), T5 (75% RFD + Compost @ 5 t ha-1), T6 (75% RFD + Dhaincha Green Manure (GM) @ 10 t ha-1), T7 (50% RFD +CD @ 2.5 t ha-1 + PM @ 1.5 t ha-1) and T8 (50% RFD + Compost @ 2.5 t ha­-1 + Dhaincha GM 5 t ha-1). Statistical analysis conducted using R programming revealed that T6 markedly improved growth metrics and yield-related traits, leading to a 12.2% rise in grain yield and a 13.24% rise in straw yield compared to T2, where only chemical fertilizers were applied. This treatment also achieved the greatest macronutrient content and uptake, outperforming other treatments (T3, T4, and T5) with equal nutrient amounts. Therefore, application of 75% recommended fertilizer dose along with dhaincha green manure (10 t ha-1) offers a promising strategy for successfully cultivating BRRI dhan71 with a good soil health. This approach offers farmers a cost-effective method to boost productivity and support long-term soil fertility, and policymakers could promote it to enhance agricultural sustainability.

Evaluation of Transplanted Aman Rice by Exploiting and Adjusting Existing Technologies

Varietal differences are a common occurrence in rice cultivation across Bangladesh. Moreover, the application of appropriate management practices (MP) is essential for optimal rice production. Against this backdrop, a study was conducted at the Agronomy Field Laboratory (AFL) of Bangladesh Agricultural University (BAU), Mymensingh, during the aman season from July to December 2023. The aim was to assess the impact of different varieties and MP on the yield and other related attributes of Transplanted Aman (T. aman) rice. The study featured five rice varieties: BR11, BRRI dhan49, BRRI dhan52, BRRI dhan75, and BRRI dhan87 and two MP, namely Farmers’ Practices (FP) and Improved Practices (IP). The experimental design was a split plot, with MP as the main plots and varieties as the subplots, replicated three times. The findings indicated that both the variety of rice and the MP significantly influenced the yield and yield-related traits. Specifically, the variety BRRI dhan87 showed superior performance, yielding the highest plant height (PH) (116.87 cm), panicle length (PL) (25.33 cm), number of effective tillers (NET) hiil-1 (10.33), number of grains panicle-1 (NGP) (129.04), 1000 grain weight (TGW) (26.03 g), Biological yield (BY) (11.88 t ha-1), grain yield (GY) (5.69 t ha-1), Harvest index (HI) (47.81%). Under the MP, the IP recorded the highest NET hiil-1 (10.47), NGP (119.35), and GY (5.48 t ha-1), showing a 13.14% increase in GY over the FP. The combination of BRRI dhan87 and IP achieved the highest GY (6.31 t ha-1). The study concludes that the highest GY of T. aman rice can be achieved by cultivating BRRI dhan87 with IP, although further trials at various locations are recommended before drawing final conclusions.

Synergistic Antifungal Activity of Green Synthesized Zinc Oxide Nanoparticles and Fungicide Against Rhizoctonia solani Causing Rice Sheath Blight Disease.

The biosynthesis of metal oxide nanoparticles using leaf extract of medicinal plants is a promising substitute for the traditional chemical method. This work aimed to synthesize zinc oxide nanoparticles using a green approach from local "Dholkolmi" (Ipomoea carnea) leaf extract which is a medicinal plant growing outside the roads of different regions of Bangladesh. The biosynthesized zinc oxide nanoparticles (ZnONPs) were characterized using ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, particle size analyzer, zeta-potential, scanning electron microscopy-energy dispersive spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The results of UV-visible spectrophotometers observed an absorption peak at 373 nm wavelength, which confirmed the synthesis of ZnONPs in the solution. ZnONP sizes determined by XRD, DLS, and TEM are approximately ~37 nm, 105.61 nm, and 19.66 nm, respectively. ZnONPs were present because of the strong oxygen and zinc signals in the EDX profile. Additionally, this research assessed the antifungal activity of the biosynthesized ZnONPs and as well as folicur-incorporated ZnONPs against Rhizoctonia solani by the poison bait technique. According to the result of this study, ZnONPs synthesized from Ipomoea carnea leaf extract showed no promising result against Rhizoctonia solani mycelial growth reduction. But folicur-incorporated ZnONPs revealed a significant finding with a maximum 100% inhibition of mycelial growth at 1:1 and 3:1 ratio of ZnONPs with folicur fungicide under in vitro conditions. In the net house experiment, folicur-incorporated ZnONPs at a 1:1 ratio of ZnONPs with folicur showed considerable disease inhibition (26.96% RLH) as compared to disease control (52.83% RLH). In the case of rainfed transplanted Aus (March-June), the highest percentage of RLH was recorded in disease control (64.61%), and the lowest RLH was found in folicur (24.79%) followed by a 1:1 ratio of ZnONPs with folicur (32.10%) in field condition. On the other hand, the highest percentage of RLH was recorded in disease control (65.31%) and the lowest RLH was found in folicur (18.14%) followed by a 1:1 ratio of ZnONPs with folicur (21.39%) in rainfed transplanted Aman (July-November) season. The findings of the in vitro and in vivo studies provided evidence that ZnONPs and folicur had a strong synergistic antifungal impact and may be employed as a possible rice sheath blight disease management agent.

Impact of Harvesting Time on Grain Yield, Physicochemical Attributes, and 2-Acetyl-1-pyrroline Biosynthesis in Aromatic Rice

Achieving a consistent grain yield while preserving persistent aroma remains a substantial challenge in aromatic rice production in Bangladesh. To address this challenge, a field experiment was conducted at the agronomy research area of Sher-e-Bangla Agricultural University, Dhaka-1207, between 15 June 2022, and 25 November 2022 (Aman season). This study aimed to evaluate the influence of harvesting time on aromatic rice performance. The experiment, following a randomized complete block design with three replications, involved two factors: factor 1 comprised various rice varieties [Bangladesh Rice Research Institute (BRRI) dhan34, BRRI dhan70, BRRI dhan80, and Tulshimala], and factor 2 comprised three harvesting times [3, 4, and 5 weeks after flowering (WAF)]. Results revealed significant impacts of variety and/or harvesting time on grain yield, physicochemical characteristics, and aroma of aromatic rice. Notably, Tulshimala and BRRI dhan80 exhibited superior milling quality, biochemical properties, and aroma characteristics among the aromatic rice types. BRRI dhan70 and BRRI dhan80 displayed higher grain yield when harvested at 5 WAF. However, Tulshimala and BRRI dhan80 showed superiority in grain 2-acetyl-1-pyrroline (2-AP) concentration when harvested 3 or 4 WAF. Earlier harvesting at 3 and 4 WAF resulted in higher percentages of grain 2-AP (60.22% and 53.96%, respectively) compared with later harvesting at 5 WAF (used as check). In conclusion, varying harvesting times markedly impact the yield, physiochemical characteristics, and aroma of aromatic rice varieties, with earlier harvesting beneficial for aroma retention in Tulshimala and BRRI Dhan80 and later harvesting for increased economic yield in BRRI dhan70 and BRRI dhan80.

Area coverage of BINA developed rice, pulse, oilseed and horticultural crop varieties in Bangladesh

The study was conducted to assess the area coverage of BINA developed rice, pulse, oilseed and horticultural crop varieties during 2022-23. Field survey data were collected from 64 districts through concern DD, DAE office. Both tabular and descriptive statistical analysis was used. It was observed that the overall area coverage of BINA developed rice varieties were 8.91%. Among the three seasons; Aus, Aman and Boro the highest area coverage was found in Aman season that was 14.54% followed by Aus 5.95% and Boro 2.93%, respectively. Among the 14 agricultural regions the highest area coverage of rice was found 15.41% in Rajshahi region (Reg-7) and the lowest was found 1.01% in Dhaka region (Reg-11). The overall area coverage of BINA developed pulse varieties were 16.32% and among the 14 regions the highest area coverage for pulses was found in Barishal region 58.51% (Reg-6). The overall area coverage of BINA developed oilseed varieties were 23.46% and among the 14 regions the highest area coverage for oilseed was found in Jashore region 16.32% (Reg-13). Among the BINA developed horticultural varieties the highest area coverage was found 4.46% for Binalebu-1 followed by Binahalud-1 (0.93%) and Binatomato-10 (0.36%). It was also observed that, among the 14 regions the highest area coverage for Binalebu-1 and Binahalud-1 were found in Rangamati agricultural region (region-4) about 483 ha (87.26%) and 45 ha (18.19%), respectively. The study identified that the overall area coverage of BINA developed rice, pulse and oilseed crops for distributed seed were 0.93%, 1.41% and 3.45%, respectively. The study also observed some constraints such as-non availability of seed, lack of training, demonstrations, field day, collaboration etc. For continuation of variety expansion, the institute should ensure quality seed supply in proper time and training, demonstration as well as collaboration among other research institutes, DAE, BADC and NGOs should be emphasized. Bangladesh J. Nuclear Agric, 37(2): 89-107, 2023

Development of Submergence Tolerant Rice Variety BRRI dhan79 for Flash Flood Ecosystem of Bangladesh

Tolerance to submergence stress is an important breeding objective for the areas where rice cultivars are subjected to complete inundation for a week or more. Submergence tolerance is an important trait for rice (Oryza sativa L.) in the flash flood-prone ecosystem. The trait is largely controlled by a major gene designated as Sub1 located on chromosome 9. Submergence of rice (Oryza sativa) by flash flooding is a major constraint to rice production in Bangladesh. Quantitative trait loci analyses have revealed that a large portion of this variation in submergence tolerance can be explained by Sub1. A newly released submergence tolerant rice variety namely BRRI dhan79 was developed by hybridization between BRRI dhan49*6/BRRI dhan52 through Marker Assisted Backcrossing and selection method where BRRI dhan52 (submergence tolerant mega variety in Bangladesh) used as Sub1 donor. It can tolerate upto three weeks complete submergence at vegetative stage whereas Sub1 donor mega variety BRRI dhan52 can tolerate on an average two weeks complete submergence condition. It can also tolerate 50-60 cm water stagnation for 15-20 days after de-submergence. The variety has satisfactorily been passed in the proposed variety trial conducted in flash flood prone farmers' field in Bangladesh. As a result, the National Seed Board (NSB) of Bangladesh approved this rice variety for commercial cultivation for the flash flood affected rainfed lowland ecosystem (Transplanted Aman season) in 2017. It meet up all the trait of modern plant likely medium plant heihght (112 cm), strong and stature culm structure, erect flag leaf with stay green leaf at maturity stage and high yield potential with 140 days growth duration (in case of three weeks submergence mature by 160 days). It can produce 5.5 t/ha grain yield under non-stress condition and 4.0-4.5 t/ha yield under three weeks submergence condition. The grain shape of the variety is medium bold. The rice production scenario in flash flood affected region of Bangladesh has been remarkably improved after releasing this rice variety. It has not only change the socio-economic status of farmers but also sustaining food security.

Enhancing Transplant Aman Rice Productivity through NPK Fertilizer Split Application Scheduling Under Zero Till Non-Puddled Condition

This experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh to evaluate the varietal response of split application of NPK fertilizer application schedule on transplant aman rice under zero till non-puddled condition. The experiment comprised three rice varieties viz. Bashiraj (local), BRRI dhan49 (inbred), Dhanigold (hybrid); and seven NPK fertilizer application schedules. The experiment was laid out in a randomized complete block design with three replications. The effect of variety, NPK fertilizer split application schedule and their interaction showed significant variation on the yield attributes and yield of aman rice. In interaction, the highest number of effective tillers hill-1 (11.66), total spikelets panicle-1 (164.00), grains panicle-1 (151.22), 1000-grain weight (38.70 g), grain yield (5.67 t ha-1) and harvest index (60.36%) were obtained from hybrid variety Dhanigold when fertilized following 3-splits of N [1/3 at 14 days after transplanting (DAT) + 1/3 at maximum tillering (MT)+ 1/3 at panicle initiation (PI)] and P (1/3 as basal + 1/3 at MT + 1/3 at PI ), and single split of K as basal (full dose). Same treatment combination also provides the highest yield of BRRI dhan49, but the local Bashiraj gave the highest yield at recommended practice where only N was top-dressed at 3 splits. Based on this result, it may be concluded that for better productivity hybrid Dhanigold and inbred BRRI dhan49 might be fertilized with 3-splits of N (1/3 at 14 DAT + 1/3 at MT + 1/3 at PI) and P (1/3 as basal + 1/3 at MT + 1/3 at PI) and full dose of K as basal during aman season under zero till non-puddled condition. On the other hand, for local variety Bashiraj 3-spilts of N either [½ as basal + ¼ at active tillering (AT) + ¼ at PI] or N (1/3 at 7 DAT + 1/3 at MT + 1/3 at PI) and P, K as single split as basal appeared as the best application schedule.

Development of Multi-Parent Advanced Generation Intercross (MAGIC) Mapping Population for QTL Analysis in Rice

A major advantage for researchers in plant and animal genetics lies in the ability to create experimental populations. Such populations mix well characterized founder genomes in controlled pedigrees, and facilitate the investigation of both the genome itself and its relationship with traits and the environment. Traditional experimental populations combine the genomes of two parents with contrasting phenotypes to identify regions of the genome affecting the trait. However, each of these populations captures only a small snapshot of the factors affecting the trait due to the narrow genetic base. It is only possible to detect those genomic regions which differ between the two founders, and all alleles occur with high frequency in the population. Recently, a multi-parent advanced generation intercross (MAGIC) strategy has been proposed to interrogate multiple alleles and to provide increased recombination and mapping resolution. The main objective of developing MAGIC populations is to promote intercrossing and shuffling of the genome, thus increased precision and resolution with which QTLs can be detected due to the increased level of recombination. The Global MAGIC is an attempt to combine traits from several gene pools that have been adapted to different environments. In addition to being a source of potential novel variation, the Global MAGIC population provides useful materials for studying the relative contributions from different crop ecotypes and the level of recombination among exploited genomes constituting this population. An eight Parent-based rice MAGIC population was initiated to develop by employing 2-way, 4-way and 8-way cross along with 8-way intercross hybridization. Nonetheless, the 2-way (Single cross), 4-way (Double cross hybrid) cross has completed during the first year of research program (2018-2019) and subsequently, 8-way cross giving rise to 2 sets (8-wcp set1) having genome ABCDEFGH and 8-wcp set-2 with genome EFGHABCD) of 8-way cross F1 genotypes has accomplished at Aman season of second year (2019-2020) of the project. The eight-way crosses of set 1 (8-wcp set-1) were further intercrossed (Boro 2019) with the reciprocal eight-way crosses set 2 (8-wcp set -2) for establishing altogether 85 eight-way intercross combinations (ABCDEFGH/EFGHABCD) and then, we render this 1-85 group as BUMpop (Bangabandhu University Mapping Population). Progeny from each of the eighty-five 8-way intercrosses were grown, keeping ~ 4 offspring per cross constituting the population size as 85 × 4 = 340 lines. The seeds of BUMpop were progressed to the F6 generation via single seed descent (SSD) method in the field.

Spatio-temporal variability of climatic variables and its impacts on rice yield in Bangladesh

Bangladesh is a significant contributor to the global food basket but is also one of the most vulnerable countries to climate change. Understanding regional climatic variability helps reduce climate risks and ensure food security. This research examined monthly, seasonal, and yearly temperature, rainfall, and relative humidity in Bangladesh using data from 35 meteorological stations from 1970–2020. The study utilized the Mann–Kendall method to evaluate trends and employed Sen’s slope to quantify their magnitude. Additionally, quantile regression was applied to analyze the impact of climatic variables on rice yield. The findings revealed that maximum (Tmax) and minimum (Tmin) temperatures were steadily increasing, with the southwest experiencing a more rapid rise compared to other regions in Bangladesh. Seasonal Tmax and Tmin rose in most parts of Bangladesh, particularly during the monsoon. In most areas, there was a significant (p < 0.05) increase in Tmax from June to September and Tmin in December. The variability of minimum temperature was considerably affected by warming throughout the country. The eastern area had the most significant (p < 0.05) annual rainfall increase rate, while the northern region had the lowest. There was evidence of inter-seasonal rainfall shipment, with post-monsoon rainfall rising compared to monsoon season. The quantile regression showed that the rice yield of Aus (summer) and Aman (wet) seasons were influenced by maximum temperature and relative humidity, whereas the rice yield of the Boro (dry) season was affected by maximum temperature, rainfall, and relative humidity. Across geographical segmentation, the regression analysis indicated a high level of variability in the northern climate. Overall, the intensity of mean temperature increased throughout the country. So, there is a need to develop heat or drought-resistant rice varieties and modernized irrigation facilities to mitigate these climate risks. However, farmers should employ automated weather-based advisory services for sustaining rice productivity and food security.

Crop production amid climate change and river water level fluctuation at northeastern region of Bangladesh: A time series analysis

The overall goal of this study was to examine the effects of climate change on the yield of four distinct crops (Aus, Aman, Boro and Wheat) in Sylhet by using secondary climate data from 1970 to 2020. The study's other goal is to assess the impact of river water levels on crop productivity in Sylhet over time. Data on crop productivity, weather variability and river water levels were gathered from the various fields. Yield vs. climatic correlation was discovered in the study, and this correlation varied according to season. To estimate the impact of climate change on rice yield, a multiple regression model is used. Climate variables in the model were found to account for 11% of the overall variation in Aus rice yield. The relationship between relative humidity and maximum temperature is positive and statistically significant. Other variables had no effect on yield because they were not significant. Furthermore, Regression results indicated that climate variables account for 60.6 percent of the overall variation in Aman rice output. Relative humidity, on the other hand, can undermine the yield. Climate variables account for 53.5 percent of the overall variation in Boro rice output, according to the findings. As a result, an increase in rainfall may have a negative impact on Boro rice yield. Maximum and minimum temperatures might have a favorable impact on Boro rice yield. Increases in maximum temperature, on the other hand, can considerably boost Wheat yield while decreases in minimum temperature can diminish Wheat yield. On the other side, the results of the regression analysis suggest that river water level has a minor impact on Aus, Aman, and Boro yield. However, as the model demonstrates, the river water level can have an impact on wheat yield. The impact of temperature and rainfall on water level was also investigated in this study because the regression model failed to produce positive results. Surprisingly, the model performs well, despite the fact that maximum temperatures have a negative impact on water levels in the Aus and Aman seasons. This shows that if warmer temperatures aid raises Aus and Aman yields, then the water level cannot sabotage the yield rise. Rainfall has a favorable impact on the water levels in the Aus, Aman, and Boro seasons, but has a negative impact on the water levels in the Wheat season. Int. J. Agril. Res. Innov. Tech. 12(2): 18-26, December 2022

Integrated Nitrogen Management on Weed Growth and Yield Performance of Transplant Aman Rice

Rice requires nitrogen in larger quantities than any other nutrient, and it is the most critical limiting factor that influences grain yield. But inappropriate sources and management of nitrogen is considered to be the most critical one among the various reasons of low rice productivity. In order to address the problem, an experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, during June to October 2020 to determine the effect of integrated nitrogen management (INM) on weed growth and yield of transplant aman rice. The experiment comprised five aman rice varieties, viz. Binadhan-7 (V1), BRRI dhan56 (V2), BRRI dhan66 (V3), BRRI dhan71 (V4) and BRRI dhan75 (V5) and four nitrogen management approaches: control (no nitrogen) (N0), 100% of recommended dose (RD) of nitrogenous fertilizer as prilled urea (150 kg ha-1) (N1), 2.5 t ha-1 poultry manure + 75% of RD of nitrogenous fertilizer as prilled urea (112.5 kg ha-1) (N2) and application of USG (1.8 g per 4 hills) (N3). Results reveal that maximum weed density and dry weight were found in BRRI dhan56 whereas minimum ones were observed in BRRI dhan66. In case of INM, application of 100% of RD of nitrogenous fertilizer as prilled urea showed maximum weed density and dry weight but minimum ones were found with application of USG. In combine, weed density and dry weight were found highest in BRRI dhan56 with 100% of RD of urea and the lowest weed density was found in BRRI dhan66 with no nitrogen treatment at 20 DAT and in BRRI dhan66 with application of USG at 35 DAT and lowest weed dry weight was obtained from Binadhan-7 with application of USG (1.8 g per 4 hills) at 20 and 35 DAT. Variety Binadhan-7 showed superior performance in terms of yield and yield attributes. Application of USG showed the highest number of grains panicle-1 and grain yield. Interaction of Binadhan-7 with application of USG produced highest number of grains panicle-1 (116.60), highest grain yield (5.21 t ha-1), biological yield (10.94 t ha-1), harvest index (47.65%) and highest BCR (1.57). So, results indicated that Binadhan-7 with application of USG (1.8 g per 4 hills) might be recommended for obtaining highest grain yield with higher nitrogen use efficiency, highest BCR as well as to control weed more effectively in aman season.

GENETIC ANALYSIS OF LOCAL AMAN RICE (ORYZA SATIVA L.) GENOTYPES BASED ON MORPHOLOGICAL TRAITS

Rice is the staple food for the majority of the global populations and the nutritional traits improvement is the prime priority for rice breeding. The study was carried out with 30 local rice varieties including two checks during the aman season of 2021 at BIRTAN, Noakhali, Bangladesh. Significant differences were found among the cultivars for the studied parameters. The lowest days to maturity were observed in both RS 40 and RS 56. The highest grain yield per plant was observed in RS 31, followed by RS 17 and RS 22 as compared with check. The number of panicles and filled grains per panicle were the most contributing variables. Genetic distances of genotypes ranged from 0.086 to 4.262. Considering the overall diversity pattern, grain yield, and other agronomic traits, RS17, RS22, RS29, RS31, and RS42 have been selected as promising genotypes for further yield and nutritional traits improvement through hybridization.

Reclamation of Coastal Soil Salinity towards Sustainable Rice Production and Mitigating Global Warming Potentials in the Changing Climate

Soil salinity has become a major constraint to rice productivity in the coastal region of Bangladesh, which threatened food security. Therefore, field experiment was conducted at salt stressed Shyamnagor Upazilla of Satkhira district to improve the soil salinity status, sustainable rice production and suppression of global warming potentials. Selected soil amendments viz. trichocompost, tea waste compost, azolla compost and phospho-gypsum (PG) were applied in the field plots one week prior to rice transplanting. In addition, proline solution (25 mM) was applied on the transplanted rice plants at active vegetative stage. Gas samples from the paddy field were collected by Closed Chamber technique and analyzed in by Gas Chromatograph. The 25% replacement of chemical fertilizer (i.e., 75% NPKS) with trichocompost, tea waste compost, Azolla compost and Phospho-gypsum amendments increased grain yield by 4.7% - 7.0%, 2.3% - 7.1% 11.9% - 16.6% and 9.5% - 14.2% during dry boro rice cultivation, while grain yield increments of 5.0% - 7.6%, 2.3% - 10.2%, 12.8% - 15.3% and 10.2% - 15.3% were recorded in wet Aman season respectively, compared to chemically fertilized (100% NPKS) field plot. The least GWPs 3575 and 3650 kg CO2 eq./ha were found in PG Cyanobacterial mixture with proline (T10) and tea waste compost with proline (T8) amended rice field, while the maximum GWPs 4725 and 4500 kg CO2 eq./ha were recorded in NPKS fertilized (100%, T2) and NPKS (75%) with Azolla compost (T5) amended plots during dry boro rice cultivation. The overall soil properties improved significantly with the selected soil amendments, while soil electrical conductivity (EC), soil pH and Na+ cation in the amended soil decreased, eventually improved the soil salinity status. Conclusively, phospho-gypsum amendments with cyanobacteria inoculation and proline solution (25 mM) application could be an effective option to reclaim coastal saline soils, sustaining rice productivity and reducing global warming potentials.

PERFORMANCE STUDY OF A WALKING TYPE 4-ROW MECHANICAL RICE TRANSPLANTER

A study was carried out at Bangladesh Rice Research Institute, Regional Station, Rangpur along with laboratory test and farmers field in Fulgachi, Lalmonirhat for field test during Aman season with BRRI dhan52 to identify the effect of plant spacing of transplanter on grain yield. Three levels of plant spacing (30 cm×13 cm, 30 cm×15 cm, 30 cm×17 cm), seedling density setting (Middle, Middle+1 and Middle+2) and RCBD with 9 plots were used for the purpose. In field experiment, three plant spacing and Middle+2 seedling density setting was used. In this walking type self-propelled rice transplanter, the field capacity, field efficiency and fuel consumption of the transplanter were 0.134 ha hr-1 , 68 % and 3.71 L ha-1 , respectively. Labor requirement for mechanical and manual transplanting were 6.75 man ha/hr and 223 men hour per hectare respectively. Cost of mechanical transplanting was Tk. 3291 per hectare as compared to Tk.13000 per hectare in case of manual transplanting. If the usage of this machine per year decreases, the operating cost per hectare will increase. From breakeven analysis with mechanical and manual operating cost, it was found that transplanter should use at least 11 hectares per year to minimize the operation cost per hectare. For 17 cm, 15 cm and 13 cm plant spacing, number of tray requirement were 218, 270 and 277 per hectare, respectively. Number of seedling tray saved for 17 cm and 15 cm spacing were 21 % and 2.53 % compared with 13 cm spacing. In 30 cm×17 cm spacing, minimum number of seedlings required maximum no. of tray saved. Grain yield in different spacing (30 cm×13 cm, 30 cm ×15 cm, 30 cm ×17 cm) and manual transplanting were 4.43, 4.97, 5.23, 4.13 t ha-1 , respectively. Results showed that, highest grain yield among plant spacing was found 5.23 t ha-1 from 30 cm×17 cm.

Seed Quality of Transplanted Aman Rice as Impacted by Rainfed in the Ripening Phase

Rainfall is the main contributor to provide soil moisture for rainfed rice (Transplanted Aman) cultivation. The aim of the study was to investigate the seed quality of different transplanted Aman rice cultivars that are influenced by rainfed during ripening phases. For this, several experiments have been performed during the transplanted Aman season of 2014, 2015, and 2016 at the Bangladesh Rice Research Institute, Gazipur. Two planting dates and three rice varieties were used in the treatment, and the treatments were organized in a randomized complete block design with three replications. T. Aman rice received huge rainfall up to vegetative phage resulting no irrigation demand in all three tested years. In all the parameters of yield and yield components, the association between planting dates and variety was not significant. Also the relationship between planting dates and variety did not greatly affect the germination percentage, seedling vigor index, high density grain shoot dry weight, and root dry weight. Sixteen august planting produced a greater number of tillers m-2, panicles m-2, grain panicle-1, 1000-grain weight, grain and straw yield in the case of yield and yield components. While, the 1000-grain weight of panicles m-2, grain panicle-1, was greatly influenced by the variety. The highest 1000 grain weight and grain yield were produced by BRRI dhan46. The SVI, HDG percent, SDW and RDW were greatly influenced by planting dates in terms of seed quality. All of these criteria were higher for planting on 16 August than for planting on 12 September. Early transplanting received more rainfall in reproductive phase than late planting. Varieties were greatly influenced by all the seed quality parameters. BRRI dhan46 received the highest GM percent, SVI, HDG percent, SDW and RDW. Specific suitable transplanting dates were selected considering minimum irrigation at reproductive phage and maximun seed quality and grain yield. Delay in transplanting demanded more irrigation and reduced seed quality and grain yield.

A Comparative Study on Hybrid and Inbred Rice Grown in Aman Season

This experiment was conducted at the experimental field of Sher-e-Bangla Agricultural University, Dhaka during the period from July to December, with a view to finding out the growth and yield performance of selected hybrid and inbred rice varieties in Aman season. There were seven treatments which comprised seven rice varieties viz. Gold-5, BRRI dhan56, BRRI dhan57, BRRI dhan62, Suborna-3, BRRI hybrid dhan4 and Moyna. The experiment layout was RCBD with three replications. Seedling of 25 days old was transplanted to the main field maintaining spacing with 25 cm X 15 cm. The plot size was 3X3m2. Collected data were analyzed with statistix10 software following the standard procedure and method. Significant variation was found among the selected inbred and hybrid rice varieties in respect of their different growth and yield characters. All the hybrid varieties contained higher amount of chlorophyll in their flag leaf at flowering to maturity compared to the inbred. BRRI hybrid dhan4 showed superiority over the hybrid and inbred varieties in different growth parameters. BRRI hybrid dhan4 also showed superiority in case of yield parameters such as panicles (14.27), filled grains panicle-1(168.43), 1000-grain weight (26.07 g), biological yield (13.33 t ha-1) and grain yield (6.13 t ha-1). Rest of the hybrid varieties viz. Shuborna 3 (5.60 t ha-1), Gold (5.15 t ha-1) and Moyna (4.86t ha-1) also provided higher grain yield compared to BRRI dhan56 (4.63 t ha-1) and BRRI dhan57 (4.25 t ha-1). Panicles hill-1, filled grains panicle-1 and 1000 grain weight mainly contributed to the higher grain yield of the hybrid varieties over the inbred.

Effect of Nitrogen Management at the Reproductive Phase in Transplanted Rice

Nitrogen (N) is not only a major nutrient but also the most limiting nutrient element for rice cultivation. Efficient N fertilizer management is critical for the economic production of rice and the long-term protection of environmental quality. Considering the above facts, two field experiments were designed at Bangladesh Rice Research Institute (BRRI) farm, Gazipur, Bangladesh during the transplanting Aman season (July to November), 2018-19 and the Boro season (December to May), 2019-20 to study the effects of four different N management on growth, yield attributes, yield and nitrogen uptake by rice variety BRRI dhan75 and BRRI dhan89. The experiment was laid out in a randomized complete block design involving four different N management at different stages (Active tillering, Panicle initiation, Flowering and Heading) replicated three times. Results revealed that 69 kg N ha-1 (29.5 kg as basal + 29.5 kg at 15 DAT + 10 kg ha-1 at heading) would be a better option for higher yield in T. Aman rice While 120 kg N ha-1 (23 kg as basal + 40 kg at 20 DAT + 40 kg at 40 DAT + 17 kg ha-1 at heading) significantly improved growth, yield attributes and grain yield as well as nitrogen uptake by grain and straw. From the results, it can be said that application of N @10 kg ha-1 for T. Aman rice and N @17 kg ha-1 for Boro rice at the heading stage would reduce sterility and give a higher yield than BRRI recommended management. Hence, the study suggests that nitrogen management at the reproductive phase gives better performance to the T. Aman and Boro rice.

Response of Biochar on Growth and Yield of Aman Rice Under Salt Stress

A pot experiment was conducted in Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during aman season, 2018 to assess the effect of biochar on rice (BRRI dhan62) under salt stress conditions. The factorial experiment was laid out in Randomized Complete Block Design (RCBD) with four replications. Three levels of salinity were used viz. Control (S0), 1600 ppm NaCl (S1), and 2800 ppm NaCl (S2) under factor A and four levels of biochar were applied viz. 0 t ha−1 (B0), 2 t ha−1 (B1), 4 t ha−1 (B2) and 6 t ha−1 (B3) under factor B. The salt materials were added on pot in two installments at 20 and 30 days after transplanting (DAT). Exposure to salinity decreased growth and yield of rice including plant height, tillers hill-1, effective tillers hill-1, grains panicle-1, 1000-grain weight, grain yield and straw yield. The magnitude of growth and yield reduction increased with increasing the salinity level. Exposure of 1600 ppm and 2800 ppm NaCl declined the grain yield of rice by 28 and 100%, respectively. Straw yield (18 and 100%, respectively) and other yield contributing parameters declined by these two levels of salinity in the same way. Application of different levels of biochar ameliorated saltinduced damages to a certain extent. Under 2800 ppm NaCl stress, application of biochar extended life duration of rice plant upto 80 DAT, whereas without biochar application rice plant died after 60 DAT. Upon exposure to 1600 ppm NaCl stress, application of 2, 4 and 6 t ha−1 of biochar increased grain yield by 37, 42 and 30%, respectively, compared with the respective salt treatments (without biochar). Biochar enhanced yield of rice under saline conditions by enhancing yield contributing attributes including effective tillers and 1000-grain weight and by reducing salt-induced damages. However, response of 4 t ha−1 of biochar was best among the biochar levels (2, 4 and 6 t ha−1 of biochar) under both saline and non-saline conditions. Bangladesh Agron. J. 2022, 25(1): 105-113