BRRI Dhan29 Research Articles

Inspection of paddy seed varietal purity using machine vision and multivariate analysis

Abstract Seed varietal purity is vital to establish a uniform plant population. If the seeds are impure, it creates an unhealthy plant population that brings labor-intensive crop production. In this study, a rapid inspection method was established to classify the paddy seed based on varietal purity using a machine vision technique with multivariate analysis methods. Three varieties of paddy seeds were taken, namely - BR 11, BRRI dhan 28 and BRRI dhan 29. The individual paddy seed image was captured using an RGB camera with white LED lighting conditions in the laboratory. An image processing algorithm was developed for extracting 20 important features (seven color features, nine morphological features, and four textural features) from 375 paddy seed images. In the next step, the significant difference of extracted features data among the paddy varieties was studied using variance analysis. Also, the principal component analysis was performed to explore the separability of paddy seed varieties. Accordingly, the paddy seed variety classification models were developed for the combination of paddy varieties and selected feature data using partial least squares-discriminant analysis (PLS-DA), Support vector machine-classification (SVM-C) and K-Nearest Neighbors (KNN) algorithm. During model development, it was seen that the morphological image features were more significant compare to color and textural image features. The accuracy of 83.8%, 93.9%, and 87.2% was achieved using combined selected features of color, morphological, and textural for the PLS-DA, SVM-C, and KNN model, respectively. Finally, it was stated that the SVM-C algorithm with selected features of color, morphological, and textural could be used to classify the paddy seed variety.

Yield and morpho physical characters of some modern aus rice varieties at Khagrachari

Aus, aman and boro are three rice cultivating seasons in Bangladesh. Among these aus is the least cultivated and grown in comparatively small scale due to prevailing drought and less availability of surface water for irrigation. Modern varieties of aus rice cover a significant area of the country conversely local cultivars cover a small area. Aus rice requires much fewer inputs than aman and boro. Due to continuous declination of groundwater level, nowadays more emphasis is given on the extension of aus cultivation throughout the country. The present field study tested yield and morphological attributes of six developed aus rice varieties viz. Binadhan-14, Binadhan-19, BRRI dhan43, BRRI dhan48, BRRI dhan55 and BRRI dhan65 to characterize yield, maturity and phenological properties. The field trial was set at Satvaiyapara of Khagrachari during 2018 following Randomized Complete Block design with dispersed plots. All data were collected at harvest and analysed statistically by Statistix 10. Findings revealed that statistically highest grain yield was produced from BRRI dhan55 (4.49 t/ha) and BRRI dhan48 (4.48 t/ha); the lowest by BRRI dhan65 (3.06 t/ ha). The yield of Binadhan-19 (4.37 t/ha) and Binadhan-14 (3.87 t/ha) was intermediate. In case of maturity, Binadhan-19 (99.33 days) had the shortest life duration and BRRI dhan48 (113.67 days), the longest. The greater portion of the farmers was keen to grow Binadhan-19 and Binadhan-14 instead of BRRI dhan43 and BRRI dhan48 mainly for its short duration, optimal yield, long and slender quality grain. Binadhan-19 might be a promising aus variety in the Khagrachari hill tracts for gaining favourable yield within a short time. Therefore, further studies are needed in jhum cultivation with local cultivars for more significant comparison and acceptability to the rice farming community.

Shading effect of multipurpose trees on growth and yield of Boro rice cv. BRRI dhan29

A field experiment was conducted during Rabi season (December-May) to compare the vegetative growth and yield of Boro rice cv. BRRI dhan29 under tree shade and ambient (shade free) condition in Boira village at Sadar upazila of Mymensingh district. In this study, twelve years old Mango (Mangifera indica), eight years old Mahogany (Swietenia macrophylla) and ten years old Sissoo (Dalbergia sissoo) trees were selected as treatment and each of the tree had six replications. The experiment was laid out in a two factorial Randomized Complete Block Design (RCBD). To achieve the objective, the parameters reflect on growth, yield and yield contributing characters were recorded at different stages of rice plants under both tree shade and ambient condition. The result showed that different treatments significantly influenced on the growth and yield contributing components viz. plant height, effective tillers hill-1, leaf number hill-1, leaf area hill-1, panicle length, filled spikelet’s panicle-1 and grain yield. The maximum (5.20 tha-1, 7.65 tha-1 and 13.20 tha-1) grain yield, straw yield and biological yield of rice was produced in the Mango ambient condition and the minimum (1.68 tha-1 ) grain yield in the Mango tree shade and straw yield and biological yield (3.64 tha-1 and 5.93 tha-1) was produced in the Mahogany tree shade area. The highest (43.87%) harvest index of rice was recorded in Mahogany tree ambient area and the lowest (24.94%) in Mango tree shade area. From the above results, it was found that maximum (68%) reduction of rice grain yield was recorded under Mango tree shade, moderate (28%) under the shade of Mahogany tree where as no rice grain yield reduction was occurred in Sissoo tree shade and ambient condition. Therefore, it can be concluded that in consideration of shade casted by different trees, Sissoo-Boro rice and Mahogany-Boro rice based agroforestry systems is suitable in second case although there was some yield loss (28%) compare to Mango-Boro rice agroforestry system.

Potentiality of Different Seed Priming Agents to Mitigate Cold Stress of Winter Rice Seedling

Seed priming has proved to be an effective pre-germination seed invigoration technique for different crops to improve seed and seedling performance under different abiotic stresses. In Bangladesh, winter rice is very often exposed to cold waves just after sowing in the nursery bed resulting in poor seed germination and seedling emergence, yellowish and thin seedlings production, and a very low survival rate. Seed priming may mitigate the cold stress during seed germination and seedling emergence and helps in the quality seedling production of winter rice. To evaluate the efficacy of different seed priming techniques in increasing seedling emergence, growth, vigor and survivability of winter rice cultivars under cold stress, a pot experiment was conducted at the Department of Agronomy, Bangladesh Agricultural University during December 2018 to January 2019. The experiment comprised two factors, (A) Winter rice variety namely, i) BRRI dhan29 and ii) BRRI dhan36; (B) Seed priming agent namely i) Control (no priming), ii) 20000 ppm NaCl, iii) 30000 ppm NaCl, iv) 20000 ppm KCl, v) 30000 ppm KCl, vi) 20000 ppm CaCl2, vii) 30000 ppm CaCl2, viii) 50 ppm CuSO4, ix) 75 ppm CuSO4, x) 10000 ppm ZnSO4, xi) 15000 ppm ZnSO4, xii) 2 ppm Na2MoO4, xiii) 3 ppm Na2MoO4, xiv) 100 ppm PEG (Polyethylene glycol 4000) and xv) 150 ppm PEG. Seeds were sown on two different dates viz., 1st December and 1st January so that seedlings are exposed to cold stress at different stages. The experiment was laid out in a completely randomized design (CRD) with three replications. Results indicated that (in most of the cases) seed priming has a positive impact on seedling emergence rate (%), root length, shoot length, root shoot ratio, root dry weight, shoot dry weight, seedling dry weight and survival rate (%). Among the priming agents, KCl and CaCl2 performed best; while priming with NaCl and PEG showed no advantages over no priming for both the sowing dates. In general, BRRI dhan36 performed better than BRRI dhan29 in terms of seedling growth because of its higher tolerance to cold stress. But, both the varieties performed similarly in terms of emergence rate and survival rate. Thus, priming is an effective tool to increase seed germination, better seedling growth, and higher seedling survivability of winter rice under cold stress, and KCl (20000 ppm) or CaCl2 (20000 ppm) can be considered as a viable priming agent.

Comparative study of purple rice and green rice (BRRI dhan28) for salt stress sensitivity

Comparative study of purple rice and green rice (BRRI dhan28) for salt stress sensitivity

Effects of zinc on growth and yield of rice cv. BRRI dhan29 under alternate wetting and drying water management practice

Insufficient zinc (Zn) and water are key concerns in agricultural production, resulting in lower yields and nutritional qualities. The goal of the study was to figure out how water management and Zn application rates affect the growth and yield of rice. The experiment was carried out in a split-plot design with three replications. The treatments consisted of two factors, a) water management, like 1) Continuous flooding (CF) and 2) Alternate wetting and drying (AWD) system and b) Zn application like 1) Control (0% Zn), 2) 75% Zn, 3) 100% Zn, 4) 125% Zn, and 5) 150% Zn of the recommended dose. All the plots received an equal amount of NPKS fertilizers. The application of Zn in both AWD and CF systems had a significant effect on a number of grains panicle-1, 1000 grain weight and grain yield. The highest value for both yield contributing traits and yield was obtained by the application of 150% Zn in the AWD system. However, the lowest value was found in the control treatment of the CF system for both the yield components and yield. It is also evident that the growth rate of yield components and yield was increased with increased doses of Zn in both AWD and CF systems. In Bangladesh, farmers involved in rice cultivation may be benefited following the treatment of 150% Zn and AWD irrigation systems.

Effect of Different Organic and Inorganic Fertilizers on the Growth and Yield of Boro Rice (BRRI dhan29)

Effect of Different Organic and Inorganic Fertilizers on the Growth and Yield of Boro Rice (BRRI dhan29)

Effects of nitrogenous fertilizers on rice yield under continuous flooding and alternate wetting and drying conditions

In rice cultivation, water and nitrogen saving strategies are becoming more crucial in order to identify efficient and useful crop production and management approaches. A study was conducted at the Soil Science Field Laboratory of Bangladesh Agricultural University, Mymensingh to examine the combined effects of irrigation method and nitrogen fertilizer on yield contributing traits and yield of rice cv. BRRI dhan29. The experiment was set up in a split-plot based on a randomized complete block design with 3 replications and 14 treatment combinations. Two irrigation methods such as continuous flooding (CF) and alternate wetting and drying (AWD) were the main factor while nitrogen fertilizers including prilled urea (PU) and urea super granule (USG) were the sub-factor. The treatment T6 (USG at 7 DAT) generated the highest plant height (cm), no. of effective tillers hill-1, panicle length (cm), no. of grains panicle-1, grain yield and biological yield during AWD condition. In terms of grain yield, the treatment combinations AWD + T6 and CF + T7 were statistically equal. In comparison to control, all AWD + USG and CF + PU treatment combinations increased straw yield and harvest index. Under both AWD and CF conditions, USG increased more grain and straw yields compared to PU. So, farmers may be advised to apply USG (216 kg ha-1) at 7 DAT under AWD conditions in order to improve rice yield and ensure food security.

Antifungal effect of glow discharge plasma and plasma activated water against brown spot disease of rice

The impact of atmospheric glow discharge plasma and plasma activated water on reducing rice seed-borne brown spot disease was investigated. It has been shown that the generation of reactive oxygen and nitrogen species by plasma containing electrons, positive or negative ions, and neutral species has antimicrobial activity. In this study, four plasmas were used for seed treatment viz., O2-air glow discharge plasma for 90 s, 120 s, air-plasma activated water for 9 and 12 min. Control (without treatment) and chemical treatment were used in order to compare the treatment effect. The plasma treatments used for this study showed a promising positive effect on seed germination and plant growth, and reduction of brown spot severity in the field. Among the plasmas, O2-air glow discharge plasma for 90s significantly increased seed germination (94.67%) compared to control (84.0%). Conidial suspension of Bipolaris oryzae treated with O2-air glow discharge plasma for 90 s and air-plasma activated water for 9 min successfully reduced the conidial germination ability of Bipolaris oryzae on Potato Dextrose Agar (PDA). The brown spot incidence and severity were significantly reduced in the plot which received seed treatment with O2-air glow discharge plasma for 90s and air-plasma activated water for 9 min. Interestingly, the same treatment remarkably enhances the plant growth parameters and yield of BRRI dhan28 compared to control treatment.

Nitrogen Use Efficiency (NUE), Growth and Yield Performance of BRRI dhan28 under Different Doses of Nitrogenous Fertilizer Application

Nitrogen Use Efficiency (NUE), Growth and Yield Performance of BRRI dhan28 under Different Doses of Nitrogenous Fertilizer Application

Effects of drought stress on pigment and protein contents and antioxidant enzyme activities in five varieties of rice (Oryza sativa L.)

Drought stress caused the decrease of pigment contents - chlorophyll a, chlorophyll b, chlorophyll a/b ratio, total chlorophyll content and carotenoids content of leaves of five rice varieties (var. BRRI Dhan-30, BRRI Dhan-32, BRRI Dhan-34, BRRI Dhan-38 and BRRI Dhan-56). Among five rice varieties, BRRI Dhan- 56 showed the least decrease of pigment content under stress. It caused the decrease of protein content of leaves of five rice varieties whereas BRRI Dhan-56 showed the least decrease (3.64%) of protein content under stress. On the other hand, drought stress increased CAT and SOD activities in the leaf of five varieties of rice and BRRI Dhan-56 showed the highest increase of CAT (37.67%) and SOD (94.17%) activity under stress. It may be assumed that higher antioxidant enzymes activities (CAT and SOD) and less reduction of protein content were related to the mechanisms of drought tolerance in rice. It is indicated that BRRI Dhan- 56 may be drought tolerant while BRRI Dhan-30, BRRI Dhan-32, BRRI Dhan-34 and BRRI Dhan-38 were drought sensitive rice varieties. Drought tolerant rice variety is selected based on pigment content, protein content and antioxidant enzymes activities (CAT and SOD).

Interactive Effect of Weeding Regimes, Rice Cultivars, and Seeding Rates Influence the Rice-Weed Competition under Dry Direct-Seeded Condition

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.

Evaluation of Some Traditional Rice (Oryza Sativa L.) Cultivars for the Earliness, Yield and Other Agronomic Traits in Southern Bangladesh

Global warming and climate change are predicted to have a major impact on rice production, necessitating both adaption and mitigation strategies. Among the agricultural crops, rice is highly vulnerable to climatic extremes such as drought, unseasonal rains, flooding, and high temperature stress. However, there is a dearth of short duration varieties which will fit well into the reduced growing period brought about by the changing climatic and rainfall pattern. With this point of view, a study was conducted at the research field of Bangladesh Agricultural Development Corporation (BADC) situated at Subarnachar sub-district under Noakhali district of Chittagong division in Bangladesh during July-November 2018 to sort out some cultivars for their earliness, adaptability, yield and other agronomic traits. Total 11 Kanihati cultivars viz., Kanihati 1, Kanihati 2, Kanihati 3, Kanihati 4, Kanihati 6, Kanihati 7, Kanihati 8, Kanihati 9, Kanihati 10, Kanihati 11 and Kanihati 12 were tested against the standard check BRRI dhan52. Test materials were arranged in a randomized complete block design with three replications in three blocks. Result reveals that Kanihati 9, Kanihati 7, and Kanihati 3 were qualified for further screening and evaluation processes for few more years as they were 20 days earlier having the yield potentials of statistically similar with BRRI dhan52
 Res. Agric., Livest. Fish.7(3): 393-402, December 2020

Yield Enhancement of T. Aman Rice in Salinity Affected Area of Noakhali District of Bangladesh Through Adoption of Variety and Gypsum Fertilizer Application

An experiment was conducted in the farmer’s field at the Moddho Jutkhali village, Subornochar, Noakhali, a salinity affected area of Bangladesh to investigate the effect of variety and gypsum fertilizer on the yield of transplant aman rice under salinity condition during July to December, 2017. The experiment was laid out in a two factor split-plot design with three replications consisting of three aman rice varieties viz., Swarna (V1, an indian variety adapted to that locality), BRRI dhan52 (V2) and Binadhan-7 (V3) and three levels of gypsum fertilizer viz., 0, 75 and 150 kg gypsum ha-1. Yield components and yield of transplant aman rice were significantly influenced by variety, level of gypsum and their interactions. Among the varieties, Swarna produced the tallest plant height (126.7 cm), highest number of grains panicle-1 (76.30), weight of 1000 grains (25.80 g), grain yield (5.44 t ha-1), straw yield (7.07 t ha-1), and biological yield (12.51 t ha-1) while Binadhan-7 showed lowest values of these respective parameters but number of total tillers hill-1 (9.99) and number of effective tillers hill-1 (8.94) were maximum in Binadhan-7. Among three gypsum levels, most of the yield contributing characters showed highest values for 150 kg gypsum ha-1 that’s why grain yield was also highest (5.32 t ha-1) for this treatment. On the other hand lowest grain yield (4.92 t ha-1) was found when no gypsum was applied. In case of treatment interaction, highest number of grains panicle-1 (80.23) and highest grain yield (5.69 t ha-1) were produced when Swarna was cultivated with 75 kg gypsum ha-1 while lowest values of grain, straw and biological yields (4.36, 5.11 and 9.47 t ha-1, respectively) were found when Binadhan-7 was cultivated without applying any gypsum. Therefore, it can be concluded that the variety Swarna with 75 kg gypsum ha-1 can be practiced for the cultivation of transplant aman rice in the salinity affected area of Noakhali, Bangladesh to obtain the highest grain yield.
 Res. Agric., Livest. Fish.7(3): 363-371, December 2020

Effect of integrated nutrient management on the growth and yield of boro rice (Oryza sativa L.) cultivars

For sustainable boro rice production in Bangladesh, a balanced fertilization to improve the current soil condition caused by mono-application of inorganic fertilizers and appropriate rice variety selection are very crucial. Therefore, an experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, during the boro season of December 2016 to May 2017 to evaluate the effect of integrated nutrient management on two boro rice cultivars. The varieties were BRRI dhan28 and BRRI dhan29 and eight kinds of nutrient management viz., control (no fertilizers), recommended dose of inorganic fertilizers (120-60-40 N, P2O5, K2O kg ha-1 + gypsum 60 kg ha-1 and ZnSO4 @ 10 kg ha-1), full dose of poultry manure @ 5 t ha-1, cowdung @ 10 t ha-1, poultry manure @ 2.5 t ha-1 + 50% prilled urea and full dose of other inorganic fertilizers, cowdung @ 5 t ha-1 + 50% prilled urea and full dose of inorganic fertilizers, poultry manure @ 2.5 t ha-1 + 75% prilled urea and full dose of inorganic fertilizers, and cowdung @ 5 t ha-1 + 75% prilled urea and full dose of other inorganic fertilizers. The experiment was laid out in a split plot design with three replications. Result showed that, yield and yield components of boro rice were significantly influenced by variety, nutrient management and interaction of variety and nutrient management. In respect of grain yield, BRRI dhan29 produced the maximum yield (5.46 t ha-1). BRRI dhan28 showed poor performance with all characters and gave the minimum yield (4.07 t ha-1). In case of nutrient managements, the highest yield and yield component were obtained from poultry manure @ 2.5 t ha-1 + 50% prilled urea and full dose of inorganic fertilizers and produced the maximum grain yield (5.70 t ha-1). In the interaction of variety and integrated nutrient management, the highest grain yield (6.83 t ha-1) and straw yield (7.61 t ha-1) was obtained from poultry manure @ 2.5 t ha-1 + 50% prilled urea and full dose of inorganic fertilizers with BRRI dhan29 variety. So, BRRI dhan29 with 2.5 t ha-1 poultry manure + 50% prilled urea and full dose of the recommended inorganic fertilizers might be a promising practice for boro rice cultivation.

Genetic variability, heritability, genetic advance and phylogenetic relationship between rice tungro virus resistant and susceptible genotypes revealed by morphological traits and SSR markers

A study was conducted to assess the resistant sources, genetic variability and phylogenetic relationship among 44 rice genotypes based on pathogenicity, genetic parameters of morphological traits and simple sequence repeat markers. Results demonstrated that, 9 genotypes were resistant, 9 were moderately resistant and the rest of the genotypes were susceptible. The higher level of phenotypic coefficients of variation and genotypic coefficient of variation was found for number of tillers hill-1, number of panicle hill-1, number of filled grain panicle-1, number of unfilled grain panicle-1, total number of spikelets and yield hill-1. High heritability along with high genetic advance was observed for yield hill−1, number of filled grains panicle−1, 1000 grain weight hill–1 and total number of spikelets panicle−1 and these could be the desirable characters for selection. Polymorphic information content of SSR markers varied from 0.152 (RM161) to 0.760 (RM8213) with a mean value of 0.448. The higher PIC value (0.760) was obtained in RM8213 succeeded by RM3471 (0.719), RM279 (0.716), RM341 (0.689), RM336 (0.665), RM565 (0.664), RM287 (0.601) and RM562 (0.600), respectively which indicated that these markers are effective for the diversity evaluation of current genotypes. Cluster analysis of data matrix of 29 SSR markers, 44 genotypes divided into ten clusters. The results were also supplemented by principal component analysis. Between resistant and susceptible genotypes highest genetic distance was found between IR69705-1-1-1-4-3 and BR11 (0.14), IR69705-1-1-1-4-3 and BRRI dhan71 (0.14) followed by IR71605-3-1-1-2-6 and BRRI dhan49 (0.34), IR71605-3-1-1-2-6 and BR11 (0.38), Matatag 9 and BR11 (0.38), IR81244 (TW-16) and BR11, BRRI dhan39, BRRI dhan48 (0.41), IR71605-3-1-1-2-6 and BRRI dhan71 (0.41), IR81244 (TW-16) and BRRI dhan71 (0.45). Based on genetic distance and disease reaction data susceptible genotypes i.e. BR11, BRRI dhan39, BRRI dhan48 and BRRI dhan71 could be crossed with any of resistant genotypes IR69705-1-1-1-4-2, IR69705-1-1-1-4-3, IR71605-2-1-5-3-4, IR71605-3-1-1-2-6, IR81244 (TW-16), Matatag 9, Utri Merah-16680, Utri Merah-16682 and Utri rajapan to develop tungro resistant variety.

Gamma radiation application to rice: Reduced glycemic index in relation to modified carbohydrate observed in FTIR spectra

This study was conducted with a popular, low price Bangladesh rice variety BRRI Dhan 29 with a view to possible carbohydrate modification targeting lower glycemic index using gamma radiation application. Irradiation process (5 and 10 ​kGy ​at a dose rate of 9.74kGy/h) altered amylose content, amylose/amylopectin ratio, swelling power, and solubility index. FTIR spectroscopy confirmed the changed molecular structures due to radiation application. Treatment with a dose of 5 and 10kGy caused increased amylose and amylose/amylopectin ratio significantly (p ​< ​0.02). The highest amylose content was found in 10 ​kGy irradiated rice (30.20%) compared to unirradiated one (17.27%). Gamma radiation caused decreased swelling and increased water solubility in rice powder. These features of carbohydrate amendment in irradiated rice lead to reduced glycemic index as investigated with the in vivo experiments. Therefore, this study suggests gamma-irradiated rice (10kGy) is beneficial for diabetic subjects keeping lower blood glucose levels.

Response of potassium nitrate on yield and yield contributing characters of boro rice cv. BRRI dhan28

The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, to explore the growth and yield performance of boro rice cv. BRRI dhan28 is influenced by foliar spray of potassium nitrate (KNO3) at four rice growth stages. The experiment consisted of four doses of KNO3 viz. 0 (Control), 0.25, 0.50 and 1.00 kg ha−1 and applied at four growth stages of rice development viz. at panicle initiation, at ear emergence, at anthesis period and at dough stage. This experiment was carried out in Randomized Complete Block Design (RCBD) with three replications with 10 m2 (4.0 m × 2.5 m) unit plot size and spacing between blocks and unit plots was 1 m and 0.5 m, respectively. Results revealed that foliar application of potassium nitrate at four growth stages significantly affected yield and yield contributing characters of BRRI dhan28. But most of the yield contributing characters did not differ significantly due to the interaction between potassium nitrate and stage of foliar spray. However, the foliar application of KNO3 @ 0.25 kg ha−1 showed the highest yield production (5.86 kg ha−1) while the lowest yield (4.85 kg ha−1) was found in control. Furthermore, better yield performances were recorded when the KNO3 was applied at panicle initiation stage rather than the other four growth stages. The total number of tillers, 1000–grain weight and grain yield, was higher with foliar spraying of a 0.25 kg ha−1 KNO3 at panicle initiation stage. From this experiment, it may be concluded that foliar application of KNO3 affected the yield performances of BRRI dhan28 and 0.25 kg ha−1 KNO3 produced the highest grain yield when applied at panicle initiation stage of boro rice.

INFLUENCE OF WEED INTERFERENCE PERIOD AND PLANTING SPACING ON THE WEED PRESSURE AND PERFORMANCE OF BORO RICE CV. BRRI DHAN29

To study the influence of weed interference period and planting spacing on the weed pressure and performance of Boro rice cv. BRRI dhan29 an experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University from December 2015 to May 2016. The experiment comprised six weed interference periods (viz. weed free, weed free up to 20 DAT, weed free up to 40 DAT and weed free up to 60 DAT, weed free up to 80 DAT and weedy condition) and three spacing of planting (viz.25 cm × 15 cm, 25 cm × 10cm, 25 cm × 20 cm) following randomized complete block design with three replications. The highest number of total tillers hill-1 (14.98), effective tillers hill-1 (12.98), filled grains panicle-1 (117.9), grain yield (5.40 t ha-1), straw yield (7.94 t ha-1) and biological yield (40.53 t ha-1) were found weed free up to 80 DAT. Considering cost and time consuming, best tillers hill-1 (15.88), effective tillers hill-1 (13.88), filled grains particle-1 (121.70) and grain yield (6.14 t ha-1) were found in spacing 25 cm × 15 cm with weed free up to 80 DAT. Weed density and dry weight were increased with the increasing weed interference period but rice grain yield increased gradually with the decreasing weed interference period. Weed free up to 80 DAT can be recommended from economic view point following the spacing of 25 cm × 15 cm for better weed suppression and higher yield of BRRI dhan29.

Genetic Analysis Reveals a Major Effect QTL Associated with High Grain Zinc Content in Rice (Oryza sativaL.)

Molecular mapping and application of quantitative trait loci (QTL) associated with a higher level of grain Zinc is a viable option to enhance zinc content in rice through breeding. An F2 population derived from a cross between a high yielding variety, BRRI dhan28, and a locally adapted Zn enriched cultivar, Kalobokri was used to map QTLs associated with higher levels of Zn in rice grain. The F2:3 progenies varied significantly (P ＜ 0.0001) in Zinc contents with a mean value remarkably higher than those in the superior parent. Through marker by trait analysis using IciMapping, we detected a large-effect QTL, qGZn3 on chromosome 3 between RM5419 and RM1164 spanning 1.83 Mb interval at the 0.05 level of significance with a threshold LOD of 10.61. This QTL showed a21.1% (R2 value) contribution to the total phenotypic variation for zinc content in the unpolished rice grains with 4.68 μg/g additive effect of Kalobokri alleles. We also detected 11 metal homeostasis related genes within the interval of qGZn3. In-silico analysis showed that four expressed sequence tags of one candidate gene (LOC_Os03g22810) encoding Cu/Zn superoxide dismutase, a metal-binding protein, are highly active in the endosperm as well as in the embryonic tissue of rice grain. Taken together, our results suggest that qGZn3 is a major QTL associated with high grain Zn content in the F2 progenies of rice. Our findings offer valuable genetic resources to facilitate breeding for high yielding and Zinc-enriched rice variety.