Bangladesh Rice Research Institute Research Articles

Yield Response and Nitrogen use Efficiency of Boro Rice Varieties as Affected by Different Methods of USG and Prilled Urea Application

An experiment was conducted at the Bangladesh Rice Research Institute (BRRI), Gazipur during Boro season of 2013-14 and 2014-15 to find out the nitrogen use efficiency and yield of boro rice var. BRRI dhan28 and BRRI dhan29 under four N management practices such as application of prilled urea using prilled urea applicator, application of USG (2.7gm) using USG applicator, broadcasting of prilled urea following three splits and a control (without urea). The experimental design was RCBD replicated thrice. BRRI dhan29 with urea broadcasted plots produced higher grain yield (7.38t ha-1) followed by BRRI dhan29 with USG application (6.65 t ha-1). Hand broadcasting with urea fertilizer showed 15.38.5and 2.5, 9.89% higher grain yield than machine application of prilled urea and USG in BRRI dhan28 and BRRI dhan29, respectively. Grain yield showed a significant quadratic response to N fertilization and significant linear response with total dry matter production in both the varieties. Higher total N was uptake from urea broadcasted plots in BRRI dhan29 followed by urea broadcasted from BRRI dhan28. BRRI dhan29 with Prilled urea applicator and BRRI dhan29 with USG treatment uptake intermediate nitrogen. N uptake in grain and total N uptake had a significant linear and quadratic response to N treatment in BRRI dhan28 and BRRI dhan29. Nitrogen use efficiency was higher in BRRI dhan29 compared to BRRI dhan28. Economic analysis showed that rice var. BRRI dhan28 and BRRI dhan29 with urea broadcast had the highest gross return of Tk.145145.00 and Tk. 158310.00 ha-1, respectively. However, the maximum cost (Tk. 151131) was involved for BRRI dhan29 with urea broadcasting, while the minimum with no urea fertilizer application for both the varieties. The highest marginal rate of return (MRR) (Tk.1146) was recorded from BRRI dhan28 with USG application using BRRI applicator.Bangladesh Agron. J. 2016, 19(1): 1-10

Performance study of some T. aman varieties under normal transplanting and double transplanting system

The experiment was conducted to study the performance of three T. Aman varieties (BR22, BRRI dhan46 and BRRI dhan49) under normal transplanting with 30, 45 and 60 days old seedlings and double transplanting ( 30 days + 30 days) system at Plant Physiology Division of Bangladesh Rice Research Institute, Joydebpur, Gazipur during T. Aman season, 2013. Interaction effect was significant only for days to maximum flowering and sterility percentage. BR22 required longer duration to complete flowering when transplanted with 60 days old seedlings, while sterility percentage was higher in BRRIdhan 49 when transplanted with same aged seedlings. Photosynthetic rate, LAI, total dry matter production, yield contributing characters and harvest index of tested varieties were insignificant under different transplanting methods; these parameters contributed to produce similar grain yield. The results revealed that rice varieties BR22, BRRI dhan46 and BRRI dhan49 showed similar performance under normal transplanting with different aged seedlings and double transplanting in respect of photosynthetic rate, tillering pattern, LAI, total dry matter production and grain yield during T. Aman season.SAARC J. Agri., 14(1): 37-45 (2016)

Soil Test Based Inorganic Fertilizer and Integrated Plant Nutrition System for Rice (<i>Oryza sativa</i> L.) Cultivation in Inceptisols of Bangladesh

A field experiment was conducted at the Bangladesh Rice Research Institute, Gazipur during 2013 to study the potential of different organic materials in integrated plant nutrition system (IPNS) and soil test based (STB) inorganic fertilizer on the growth, nutrient uptake and yield of rice (<i>Oryza sativa</i> L.): variety BRRI dhan29. Five treatments were laid out in a randomized complete block design with four replications. The treatments were: (1) soil test based inorganic fertilizer (NPKS @ 138-7-80-3 kg ha-1), (2) cow dung (3 t ha-1), (3) poultry manure (2 t ha-1), (4) mustard oil cake (2 t ha-1) and (5) control. Organic fertilizers were applied on dry weight basis. Inorganic fertilizers were applied along with poultry manure (PM), cow dung (CD) and mustard oil cake (MOC) as IPNS. Soil test based STB fertilizer and PM in IPNS provided maximum grain yield of rice (6.11 t ha-1). Maximum plant height and tiller numbers were found in MOC treatment, while the numbers of filled grains were higher in STB fertilizer and PM treated plots. The application of different organic sources as IPNS significantly influenced the N, P, K and S uptake in rice. However, the highest N, P, K and S uptake were found in the PM treatment. The benefit cost ratio of different treatments followed the order of STB>PM>CD>Control>MOC. Considering yield potential and BCR, STB fertilizer and PM treatments were found economically profitable. However, from environmental point of view and sustainable management of soil health and crop productivity, application of PM and CD in rice-rice cropping system is recommended for rice cultivation.The Agriculturists 2016; 14(1) 33-42

Response of Nerica Rice to Nitrogen Fertilization

An experiment was conducted during T. Aman season, 2014 at the Agronomy Research Field, Bangladesh Rice Research Institute, Gazipur to determine the optimum rate of nitrogen fertilizer for higher yield in nerica rice. The experiment comprised of three rice varieties viz. NERICA1, NERICA10 and BRRI dhan57; and five nitrogen levels viz. 0, 23, 46, 69 and 92 kg ha-1. The rice var. BRRI dhan57 with 69 and 92 kg N ha-1 produced significantly identical with higher panicles m-2. But NERICA1 and NERICA10 produced higher number of panicles with 46 and 69 kg N ha-1, respectively. However, BRRI dhan57 with 46 kg N ha-1 produced highest grains panicle-1 but NERICA1 and NERICA10 produced higher number of grains panicle-1 with 23 kg N ha-1. The highest percentage of sterility was recorded in NERICA10 with 69 kg N ha-1. The regression analysis gave the optimum dose of nitrogen for NERICA1, NERICA10 and BRRI dhan57 which were 69.25, 74.25 and 85.75 kg N ha-1, respectively.Bangladesh Agron. J. 2015, 18(2): 9-14

Agro-Morphological, Physico-Chemical and Molecular Characterization of Rice Germplasm with Similar Names of Bangladesh

Thirty-one duplicate and similar named rice germplasms of Bangladesh were studied to assess the genetic variation for the agro-morphological and physico-chemical traits and simple sequence repeat banding patterns during 2009–2012 at Bangladesh Rice Research Institute. The range of variations within the cultivar groups showed higher degree. The principal component analysis showed that the first five components with vector values > 1 contributed 82.90% of the total variations. The cluster analysis grouped the genotypes into four clusters, where no duplicate germplasm was found. The highest number (11) of genotypes was constellated in cluster I and the lowest (3) in cluster II. The intra- and inter-cluster distances were the maximum in cluster I (0.93) and between clusters I and IV (24.61), respectively, and the minimum in cluster IV (0.62) and between clusters I and III (5.07), respectively. The cluster mean revealed that the crosses between the genotypes of cluster I with those of clusters II and IV would exhibit high heterosis for maximum good characters. A total of 350 alleles varied from 3 (RM277) to 14 (RM21) with an average of 7.8 per locus were detected at 45 microsatellite loci across the 31 rice accessions. The gene diversity ranged from 0.48 to 0.90 with an average of 0.77, and the polymorphism information content values from 0.44 (RM133) to 0.89 (RM206) with an average of 0.74. RM206, RM21, RM55, RM258 and RM433 were considered as the best markers on the basis of their higher polymorphism information content values. The dendrogram from unweighted pair-group method with arithmetic average clustering also classified the genotypes into four groups, where group IV comprised of 20 genotypes and group III of one genotype, but no duplicate was found. Finally, similar and duplicate named rice germplasms need to be conserved in gene bank as are distinct from each other.

Growth of Wheat (Triticumaestivum L.) under Raised Bed Planting Method in Rice-Wheat Cropping System

CORRECTION: Due to a number of formatting and layout issues, the PDF of this paper was replaced on 10th October 2016. The page numbers of this article have changed from 45-54 to 47-56.An experiment was conducted at the Bangladesh Rice Research Institute, Gazipur during Rabi season 2001-02 and 2002-03 (November to March) to evaluate the effect of raised bed planting method on different crop growth parameters, which influence the wheat productivity. Total tiller production, leaf area index (LAI), dry mater production (DMP), crop growth rate (CGR) and agronomic productivity of wheat under bed planting on 70, 80 and 90 cm wide beds with two and three plant rows bed-1 and conventional method were investigated. The number of tillers m-2 in 70 cm beds with both two and three rows were statistically identical to conventional method. Wheat plants grown on narrow beds (70 cm) produced similar LAI to that grown in conventional method but plants in wider beds (80 and 90 cm) had less LAI than that in conventional method. Similarly, DMP and CGR in 70 cm beds were either comparable or higher than conventional method. Grain yield of 70 cm beds were higher than conventional method. Wheat in 70 cm beds increased number of panicles m-2, number of grains panicle-1 and 1000-grain weight of wheat.Bangladesh Rice j. 2015, 19(2): 47-56

Increasing Crop Diversity and Productivity of Rice (Oryza Sativa L.)-Wheat (Triticumaestivum L.) Cropping System through Bed Planting

CORRECTION: Due to a number of formatting and layout issues, the PDF of this paper was replaced on 10th October 2016. The page numbers of this paper have changed from 35-44 to 37-46.Adoptions of new crop establishment methods, changing management practices and inclusion of new crops in the rice-wheat cropping system are very important for maintaining and increasing system productivity. Experiments were conducted at the Bangladesh Rice Research Institute, Gazipur and farmers’ fields in Chuadanga during 2002-03 to evaluate the performances of rice, wheat and mungbean in bed planting and to evaluate the system productivity of Rice-Wheat-Mungbean cropping pattern. Wheat-Mungbean-Direct seeded rice (DSR), Wheat-Mungbean-Transplant rice (TPR), Wheat-Fallow-DSR and Wheat-Fallow-TPR cropping system under bed planting and conventional methods were evaluated. Grain yields of wheat, mungbean, rice and rice equivalent yield (REY) under bed planting were significantly higher (25.41, 40.91, 13.00 and 21.12%, respectively) than the conventional method. The Wheat-Mungbean-Rice cropping pattern produced significantly greater REY (38.25%) than Wheat-Fallow-Rice cropping pattern. Total variable cost was lower (17.33%) in bed planting than conventional method. Gross return, gross margin and benefit-cost ratio of Wheat-Mungbean-Rice cropping system in bed planting were higher (14.43, 40.99 and 38.52%, respectively) than the conventional method.Bangladesh Rice j. 2015, 19(2): 37-46

Effect of potassium fertilization on yield and potassium nutrition of Boro rice in a wetland ecosystem of Bangladesh

ABSTRACTEffect of potassium (K) fertilization (0, 20, 40, 60, 80 and 100 kg K ha−1) on yield, nitrogen (N) and K nutrition of Boro (dry season) rice and apparent soil K balance was studied. Experiment was conducted at Bangladesh Rice Research Institute (BRRI) regional station farm, Habiganj, Bangladesh during 2007–2008 to 2009–2010 in a wetland rice ecosystem under haor area. Cropping pattern was Boro–Fallow–Fallow. A popular rice variety BRRI dhan29 was tested in a randomized complete block design with three replications. Results indicated that BRRI dhan29 maintained an average grain yield of 5.19 t ha−1 year−1 without K fertilization. Potassium fertilization significantly increased the grain yield to 6.86 t ha−1 year−1. Quadratic equations best explained the progressive increase of rice yield with increasing K rates. Optimum dose of K in 3 years ranged from 78 to 93 kg ha−1. Internal N use efficiency of rice decreased with increasing K rates. However, K use efficiency was inconsistent. Apparent K balance study revealed that application of 100 kg K ha−1 was not able to maintain a positive K balance in soil under wetland ecosystem with Boro–Fallow–Fallow cropping system. However, K fertilization decreased the negativity of K balance in soil.

Seed Yield and Quality of Lowland Rice (<i>Oryza sativa</i> L.) as Influenced by Nitrogen from Organic and Chemical Sources

A field experiment was conducted at the Bangladesh Rice Research Institute (BRRI) experimental farm during boro season of 2010-11 to determine the effect of nitrogen from organic and chemical sources on rice seed yield and quality. Six treatments- (i) N-control, ii) Optimum dose of nitrogen (164 kg N ha-1) from urea, iii) 50% N from urea and 50% N from CD (cow dung), iv) 50% N from urea and 50% N from PM (poultry manure), v) 100% N from CD and vi) 100% N from PM were compared. The experiment was conducted in a randomized complete block design with four replications. Two boro varieties – BRRI dhan28 and BRRI dhan29 were used as test crops. The urea + PM treatment gave similar seed yields to that of urea in both the varieties. The PM treatment gave similar seed yield to that of urea + PM in BRRI dhan28, but BRRI dhan29 gave significantly lower seed yield in PM than the urea + PM. Sole cowdung or poultry manure application produced significantly lower seed yield than urea + PM treatment and sole urea application. The application of N from cowdung and poultry manure had no effect on rice seed quality as compared to that obtained with urea.The Agriculturists 2015; 13(1) 109-118

Study of Qualitative Characters of Balam Rice (Oryza sativa L.) Land Races of Bangladesh

Twenty-one qualitative agro-morphological characters of 40 Balam rice were studied during T. Aman 2009 and T. Aman 2011 seasons at Bangladesh Rice Research Institute, Gazipur. Single seedling was transplanted using spacing within and between rows of 20 and 25 cm. The fertilizers were applied at the rate of 60-50-40-10 kg NPKS per hectare. The qualitative characters were recorded using procedure of DUS tests for inbreed and hybrid rice of Bangladesh. The presence and split or two-cleft shape type penultimate leaf ligule showed no variation. In total, 24 land races (60%) showed colorless leaf sheath and basal leaf sheath, 14 (35%) had green leaf blade, 16 (40%) had strong surface pubescence of penultimate leaf blade, 33 (82%) showed colorless auricles and collar, 30 (75%) had white color of stigma, 33 (82%) showed erect blade of flag leaf, 31 (77%) had erect curvature of lateral tiller, 30 (75%) showed colorless nodes, 17 (42%) had weak intensity of color in internodes, 14 (35%) showed yellowish to straw color lemma and palea and 18 (45%) had its medium intensity, 16 (40%) showed yellowish/straw color apiculus, 35 (87%) had awnless grain and 23 (58%) showed intermediate type of leaf senescence. Besides, Balam rice along with BR7, BR16, BRRI dhan50 and Nizersail were grouped into four major clusters by the UPGMA clustering method based on Dice coefficient. Cluster III was the largest group with thirty genotypes. The dendrogram revealed that the genotypes B7 (acc. no. 853) and B23 (acc. no. 878) was 100% duplicate or similar. The genetic distance ranging from 0.0 to 9.995 also indicated wide genetic variation among the germplasm. Finally, Balam rice showed unique feature of valuable genes for safe conservation in Gene bank and sustainable utilization in future breeding programs regarding intellectual property rights.

Diversity Level, Spearman’s Ranking and Core Collections from 98 Rice Germplasm through Quantitative, Qualitative and Molecular Characterizations

Ninety-eight genotypes (40 genotypes of Balam, 27 of Jesso-Balam, 21 of Kartiksail and 10 of Dhaliboro groups, respectively) of similar or duplicate named rice accessions along with HYV’s were studied for quantitative, qualitative and molecular characters at Bangladesh Rice Research Institute during 2009-12. For estimating diversity level, the genotypes were divided into five populations. The PIC ranged from 0.50 (Dhaliboro) to 0.74 (Balam) with 0.69 for HYVs, indicating the existence of more diversity and broader genetic base in Balam land race cultivars. Similarly, genetic diversity with an average of 0.83 ranged from 0.55 (Dhaliboro) to 0.77 (Balam) and 0.73 for HYV’s. The Shannon’s information index ranged from 1.00 (Dhaliboro) to 1.73 (Balam) and it was 1.48 for HYV’s. The number of different allele ranged from 3.56 (Dhaliboro) to 7.80 (Balam), while the number of effective allele from 2.63 (Dhaliboro) to 5.11 (Balam) and it was 5.18 and 4.14 for HYV population, respectively. Analysis of molecular variance showed that the maximum percentage of variation was present among individuals within populations (85%), followed by among populations (15%). The spearman’s rank correlation coefficient was found highly significant (rs=0.51; t=2.98) between ranking of inter-genotype (D=√D2) and Nei’s genetic distances, indicating strong association between them. The correlation tests revealed that SSR diversity analysis is the most powerful method for grouping. But, combination of quantitative and molecular methods may be the best. Finally, 21 core collections were selected from Balam group. The selected core accessions need to conserve as active collection in Genebank, utilize as parents in hybridization programs and develop QTL map for unlocking valuable genes.

Validation of Integrated Pest Management Practices for Rice Insect in North-west Region of Bangladesh

Integrated Pest Management (IPM), developed by the Bangladesh Rice Research Institute (BRRI) for management of rice insect pests, was demonstrated and validated through intensive investigation in farmer’s fields of Pirganj and Taraganj in Rangpur district during 2012–2014 in two T. Aman and Boro seasons. A portion of each farmer’s field kept under the respective farmers’ supervision without any intervention, which was treated as control treatment (T4). The other portion was managed with three treatment combinations ie, T1=Prophylactic use of insecticide, T2=Perching + sweeping + need based insecticide application and T3=Perching only. BRRI dhan52 and BRRI dhan58 were used in Aman and Boro seasons respectively. RCB design was followed with eight replications for data analysis. The insect infestation was monitored fortnightly by visual counting from 20 hills and also 20 complete sweeps. The insect infestation, yield and yield contributing characteristics were analysed by one way analysis of variance by Tukeys’ post hoc test. The objective of this studies were to validate and demonstrate the IPM techniques in farmers' field. Yellow stem borer, rice leaf roller, long horned cricket, grasshopper, green leafhopper, brown planthopper, white-backed planthopper and gall midge were found as pests in both the locations. However, insect infestation was below the economic threshold level (ETL). No significant differences were observed for insect infestation among the treatments. Natural enemies eg, spider, ladybird beetle, dragon fly, damsel fly, carabid beetle and staphylinid beetle were noticed in both the locations. In some seasons and also locations some natural enemies were not found particularly where indiscriminate/continuous insecticide was used. Thus, it was indicated that indiscriminate/continuous use of insecticide has the detrimental effect on the population of natural enemies. Also, refrained from insecticide application at early crop stages (30-40-day after transplanting) natural enemy populations increased, which might reduce insect population below the ETL. Significantly lower yield was observed at farmers managed fields in both the locations. Therefore, it was found that indiscriminate/continuous use of insecticide had no effect on yield and yield contributing characters of rice, when insect infestation below the ETL. So, farmers could avoid continuous/indiscriminate use of insecticide, which might ultimately save production cost and the environment from insecticidal pollution as well.Bangladesh Rice j. 2015, 19(1): 17-31

Assessment of Appropriate Doses of GA3 and Row Ratio for Better Seed Yield of a Promising Hybrid Rice Variety

A field experiment was carried out at the Bangladesh Rice Research Institute (BRRI) farm, Gazipur during dry season 2013-14 to find out the appropriate GA3 dose and row ratio for hybrid seed production. GA3 doses were applied @ 0, 80, 160, 240 and 320 g ha-1 with different row ratio. Results revealed that GA3 application influenced the panicle exsertion rate only. The calculated optimum GA3 dose was 302.4 g ha-1 with the highest PER (84.62%). Seed yield and OCR were influenced by row ratio. The highest OCR was observed with 2:12 row ratio while the highest seed yield was found in 2:14 row ratio.Bangladesh Rice j. 2015, 19(1): 57-61

Growth and Yield Performance of Tidal Local Aman Rice as Influenced by USG Application at Non Tidal Condition

An experiment was carried out at research field of Bangladesh Rice Research Institute, Gazipur to evaluate the performance of tidal local aman rice as influenced by urea super granule (USG) at non-tidal condition. Four tidal local aman varieties such as Sadamota, Razashail, Kutiagoni and Kalagura were used as planting materials. Nitrogen was applied as USG (1.8g) at 10 days after transplanting (DAT), 25 DAT, before panicle initiation (BPI) stage (date of PI stage of these 4 varieties were identified from previous experience) and no nitrogen (control). The experiment was laid out in a split-plot design where varieties in main plot and USG in sub-plot with three replications. Varietals response was significant on plant height, effective tillers hill-1, grains panicle-1 and grain yield. All the yield and yield components were influenced significantly by the time of USG application. Higher dry matter was produced by all the varieties when USG was applied at early growth stage (10 to 25 DAT) but crop lodges at milking stage due to more vegetative growth resulting increases sterility, decreases grain fertility and yield. On the other hand, when USG was applied at BPI stage grain fertility and yield were increased. The highest grain yield (3.51 t ha-1) was recorded from Kalagura when USG applied before panicle initiation stage. So, application of USG at BPI stage in local aman rice in non-tidal condition increased yield resulting higher gross and net return in all varieties.Bangladesh Agron. J. 2015, 18(1): 71-80

Long-Term Effects of Sulfur and Zinc Fertilization on Rice Productivity and Nutrient Efficiency in Double Rice Cropping Paddy in Bangladesh

Sulfur (S) and zinc (Zn) deficiencies are frequently reported in Bangladesh rice paddy. However, its effects on rice productivity and soil fertility need to be reevaluated as sulfur oxides (SOx) and heavy metals are increasingly emitted to the environment in the recent years. To examine the long-term effects of S and Zn fertilization on rice yield and nutrient efficiency, the standard fertilization plot of nitrogen, phosphorus, potassium, sulphur, and zinc (NPKSZn) was installed in a typical double rice cropping paddy at the Bangladesh Rice Research Institute (BRRI) farm in 1985. The recommended treatment (NPKSZn) and the comparison treatments (NPKZn and NPKS) were selected for calculating S and Zn efficiencies. The same levels of chemical fertilizers in NPKSZn treatment were applied with the rates of N-P-K-S-Zn as 80–25–35–20–5 kg ha−1 and 120–25–35–20–5 kg ha−1 in the wet and dry seasons, respectively. The changes in rice productivity, as well as S and Zn fertilization efficiencies, were monitored for 23 years. Sulfur fertilization significantly increased the mean grain and straw yields by around 13% in the wet season and only 4–5% in the dry season. The mean S fertilization efficiencies were 9.3% and 5.3% in the wet and dry seasons, respectively. Sulfur fertilization efficiency was relatively high until 1997 (the 13th year after the installation). Thereafter, however, S fertilization did not increase rice productivity or efficiency, regardless of the season. Also, Zn fertilization did not result in a significant increase in rice productivity, and its fertilization efficiency was similar level with a mean of 1.2%, irrespective of the season. This study revealed that S and Zn fertilization may no longer be required to increase rice productivity in Bangladesh paddy soil due to fast industrialization and urbanization.

Genetic divergence of jesso-balam rice (Oryza sativa L.) of Bangladesh

In total 27 genotypes of Jesso-Balam pure line rice germplasm were studied for fourteen morpho-physiological and four physico-chemical characters at Bangladesh Rice Research Institute, during T. Aman 2009 and T. Aman 2011 seasons. According to principal component scores, the two-dimensional scatter diagram (Z1-Z2) has apparently distributed the genotypes into seven clusters. According to Mahalanobis’ D2 statistic for the studied characters, the genotypes were clubbed into seven groups. The highest number of genotypes (6) were included in clusters I and III and the lowest two (2) in cluster V and VII. It was also revealed that no duplicate was existed among the genotypes. The intra-cluster distance was maximum (0.77) in cluster III and minimum (0.28) in cluster VII, while the maximum intercluster distance (28.37) was observed between the clusters III and IV and the minimum (2.49) between the clusters I and VII. The cluster V has produced the highest means for plant height (148.18 cm), straw yield per hill (39.97 g), panicle length (28.14 cm) and protein content (9.61%). But, the cluster IV has showed the highest means for seedling height (69.5 cm), flag and penultimate leaf area (1059.5 cm2), culm diameter (5.8 cm), filled grain number per panicle (3.64), grain length (8.63 mm) and 1000-grain weight (21.78 g), while the cluster VII had the highest means for grain yield per hill (31.27 g) and effective tiller number per hill (13.5) and the lowest mean for days to maturity (144). Therefore, the genotypes of cluster V need to be crossed with the genotypes of cluster IV or cluster VII, for developing new Balam rice with maximum other good characters. Finally, it could be concluded that the studied Jesso-Balam pure lines germplasm is a good source of valuable genes.Int. J. Agril. Res. Innov. & Tech. 5 (1): 22-27, June, 2015

Allelic diversity of newly characterized submergence-tolerant rice (Oryza sativa L.) germplasm from Bangladesh

A total of 300 germplasm accessions collected from submergence-prone areas of Bangladesh were selected from the genebank of the Bangladesh Rice Research Institute (BRRI) for an allelic diversity study on submergence tolerance during the vegetative stage. Through screening under controlled submergence for three consecutive years, eight accessions were selected for having submergence tolerance with survival ranging from 71.2 to 95.4 %. A total of 20 SUB1-region SSR and Indel markers, spanning from 4.5 to 8.6 Mb on chromosome 9, were used to study the allelic diversity of 16 selected rice accessions, including the eight submergence-tolerant accessions and eight sensitive and tolerant checks. A total of 58 alleles were detected at the loci of the 20 markers across the 16 rice accessions. The number of alleles per locus ranged from two to five, with an average of 2.90 alleles across the 20 loci. Genetic similarity analysis using the unweighted pair-group method using arithmetic mean (UPGMA) clustering system generated two major genetic clusters, each of them with three subgroups. DG1-349, Kalojoma, DSL-78-8, Damsi and Putidepa were identified as having higher submergence tolerance but not possessing the same resistance allele as FR13A. Furthermore, RT-PCR analysis of SUB1A, the gene underlying the SUB1 QTL, showed that the transcript abundance in these accessions was significantly less than that of FR13A. Thus, these accessions were selected as potential genetic donors for identifying novel submergence-tolerance QTLs.

Validation of the AquaCrop model for irrigated rice production under varied water regimes in Bangladesh

Crop growth simulation models of varying complexity have been developed to predict the effects of soil, water, nutrients and climate on biomass and grain yields and water use efficiency of different crops. In this study, the AquaCrop model was calibrated and validated for rice crop growth modeling under different irrigation water regimes at the Bangladesh Rice Research Institute, Gazipur, Bangladesh during the 2008–09 and 2009–10 winter (dry) seasons. Three irrigation water regimes were examined: irrigation with continuous standing water (CSW), and irrigation at 3 or 5 days after water disappearance (3 or 5 DAWD) from the field as potential water saving adaptations. Model performance was evaluated in terms of prediction error (Pe), coefficient of determination (R2), the normalized root mean squared error (NRSME), the Nash–Sutcliffe model efficiency coefficient (EF) and Willmott’s index of agreement (d). The model calibration yielded 0.94<R2<0.99, 14.5<NRMSE<21.6, 0.83<EF<0.95 and 0.97<d<0.99 in simulating canopy cover (CC) percentage and above-ground biomass. Model validation yielded 0.98<R2<0.99, 8.6<NRMSE<12.9, 0.94<EF<0.97 and d=0.99 in simulating CC percentage and above-ground biomass. In calibration and validation, respectively, the prediction errors for grain yield varied from 5.55 to 7.70% and 8.22 to 11.54%, and for biomass production from 2.62 to 5.19% and 7.95 to 11.15%, indicating good model performances. Based on crop yield, water use and its use efficiency, the IR69515-KKN-4-UBN-4-2-1-1 genotype showed better productivity in the dry season under the 3 DAWD irrigation water regime compared to the other examined treatments, which was shown by both the experimental data and the model simulations using FAO recommended conservative model parameters. The FAO AquaCrop model was able to predict rice growth and yield with acceptable accuracy under different water regimes, making this model a suitable candidate to facilitate local scenario studies related to irrigation scheduling, yield prediction or studies related to climate change and adaptation.

GENETIC DIVERSITY AMONG MAINTAINER LINES OF RICE (Oryza sativa L.) BASED ON CLUSTER ANALYSIS

An experiment was conducted at the experimental field of Bangladesh Rice Research Institute (BRRI), Gazipur during T. Aman season 2007. Ten maintainer lines were evaluated to identify most diverse maintainer lines in respect of morphological traits for developing heterotic rice hybrids based on clustering and days to maturity. Based on mean values of different morphological traits and maturity, 10 maintainer lines were classified into four distinct clusters. Maximum Euclidean distance from centroids was observed in cluster 2 whereas cluster 3 and 4 found in the centroids. Most of the maintainer lines were grouped into early and medium maturing clusters while the remaining two lines were clustered into very early and late maturing clusters. Very early maturing group contained maintainer line (D.ShanB) with dissi cyto source and fell into cluster 3. It had short plant stature with short flag leaf but had high spikelet fertility and thousand grain weight. Early maturing group contained maintainer lines having 4 different cyto sources revealed early maturing group featured with cyto source variation with high panicle number/m2 and very good yield potentiality. Grouping the maintainer lines on the basis of maturity period yield per plot was proportionally higher in late maturing line. Only a single line Gan46B fell into late maturing group and had highest yield. This fact suggests possibility of corresponding CMS line of Gan46B could be used as female if restorer lines are selected from early maturing group. Medium maturing group had some added advantage like medium duration with diverse cyto sources and good yielding ability. If restorer lines are selected from late maturing group with high yield potentiality proper hybrid rice combination become available for Boro season and it would be better because rice hybrid perform better under irrigated Boro eco system. One hundrade and nineteen days growth duration also very good for T. Aman season.

Impacts of urea deep placement on nitrous oxide and nitric oxide emissions from rice fields in Bangladesh

Urea deep placement (UDP) increases nitrogen use efficiency (NUE) in lowland rice fields by reducing ammonia volatilization, surface runoff and increasing nitrogen uptake. However, its effects on N losses as nitrous oxide (N2O) and nitric oxide (NO) are not yet clear. We conducted field experiments at two locations of Bangladesh — Bangladesh Agricultural University (BAU) and Bangladesh Rice Research Institute (BRRI) — to determine the effects of UDP vs broadcast urea on N2O and NO emissions from rice fields.N2O and NO emissions were measured from three N fertilizer treatments (control [0kgN/ha], UDP, broadcast urea) using automated gas sampling and analysis system continuously for three rice growing seasons — Aus (May–Aug), Aman (Aug–Dec) and Boro (Jan–May). Urea was applied as 2–3 split application, while for UDP treatment, urea briquettes were deep placed (7–10cm depth) between 4 hills of rice at alternate rows to meet recommended N rates in a single application. Treatments were arranged in a randomized complete block design with three replications and N2O and NO measurements were done at every three-hour interval.N2O emissions were sporadic and event specific. Peaks in N2O emissions were observed after broadcast application of urea, during dry period and after re-flooding of the dry soil. For the rest of the time during the rice-growing season, emissions were very low to negligible. However, across the rice-growing seasons, UDP significantly (P<0.05) reduced N2O emissions compared with broadcast urea. Moreover, N2O emissions showed significant spatial and seasonal variations. They were higher during Boro season compared with Aus and Aman seasons and at BAU site than that of BRRI. Conversely, emissions between Aus and Aman seasons and between control and UDP treatments were similar. In contrast to N2O emissions, NO emissions were negligible and not affected by fertilizer treatment. However, significant spatial and seasonal variations were observed, with higher NO emissions at BRRI site compared with BAU and during Boro than that of Aus season.