Bangladesh Rice Research Institute Dhan29 Research Articles

Participatory Variety Testing to Replace Old Mega Rice Varieties with Newly Developed Superior Varieties in Bangladesh

The Bangladesh Rice Research Institute (BRRI) has released more than 100 inbred rice varieties. Still, an old mega variety BRRI dhan28 dominates the farmers’ fields during the dry winter (Boro season: November–June) season. This variety is very susceptible to different diseases and insects, causing lower yield performance than its potential. To replace this variety, current on-farm research was planned to evaluate the newly developed four superior rice varieties: BRRI dhan58, BRRI dhan63, BRRI dhan67, and BRRI dhan74 during Boro season in 2017 and 2018. The objective was to create data and popularize new varieties among farmers all over the country. We conducted 15 on-farm trials with farmers’ active participation at Senbag, Fulgazi, and Mirsarai Upazila of Noakhali, Feni, and Chattogram districts, respectively, in Bangladesh. The results demonstrate that BRRI dhan74 produced the highest grain yield among the tested varieties, followed by BRRI dhan67, BRRI dhan63, and BRRI dhan58, while BRRI dhan28 produced the lowest. However, BRRI dhan67 obtained the highest preference scores from the farmers and extension personnel due to its medium and slender grains, shorter growth duration, resistance to lodging, less disease, and less insect invasion. Moreover, stability indices for yield revealed that BRRI dhan67 was the most stable, adaptive, and appropriate variety, followed by BRRI dhan74, across the locations. Farmers showed keen interest to grow BRRI dhan67 by themselves instead of BRRI dhan28 all over the study locations. The neighboring farmers also expressed their curiosity about cultivating BRRI dhan67 over BRRI dhan28 by collecting seeds from the participating farmers. Thus, BRRI dhan67 could be a perfect replacement for BRRI dhan28. However, conducting participatory varietal evaluation trials across the agroecological zones of the country is recommended to validate the results of this study.

Ectopic expression of Vigna radiata's vacuolar Na+/H+ antiporter gene (VrNHX1) in indica rice (Oryza sativa L.)

It is essential to develop high salt-tolerant rice varieties in order to cultivate the salt-affected lands. In this study, Na+/H+ exchanger 1 (NHX1) gene isolated from Vigna radiata L. Wilczek was transferred in Bangladesh Rice Research Institute (BRRI) developed two indica rice genotypes BRRI Dhan28 and BRRI Dhan29 using in-planta approach for improvement of salinity tolerance. Embryonic axes of matured dehusked rice seeds were injured and co-cultivated with Agrobacterium strain harboring VrNHX1 gene and finally regenerated. GUS histochemical assay and PCR amplification of GUS-a and VrNHX1 were performed to confirm the transformation. Expression confirmation was done by semi-quantitative RT-PCR. Under salinity stress, transgenic lines showed higher chlorophyll, relative water content and decreased electrolyte leakage, proline content, lipid peroxidation level, and catalase enzyme activity which represent the better physiology than control plants. Moreover, under salinity stress (150 mM), transgenic lines exhibited superior growth and salt tolerant than non-transgenic plants.

INFLUENCE OF SEED SOURCE ON PLANT GROWTH, YIELD AND YIELD GAP OF RICE (ORYZA SATIVA L.)

Seed source is influenced on plant growth and yield of a crop. The objective of this research was to investigate the plant growth and yield including gap of rice collected seed from different sources in Bangladesh. The seed of rice variety BRRI dhan28 of Oryza sativa L. was used as study material. The treatments were consisted of four sources of seed viz. Bangladesh Agricultural Development Corporation (BADC), private seed company, farmers’ own seed and seed from local market. The seed was also obtained from Bangladesh Rice Research Institute (BRRI) that was used for control. Data regarding plant growth parameters (plant height, leaf area, absolute growth rate, AGR and relative growth rate, RGR); yield attributes (number of spikelet/panicles, 1000-grain weight and yield/ton); and percentage of yield gap were investigated. Minimum plant growth parameters except RGR and all yield attributes of rice were observed in the seed of BRRI followed by BADC; while the highest RGR was observed in the seed of BRRI and BADC simultaneously. The yield gap of rice was the highest in the seed of the market. The plant growth and grain yield of rice were comparatively higher in the seed of BRRI followed by BADC and company due to higher knowledge of seed production and processing technology; while higher yield gap were observed in the seed of farmer and market due to poor seed production and processing facilities as well as their poor knowledge.

Most of the popular rice varieties in Bangladesh are of medium glycemic index (GI)

Objective: Carbohydrate rich food is the most widely consumed nutrient globally, but when consumed in excess it can have undesirable effects on health. Glycemic index (GI) could be a degree of the impacts of carbohydrates on blood glucose levels.Materials and methods: We selected eight Bangladesh Rice Research Institute (BRRI) developed varieties and two local varieties.Results and Discussion: The highest amount of carbohydrate was measured in BRRI Dhan-29 variety (81.18%), and the lowest amount was found in BR-26 (78.03%). The highest starch digestibility was found in BRRI Dhan-40 (86.56%), and the lowest starch digestibility was found in BRRI Dhan-28 (70.20%).GI ranged from 49.87 to 74.20 in parboiled varieties. Only two varieties (BR-16 and Pajam) are in the low GI group (55 and below), with most of the varieties are within medium GI group (56-69) (BR-11, BR-26, BRRIDhan-28, BRRIDhan-30 and BRRIDhan-40). High GI value (70 and above) are BRRI Dhan-29 and Chinigura. Although BR-16 had the highest amylose content and lowest GI value, however, in some cases, for example, BRRI-Dhan-29 has high amylose content as well as a high GI value. There was no significant correlation between GI and amylose content. However, when the elevated rapidly digestible starch value of BRRI Dhan-29 is being considered, at that point, it clarifies the higher GI value. A noteworthy relationship (r=0.62, p< 0.01) was found between GI values and RDS content.Conclusion: Low GI rice with good nutritional composition may encourage farmers as well as consumers for their high demand and economic benefit.International Journal of Human and Health Sciences Vol. 05 No. 04 October’21 Page: 484-490

Moisture Stress and Different Rates of Nutrients on Growth and Yield of Rice

The experiment was conducted at the Bangladesh Rice Research Institute (BRRI) Gazipur farm during Boro 2003-04 seasons to observe the moisture stress effects in relation to nutrient rates on growth and yield of rice. The treatments were three moisture stresses (NS= Always saturated condition i.e. 1-2 cm standing water; VPS= Withholding water at the vegetative phase i.e. 15 days after transplanting (DAT) to maximum tillering stage; RPS=Withholding water at the reproductive phase i.e. PI to flowering stage) and three fertilizer doses (F0= No fertilizer; HD= Half of the optimum dose and OD= Optimum dose i.e. 120-60-40-10-2 kg ha-1 of N, P2O5, K2O, S and Zn respectively). The treatments were applied in high yielding variety BRRI dhan29. The result showed that irrespective of nutrient rates, drought stress decreased plant height, tiller number and shoot dry weight. Unstressed plants (NS) produced the highest grain yield (3.14 to 6.51 tha-1) followed by vegetative phase stressed (VPS) plants (2.73 to 4.50 tha-1). The reproductive phase stressed (RPS) plants produced the lowest grain yield (2.54 to 4.20 t ha-1). Regardless of water stress, application of optimum dose (OD) of nutrients produced the highest grain yield followed by half dose (HD) of nutrients. No fertilizer treatment (F0) produced the lowest grain yield. Due to water stress, the highest grain yield reduction occurred in OD (22-32%) followed by HD (12-19%) and the lowest in F0 (4-15%).
 Bangladesh Rice j. 2018, 22(2): 23-30

Effect of Seed Rate on Seedling Quality for Mechanical Rice Transplanting

A study was conducted in the Farm Machinery and Postharvest Technology Division, Bangladesh Rice Research Institute (BRRI), Gazipur in the irrigated dry season (Boro) of 2012-13. It was aimed at identifying the optimum seed rate of different graded rice variety for mat type seedlings preparation and suitable seedling adjustment option of the rice trans planter to maintain required number of seedlings dispensed per stroke by the rotary picker of the trans planter. Walk behind type 4-rows rice trans planter (DP 480) was used to conduct the study. The experiment was followed as two factorial completely randomized design (CRD) with three replications. Three categories of rice variety as short and bold grain (cv. BR3), medium and slender grain (cv. BRRI dhan28) and extra-long and slender grain (cv. BRRI dhan50) were considered as main factor whereas seed rate of 100, 120, 130, 140, 150 and 160g pertray (280×580×25 mm) were considered as sub-factor. Irrespective of rice category, seedling emergence decreased with the increase of seed rate. Seedling emergence decreased from 77 to 56, 74 to 57 and 77 to 54% in BR3, BRRI dhan28 and BRRI dhan29 respectively with the increase of seed rate from 100 to 160g per tray. Seed rate did not affect the seedling height significantly whereas it was varied with the rice verities only and BRRI dhan50 produced higher seedling length. However, number of leaf, stem thickness and shoot dry weight decreased and root-shoot ratio increased significantly with the increase of seed rate. The highest shoot dry weight was observed in BR3 followed by BRRI dhan50. Seedling strength also decreased with the increase of seed rate. The highest seedling strength (0.043 mg cm-1) was observed for the seed rate of 100g of BR3 and the lowest (0.020 mg cm-1) for the seed rate of 160g of BRRI dhan28. The number of seedling increased and percentage of missing hills decreased with the increase of both the seed rate and seedling adjustment option of the rice transplanter irrespective of variety. In case of BR3, seedling dispensed per stroke and percentage of missing hills varied from 4.3 to 5.7 and 6.8 to 7.8 for the seed rates of 140, 150 and 160 g of seeds tray-1 for 5 to 7 seedling adjustment option of the rice transplanter respectively. Seedlings per stroke and percentage of missing hills of BRRI dhan28 for the seed rate of 130, 140 and 150 g of seeds tray-1 was found almost same for 5 to 7 seedling adjustment options of the rice transplanter (4.2 to 6.3 and 5.7 to 9.8). However, there was minimum difference of seedlings per stroke and percentage of missing hills among 120, 130 and 140 g of seeds tray-1 for the option of 4 to 7 (4.0 to 5.6 and 3.9 to 7.8 respectively) for BRRI dhan50. It can be concluded that 140 g of seeds tray-1 for short and bold grain (BR3) and 130 g of seeds tray-1 for medium and slender grain (BRRI dhan28) under the seedling adjustment options of 5 to 7 and 120 g of seeds tray-1 for extra-long and slender grain (BRRI dhan50) under the seedling adjustment options of 4 to 7 may be used for desired seedlings per hill and minimum missing hills along with good quality of seedling.
 Bangladesh Rice j. 2018, 22(1): 9-23

Efficacy and Economics of Different Need Based Nitrogen Management Approaches in Winter Rice

This experiment aimed to study the efficacy of different nitrogen (N) management approaches in winter rice. The experiment consisted of two rice varieties: 1) BRRI (Bangladesh Rice Research Institute) dhan29-an inbred and 2) Dhanigold-a hybrid, and eight N management approaches: 1) BRRI recommended N (control), 2) Soil analysis based N management, 3) N application based on Agro-ecological zone, 4) 20 kg·N·ha-1 at ≤35 SPAD (Silicon photon activate diode) value, 5) 30 kg·N·ha-1 at ≤35 SPAD value, 6) 20 kg·N·ha-1 at ≤3.0 LCC (leaf colour chart) value, 7) 30 kg·N·ha-1 at ≤3.0 LCC value and 8) Urea Super Granule. Between two varieties, hybrid Dhani gold produced higher grain yield (6.67 t·ha-1) than the inbred BRRI dhan29. Application of 20 kg·N·ha-1 at ≤3.0 LCC value gave the highest grain yield (7.10 t·ha-1), whereas the lowest grain yield (5.92 t·ha-1) was found from the SPAD approach with 20 kg·N·ha-1 at ≤35 SPAD value. In case of treatment interaction highest grain yield (7.34 t·ha-1) was found in BRRI dhan29 coupled with 20 kg·N·ha-1 at ≤3.0 LCC value with 18 kg·N·savings·ha-1 over control, maximum gross income (146,800 BDT·ha-1) and net benefit (142,120 BDT·ha-1), which was statistically identical with the grain yield from the interaction of Dhani gold and 30 kg·N·ha-1 at ≤3.0 LCC value but required 42 kg·extra·N·ha-1 (over control). The lowest grain yield (5.19 t·ha-1) was found when Dhanigold was coupled with 30 kg·N·ha-1 at ≤35 SPAD value, while the 20 kg·N·application·ha-1 at ≤35 SPAD value gave moderate yield (6.87 t·ha-1) with considerable higher gross (139,600 BDT·ha-1) and net (136,090 BDT·ha-1) incomes than the control (gross: 121,000 and net: 115,600 BDT·ha-1). The results reveal that 20 kg·N·ha-1 at ≤3.0 LCC value appeared as the promising practice for inbred BRRI dhan29, and 30 kg·N·ha-1 at ≤35 SPAD value for hybrid Dhanigold in terms of yield, N use efficiency and economic benefit of winter rice.

Mature Embryo-Based in vitro Regeneration of Indica Rice Cultivars for High Frequency Plantlets Production

The study was conducted at Biotechnology Division of Bangladesh Rice Research Institute (BRRI) to investigate the effects of plant growing medium and plant growth regulator (PGR) for the callus induction and high frequency plantlets regeneration of indica rice. Ten indica rice varieties viz. BR5, BR11, BRRI dhan28, BRRI dhan29, BRRI dhan33, BRRI dhan41, BRRI dhan47, BRRI dhan48, BRRI dhan49 and BRRI dhan50 were cultured on MS, N6 and LS media. The MS medium was found better for callus induction as compared to N6 and LS media. Among the tested varieties BRRI dhan48 induced the highest percent and best quality callus. Interaction effects of BRRI dhan48 to MS medium yielded 71.55% callus induction. The regeneration efficiency of BRRI dhan48 was tested on MS medium supplemented with different combination of NAA plus BAP and NAA plus kinetin. MS medium supplemented with 2.0 mg L-1 NAA and 2.0 mg L-1 Kn was found the best in respect of percent regenerated (76.67%) plantlet as well as for the growth of plantlets in vitro.Bangladesh Rice j. 2016, 20(2): 81-87

Nitrogen application in direct wet-seeded rice under alternate wetting and drying irrigation condition: Effects on grain yield, dry matter production, nitrogen uptake and nitrogen use efficiencies

ABSTRACTYield, dry matter production, nitrogen (N) uptake and nitrogen use efficiency (NUE) of Bangladesh Rice Research Institute (BRRI) dhan29 were investigated during two consecutive dry (Boro) seasons of 2009–10 and 2010–11. The experiments were set up in a randomized complete block design with three replication having six nitrogen (N) levels of 0, 40, 80 120, 160 and 200 kg ha−1. Nitrogen fertilization increased yield characters, dry matter production and N uptake. The economic optimum rate of N was 166 and 155 kg ha–1 in first and second year, respectively, with corresponding yield of 7.1 and 6.5 t ha−1. NUEs were higher in the first year, decreased with increasing N rates in most cases. Gross return over fertilizer reached the highest Tk 692 in 2009–10 and Tk 489 in 2010–11 with 160 kg N ha–1. The results suggest that BRRI dhan29 should receive an average of 160 kg N ha−1 for economic optimum yield.

Feasibility of Introducing Rice Based Four Crops Pattern in Rangpur Region of Bangladesh

An experiment was conducted at Bangladesh Rice Research Institute (BRRI) Farm at Rangpur during July 2014 - June 2016 to introduce a 4-crops pattern with the aim of increasing cropping intensity, productivity, income and soil fertility. The experimental design was RCB with 3 replications. Four cropping patterns were tested which were: CP1 = T. Aman (BRRI dhan62)-Potato (Cardinal)-Mungbean (BARI Mung-6)-T. Aus (BRRI dhan48), CP2 = T. Aman (BRRI dhan62)-Mustard (BARI Sorisha-14)-Mungbean (BARI Mung-6)-T. Aus (BRRI dhan48), Farmers’ improved practice (FIP) = T. Aman (BR11)-Potato (Cardinal)-Maize (NK 40) and Farmers’ general practice (FP) = T. Aman (BR11)-Boro (BRRI dhan28)- Fallow. In T. Aman 2014, BRRI dhan62 produced 3.87 and 3.85 t ha-1 grain yields under CP1 & CP2 (4 crops systems), respectively; BR11 gave grain yield of 4.62 and 4.36 t ha-1 in FIP and FP (3 and 2 crop system), respectively. In T. Aman 2015, BRRI dhan62 produced grain yield of 4.23 and 4.19 t ha-1 in CP1 and CP2, and BR11 gave grain yield of 5.95 and 5.92 t ha-1 in FIP and FP, respectively. After T. Aman, potato yield was 24.66 t ha-1 in CP1 and 24.17 t ha-1 in FIP during 2014-15. In CP2, 2nd crop mustard yield was 1.16 t ha-1 and3rd crop mungbean yield was only 0.98 t ha-1.In CP1, 3rd crop mungbean yield was only 0.83 t ha-1. After potato in FIP, maize yield was 8.38 t ha-1. After T. Aman (BR11) in FP, grain yield of BRRI dhan28 was 5.42 t ha-1. The yield of BRRI dhan48 in CP1 and CP2 (as 4th crop) was 4.5 t ha-1. Similar results of different crops were obtained in 2015-16. The rice equivalent yield (REY) was found to be 30.05 & 35.95 t ha-1yr-1 in CP1 during 1st and 2nd yearfollowed by FIP (23.92 & 29.82 t ha-1yr-1, respectively). The REY was higher in 2nd year compared to 1st year. In 2014-15 the highest net return of Tk.2,42,560 ha-1 was observed in CP1 followed by FIP(Tk.1,58,380 ha-1); in 2015-16, the highest net return was in CP1 (Tk.2,16,960 ha-1) followed by FIP(Tk.1,24,620 ha-1). Potato based cropping pattern was thus, the most suitable and profitable pattern in this area. T. Aman (BRRI dhan62)-Potato (Cardinal)-Mungbean (BARI Mung-6)-T. Aus (BRRI dhan48) may, therefore, be the most suitable and profitable cropping pattern in medium high lands of Rangpur region. The Agriculturists 2017; 15(1) 116-126

Performance Evaluation of BRRI Power Weeder for Low Land Rice (<i>Oryza sativ</i> L.) Cultivation

Mechanical intervention in crop production is increasing rapidly in Bangladesh. Researchers are finding ways to manage weeds in rice field using suitable mechanical devices instead of conventional hand weeding. A study was conducted to evaluate the field performance of BRRI (Bangladesh Rice Research Institute) power weeder compared to BRRI weeder and hand weeding in the farmers’ field at Rashidpur in Mithapukur upazila under Rangpur district during boro season of 2014-15. Three treatments: T1 = BRRI weeder (BW), T2 = BRRI power weeder (BPW) and T3 = Hand weeding (HW) were used in the experiment. The experiment was carried out in a randomized complete block design (RCBD) and replicated in four farmers’ plots. Rice variety BRRI dhan28 was selected for the experiment. The effective field capacity of BW and BPW was found to be 0.06 and 0.09 ha hr-1, respectively. The weeding efficiency was the highest in HW (92%), followed by BPW (78%) and BW (73%). It was found that BW damaged the lowest number of plants (9%) compared to BPW (11%) during weeding operation, although the damaged plants recovered after a few days. BW and BPW reduced 74 and 85% of labor requirement in weeding operation compared to HW. The highest weeding cost was involved in HW (Tk. 4287 ha-1) compared to BW (Tk. 1103 ha-1) and BPW (Tk. 950ha-1). Weed control methods exerted insignificant effect on grain yield. BRRI power weeder and BRRI weeder reduced weeding cost, enhanced weed control and improved the labor efficiency without sacrificing grain yield. The highest BCR was obtained in BPW (1.22) followed by BW (1.16) and HW (1.11). BRRI power weeder and BRRI weeder appeared to be economic, easy and also environmentally safe weed control device in low land rice cultivation. The Agriculturists 2017; 15(1) 40-48

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

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

Genetic diversity analysis of stress tolerant rice (Oryza sativa L.)

Fourteen rice genotypes, composed of six salt tolerant, three submergence tolerant, two drought tolerant genotypes along with three high yielding genotypes, released from Bangladesh Rice Research Institute (BRRI) were used for genetic diversity analysis using 40 simple sequence repeats (SSR) markers. All of the used SSR markers were found polymorphic among the 14 rice genotypes. The amplicon size ranged from 75 bp (RM436) to 330 bp (RM26360). A total of 168 alleles were detected, the number of alleles per locus ranged from 2 (RM252, S03120) to 6 (RM570, S12055, S11033) with an average of 4.2 alleles per locus. Polymorphic information content (PIC) value varied from 0.21 (RM252) to 0.76 (S07024) with an average of 0.57. From genetic distance co-efficient, the highest and lowest genetic distant varieties were found for BRRI dhan28 vs. BRRI dhan43 (0.82%) and BRRI dhan40 vs. BRRI dhan44 (0.37%) respectively. Unweighted pair group method with arithmetic mean (UPGMA)-cluster analysis divided the rice genotypes into four distinct clusters. The information obtained from this study would be useful for planning the breeding program to develop stress tolerant rice variety with high yielding ability and fine grain quality. Key words: Genetic diversity, simple sequence repeats (SSR) markers, stress tolerant, rice.

Genetic diversity analyzed by quantitative traits among rice (Oryza sativa L.) genotypes resistant to blast disease

Genetic diversity was studied for blast resistant and susceptible genotypes using 13 morphological characters. Plant height, days to flowering and maturity, panicle length, number of spikelet per panicle, number of filled grain per panicle, number of unfilled grain per panicle, 1000-grain weight and yield per hill were indicated as important contributors to genetic divergence in 14 rice genotypes. The first 3 principal components accounted for 78.72% of the total variation among resistant and susceptible rice genotypes. The genotypes were grouped into 7 clusters according to Mohalanobis’s D2 statistics and canonical vector analysis. On the basis of cluster distances, high yielding along with highly susceptible genotype, Bangladesh Rice Research Institute (BRRI) dhan29 could be crossed with resistant genotypes, BR 6017-3-3-4-1 and Zong-yu 7. Similarly, BRRI dhan28 could be crossed with Qing Liali No.1 for the development of blast resistant rice varieties with higher yield. Key words: Blast disease, genetic diversity, quantitative traits, rice, resistant genotypes.

Evaluation of Growth and Yield of Selected Hybrid and Inbred Rice (<i>Oryza sativa</i> L) Varieties Grown in Boro Season

Pot experiments were conducted in net house during Boro 2002 and 2003 at Bangladesh Rice Research Institute (BRRI) to compare the growth and yield of hybrid and inbred rice varieties under controlled condition. Hybrid variety Sonarbangla-1 and BRRI hybrid dhan1 and inbred modern variety BRRI dhan29 were used in both the years. During Boro 2002, Sonarbangla-1 and BRRI hybrid dhan1 had higher plant height and tillers hill-1 compared to BRRI dhan29. The largest leaf area of 75cm2 hill-1 was recorded in BRRI hybrid dhan1 at 30 DAT but at 60 and 90 DAT, Sonarbangla-1 had the highest leaf area of 723 and 1406 cm2 hill-1, respectively. The highest shoot dry matter production was recorded in BRRI hybrid dhan1 at 30 DAT but in Sonarbangla-1 at 60 and 90 DAT. Rooting depth and root dry weight of Sonarbangla-1 were 15- 20% higher than those of BRRI hybrid dhan1 and BRRI dhan29. At harvest, the largest number of panicles hill-1 was observed in BRRI dhan29 followed by Sonarbangla-1. The number of grains panicle-1, 1000-grain weight and grain yield were higher in Sonarbangla-1 followed by BRRI dhan29. During Boro 2003, highest plant height, number of tillers hill-1, leaf area and shoot dry matter were recorded in BRRI hybrid dhan1 at all DAT, followed by Sonarbangla-1 in most cases. Rooting depth and root dry weight were the highest in Sonarbangla-1 followed by BRRI hybrid dhan1. At harvest, highest number of panicles hill-1 were observed in BRRI dhan29 and Sonarbangla-1 but BRRI hybrid dhan1 had the highest number of grains panicle-1. Sonarbangla-1 had the highest 1000-grain weight and grain yield.

Influence of Nitrogen on Growth Performance of Hybrid and Inbred Rice (<i>Oryza sativa</i> L.) Varieties in Boro Season

Field experiments were conducted during boro season of 2002 and 2003 at the Bangladesh Rice Research Institute (BRRI) farm having silty clay loam soil. Hybrid variety Sonarbangla-1 and BRRI hybrid dhan1 and modern inbred variety BRRI dhan29 were used in the experiments. Zero to 160 kg N ha-1 with 40 kg interval and different application schedules, chlorophyll meter based (SPAD35) N application and urea supper granules (USG) @ 80 kg N ha-1 were used as N treatments. During boro 2002, BRRI hybrid dhan1 had 10-15% higher tiller number, leaf area index (LAI) and crop growth rate (CGR) than Sonarbangla-1 and BRRI dhan29. Among the N managements, N9 (USG), N5 (160 kg N ha-1 with basal), N6 (160 kg N ha-1 without basal), and N7 (SPAD based N application with basal) showed 10-15% higher plant height, tiller hill-1, LAI and CGR. During boro 2003, Sonarbangla-1 and BRRI hybrid dhan1 had 10-15% higher plant height, tiller hill-1, LAI and CGR compared to the BRRI dhan29. Among the N management, N9 (USG), N5, N6, N7, N3 (120 kg N ha-1 with basal) and N4 (120 kg N ha-1 without basal) treated plots performed better in terms of growth. The LAI and CGR were reduced by 20-25 % at 60 DAT during 2003 compared to 2002 due to cold and the growth of BRRI dhan29 was restricted much.

Evaluation of SPAD and LCC based nitrogen management in rice (<i>Oryza sativa</i> L.)

A study was conducted during Boro and T. Aman seasons of 2002 at Bangladesh Rice Research Institute (BRRI), Gazipur to see the relationship of SPAD (Soil plant analysis development) reading with chlorophyll and N contents of leaves and to determine the critical LCC value for rice crops. Hybrid varieties Sonarbangla-1 and BRRI hybrid dhan0l were used for both rice crops and BRRI dhan29 and BRRI dhan31 were used as checks for Boro and T. Aman crops, respectively. Sonarbangla-1, BRRI hybrid dhan0l and BRRI dhan29 had similar leaf chlorophyll contents in Boro season. The maximum chlorophyll content (1.6-1.8 mg/g leaf) was observed at 39-42 soil plant analysis development (SPAD) value. In T. Aman season, the inbred BRRI dhan3l showed lower amount of chlorophyll (1.2-1.4 mg/g leaf) at 39-42 SPAD value compared to the hybrids Sonarbangla-1 and BRRI hybrid dhan 0l. Seasonal variation in chlorophyll content between Sonarbangla-1 and BRRI hybrid dhan0l was not large. Relationship between SPAD value and chlorophyll content was very close (R2 =>0.8) at panicle initiation and flower initiation stages for all the varieties. Similar relationship was also observed in case of SPAD value and nitrogen content in leaves. The results indicated that the rice leaves showing higher SPAD readings (>35) had higher chlorophyll and nitrogen contents. The adjusted critical LCC values were 3.0 for Boro and 3.5 for T. Aman seasons for all rice varieties. Key Words: Chlorophyll; nitrogen.DOI: 10.3329/bjar.v34i4.5841Bangladesh J. Agril. Res. 34(4) : 661-672, December 2009