A newly released drought tolerant rice variety BRRI dhan66 suitable for rainfed lowland ecosystem of Bangladesh is an improvement over existing drought tolerant rice varieties. The variety has satisfactorily been passed in the proposed variety trial conducted in the farmers’ field. As a result, National Seed Board (NSB) approved this variety for commercial cultivation in the wet season (T. Aman) in 2014. It has modern plant type with 120 cm plant height and matures in 110-115 days. The important feature of this variety is higher drought tolerance during reproductive stage. It can produce 4.5-5.0 t/ha grain yield without irrigation during reproductive stage. It can produce satisfactory yield when soil moisture remains <20% and perch water table depth is more than 70-80 cm from the surface. The seed size of the variety is 24 g with intermediate long bold grain. It has long, wide and erect flag leaf with deep green colour. It is highly promising as a drought tolerant rice variety for cultivation in the drought prone area, which helps farmers’ to get rid of huge economic loss and is contributing in sustaining food security. Bangladesh Rice j. 2019, 23(1): 45-55

A newly released zinc enriched, high yielding, slender and red pericarp grain containing rice variety BRRI dhan84, suitable for dry ecosystem (Boro season) of Bangladesh is an improvement over existing zinc enriched rice varieties for Bangladesh. The main objective of this research was to develop the of high yielding rice varieties with improved nutritional quality in term of high zinc (Zn≥24 mg/kg) in polished grain. The study was taken in 2004 by crossing between BRRIdhan29/IR68144//BRRI dhan28///BR11 and it takes near about 13 years to develop the targeted variety. After selection of one homozygous advanced line (BR7831-59-1-1-4-5-1-9-P1) the Regional Yield Trial (RYT) was conducted in Boro 2014-15 saeson and the Advanced Line Adaptive Research Trial (ALART) was evaluated at different farmers’ field in Boro 2015-16 season and different yield trials were conducted using Randomized Complete Block Desing (RCBD). The variety has satisfactorily passed the Proposed Variety Trial (PVT) conducted in the farmers’ field in Boro 2016-17 season. As a result National Seed Board (NSB) approved this variety for commercial cultivation in the dry season (Boro season) in 2017. It has modern plant type with 96 cm plant height and matures by 140 days. The salient feature of this variety is the red colored grain, earlier than check variety, the proposed variety showed higher yield than check variety BRRI dhan28. Identifying characters of this variety are dark green leaf, semi erect flag leaf, long slender and red colored grain. It can produce 6.0-6.5 t/ha grain yield. Thousand grain weight of the variety is 22.8 g and it has colored grain tip. The rice has zinc content 27.6 mg/kg, 25.9% amylose content with 9.7% protein content. BRRI dhan84 was released as a high yielding, zinc enriched rice variety to meet  the nutritional (zinc) demand of the country. The zinc enriched BRRI dhan84 is a superb variety for cultivating in the dry (Boro) season and farmers can be economically benefited and the country will be nutritionally benefited by the cultivation of BRRI dhan84.

Biofortification of rice with improved grain zinc (Zn) content is the most sustainable and cost‐effective approach to address Zn malnutrition in Asia. Genomics‐assisted breeding using precise and consistent Zn quantitative trait loci (QTLs), genes, and haplotypes can fast‐track the development of Zn biofortified rice varieties. We conducted the meta‐analysis of 155 Zn QTLs reported from 26 different studies. Results revealed 57 meta‐QTLs with a significant reduction of 63.2% and 80% in the number and confidence interval of the Zn QTLs, respectively. Meta‐quantitative trait loci (MQTLs) regions were found to be enriched with diverse metal homeostasis genes; at least 11 MQTLs were colocated with 20 known major genes involved in the production of root exudates, metal uptake, transport, partitioning, and loading into grains in rice. These genes were differentially expressed in vegetative and reproductive tissues, and a complex web of interactions were observed among them. We identified superior haplotypes and their combinations for nine candidate genes (CGs), and the frequency and allelic effects of superior haplotypes varied in different subgroups. The precise MQTLs with high phenotypic variance, CGs, and superior haplotypes identified in our study are useful for an efficient Zn biofortification of rice and to ensure Zn as an essential component of all the future rice varieties through mainstreaming of Zn breeding.

Drought is the second most treacherous climate-related risk for rice production in rainfed lowland areas. To counter this climate vulnerability, a new rice variety with enhanced drought tolerance was developed. The promising line IR82589-B-B-84-3 was subjected to advanced yield trials to evaluate specific and general adaptability with standard check in on-station as well as on-farm conditions of Bangladesh following randomized complete block (RCB) design with three replications in wet (T. Aman) season. IR82589-B-B-84-3 was developed as a drought-tolerant rice variety BRRI dhan71, which plant height 108 cm and growth duration 115 days after proper evaluation by National Seed Board (NSB) Bangladesh. It was found that this variety is the higher drought tolerance (up to 28 days) during reproductive stage. It can produce 5.5 t/ha grain yield in standard condition and 4.0 t/ha grain yield in medium drought condition but 3.0-3.5 t/ha grain yield in severe drought condition. Grain yield is also not affected by water scarcity during reproductive stage where parch water table depth is more than 70-80 cm from the surface and reduced soil moisture (<20%). Thousand grain weight of the variety is 24 gm, amylose content is 24%. It has long, erect and deep green colored flag leaf. The results indicated that farmers can maximize net profit by cultivating BRRI dhan71 because it required less input, early maturing than existing varieties, drought tolerant and they also get opportunity to cultivate Mustard, Barley, Potato and vegetables after harvesting it. Thus total productivity will be augmented and food security can also be sustained by the cultivation of BRRI dhan71.

Rice Tungro disease poses a threat to rice production in Asia. Marker assisted backcross breeding is the most feasible approach to address the tungro disease. We targeted to introgress tungro resistance locus tsv1 from Matatag 1 into a popular but tungro susceptible rice variety of Bangladesh, BRRI dhan71. The tsv1 locus was traced using two tightly linked markers RM336 and RM21801, and background genotyping was carried out using 7 K SNPs. A series of three back crosses followed by selfing resulted in identification of plants similar to BRRI dhan71. The background recovery varied at 91–95% with most of the lines having 95%. The disease screening of the lines showed moderate to high level of tungro resistance with a disease index score of ≤ 5. Introgression Lines (ILs) had medium slender grain type, and head rice recovery (59.2%), amylose content (20.1%), gel consistency (40.1 mm) and gelatinization temperature were within the acceptable range. AMMI and Kang’s stability analysis based on multi-location data revealed that multiple selected ILs outperformed BRRI dhan71 across the locations. IR144480-2-2-5, IR144483-1-2-4, IR144484-1-2-2 and IR144484-1-2-5 are the most promising lines. These lines will be further evaluated and nominated for varietal testing in Bangladesh.