BackgroundGenetic diversity among rice cultivars from Bangladesh and North East India was assessed using a custom 384-SNP microarray assay. A total of 511 cultivars were obtained from several sources, choosing landraces likely to be from the aus subpopulation and modern improved cultivars from Bangladesh. Cultivars from the OryzaSNP set and Rice Diversity Panel 1 (RDP1) were also included for reference.ResultsThe population analysis program STRUCTURE was used to infer putative population groups in the panel, revealing four groups: indica (76 cultivars), japonica (55) and two distinct groups within the aus subpopulation (aus-1 = 99, aus-2 = 151). Principal Component Analysis was used to confirm the four population groups identified by STRUCTURE. The analysis revealed cultivars that belonged to neither aus-1 nor aus-2 but which are clearly aus based on the combined probabilities of their membership of the two aus groups which have been termed aus-admix (96). Information obtained from the panel of 511 cultivars was used to assign rice groups to 74 additional landraces obtained from Assam and West Bengal. While both the aus-1 and aus-2 groups were represented approximately equally in India, aus-2 (which includes cultivar N 22) was more common in Bangladesh, but was not found at all in West Bengal.ConclusionsExamining the distribution of landrace names within theaus-1 and aus-2 groups suggests that aus-1 is associated with the term “boro”, a word used to describe a winter growing season in Bangladesh and Assam. The information described here has been used to select a population of 300 cultivars for Genome Wide Association studies of the aus rice subpopulation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-015-0068-z) contains supplementary material, which is available to authorized users.

No abstract

An experiment was conducted at the Soil Science Field Laboratory of Bangladesh Agricultural University, Mymensingh during boro season of 2014 to evaluate the effect of deep placement of nitrogen (N) fertilizers on N use efficiency and yield of BRRI dhan29 under flooded condition. The soil was silt loam in texture having pH 6.27, organic matter content 1.95%, total N 0.136%, available P 3.16 ppm, exchangeable K 0.095 me%, available S 10.5 ppm and EC 348 μS cm -1 . . All the treatments except T 6, T 7 and T 8 received 25 kg P and 64 kg K ha -1 as TSP and MoP respectively. In T 6, T 7 and T 8 treatments, P and K were supplied from NPK briquettes. Prilled urea was applied in three equal splits. USG and NPK briquettes were applied at 10 DAT and were placed at 8-10 cm depth within four hills at alternate row. After deep placement of USG and NPK briquette, and each split application of PU, the water samples were collected for 5 consecutive days and analyzed for NH 4 -N concentration in surface water. After application of N fertilizers, the NH 4 -N in floodwater reached peak on the 2 nd day in PU treated plots and then decreased rapidly over time. In the USG and NPK briquette treated plots, the NH 4 -N was generated slowly but spontaneously over the entire growth period as compared to PU indicating a beneficial role of USG and NPK briquette.

No abstract

No abstract