Comparisons were made in the C1 generation between the untreated controls (2x) and colchicine‐treated diploids (C2x) for variation of leaf mesophyll cell size and chloroplast number. Differences were found in that the cell section area and the number of chloroplasts per cell in all the seven lines investigated were significantly greater in the C2x selections compared with the 2x controls using coded determination. In each case, there was an enhancement of chloroplast number independent of the variation in cell size.

Vitamin A deficiency remains a common public health problem among the rice-dependent poor people in the developing countries of Asia. Conventional milled rice does not contain provitamin A (β-carotene) in is edible part (endosperm) and is also deficient in essential minerals, such as iron and zinc. Transgenic Golden Rice event GR2E, which produces β-carotene in its endosperm, was used as a parent to introgress the transgene locus conferring β-carotene biosynthesis into a widely grown rice variety, BRRI dhan29, which covers around 26.1% of the irrigated rice area (4.901 Mha) of Bangladesh in the dry season. The current study reports the introgression process and field performance of GR2E BRRI dhan29 Golden Rice. The background recovery of GR2E BRRI dhan29 lines at BC5F2 generation was more than 98% with a 6K SNP-chip set. The transgenic GR2E BRRI dhan29 yielded 6.2 t/ha to 7.7 t/ha with an average of 7.0 ± 0.38 t/ha, while the non-transgenic BRRI dhan29 yielded 7.0 t/ha under confined field conditions in Bangladesh. Moreover, no significant difference between GR2-E BRRI dhan29 Golden Rice and non-transgenic BRRI dhan29 in any measured trait was observed in the multi-location trials conducted at five locations across the country. Furthermore, the appearance of cooked and uncooked rice was similar to that of BRRI dhan29 except for the yellow color indicating the presence of carotenoids. Total carotenoid content in the selected introgression lines ranged from 8.5 to 12.5 μg/g with an average of 10.6 ± 1.16 μg/g. This amount is sufficient to deliver approximately 66 and 80% of the recommended daily intake of vitamin A for children and women, respectively, assuming complete substitution of white rice in the diet with Golden Rice. However, the lead selected line(s) need further evaluation at open field conditions before deciding for commercial cultivation. A large-scale feeding trial among the malnourished community with this newly developed GR2-E BRRI dhan29 Golden Rice is also required to validate its efficacy in alleviating vitamin A deficiency.

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In total 40 land races of Balam rice of Bangladesh were studied at BRRI during 2009-11. The analysis of variance of 38 morpho-physicochemical characters showed highly significant differences among the genotypes. The mean performances showed high degree of variations among the genotypes. The culm height varied from 61.5 (B31) to 137.26 cm (B11), effective tiller number per hill from 6.33 (B34) to 24.67 (B30), straw yield per hill from 8.44 (B21) to 57.93 g (B39), primary branch number from 6.33 (B21) to 14.33 (B17), secondary branch number from 11 (B26) to 50 (B29), grain length from 6.43 (B33) to 10.83 mm (B8), 1000-grain weight from 16.44 (B32) to 33.22 g (B39) and grain yield per hill from 8.47 (B26) to 33.31 g (B17), respectively. The mean separations showed that no single duplicate genotype was present in the land races. Besides, high GCV and h 2 b together with high GAPM were observed in culm height, 1000-grain weight, LB ratio, panicle exertion, secondary branch number, plant height etc. suggested that selection may be effective for these characters in segregating generations. In correlation coefficients between different characters, 63 correlation coefficients were positive in nature and only 10 estimates were negative. This represents very highly favorable situation for obtaining high response to selection in improving yield and yield components in rice germplasm evaluated. Therefore, these characters emerged as most important associates of grain yield in rice. Finally, the traditional rice germplasm can offer valuable gene pools, which need to be characterized by using molecular tools for QTL mapping of valuable traits.

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