Background: High yielding rice varieties are usually low in grain iron (Fe) and zinc (Zn) content. These two micronutrients are involved in many enzymatic activities, lack of which cause many disorders in human body. Biofortification is a cheaper and easier way to improve the content of these nutrients in rice grain. Results: A population panel was prepared representing all the phenotypic classes for grain Fe-Zn content from 485 germplasm lines. The panel was studied for genetic diversity, population structure and association mapping of grain Fe-Zn content in the milled rice. The population showed linkage disequilibrium showing deviation of Hardy-Weinberg's expectation for Fe-Zn content in rice. Population structure at K = 3 categorized the panel population into distinct sub-populations corroborating with their grain Fe-Zn content. STRUCTURE analysis revealed a common primary ancestor for each sub-population. Novel quantitative trait loci (QTLs) namely qFe3.3 and qFe7.3 for grain Fe and qZn2.2, qZn8.3 and qZn12.3 for Zn content were detected using association mapping. Four QTLs, namely qFe3.3, qFe7.3, qFe8.1 and qFe12.2 for grain Fe content were detected to be co-localized with qZn3.1, qZn7, qZn8.3 and qZn12.3 QTLs controlling grain Zn content, respectively. Additionally, some Fe-Zn controlling QTLs were co-localized with the yield component QTLs, qTBGW, OsSPL14 and qPN. The QTLs qFe1.1, qFe3.1, qFe5.1, qFe7.1, qFe8.1, qZn6, qZn7 and gRMm9-1 for grain Fe-Zn content reported in earlier studies were validated in this study. Conclusion: Novel QTLs, qFe3.3 and qFe7.3 for grain Fe and qZn2.2, qZn8.3 and qZn12.3 for Zn content were detected for these two traits. Four Fe-Zn controlling QTLs and few yield component QTLs were detected to be colocalized. The QTLs, qFe1.1, qFe3.1, qFe5.1, qFe7.1, qFe8.1, qFe3.3, qFe7.3, qZn6, qZn7, qZn2.2, qZn8.3 and qZn12.3 will be useful for biofortification of the micronutrients. Simultaneous enhancement of Fe-Zn content may be possible with yield component traits in rice.

Three plant oils (Cymbopogon citratus, Cymbopogon martini, and Pelargonium graveolens) were developed as EC formulations and tested for their physical stabilities. EC formulations (10EC, 20EC and 30EC) of C. citratus, C. martini and P. graveolens had emulsion stability, spontaneity property, heat and cold stability. EC formulated plant oils were screened against the major seed borne fungi of rice such as Curvularia lunata, Fusarium moniliforme, Bipolaris oryzae, and Sarocladium oryzae. The level of inhibition varied among the concentrations of EC formulations. Among the three EC formulations, that of C. citratus oil 30EC recorded 100% inhibition on the mycelial growth of test pathogens. In the blotter paper method, rice seeds treated with a formulation of C. citratus oil 30EC controlled the infection of C. lunata, F. moniliforme, B. oryzae and S. oryzae in rice seed to the tune of 66.0%, 60.4%, 66.0% and 69.1%, respectively. Seed soaking with formulation of C. citratus oil 30EC showed the highest percentage of normal seedlings, the lowest number of abnormal seedling and fresh ungerminated seeds when tested with the roll-towel method. Seed soaking with 30EC formulation of C. citratus oil increased seed germination, shoot length, root length and vigour of rice seedlings when tested with the plastic tray method. Transmission of pathogens from seed to seedling was reduced significantly by the 30EC formulation of C. citratus oil when tested with the plastic pot method. The effect of the storage life of the 30EC formulation of C. citratus oil showed that it had retained their antifungal effect till the end of the incubation period (120 days), and is able to inhibit the mycelial growth of all test pathogens to the 100% level.

No abstract

No abstract