Genotype × environment interactions for grain iron and zinc content in rice

BACKGROUND

Nutrient deficiency in humans, especially in children and lactating women, is a major concern. Increasing the micronutrient concentration in staple crops like rice is one way to overcome this. The micronutrient content in rice, especially the iron (Fe) and zinc (Zn) content, is highly variable. The identification of rice genotypes in which there are naturally high Fe and Zn concentrations across environments is an important target towards the production of biofortified rice.

RESULTS

Phenotypic correlations between grain Fe and Zn content were positive and significant in all environments but a significant negative association was observed between grain yield and grain Fe and Zn. Promising breeding lines with higher Zn or Fe content, or both, were: IR 82475-110-2-2-1-2 (Zn: 20.24-37.33 mg kg^-1 ; Fe: 7.47-14.65 mg kg^-1 ); IR 83294-66-2-2-3-2 (Zn: 22-37-41.97 mg kg^-1 ; Fe: 9.43-17.16); IR 83668-35-2-2-2 (Zn: 27.15-42.73 mg kg^-1 ; Fe: 6.01-14.71); IR 68144-2B-2-2-3-1-166 (Zn: 23.53-40.30 mg kg^-1 ; Fe: 10.53-17.80 mg kg^-1 ) and RP Bio 5478-185M7 (Zn: 22.60-40.07 mg kg^-1 ; Fe: 7.64-14.73 mg kg^-1 ). Among these, IR82475-110-2-2-1-2 (Zn: 20.24-37.33 mg kg^-1 ; Fe: 7.47-14.65 mg kg^-1 ) is also high yielding with 3.75 t ha^-1 . Kelhrie Cha (Zn: 17.76-36.45 mg kg^-1 ; Fe: 7.17-14.77 mg kg^-1 ), Dzuluorhe (Zn: 17.48-39.68 mg kg^-1 ; Fe: 7.89-19.90 mg kg^-1 ), Nedu (Zn: 18.97-43.55 mg kg^-1 Fe: 8.01-19.51 mg kg^-1 ), Kuhusoi-Ri-Sareku (Zn: 17.37-44.14 mg kg^-1 ; Fe: 8.99-14.30 mg kg^-1 ) and Mima (Zn: 17.10-45.64 mg kg^-1 ; Fe: 9.97-17.40 mg kg^-1 ) were traditional donor genotypes that possessed both high grain Fe and high Zn content.

CONCLUSION

Significant genotype × location (G × L) effects were observed in all traits except Fe. Genetic variance was significant and was considerably larger than the variance of G × L for grain Zn and Fe content traits, except grain yield. The G × L × year variance component was significant in all cases. © 2020 Society of Chemical Industry.

Pyramiding of drought yield QTLs into a high quality Malaysian rice cultivar MRQ74 improves yield under reproductive stage drought

BACKGROUND

With the objective of improving the grain yield (GY) of the Malaysian high quality rice cultivar MRQ74 under reproductive stage drought stress (RS), three drought yield QTLs, viz. qDTY 2.2, qDTY 3.1 , and qDTY 12.1 were pyramided by marker assisted breeding (MAB). Foreground selection using QTL specific markers, recombinant selection using flanking markers, and background selections were performed in every generation. BC1F3 derived pyramided lines (PLs) with different combinations of qDTY 2.2, qDTY 3.1 , and qDTY 12.1 were evaluated under both RS and non-stress (NS) during the dry season (DS) of 2013 and 2014 at IRRI.

RESULTS

The GY reductions in RS trials compared to NS trials ranged from 79 to 99 %. Plant height (PH) was reduced and days to flowering (DTF) was delayed under RS. Eleven BC1F5 MRQ74 PLs with yield advantages of 1009 to 3473 kg ha(-1) under RS and with yields equivalent to MRQ74 under NS trials were identified as promising drought tolerance PLs. Five best PLs, IR 98010-126-708-1-4, IR 98010-126-708-1-3, IR 98010-126-708-1-5, IR 99616-44-94-1-1, and IR 99616-44-94-1-2 with a yield advantage of more than 1000 kg ha(-1) under RS and with yield potential equivalent to that of MRQ74 under NS were selected. The effect of three drought grain yield QTLs under RS in MRQ74 was validated. Under NS, PLs with two qDTY combinations (qDTY 2.2 + qDTY 12.1 ) performed better than PLs with other qDTY combinations, indicating the presence of a positive interaction between qDTY 2.2 and qDTY 12.1 in the MRQ74 background.

CONCLUSION

Drought tolerant MRQ74 PLs with a yield advantage of more than 1000 kg ha(-1) under RS were developed. Differential yield advantages of different combinations of the qDTYs indicate a differential synergistic relationship among qDTYs.

Agronomic improvements can make future cereal systems in South Asia far more productive and result in a lower environmental footprint

South Asian countries will have to double their food production by 2050 while using resources more efficiently and minimizing environmental problems. Transformative management approaches and technology solutions will be required in the major grain-producing areas that provide the basis for future food and nutrition security. This study was conducted in four locations representing major food production systems of densely populated regions of South Asia. Novel production-scale research platforms were established to assess and optimize three futuristic cropping systems and management scenarios (S2, S3, S4) in comparison with current management (S1). With best agronomic management practices (BMPs), including conservation agriculture (CA) and cropping system diversification, the productivity of rice- and wheat-based cropping systems of South Asia increased substantially, whereas the global warming potential intensity (GWPi) decreased. Positive economic returns and less use of water, labor, nitrogen, and fossil fuel energy per unit food produced were achieved. In comparison with S1, S4, in which BMPs, CA and crop diversification were implemented in the most integrated manner, achieved 54% higher grain energy yield with a 104% increase in economic returns, 35% lower total water input, and a 43% lower GWPi. Conservation agriculture practices were most suitable for intensifying as well as diversifying wheat-rice rotations, but less so for rice-rice systems. This finding also highlights the need for characterizing areas suitable for CA and subsequent technology targeting. A comprehensive baseline dataset generated in this study will allow the prediction of extending benefits to a larger scale.