Anitha Raman

Drought yield index to select high yielding rice lines under different drought stress severities.

BackgroundDrought is the most severe abiotic stress reducing rice yield in rainfed drought prone ecosystems. Variation in intensity and severity of drought from season to season and place to place requires cultivation of rice varieties with different level of drought tolerance in different areas. Multi environment evaluation of breeding lines helps breeder to identify appropriate genotypes for areas prone to similar level of drought stress. From a set of 129 advanced rice (Oryza sativa L.) breeding lines evaluated under rainfed drought-prone situations at three locations in eastern India from 2005 to 2007, a subset of 39 genotypes that were tested for two or more years was selected to develop a drought yield index (DYI) and mean yield index (MYI) based on yield under irrigated, moderate and severe reproductive-stage drought stress to help breeders select appropriate genotypes for different environments.ResultsARB 8 and IR55419-04 recorded the highest drought yield index (DYI) and are identified as the best drought-tolerant lines. The proposed DYI provides a more effective assessment as it is calculated after accounting for a significant genotype x stress-level interaction across environments. For rainfed areas with variable frequency of drought occurrence, Mean yield index (MYI) along with deviation in performance of genotypes from currently cultivated popular varieties in all situations helps to select genotypes with a superior performance across irrigated, moderate and severe reproductive-stage drought situations. IR74371-70-1-1 and DGI 75 are the two genotypes identified to have shown a superior performance over IR64 and MTU1010 under all situations.ConclusionFor highly drought-prone areas, a combination of DYI with deviation in performance of genotypes under irrigated situations can enable breeders to select genotypes with no reduction in yield under favorable environments compared with currently cultivated varieties. For rainfed areas with variable frequency of drought stress, use of MYI together with deviation in performance of genotypes under different situations as compared to presently cultivated varieties will help breeders to select genotypes with superior performance under all situations.

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.

Can productivity and profitability be enhanced in intensively managed cereal systems while reducing the environmental footprint of production? Assessing sustainable intensification options in the breadbasket of India

Highlights • Higher cereal productivity can be achieved with lower environmental footprint through conservation agriculture.• Wheat productivity and profitability can be increased by zero-tillage and early sowing.• Kharif maize appears to be a suitable and profitable alternative to rice in northwest India.• Productivity and resource efficiency of transplanted rice can be improved by BMPs.• Directly sown rice has potential to save water, energy and global warming potential compared to transplanted rice.

Breeding drought tolerant rice for shallow rainfed ecosystem of eastern India

Highlights • For vegetative-stage drought screening in the dry season, maintaining the soil water potential above −20 kPa as monitored at 30 cm depth is recommended to be able to clearly distinguish between tolerant and susceptible genotypest.• This study identified some genotypes that were susceptible to drought in reproductive-stage drought stress but showed tolerance of vegetative-stage drought stress, indicating the distinct response of rice to drought stress at these two growth stages.• Combining tolerance of vegetative-stage drought with tolerance of reproductive-stage drought could be accomplished by performing separate vegetative- and reproductive-stage drought stress screening trials, which in this study resulted in the identification of genotypes IR72667-16-1-B-B-3, IR78908-126-B-2-B, and IR79970-B-47-1 as tolerant of both stages of drought stress.• The development of improved varieties with combined tolerance of drought stress at multiple growth stages will help farmers in rainfed rice-growing regions maintain stable yields across increasingly unpredictable climatic conditions.