Yield loss of Oryza glaberrima caused by grain shattering under rainfed upland conditions

The general perception of Oryza glaberrima as low yielding is a potential drawback to intraspecific breeding of this species. Yields of 21 O. glaberrima accessions were evaluated alongside four O. sativa check varieties under two conditions in which panicles were both covered by paper sacks to avoid grain shattering (potential yield plot) and also not covered (control plot) in a rainfed upland field of Benin in 2010 and 2011. Average potential yields of O. glaberrima with panicles covered were 2.42 and 3.65 t ha-1 in 2010 and 2011, respectively, while those of O. sativa were respectively 2.99 and 3.49 t ha-1. Although there was no significant difference between potential yield and control yield in O. sativa, 19 O. glaberrima accessions showed significant yield reduction by grain shattering — the average percentages of lost yield by shattering were 57.88% in 2010 and 66.76% in 2011. These results suggest that low yield of O. glaberrima is due to grain shattering and that its potential yield would not be inferior to O. sativa if the grain shattering problems were overcome. Two O. glaberrima accessions, TOG 12303 and TOG 9300, possessing strong resistance to grain shattering comparable to O. sativa checks, were identified.Keywords: Panicles, paper sacks, potential yield, yield reduction

Moving toward rice self-sufficiency in sub-Saharan Africa by 2030: Lessons learned from 10 years of the Coalition for African Rice Development

The Coalition for African Rice Development (CARD) was initiated as a policy framework with the aim of doubling rice production in sub-Saharan Africa (SSA) over the period from 2008 to 2018. This paper assesses the contribution of the CARD policy to rice production and forecasts the local rice supply and demand to provide a better understanding of the policies needed to attain rice self-sufficiency by 2030. A combination of the autoregressive integrated moving average method and counterfactual approach was adopted using rice statistical data from 23 countries in SSA. The results showed that the contribution of CARD to paddy rice production in 2018 was 10.2 million tons, equivalent to 74% of the target. This contribution resulted from increases in area and yield of 23% and 19%, respectively. However, the yield growth rate was not sustainable in almost two-thirds of countries. Investments in supply-push factors such as fertilizer and irrigation development, which were the focus in the past, have limited effects on rice production. We conclude that sustainable investments in demand-pull factors such as the private-led modern milling sector and contract farming development should be prioritized to achieve rice self-sufficiency in SSA

Leaf Eh and pH: A Novel Indicator of Plant Stress. Spatial, Temporal and Genotypic Variability in Rice (Oryza sativa L.)

A wealth of knowledge has been published in the last decade on redox regulations in plants. However, these works remained largely at cellular and organelle levels. Simple indicators of oxidative stress at the plant level are still missing. We developed a method for direct measurement of leaf Eh and pH, which revealed spatial, temporal, and genotypic variations in rice. Eh (redox potential) and Eh@pH7 (redox potential corrected to pH 7) of the last fully expanded leaf decreased after sunrise. Leaf Eh was high in the youngest leaf and in the oldest leaves, and minimum for the last fully expanded leaf. Leaf pH decreased from youngest to oldest leaves. The same gradients in Eh-pH were measured for various varieties, hydric conditions, and cropping seasons. Rice varieties differed in Eh, pH, and/or Eh@pH7. Leaf Eh increases and leaf pH decreases with plant age. These patterns and dynamics in leaf Eh-pH are in accordance with the pattern and dynamics of disease infections. Leaf Eh-pH can bring new insight on redox processes at plant level and is proposed as a novel indicator of plant stress/health. It could be used by agronomists, breeders, and pathologists to accelerate the development of crop cultivation methods leading to agroecological crop protection

Hedonic Pricing of Rice Attributes, Market Sorting, and Gains from Quality Improvement in the Beninese Market

Latent class analysis is applied to a hedonic price model to examine the presence of heterogeneity in consumer valuation of quality attributes in the Beninese rice market. Three classes of consumers are found in proportions of 5, 56, and 39 percent. We employ a partial equilibrium model and find modest gains in consumer surplus from an increase in head rice and reduction in chalkiness. The results provide evidence of market sorting, which should be taken into consideration in upgrading rice value chains. Also, it is important to assess potential gains from quality improvement to determine priorities for research and development

Evaluation of sixteen reference evapotranspiration methods under sahelian conditions in the Senegal River Valley

Study region: Reference evapotranspiration (ETo) plays a key role in irrigation sys-tems design, water management under irrigated and rainfed production. Underthe sahelian conditions in the Senegal River Valley that receives less than 300 mmannual rainfall, rice crop water use should be estimated for the sustainability of theresource. Study focus: However the Penman–Monteith (PM) equation is revealed the mostaccurate one; it necessitates several climatic parameters that are not always avail-able mostly in the developing countries. The objective of this study was to evaluatethe performance of 16 ETo equations against the ASCE-PM equation under thesahelian conditions at Ndiaye and Fanaye (Senegal) for alternate equation forETo estimation with less climatic parameters. The results showed that the Har-greaves, modified Hargreaves, Ravazzani and Tralkovic equations systematicallyoverestimated ETo with the highest percentage error of estimate (PE). In contrast,Makkink–Hansen, Oudin and Turc equations systematically underestimated ETo.Temperature based equations of Romenenko and Schendel performed relativelybetter at Fanaye with 5.5% and 9.6% PE, fitting slopes of 0.92 and 1.05, and meanratio (MR) of 1.00 and 1.14, respectively. Mass transfer equations of Trabert andMahringer also had good performance compared to the Penman–Monteith equa-tion. New hydrological insights for the region: Overall, Valiantzas, Trabert, Romanenko,Schendel and Mahringer equations were the promising equations that could be usedfor reference evapotranspiration estimation in the Senegal River Valley

Effects of Alternate Wetting and Drying Irrigation Regime and Nitrogen Fertilizer on Yield and Nitrogen Use Efficiency of Irrigated Rice in the Sahel

The objectives of this study were to investigate water saving strategies in the paddy field and to evaluate the performance of some of the newly released rice varieties. Field experiments were conducted at Fanaye in the Senegal River Valley during two rice growing seasons in 2015. Three irrigation regimes ((i) continuous flooding, (ii) trigging irrigation at soil matric potential (SMP) of 30 kPa, (iii) trigging irrigation at SMP of 60 kPa) were tested in an irrigated lowland rice field. Irrigation regimes (ii) and (iii) are alternate wetting and drying (AWD) cycles. Four inbred rice varieties (NERICA S-21, NERICA S-44, Sahel 210 and Sahel 222) and one hybrid rice (Hybrid AR032H) were evaluated under five nitrogen fertilizer rates (0, 50, 100, 150 and 200 kg N ha−1). The results showed that rice yield varied from 0.9 to 12 t ha−1. The maximum yield of 12 t ha−1 was achieved by NERICA S-21 under AWD 30 kPa at 150 kg N ha−1. The AWD irrigation management at 30 kPa resulted in increasing rice yield, rice water use and nitrogen use efficiency and reducing the irrigation applications by 27.3% in comparison with continuous flooding. AWD30 kPa could be adopted as a water saving technology for water productivity under paddy production in the Senegal River Middle Valley. Additional research should be conducted in the upper Valley, where soils are sandier and water is less available, for the sustainability and the adoption of the irrigation water saving practices across the entire Senegal River Valley

Suitable management options to improve the productivity of rice cultivars under salinity stress

Growing rice in saline soils by minimizing damage on growth and yield remains a challenge. We conducted field experiments in the Africa Rice research field located in the Senegal River delta (16° 11ʹ N, 16° 15ʹ W) to study the effects of three management options of fertilization e.g. (i) nitrogen, phosphorus, and potassium fertilization: NPK; (ii) NPK combined with zinc: NPK-Zn, and (iii) NPK combined with gypsum: NPK-gypsum on the soil salinity level, the nutrient uptake and the productivity of different rice cultivars. The whole objective of this study is to determine how zinc or gypsum associated to NPK fertilizer can improve the growth and productivity of rice crop in saline soil. Results showed that the initial soil salinity level was reduced rapidly in plots treated with gypsum. The leaf-K/Na ratio, agronomic nitrogen use efficiency (ANUE), and grain yield of rice cultivars under the salinity stress were improved by the NPK-gypsum and NPK-Zn options relatively to the NPK option, suggesting that NPK-gypsum and NPK-Zn are suitable management options in reducing adverse effect of low K/Na, low ANUE as well as to improve rice yield under salinity stress

Climate smart rice innovations to reduce the impact of climate change on the livelihood of value chain actors

Introduction Rice is a major source of nutrients, largely contributing to the food and nutrition security for millions of people in Africa although most countries still rely on huge imports to meet local demand. Extreme temperatures, drought, flooding, and high salinity are climate change related stresses that negatively affect rice yield and grain quality. Thus, tackling these constraints is a critical action to increasing rice self sufficiency in Cameroon and Africa in general. Methods The Africa Rice Center in partnership with the National Agricultural Research and Extension Services of its 28 member States operating within the framework of the Africa-wide Taskforces has developed, tested, validated, and are deploying breeding, agronomic and post-harvest approaches to mitigate the negative impacts of climate change on rice yield and quality in Africa. Results Breeding approaches have led to the development of drought, cold, submergence, stagnation flood, salinity, and anaerobic germination tolerant varieties that are also resistant or tolerant to biotic stresses. These have demonstrated better yields and grain quality under stressed conditions compared to counterparts lacking those specific traits. The system of rice intensification and alternate wetting and drying, mid-season drainage, smart-valleys approach for inland development, solar-powered irrigation system, no-till and rice straw mulching are agronomic approaches developed and these approaches have demonstrated significant increase in yield and grain quality compared to alternative approached under climate change stress conditions. Post-harvest approaches have focused on reducing grain breakages, chalkiness, mycotoxin contamination, insecticide and fungicide use, deforestation and value addition to broken rice and rice milling byproducts using environmentally friendly methods. Post-harvest innovations here include using improved rice parboiling fueled by rice husk, solar-powered hermetic storage systems, processing of fine broken rice into flour for porridges and bakery products and use of rice husk fan-assisted stoves for household cooking and the cottage processing industry. Conclusions and recommendations Although climate change is a serious threat to rice production affecting both yield and quality, African governments will have to implement policy measures that enhance the scaling and adoption of climate smart rice innovation developed by AfricaRice to mitigate the impact of climate change if they aspire to reduce rice imports

Valuation of rice postharvest losses in Sub-Saharan Africa and its mitigation strategies

Data on rice harvest and postharvest loss in Sub-Sahara Africa (SSA) is scanty making it difficult for stakeholders to appreciate the loss and set priority areas for loss reduction along the value chain. To address this problem, a protocol was developed and validated for postharvest loss (PHL) quantification in SSA. Quantitative losses at each segment were determined by field measurements. Interactive effect of origin of rice (domestic versus imported) and type of processing (white versus parboiled milled) on rice price in 33 markets in Africa was used to estimate qualitative loss for both white and parboiled milled rice. Total PHL for rice in SSA in 2018 is estimated at about US$ 10.24 billion, representing 47.63% of the expected total production. The highest loss recorded was quantitative loss before and during harvesting, followed by qualitative loss along the entire value chain, quantitative loss during milling, parboiling, threshing in that order, with the lowest being quantitative loss during drying. Priority areas to be targeted for PHL reduction in SSA and some loss mitigation tools and technologies piloted or suitable for SSA are proposed

Why NERICA is a successful innovation for African farmers

This paper responds to ‘Funding international agricultural research and the need to be noticed: a case study of NERICA rice’ by Stuart Orr, James Sumberg, Olaf Erenstein and Andreas Oswald, published in this issue of Outlook on Agriculture. In summary, the article by Orr et al, based on an internal WARDA document written in November 2003 and augmented with results from Internet searches, is outdated and does not seem to be fair, objective or useful. We invite the authors to visit WARDA or any of its partners in Sub-Saharan Africa for evidence of the impact of NERICA varieties or the other improved varieties and technologies that have been developed and disseminated by WARDA in recent years