ROK varieties: High Yielding Climate Resilient Rice Varieties for Africa

Climate resilient ROK varieties for enhanced rice productivity and nutrition

The technology is a group of improved, early-maturing rice varieties comprising ROK 42 and ROK 43, developed by AfricaRice and released in Sierra Leone in 2025 to improve productivity across rainfed lowland and upland systems. ROK 42 tolerates flooding and iron toxicity, matures in about 105 days and has a yield potential of 6 t/ha, while drought-tolerant ROK 43 matures in 90–96 days and has a yield potential of 4.5 t/ha. Their reported yield advantages of approximately 20% over ROK 24 and 15% over ROK 34, respectively, can support increased domestic rice production and food security. Their complementary adaptation offers practical options for national seed and extension programmes seeking to strengthen rice self-sufficiency and climate resilience, with deployment guided by local growing conditions.

This technology is pre-validated.

9•9

Scaling readiness: idea maturity 9/9; level of use 9/9

Positive impacts: 12

Intersectional group	Potential positive impacts
Resource-constrained women farming flood- and iron-toxicity-affected lowlands	Production resilience: ROK 42’s tolerance can help protect production under these stresses. Food availability: Its reported ~20% yield advantage over ROK 24 may increase household rice supplies. Income opportunity: Additional marketable grain may support earnings where women control sales.
Resource-constrained young farmers in drought-prone uplands	Drought resilience: ROK 43’s tolerance can help manage unreliable rainfall. Earlier harvest: Maturity in 90–96 days can bring forward food supplies and sales. Marketable surplus: Its reported ~15% yield advantage over ROK 34 may increase grain available for sale.
Low-income smallholder households exposed to seasonal food shortages and climate shocks	Risk management: Selecting the locally appropriate variety can reduce exposure to specific production stresses. Household consumption: Higher yields may increase rice retained for food. Seasonal planning: Early maturity may help households manage harvest timing and seasonal risks.
Women and young entrepreneurs with limited capital entering seed multiplication or sales	Product opportunity: The two varieties serve distinct lowland and upland seed markets. Customer appeal: Early maturity, reported yield gains and grain quality provide selling points. Enterprise income: Seed multiplication and distribution offer potential earnings where demand and margins are viable.

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Unintended impacts: 12
Mitigations: 12

Barriers: 12
Mitigations: 12

Climate adaptability: Highly adaptable

Flood/drought tolerance and early maturity support adaptation; suitability requires local validation.

Farmer climate change readiness: Moderate improvement

Supports seasonal risk management, conditional on seed access, training and crop management.

Biodiversity: No impact on biodiversity

Direct benefits are undocumented; habitat protection remains management-dependent.

Environmental health: Does not improve environmental health

Potentially reduces pesticide use and land-expansion pressure; benefits are unmeasured and management-dependent.

Soil quality: Does not affect soil health and fertility

Iron-toxicity tolerance does not improve soil; fertility benefits depend on soil and residue management.

Water use: A bit less water used

Drought tolerance supports adaptation; early maturity may reduce requirements, but savings are unverified.

Problem

Low national productivity: Low yields limit rice output from existing cultivated land and constrain the sector’s contribution to domestic food supply.
Food insecurity: Insufficient and unstable production threatens the availability of rice for household consumption, particularly following poor growing seasons.
Climate vulnerability: Irregular rainfall, drought and flooding expose rice-growing areas to production shocks and increase uncertainty over national harvests.
Water constraints: Limited water availability affects upland production, while excessive water and flooding threaten crops in lowland environments.
Soil constraints: Iron toxicity restricts rice growth and productivity in affected lowlands, reducing the contribution of these areas to national output.
Pests and diseases: Insect pests, blast and Rice Yellow Mottle Virus threaten crop performance and add to production losses.
Planning challenges: Differences between upland and lowland conditions complicate the targeting of seed, extension services and agricultural support programmes.

Solution

National production: Reported yield advantages of approximately 20% for ROK 42 over ROK 24 and 15% for ROK 43 over ROK 34 offer scope to increase domestic rice output.
Food security: Yield potentials of 6 t/ha for ROK 42 and 4.5 t/ha for ROK 43 can increase staple food availability when supported by suitable growing conditions and crop management.
Climate resilience: Flood tolerance in ROK 42 and drought tolerance in ROK 43 address contrasting water-related risks across rainfed rice systems.
Lowland productivity: ROK 42’s tolerance to iron toxicity helps maintain production in affected lowland soils, although it does not remove the underlying soil constraint.
Seasonal adaptation: Maturity in about 105 days for ROK 42 and 90–96 days for ROK 43 can help fit production within the rainy season and reduce exposure to some late-season risks.
Harvest protection: Reported resistance to lodging, blast and insect pests in both varieties, together with ROK 42’s resistance to Rice Yellow Mottle Virus, can help limit crop losses.
Sustainable intensification: Higher yields offer scope to produce more rice on existing farmland, with seed and extension programmes targeting each variety to its appropriate environment.

Key points to design your project

Low rice yields, drought, flooding and soil constraints can undermine national production and food security. ROK 42 and ROK 43 offer complementary options for improving productivity and resilience in rainfed lowland and upland systems. Government programmes can assess this potential through local trials, then support deployment in suitable areas through quality seed supply and extension services.

National objectives: Set measurable targets for rice productivity, domestic supply and food security, aligned with national agricultural and climate adaptation priorities.
Local validation: Confirm agronomic performance and suitability under local conditions, and meet applicable national variety release and seed requirements before wider deployment.
Geographic targeting: Assess ROK 42 for rainfed lowlands affected by flooding and iron toxicity, and ROK 43 for upland and suitable boli systems exposed to drought.
Seed systems: Establish arrangements for quality seed multiplication, quality assurance and timely distribution in coordination with research institutions and seed-sector actors.
Implementation planning: Estimate seed needs using reported rates of 35–40 kg/ha for ROK 42 in inland valley swamps and 60 kg/ha for ROK 42 in boli systems and for ROK 43, subject to local validation.
Extension support: Train extension agents and farmers on variety selection and crop management; clarify and locally validate the fertilizer recommendation before issuing guidance.
Policy alignment: Integrate deployment into national rice, seed and extension programmes, supporting higher production on existing farmland.
Impact monitoring: Track seed access, adoption, yields, production and performance under environmental stresses. Treat the reported yield advantages of approximately 20% for ROK 42 and 15% for ROK 43 over their respective local checks as reference figures, not guaranteed local outcomes.

Cost vs. revenue

Data reliability of this estimate:: 80 %

Return on investment 23 %

Every USD invested returns USD 0.23 net income.

Detailed financial information ›

IP

Open source / open access

Technical characteristic	ROK 42	ROK 43
Developer	AfricaRice	AfricaRice
Country and year of release	Sierra Leone, 2025	Sierra Leone, 2025
Variety maintenance	AfricaRice / SLARI	AfricaRice / SLARI
Species	Oryza sativa	Oryza sativa
Genetic nature	Pure line	Pure line
Pedigree	ART309-B-145-1-5	ART34-113-3-2-B-1
Parents	NERICA-L-19//IRRI 119	WAB638-1/BRS PRIMAVERA
Production environment	Rainfed lowlands: inland valley swamps, riverine lowlands and boli systems	Rainfed uplands and boli systems
Days to 50% heading	75 days after sowing	60 days after sowing
Days to maturity	About 105 days after sowing	90–96 days after sowing
Yield potential	6 t/ha	4.5 t/ha
Reported yield advantage	Approximately 20% over ROK 24	Approximately 15% over ROK 34
Plant height	105 cm	115 cm
Tillering ability	High	High
Disease resistance	Blast and Rice Yellow Mottle Virus (RYMV)	Blast
Insect/pest resistance	Reported; specific pests not identified	Reported; specific pests not identified
Lodging resistance	Reported	Reported
Abiotic stress tolerance	Flooding and iron toxicity	Drought
1,000-grain weight	28.9 g	29.6 g
Grain shape and colour	Medium; white	Slender; white
Grain length × width	Not provided	10.1 × 2.24 mm
Aroma	Not specified	Aromatic
Milling and cooking quality	High milling recovery and good cooking quality; percentages not provided	High milling recovery and good cooking quality; percentages not provided
Other reported traits	Well-filled grains and attractive appearance	Well-filled spikelets, attractive appearance, slow senescence and easy threshing
Seed rate	35–40 kg/ha in inland valley swamps; 60 kg/ha in boli systems	60 kg/ha
Plant spacing	20 × 20 cm	20 × 20 cm
Fertilizer recommendation as submitted	NPK 15:15:15 at “60:40:40”; units and nutrient basis require clarification	NPK 15:15:15 at “60:40:40”; units and nutrient basis require clarification

Yield potentials and reported advantages depend on growing conditions and crop management; suitability outside Sierra Leone requires local validation.

Scaling Readiness describes how complete a technology's development is and its ability to be scaled. It produces a score that measures a technology's readiness along two axes: the level of maturity of the idea itself, and the level to which the technology has been used so far.

Each axis goes from 0 to 9 where 9 is the “ready-to-scale” status. For each technology profile in the e-catalogs we have documented the scaling readiness status from evidence given by the technology providers. The e-catalogs only showcase technologies for which the scaling readiness score is at least 8 for maturity of the idea and 7 for the level of use.

The graph below represents visually the scaling readiness status for this technology, you can see the label of each level by hovering your mouse cursor on the number.

Scaling readiness score of this technology

Maturity of the idea 9 out of 9

Uncontrolled environment: validated

Level of use 9 out of 9

Common use by intended users, in the real world

Maturity of the idea										Level of use
9
8
7
6
5
4
3
2
1
	1	2	3	4	5	6	7	8	9

Positive impact 12

Intersectional group	Potential positive impacts
Resource-constrained women farming flood- and iron-toxicity-affected lowlands	Production resilience: ROK 42’s tolerance can help protect production under these stresses. Food availability: Its reported ~20% yield advantage over ROK 24 may increase household rice supplies. Income opportunity: Additional marketable grain may support earnings where women control sales.
Resource-constrained young farmers in drought-prone uplands	Drought resilience: ROK 43’s tolerance can help manage unreliable rainfall. Earlier harvest: Maturity in 90–96 days can bring forward food supplies and sales. Marketable surplus: Its reported ~15% yield advantage over ROK 34 may increase grain available for sale.
Low-income smallholder households exposed to seasonal food shortages and climate shocks	Risk management: Selecting the locally appropriate variety can reduce exposure to specific production stresses. Household consumption: Higher yields may increase rice retained for food. Seasonal planning: Early maturity may help households manage harvest timing and seasonal risks.
Women and young entrepreneurs with limited capital entering seed multiplication or sales	Product opportunity: The two varieties serve distinct lowland and upland seed markets. Customer appeal: Early maturity, reported yield gains and grain quality provide selling points. Enterprise income: Seed multiplication and distribution offer potential earnings where demand and margins are viable.

Unintended impact 12

Intersectional group	Potential unintended impacts	Corresponding mitigation
Resource-constrained women farming flood- and iron-toxicity-affected lowlands	Workload increase: Larger harvests may add processing labour. Income capture: Others may control additional sales revenue. Financial exposure: Input spending may rise without assured returns.	Labour support: Facilitate shared harvesting and processing services. Income control: Include women in marketing arrangements and household benefit discussions. Phased adoption: Test small areas and assess net margins before expansion.
Resource-constrained young farmers in drought-prone uplands	Overconfidence: Drought tolerance may be mistaken for protection against all droughts. Debt pressure: Borrowing for expansion may exceed realised earnings. Price disappointment: Aromatic grain may not earn an expected premium.	Risk awareness: Explain performance limits and demonstrate local results. Prudent investment: Use conservative budgets and phased investment. Market verification: Check buyer preferences and prices before scaling.
Low-income smallholder households exposed to seasonal food shortages and climate shocks	Food–cash trade-off: Sales may leave inadequate household rice stocks. Varietal concentration: Replacing existing varieties may narrow risk management options. Resource strain: Expansion may stretch labour and input budgets.	Food planning: Account for household food needs before selling. Gradual introduction: Retain locally useful varieties alongside initial plantings. Capacity planning: Match planted area to household resources.
Women and young entrepreneurs with limited capital entering seed multiplication or sales	Unsold stocks: Demand may fall below production forecasts. Quality liability: Poor-quality seed may damage trust and income. Unequal returns: Larger partners may capture disproportionate margins.	Demand planning: Assess markets and seek advance orders where feasible. Quality assurance: Maintain traceability, testing and appropriate storage. Fair agreements: Clarify prices, responsibilities and payment terms.

Barriers 12

Intersectional group	Potential barriers	Corresponding mitigation
Resource-constrained women farming flood- and iron-toxicity-affected lowlands	Seed affordability: Limited cash may restrict purchases. Land access: Limited control over suitable plots may restrict adoption. Training access: Timing and mobility constraints may limit participation.	Affordable access: Offer accessible pack sizes and targeted seed support. Land-use inclusion: Include women in plot selection and land-use arrangements. Accessible training: Hold nearby demonstrations at suitable times.
Resource-constrained young farmers in drought-prone uplands	Working capital: Limited funds may delay seed and input purchases. Land insecurity: Uncertain access may discourage investment. Limited experience: Unfamiliar management may reduce performance.	Finance access: Link farmers to affordable, seasonally appropriate finance. Secure arrangements: Support clear seasonal land-use agreements. Practical support: Provide demonstrations and extension follow-up.
Low-income smallholder households exposed to seasonal food shortages and climate shocks	Seed availability: Quality seed may arrive too late for planting. Adoption risk: Households may be unable to absorb a failed trial. Management costs: Recommended inputs may exceed household budgets.	Timely supply: Estimate demand early and organise local distribution. Small-scale trials: Support demonstration plots before wider adoption. Local costing: Validate management requirements and costs before promotion.
Women and young entrepreneurs with limited capital entering seed multiplication or sales	Starting material: Authentic multiplication seed may be difficult to secure. Quality requirements: Testing, certification and storage costs may constrain entry. Market access: Limited distribution networks may restrict sales.	Supply agreements: Establish links with authorised seed sources. Shared services: Facilitate quality assurance services and regulatory guidance. Distribution partnerships: Connect entrepreneurs with agro-dealers, farmer organisations and extension providers.

Cost of the investment Sum of all fixed and operational expenses.	USD 1,076 per hectare
Gross revenue Sum of all income before subtracting costs.	USD 1,320 per hectare
Net income Gross revenue minus total cost.	USD 244 per hectare
Return on investment Percentage of income earned for each dollar invested, calculated as: (income ÷ cost of investment) × 100	23 % per hectare

References:

ROI Calculation sheet.pdf (PDF, 219.85 KB)

Countries with a green colour: Tested & adopted
Countries with a bright green colour: Adopted
Countries with a yellow colour: Tested
Countries with a blue colour: Testing ongoing

Countries where the technology is being tested or has been tested and adopted
Country	Testing ongoing	Tested	Adopted
Sierra Leone	–No ongoing testing	Tested	Adopted

This technology can be used in the colored agro-ecological zones. Any zones shown in white are not suitable for this technology.

Agro-ecological zones where this technology can be used
AEZ	Subtropic - warm	Subtropic - cool	Tropic - warm	Tropic - cool
Arid	–	–	–	–
Semiarid		–
Subhumid		–
Humid		–

Source: HarvestChoice/IFPRI 2009

The United Nations Sustainable Development Goals that are applicable to this technology.

Goal 1: no poverty

Increased marketable surplus may improve income; poverty impacts are unmeasured.

Goal 2: zero hunger

Reported yield gains of approximately 20% and 15% support increased rice availability under suitable conditions.

Goal 13: climate action

Flood and drought tolerance directly support adaptation; mitigation remains unverified.

Select the appropriate variety: Use ROK 42 for rainfed lowlands, inland valley swamps (IVS), riverine lowlands and boli systems, particularly where flooding and iron toxicity occur; use ROK 43 for upland and boli systems where drought is a concern.
Prepare the field: Clear and prepare a field suited to the selected variety to support seed establishment and crop growth.
Plant at the start of reliable rains: Use 20 cm × 20 cm spacing, with seed rates of 35–40 kg/ha for ROK 42 in IVS, 60 kg/ha for ROK 42 in boli, and 60 kg/ha for ROK 43.
Apply fertilizer and control weeds: The submission specifies NPK 15:15:15 at 60:40:40, but does not clarify the units or nutrient basis; confirm the application rate with local extension services and keep fields free of weeds, especially during early growth.
Monitor crop health: Check regularly for pests and diseases; both varieties have reported resistance to blast, insect pests and lodging, while ROK 42 also resists Rice Yellow Mottle Virus.
Harvest at maturity: Harvest ROK 42 at approximately 105 days after sowing and ROK 43 at 90–96 days, depending on growing conditions.
Thresh, dry and store: Thresh harvested rice, dry the grain properly and store it in clean bags in a dry, well-ventilated place to maintain quality.