The data reveal a climate that refuses to sit still. Relative humidity in the study area fluctuated between a low of 42.46 percent in 2006 and a high of 65.09 percent in 2022, a range wide enough to alter evaporation rates, disease pressure, and the water balance of paddy fields. Maximum temperatures ranged from 36.88 degrees Celsius in 2022 to a scorching 42.27 degrees Celsius in 2010, while minimum temperatures displayed an even more dramatic spread, dipping to 5.48 degrees Celsius in 2015 and climbing to 11.96 degrees Celsius in 2017. Such nocturnal temperature swings matter enormously for rice, because cool nights slow crop development while warm nights accelerate respiration and erode the biomass a plant has spent the day building.

Rainfall, the single most consequential variable for rainfed and irrigated agriculture alike, proved the most volatile of all. Annual totals climbed from 454.9 millimeters in 2018 to an extraordinary 3,101.6 millimeters in 2021, before collapsing back to 1,505.9 millimeters in 2022. To put those numbers in perspective, the 2021 figure was nearly seven times the 2018 total, a swing that no farming calendar can comfortably absorb. The authors found that such excessive annual rainfall induced flooding, particularly during critical growth stages of the rice crop, and that these flood events translated directly into reduced yields. For a region where rice is both a staple and a commercial crop, the implications are sobering.

Methodologically, the study leaned on a battery of statistical tools designed to extract reliable signals from noisy environmental data. Descriptive statistics such as means and percentages established the baseline climatology, while Spearman’s rank correlation, tested for significance with Student’s t-test, quantified the strength and direction of associations between each climatic variable and rice yield. To detect whether the underlying climate variables were trending over time rather than merely fluctuating, the researchers applied the Mann-Kendall non-parametric trend test, a workhorse of hydro-climatological research that is robust to outliers and does not assume normally distributed data. Sen’s Slope estimator complemented the Mann-Kendall test by providing a robust measure of the magnitude of any trend, expressed as the rate of change per year.

The correlation results upended some intuitive expectations. Maximum temperature showed a positive correlation with rice yield, with a Spearman coefficient of 0.311, and minimum temperature was similarly positive at 0.301. Rainfall, by contrast, was negatively correlated with yield at -0.455, and relative humidity was also negative at -0.255. In other words, in this irrigated setting, hotter years were associated with better harvests while wetter, more humid years were associated with worse ones. The most plausible explanation lies in the fact that Kadawa’s rice is grown under the Kano River Irrigation Project, where water supply does not depend primarily on rainfall. In such systems, abundant sunshine and warmth can boost photosynthesis and crop growth, whereas torrential rainfall overwhelms drainage infrastructure and floods fields at sensitive stages such as flowering and grain filling.

This finding carries a broader lesson for climate impact research: the direction of climate-yield relationships is not universal but depends on the farming system in question. In rainfed rice systems across West Africa, rainfall and yield typically move together, and drought is the dominant threat. Kadawa’s irrigated regime inverts that logic. The negative rainfall-yield correlation of -0.455 is the strongest association in the dataset, suggesting that water excess, not water scarcity, is the principal climatic hazard facing farmers there. It is a reminder that adaptation strategies must be tailored to local hydrological realities rather than copied wholesale from other regions, and that irrigation schemes themselves can create new vulnerabilities when drainage lags behind water delivery.

The marked temporal instability documented in the study echoes a wider body of evidence on climate and agriculture. Global analyses have estimated that climate variation explains roughly a third of worldwide crop yield variability, and West Africa has repeatedly been flagged as a hotspot where rainfall variability and hydroclimatic extremes intersect with food insecurity. Within Nigeria specifically, recent studies have documented warming trends in major cities using the same non-parametric methods employed at Kadawa, and modeling work with the APSIM crop simulation platform has projected climate change effects on rice production across the wider Kano River Irrigation Scheme. The Kadawa study grounds these larger-scale findings in a concrete, thirty-year local record, showing that the variability long predicted for the Sahel is already inscribed in the region’s yield statistics.

The physiological mechanisms linking the observed climate extremes to rice performance are well understood from plant science. Rice is particularly sensitive to temperature during its reproductive phase: daytime temperatures above roughly 35 degrees Celsius can cause spikelet sterility by disrupting anther dehiscence and pollen viability, while high night temperatures increase respiration losses and shorten the grain-filling period. Cold minima, such as the 5.48 degrees Celsius recorded in 2015, can delay seedling establishment and slow early vegetative growth. Flooding, meanwhile, deprives roots and soil of oxygen, promotes toxic reduced compounds, and can fully submerge plants, with complete submergence for more than a few days often proving fatal to intolerant varieties. Humidity shapes the microclimate of the canopy and influences the incidence of fungal diseases such as sheath blight, which thrives under warm, moist conditions.

Against this backdrop, the authors argue that rice cultivation in Kadawa is growing steadily more vulnerable to climatic variability, and they outline a portfolio of adaptive responses. Chief among these are climate-resilient rice varieties, including submergence-tolerant cultivars. Breeding programs have made notable progress here: the SUB1A quantitative trait locus, originally identified in the Indian landrace FR13A, confers tolerance of complete submergence and has been introgressed into popular varieties across South and Southeast Asia, with ongoing research extending these gains and elucidating the underlying metabolic and physiological mechanisms. Deploying such genetics in West African irrigation schemes could buffer harvests against the flood years that the Kadawa record shows are increasingly disruptive.

Equally important, the study emphasizes, are engineering and water-management measures. Improved drainage infrastructure would allow excess rainfall to be evacuated from fields before it reaches damaging depths, directly addressing the negative rainfall-yield relationship at the heart of the findings. Enhanced water-management practices, from regulated irrigation scheduling to field-level water control, would help farmers exploit Kadawa’s warmth and sunshine while shielding the crop from moisture extremes. The authors frame these interventions within the broader agenda of climate-smart agriculture, which seeks to sustain high and stable yields under changing climatic conditions rather than simply maximizing output in good years. As the 2021 to 2022 rainfall collapse demonstrates, the cost of inaction is not hypothetical: a farming system calibrated to one year’s climate can be blindsided the next. With Nigeria among West Africa’s largest rice producers and demand for the grain still rising, the thirty-year Kadawa record offers both a warning and a practical roadmap for keeping harvests stable on a warming, whipsawing climate frontier.

Subject of Research: Long-term climate variability and its effects on rice yield in Kadawa, Kano State, Nigeria

Article Title: Assessing long‑term climate variability and its effects on rice yield in the Kadawa Area, Kano State, Nigeria

Article References: Assessing long‑term climate variability and its effects on rice yield in the Kadawa Area, Kano State, Nigeria. (n.d.). https://doi.org/10.1007/s00704-026-06578-0

Image Credits: AI Generated

DOI: 10.1007/s00704-026-06578-0

Keywords: climate variability, rice yield, Nigeria, Kano State, Kadawa, rainfall, temperature, flooding, irrigation, Mann-Kendall trend test, climate-smart agriculture, submergence tolerance

Samba Mahsuri occupies a special place in Indian agriculture. The variety, developed decades ago, is prized for its excellent cooking and eating quality, with slender, fine grains that command strong consumer preference across southern and eastern India. Its popularity, however, has always been tempered by two weaknesses. It matures late, extending the crop’s exposure to end-of-season water shortages, and it is highly sensitive to both drought and flash flooding. In the rainfed lowland agro-ecosystem, where fields depend on erratic monsoon rainfall rather than assured irrigation, these weaknesses translate into devastating yield losses in bad years. Farmers who grow Samba Mahsuri do so for its market value, but they accept a substantial risk every time they sow it.

The strategy the researchers employed is known as QTL pyramiding. Quantitative trait loci, or QTLs, are stretches of the genome that harbor genes influencing complex, quantitatively inherited traits such as yield under stress. Unlike single-gene resistances, drought tolerance is controlled by many loci of small to moderate effect, and breeding programs have identified several major-effect QTLs that reliably improve grain yield when water is scarce. Two of the most consistent are qDTY2.1 on chromosome 2 and qDTY3.2 on chromosome 3, both of which have been shown in previous studies to enhance yield under reproductive-stage drought across multiple genetic backgrounds. By combining these with the Sub1 locus, which confers remarkable tolerance to complete submergence for up to two weeks, the team aimed to build a single variety capable of withstanding the two most damaging water-related stresses of the rainfed lowlands.

The breeding material itself was elegant in design. The researchers crossed two advanced lines, each of which already carried the Sub1 submergence-tolerance locus in the Samba Mahsuri background: SM-Sub1-DTY2.1, which carries qDTY2.1 and is known as DRR Dhan 50, and SM-Sub1-DTY3.2, which carries qDTY3.2. From this cross, they generated a population of 990 F2 plants. Each plant was genotyped using simple sequence repeat markers linked to the two drought-tolerance QTLs, allowing the team to identify individuals that had inherited both genomic regions in homozygous form. Of the 990 plants screened, 62 such QTL-pyramided lines were identified and advanced to the F3 generation, each one now carrying the drought-tolerance loci from both parents alongside the Sub1 submergence-tolerance gene.

A crucial complication soon emerged. Because both donor parents had been selected for earlier maturity than the original Samba Mahsuri, the pyramided lines segregated for time to flowering and maturity. Maturity is not a trivial trait: farmers time their sowing, harvesting, and water management around it, and any new version of a mega-variety must match the photoperiod and duration expectations of the regions where it will be grown. The team therefore carefully selected only those lines showing uniform maturity, advancing them through the F4 to F6 generations until lines true-breeding for both the stacked QTLs and an acceptable maturity class were obtained. This step illustrates a lesson that runs through modern marker-assisted breeding: stacking useful genes is only half the job, and the other half is restoring the agronomic package that made the original variety successful.

Four of the resulting QTL-pyramided lines were then evaluated in detail for agronomic and physiological performance under both control and drought-stress conditions. The researchers measured a battery of traits, including grain yield, plant height, tiller number, leaf rolling, chlorophyll content, and relative water content, comparing the pyramided lines against the recurrent parent Samba Mahsuri and the single-QTL parental lines. The results were unambiguous. The pyramided lines lost significantly less grain yield under drought stress than either Samba Mahsuri or the lines carrying only one drought QTL, confirming that the two loci act additively or even synergistically when combined in the same genetic background. Physiological measurements supported the yield data, indicating that the pyramided lines maintained better plant water status and photosynthetic capacity as soil moisture declined.

The standout performer was a line designated QPL 62. This line showed the least reduction in grain yield under drought of any material tested, and it also matured 16 days earlier than Samba Mahsuri, an advantage that reduces its exposure to terminal water stress and allows earlier harvesting. Just as importantly, molecular profiling showed that QPL 62 retained more than 95 percent similarity to the Samba Mahsuri genetic background, and its grain and cooking quality characteristics remained essentially indistinguishable from those of the original variety. In other words, the breeders had inserted the drought and flood insurance policies without disrupting the qualities that farmers and consumers actually care about. This recovery of the recurrent parent genome is the central promise of marker-assisted backcrossing and pyramiding approaches, and the present study shows it can be achieved even when combining multiple stress-tolerance loci simultaneously.

The implications extend well beyond a single variety. Rainfed lowlands account for a substantial share of rice production in South and Southeast Asia, and climate projections suggest that both the frequency of mid-season droughts and the intensity of flood events will increase in the coming decades. Varieties that combine tolerance to multiple abiotic stresses are therefore a central goal of national and international breeding programs. The Sub1 locus has already been successfully introgressed into numerous popular varieties, including Swarna and Samba Mahsuri itself, producing flood-tolerant versions now grown on millions of hectares. Adding yield-enhancing drought QTLs on top of Sub1, as this study demonstrates in Samba Mahsuri, represents the logical next generation of climate-resilient rice, and the pyramiding framework can in principle be replicated in any elite cultivar for which Sub1 versions and drought-QTL donors are available.

The authors note that QPL 62 is now ready to be taken forward into multi-location QTL near-isogenic line trials, the standard pathway toward commercial release in India. If those trials confirm its performance across diverse environments, the line could eventually be notified as a climate-resilient version of Samba Mahsuri, giving farmers the same prized grain quality with dramatically reduced risk from drought and flooding. The work was supported by the Indian Council of Agricultural Research Network Project on Translational Genomics in Crop Plants and by an Anusandhan National Research Foundation JC Bose National Fellowship. As extreme weather increasingly tests the world’s rice fields, studies like this one show that the tools of genomics can convert a beloved but vulnerable variety into one that can weather the storm, and the flood, on its own genetic merits.

Subject of Research: Marker-assisted pyramiding of drought and submergence tolerance QTLs in rice variety Samba Mahsuri to develop a climate-resilient cultivar.

Article Title: Pyramiding of Multiple QTL for Drought and Submergence Tolerance for Infusing Climate-Resilience in Rice Variety Samba Mahsuri

Article References: Jain, P., Kapoor, R. T., Kumar, M., Yadav, N., Rani, M., Joshi, R., Rai, V., Bisht, D. S., Gaikwad, K., & Singh, N. K. (2026). Pyramiding of Multiple QTL for Drought and Submergence Tolerance for Infusing Climate-Resilience in Rice Variety Samba Mahsuri. Indian Journal of Genetics and Plant Breeding, 86(3), 279-291. https://doi.org/10.1007/s44489-026-00028-x

Image Credits: AI Generated

DOI: 10.1007/s44489-026-00028-x

Keywords: rice, Samba Mahsuri, QTL pyramiding, drought tolerance, submergence tolerance, qDTY2.1, qDTY3.2, Sub1, marker-assisted selection, climate resilience, molecular breeding, rainfed lowland