Rising CO2 and UV-B Put Two Moringa Species on Divergent Paths, Study Finds

In the arid landscapes of the United Arab Emirates, two trees from the same genus are being tested against the future itself. Researchers at United Arab Emirates University have grown Moringa oleifera and Moringa peregrina inside open-top chambers, exposing the plants to elevated carbon dioxide, enhanced ultraviolet-B radiation, and the two stressors in combination. The results, published in The Science of Nature, reveal that even closely related species can respond to climate change in strikingly different ways, with implications for which trees farmers and restoration ecologists should bet on as the atmosphere warms and shifts.

The experiment was designed around a simple but urgent question: how will the two dominant drivers of atmospheric change, rising CO2 and shifting UV-B radiation, affect the growth and physiology of plants that are increasingly promoted as climate-smart crops? Moringa oleifera, the well-known drumstick tree cultivated across South Asia and Africa for its nutritious leaves, and Moringa peregrina, a hardier, drought-adapted relative native to the Arabian Peninsula and the Horn of Africa, were both raised under controlled environmental treatments. Open-top chambers allowed the plants to experience near-natural field conditions of light, temperature, and airflow while the researchers precisely manipulated the concentrations of gases and the dose of UV-B reaching the foliage.

Elevated CO2 produced a clear growth dividend, but only for one of the two species. Moringa oleifera grown under enriched CO2 grew taller than its Arabian cousin, suggesting that the drumstick tree is better positioned to exploit the carbon fertilization effect, the phenomenon by which higher atmospheric CO2 accelerates photosynthesis and biomass accumulation in many C3 plants. Decades of free-air CO2 enrichment experiments worldwide have documented this effect across a wide range of crops, though its magnitude varies enormously between species and growing conditions. The new findings indicate that Moringa oleifera sits on the responsive end of that spectrum, while Moringa peregrina, despite its reputation for toughness in harsh environments, did not translate the extra carbon into comparable height gains.

UV-B radiation told the opposite story. When the plants were exposed to enhanced ultraviolet-B, the lowest plant heights were recorded in both species, confirming that this high-energy component of sunlight remains a potent growth suppressant even as background levels shift with stratospheric ozone dynamics. UV-B photons damage photosynthetic machinery, trigger the production of reactive oxygen species, and force plants to divert energy and carbon into protective compounds such as flavonoids and other phenolics rather than into new tissue. For both moringas, the cost of that defense was measurable in stature, a reminder that the benefits of carbon fertilization can be eroded when plants simultaneously face radiation stress.

The photosynthetic pigments told a consistent tale. Chlorophyll a, chlorophyll b, and carotenoid content were substantially higher in CO2-enriched Moringa oleifera than in Moringa peregrina under the same treatment, indicating a more vigorous light-harvesting apparatus and a greater capacity to convert the additional carbon into chemical energy. Carotenoids matter here beyond photosynthesis: they participate in photoprotection, quenching excess excitation energy before it generates damaging radicals. Yet UV-B exposure significantly reduced photosynthetic pigments in both species, consistent with its well-documented ability to degrade chlorophyll and impair the thylakoid membranes where the light reactions of photosynthesis take place. The pigment data thus reinforce the growth data, painting a picture in which CO2 lifts one species up while UV-B drags both down.

Perhaps the most surprising results emerged from the nutrient analysis. Under elevated CO2, Moringa oleifera accumulated significantly higher concentrations of nitrogen, magnesium, calcium, and boron than Moringa peregrina. Nitrogen is the backbone of chlorophyll and photosynthetic enzymes, magnesium sits at the center of every chlorophyll molecule, and calcium structures cell walls and acts as a ubiquitous intracellular signal, so higher levels of these elements underpin the superior growth and pigment performance observed in the drumstick tree. Boron, required in small amounts for cell wall cross-linking and pollen tube growth, rounds out a profile of enhanced mineral nutrition in the species that grew best.

Moringa peregrina, however, was not simply outperformed. The Arabian species concentrated greater amounts of potassium, iron, manganese, copper, zinc, and sulfur under elevated CO2. Each of these elements plays a distinct role in stress physiology: potassium regulates stomatal opening and cellular water balance, iron and copper are cofactors in electron transport chains and antioxidant enzymes, manganese powers the water-splitting reaction of photosystem II and supports antioxidant defenses, zinc stabilizes proteins and membranes, and sulfur feeds the synthesis of glutathione and other sulfur-containing protectants. A leaf enriched in this suite of micronutrients is, in effect, chemically armored, suggesting that Moringa peregrina invests its mineral resources in resilience machinery rather than in rapid extension growth.

This divergence in nutrient allocation strategies carries practical weight. Moringa oleifera has been championed as a versatile climate-smart plant for nutritional security in semi-arid regions, prized for protein-rich leaves and fast growth. The new data support that reputation under future CO2 levels, at least when UV-B is not overwhelming. But Moringa peregrina, which grows wild in some of the driest habitats on the Arabian Peninsula and is valued locally for its oil-rich seeds, appears to build a different kind of advantage, one based on micronutrient-dense tissue and stress-hardy biochemistry. For breeders and land managers, the two species may therefore serve complementary roles: oleifera for productivity, peregrina for persistence and possibly for nutritional profiles enriched in iron, zinc, and other elements often lacking in human diets.

The study also contributes to a broader scientific debate about whether the greening effect of rising CO2 will compensate for the stresses that accompany it. Elevated CO2 generally improves water-use efficiency and stimulates photosynthesis in C3 plants, but those gains can be offset by heat, drought, ozone, and radiation stress, and they often come at the price of lower tissue nutrient concentrations. By testing CO2 and UV-B together in realistic field-adjacent conditions, the UAE team has added a rare data point from a hyper-arid environment, where the interaction between carbon enrichment and solar radiation stress may differ from temperate agricultural systems. The finding that one moringa species thrives while the other retools its chemistry under the same future atmosphere underscores a central lesson of modern plant science: climate resilience is not a single trait but a portfolio, and different species hold different shares.

For now, the message for the Arabian Peninsula and similar regions is one of cautious optimism. The drumstick tree looks set to grow taller and photosynthesize harder in a carbon-rich world, provided ultraviolet-B stress remains within tolerable bounds, while its native relative offers a hardier, micronutrient-rich alternative for the harshest sites. As the researchers note, understanding these combined effects is essential for predicting how crop systems and ecosystems will fare as the climate changes. The moringa experiment suggests that the winners of the next century will not simply be the plants that grow fastest, but those that can balance growth against defense, and that balance is written, element by element, in their leaves.

Subject of Research: Growth and physiological responses of two Moringa species to elevated CO2 and UV-B radiation

Article Title: Evaluating growth and physiological responses of Moringa peregrina and Moringa oleifera to elevated CO₂ and UV-B radiation in open-top chambers for climate resilience

Article References: Alshehhi, O. M. S., Hayat, F., Kandhan, K., AL-Zayadneh, W., Sheteiwy, M. S., & Alyafei, M. (2026). Evaluating growth and physiological responses of Moringa peregrina and Moringa oleifera to elevated CO₂ and UV-B radiation in open-top chambers for climate resilience. The Science of Nature, 113(6), Article 131. https://doi.org/10.1007/s00114-025-02041-8

Image Credits: AI Generated

DOI: 10.1007/s00114-025-02041-8

Keywords: Moringa oleifera, Moringa peregrina, elevated CO2, UV-B radiation, open-top chambers, photosynthetic pigments, plant nutrition, climate resilience, environmental stress, arid agriculture, chlorophyll, micronutrients