Rice Plants Wilting from Ozone? Here’s How AWD Helps Them Recover

Across the vast rice fields of Asia, rice stands as a pillar of human survival. More than half of the world’s population depends on these small golden grains for daily nourishment. But in recent years, rice has faced a new, invisible, and far more unpredictable threat: ozone pollution.

Unlike the protective ozone layer high in the atmosphere, ground-level ozone is harmful. It forms from industrial and vehicle emissions and can damage plant leaves, stunt growth, and even weaken rice stems. When stems lose their strength, rice can collapse before harvest. This phenomenon, known as lodging, can be devastating: grains fail to fill properly, yields drop sharply, and farmers lose months of hard work in a single storm.

Amid this growing threat, a simple irrigation method known as Alternate Wetting and Drying (AWD) has emerged as a promising solution. AWD is known for saving water while maintaining crop yields—but can it also help rice withstand stem damage caused by ozone?

When Ozone Reaches the Rice Field

Over the past decades, ground-level ozone concentrations have risen dramatically, especially in rapidly industrializing countries. Levels have increased from the low teens to nearly 50 ppb—high enough to affect plant health.

For rice, ozone is a silent enemy. It disrupts photosynthesis, slows growth, and, worst of all, weakens the stem. The lower part of the stem—normally strong enough to support the weight of a maturing rice panicle—becomes fragile. On windy or rainy days, many stems simply fall over. This is lodging, a threat often unnoticed until the damage is too late to fix.

Research shows that ozone exposure can increase the risk of lodging by several tens of percent. With the world struggling to secure enough food for a growing population, this is a danger that cannot be ignored.

AWD: Less Water, Stronger Stems

AWD is not a new technology—it’s a simple method that has become increasingly relevant amid water shortages and climate change. Instead of keeping fields constantly flooded, farmers allow the soil to dry slightly before irrigating again.

Surprisingly, this intermittent watering strengthens the plant’s root system and results in sturdier stems. In many cases, rice grown with AWD develops thicker, heavier, and more robust stems.

Field observations show that AWD can:

• Reduce lodging risk by 10–20%

• Increase stem diameter and structural strength

• Stabilize soil moisture conditions

• Lower greenhouse gas emissions, particularly methane

Can AWD Counter the Effects of Ozone?

When researchers examined whether AWD could offset ozone damage, the results were balanced and realistic.

AWD clearly strengthens rice stems—improving stem mass, increasing base diameter, and enhancing internal tissue structure. However, when ozone levels become high, its negative effects are still noticeable. Stems may still weaken, and the risk of lodging remains.

In other words, AWD is a strong ally—but not an absolute shield—against the growing threat of ozone pollution.

Why This Matters for the Future of Global Food Security

For many countries, especially in Asia, rice is more than just a crop—it is the backbone of the economy and a symbol of national food security. But rising pollution, worsening water scarcity, and increasingly extreme climate conditions are making rice production more vulnerable.

This is why simple innovations like AWD are incredibly important. AWD not only conserves water but also improves plant resilience. When combined with other strategies—such as developing ozone-tolerant rice varieties, improving soil management, and reducing industrial pollution—we have a stronger chance of keeping rice fields productive.

AWD alone is not the complete answer, but it is a crucial piece of the larger puzzle.

Among the Rice Swaying in the Wind

Imagine a rice field at dusk. The wind glides gently through the panicles, the air carrying the scent of wet soil, and rows of rice stand tall as if guarding the future of global food security. This is the hope shared by farmers, scientists, and communities around the world.

In the face of new challenges like ozone pollution, small steps—like managing irrigation differently—can make a meaningful impact. From saving water, to strengthening stems, to applying simple technology with care, the future of rice is being protected one field at a time.

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