Yield and Physiological Responses of Chickpea Cultivars to Arbuscular Mycorrhizal Fungi Inoculation under Drought Stress

In the dry, cool seasons of central India, farmers grow a vital crop called chickpea. This legume is a cornerstone of food security, providing essential protein to millions of people. However, the crop faces a relentless enemy: the weather. Chickpeas are typically planted after the monsoon rains, relying entirely on the water left behind in the soil. As the season progresses and the sun grows hotter, this stored moisture slowly evaporates. By the time the plants are ready to produce their seeds, the soil is often bone dry. This specific type of water shortage, known as terminal drought, strikes just when the plant needs water the most, often causing harvests to fail or shrink dramatically.

To survive this dry spell, plants have developed internal defense systems. When water becomes scarce, they produce certain chemicals to protect their cells and keep their leaves green. One such chemical is proline, which acts like a sponge to hold water inside the plant's cells. Another defense is an enzyme called superoxide dismutase, which acts as a cleanup crew, removing harmful byproducts that build up when a plant is stressed. Scientists have long known that a type of beneficial fungus, which lives inside plant roots, can help crops access more water and nutrients. This partnership, called mycorrhiza, is like a natural extension of the plant's own root system, reaching further into the soil to find what the plant needs. The question researchers have been asking is whether this natural partnership can help different types of chickpeas survive the harsh end of the season, and if some types of chickpeas are simply better at using this help than others.

A researcher at Dr. Panjabrao Deshmukh Krishi Vidyapeeth in Akola, India, set out to answer these questions in a field experiment conducted over two growing seasons. They selected seven different varieties of chickpea, ranging from local favorites to newer, high-yielding types. In their fields, they created two distinct conditions. In one set of plots, the plants received regular watering at critical times, ensuring they had enough moisture to finish their growth cycle. In the other set, the plants received no water after the initial planting, forcing them to endure the natural drying of the soil. Crucially, all the plants in the experiment were treated with the beneficial mycorrhizal fungi at the time of planting, allowing the researcher to see how the fungi performed under both wet and dry conditions.

The results were clear and consistent. As expected, the plants that faced the dry conditions produced less grain and less straw than their well-watered neighbors. The lack of water caused the leaves to lose their green color faster and reduced the amount of water the plants could hold in their tissues. However, the dry plants also showed a massive increase in their internal defenses. They produced significantly more proline and activated their cleanup enzymes much more strongly than the watered plants. This confirmed that the plants were fighting hard against the stress, but the battle came at a cost to their final yield.

Not all chickpea varieties fought the drought with the same success. The researcher found that one specific variety, named JAKI-9218, stood out as the most resilient. When the water ran out, this variety lost the least amount of its potential yield, dropping by only about ten percent compared to its watered counterparts. It also managed to keep its leaves greener and held onto more water in its tissues than any other variety tested. Furthermore, JAKI-9218 was the most effective at ramping up its internal defenses, producing the highest levels of protective proline and showing the strongest response in its antioxidant enzymes. Two other varieties, PDKV Kanak and PDKV Kanchan, also performed well, showing similar but slightly less dramatic resilience.

In contrast, other varieties struggled significantly more. One variety, Gulak-1, suffered the most, losing over twenty percent of its potential yield under the same dry conditions. It also showed the weakest ability to hold water in its leaves and the least effective increase in its protective chemicals. The study demonstrated that while the beneficial fungi helped all the plants to some degree, the genetic makeup of the chickpea itself determined how well it could handle the stress. The most tolerant varieties were able to maintain their photosynthesis and water balance better, allowing them to produce a harvest even when the soil was dry.

These findings suggest a practical path forward for farmers in drought-prone regions. By planting the most resilient varieties, such as JAKI-9218, and ensuring they are inoculated with the beneficial mycorrhizal fungi, it is possible to sustain chickpea production even when the rains fail at the end of the season. The research does not claim to have solved the problem of drought, but it identifies specific tools that work together effectively. The combination of a tough genetic variety and a natural soil partner offers a reliable way to protect the harvest, ensuring that this important crop can continue to feed communities despite the challenges of a changing climate.