Mechanical stimuli can improve plant defense against pests and diseases

A study analyzed the impact of water spraying on tomato plants. It showed that this form of mechanical stimulation can improve growth and defense against pests and diseases. The research investigated how the size of water droplets affects plant development and resistance. The results suggest that spraying with larger droplets may be a promising alternative for crop protection, especially in a climate change scenario.

The experiment, led by Man-Qun Wang's team, sprayed tomato plants with water twice a day. The focus was to understand how different droplet sizes influence the plants' growth and resistance to Helicoverpa armigera and Botrytis cinerea, two common agents of crop destruction. The researchers prevented the water from reaching the soil, ensuring that the impact was exclusively on the aerial part of the plant.

Spraying with larger droplets improves defenses

The results showed that spraying with large droplets (1.000 micrometers) generated more compact and smaller plants, compared to plants sprayed with small droplets (200 micrometers) or that were not sprayed at all.

Metabolic analyses revealed significant changes in hormones involved in plant defense. Plants exposed to larger droplets had higher levels of chlorogenic acid, a defense metabolite. This resulted in greater resistance against destruction by insect larvae and gray mold.

Another factor observed was the reduction in the emission of volatile organic compounds (VOCs) by plants sprayed with large droplets. These compounds, usually responsible for attracting insects, made the plants less attractive to egg-laying moths, resulting in a 74% reduction in the number of eggs laid on the leaves.

Climate challenges and sustainable agricultural practices

In a scenario of climate change, which is affecting agriculture through high temperatures, irregular rainfall patterns and the increase in pests and diseases, these findings gain relevance. The application of mechanical stimuli, such as water spraying, may offer a promising solution to improve plant defense in a more environmentally friendly way.

The researchers suggest that continued development of water droplet spraying and atomization technologies could contribute to more efficient and sustainable agricultural practices.

More information can be found at doi.org/10.1021/acs.jafc.4c05131