The Role of Potassium Iodate in Mitigating the Damages of Water Deficit in Coffee Plants

Water deficit impacts plant growth and development, causing physiological disturbances that trigger oxidative stress. As an alternative, exogenous application of a sort of molecule can minimize these damages and reduce productivity losses. The iodine (I) supplementation has shown considerable benefits to stressed plants. Nevertheless, there are no results about I mitigating the water deficit stress in coffee plants. Coffee plants were grown in 10-L pots arranged wholly randomized. Four doses of potassium iodate (KIO₃) were tested: 0.0, 2.5, 5.0, and 10.0 mg dm⁻³ of soil, then the plants were subjected to water deficit and compared to treatments with no KIO₃ and water deficit (Control). The water deficit damaged biomass and relative growth of the coffee plant. However, the application of 2.5 mg dm⁻³ of KIO₃ attenuated some symptoms, increasing: photosynthetic efficiency, relative water content, water deficit tolerance index, content of photosynthetic pigments, and compatible osmolytes. In addition, we observed the stimulation of the antioxidant enzymatic system, allowing higher cell membrane stability. Doses of 5.0 and 10.0 mg dm⁻³ of KIO₃, in spite of induced higher activation of the antioxidant system it was observed a possible toxicity effect due to excess KIO₃. The application of 2.5 mg dm⁻³ KIO₃ via soil can modulate metabolic and biochemical processes, allowing an improvement in the growth and development of coffee plants subjected to water deficit, suggesting that it could serve as a viable strategy for managing coffee plants under drought conditions.