While various studies have attempted to investigate the efficacy of biochars in enhancing plant seedlings, research on the application of biochar specifically for Coffea arabica L. seedlings in drought conditions remains restricted. To reveal the mitigation of biochar in the Coffee. seedlings under drought stress, the impacts of different biochar doses on soil physicochemical, biological, and hydrological parameters, as well as the growth of Coffee seedlings were evaluated. To mimic the effect of drought stress, utilizing three different levels of water holding capacity (20 %, 40 %, and 60 % of WHC) was performed with three different corncob biochar application rates of 1 %, 2.5 %, and 5 % w/w of soil. The results revealed that corncob biochar application increased pH, cation exchange capacity and organic matter. While soil microbial respiration, microbial biomass carbon, and dissolved organic carbon had increased in application biochar 1 and 5 % under both drought and no drought conditions. Corncob biochar at 1 % application rate enhanced the growth and chlorophyll content under drought condition significantly (p < 0.05). However, no statistically significant differences were observed between biochar application and water holding capacity on membrane damage and total soluble sugar content under drought conditions. The relative water and proline content had increased in biochar application at 1 %. Based on these findings, the application of biochar into coffee seedling production systems may help mitigate the adverse effects of water scarcity while promoting long-term soil health and agricultural resilience, particularly in tropical and subtropical highland regions where climate change-induced drought events are becoming more frequent.

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.