Use of Trichoderma harzianum on the performance of young Inga laurina (Sw.) Willd. (Fabaceae) plants in response to drought.

Abstract

Climate change is among the main causes of alterations in natural ecosystems, generating major impacts on native vegetation. Drought is considered one of the main threats to ecosystems under global climate change since it limits growth and the mobilization of carbohydrates, alters the photosynthetic rate, decreases productivity, and can cause higher rates of plant mortality. Studies have been using species of the fungus Trichoderma in the inoculation of plants under conditions of water stress, such as drought, however, its use in native tree plants is still scarce. Considering that Inga laurina (Sw.) Willd (Fabaceae) is a tree species found preferentially in humid or flooded regions and can be used in the recovery of degraded areas, the aim is to analyze the performance of young plants of I. laurina, inoculated and not inoculated with Trichoderma harzianum and kept in conditions of moderate drought and in pot capacity. After 21 days, we evaluated the length of the aerial part and root, the fresh and dry mass of the root, stem, and leaves, the number of leaves and the diameter of the collar, the total soluble carbohydrate content of the leaves and roots and the photosynthetic pigments in the leaves of the plants from each treatment. The results were statistically analyzed using the GraphPrim 8.0 statistical program. Plants kept in moderate drought, whether inoculated or not, showed no significant difference in terms of growth parameters. The chlorophyll a, chlorophyll b, total chlorophyll, and total carotenoid contents were lower in the plants under moderate drought as compared to the non-inoculated control plants, while the chlorophyll a/b ratio was higher in the inoculated plants. The content of total soluble carbohydrates was higher in the leaves of plants kept in moderate drought, with no significant difference observed in the roots of plants kept in the different treatments. When comparing leaves and roots for each treatment, there was a higher total soluble carbohydrate content in the roots, regardless of the treatment. Overall, there was a positive effect of T. harzianum in promoting growth and protecting I. laurina; the inoculated plants performed similarly to the plants in the control condition.