Substrate Stabilization Using Humus with Tannery Sludge in Conilon Coffee Seedlings

The objective of this study was to evaluate the capacity to stabilize substrate with tannery sludge and soil in the development and physiology of Conilon coffee seedlings. The treatments consisted of fixed doses of tannery sludge (30% of volume) and different proportions of humus in the substrate (10, 20, 30, 40% and of humus), in addition to treatments with and without conventional soil fertilizer. The biometric and physiological evaluations were measured 210 days after planting the cuttings. Humus allowed the substrate to stabilize, causing the coffee seedlings to develop well, when compared to the conventional substrate, especially in the proportion of 30% of humus, with a higher Dickson quality index in coffee seedlings. Regarding the physiological aspects, there were no changes in the secondary compound indexes or in the nitrogen balance and leaf chlorophyll. Also, there was no damage to the photosynthetic apparatus evaluated by the quantum efficiency of Photosystem II. Treatment 6 composed of 100% of soil, presented the lowest mean of net photosynthetic rate, due to stomatal effects.