INFLUENCE OF THE USE OF BIOSTIMULANTS ON THE GROWTH OF SEEDLINGS OF Khaya senegalensis A. JUSS

Abstract

The use of effluents from septic biodigestor strains is an alternative to produce Khaya senegalensis A. Juss seedlings in a sustainable way. This species has characteristics that add commercial value to wood in addition to providing a range of timber and non-timber products. The aim of this study was to evaluate the growth of Khaya senegalensis A. Juss seedlings with the application of increasing doses of effluent: 0, 25, 50, 75 and 100% and with inoculation of genus Bacillus subtilis isolated A6. The substrate used was subsoil, sand and commercial substrate Bioflora in the ratio 1:1:1 in tubes (capacity: 290 cm³), and the statistical design was in blocks completely randomized in the factorial scheme 5x2 (5 effluent doses and two inoculation conditions, with and without inoculation). After 90 days, the following variables were evaluated: stem diameter, height, number of leaves. Also, photosynthetic variables were evaluated: CO₂ assimilation, stomatic conductance, transpiration, and instantaneous efficiency of carboxylation. Finally, leaf dry mass (LDM), root (MSR), stem (SDM) and total (TDM) were evaluated as well. However, there was no significant difference in seedling growth with or without inoculation, except for leaf dry mass. The best results were observed when using 100% effluent application every 7 days. The seedlings with inoculation of Bacillus subtilis isolated A6 and irrigated with 100% of the effluent dose showed higher leaf dry mass, thus indicating the combination of these bacteria with the effluent as biostimulants in the growth of the aerial part of the Khaya senegalensis A. Juss seedlings.vegetative development and bulbing and reduce productivity. During the growing cycle, under favorable weather conditions, weekly splitting increases the commercial productivity of class 3 bulbs and of that above class 3. Under less favorable climatic conditions, the increase in plant density contributes to an increase in commercial productivity and of class 2 bulbs. The increase in plant density reduces the chlorophyll content, and from 500,000 plants onwards, it reduces the number of leaves, increases class 2 bulbs, and reduces class 3 bulbs and those from classes above 3. Nutrient splitting and plant density do not interfere with the flowering of onion bulbs.