Trichoderma harzianum associado a substâncias húmicas no desenvolvimento de porta-enxerto de citros

Abstract

In citriculture, the use of quality seedlings influences from the beginning to the end of the production chain, but it takes 12 months for a complete citrus seedling to be formed, with the rootstock growing period being the longest. The use of growth promoters has been studied as an alternative to accelerate the development of rootstocks and improve the production process. Thus, the objective of this work was to evaluate the development of the ‘Swingle’ citrumelo rootstock on substrates containing doses of Trichoderma harzianum isolated and associated with humic substances. The experimental treatments consisted of five doses of a commercial product based on Trichoderma harzianum and the control (0, 1x107 , 1x108 , 1x109 , 1x1010 and 2x1010 viable conidia per plant) in a factorial with the presence or absence of a commercial product based on humic substances (0 mL and 5 mL), totaling 36 parcels (6x2x3 factorial). Five evaluations were made, one every 30 days after the application of the first dose. Among all variables analyzed, doses of humic substances were not relevant and there was no significance between humic factors and Trichoderma harzianum. The doses of Trichoderma harzianum, evaluated in an advanced way, were determined after 90 days of its application. The dose 2x1010 viable conidia per plant was harmful for all morphological variables. The dose 1x109 viable conidia per plant caused numerically superior results in the development of the variables number of leaves and stem diameter, at 150 days this dose stood out in root volume, root dry mass and IQD, indicating that Trichoderma harzianum it has the potential to promote the growth of ‘Swingle’ citrumelo and possibly shorten the time for grafting and seedling formation.