Banca de QUALIFICAÇÃO: ALVERLAN DA SILVA ARAÚJO

Humic substances in growth and attenuation of water stress in forest species

Organic matter; humic and fuvic acids; Plant metabolism; networks bibliometrics

Humic substances (SH) are among the most trained biostimulants in the world due to their ability to promote plant growth, increase the availability of nutrients and their absorption by plants, in addition to promoting the production of phytohormones responsible for vegetative growth and acting on complexation of toxic toxic metals in soil and plants. This work began with a systematic and bibliometric survey of published works on humic production in the growth of forest species and mitigation of water stress. The research was carried out in the Capes dissertations and theses catalog and in Scopus (Elsevier). In the database of dissertations and theses, the term “Humic substances” was used as a keyword, while on the Scopus platform a combination of keywords was used: (“humic substances*”) AND (“plant growth” OR “growth root” OR “water stress”). The data obtained from the Capes dissertation and theses database were tabulated in Excel, while the Scopus portfolio was exported in CSV format and the data was processed using the VOSviewer program to plot bibliometric networks. The experimental research aimed to evaluate the effects of different types of humic substances on the growth of Myrciaria floribunda and Shinus terebinthifolius. Seeds containing one centimeter of radicle were placed in falcon tubes containing 50 mL of SH soil, termite mound and filter cake. The experimental design was in DIC with 5 concentrations (0 mg L -1 (distilled water – control), 25 mg L-1, 50 mg L-1, 100 mg L-1 and 200 mg L-1) and 6 replications. After eight days of cultivation, root size was measured to verify the effect of HS. The greenhouse experiments were installed in DIC with the best concentration of each SH and two evaluation periods (90 and 120 days after transplanting) with six replications. Morphometric and physiological variables were evaluated. In the Capes database of dissertations and theses, 757 works were collected, after reading the titles and abstracts and applying the inclusion and exclusion filters, this number was reduced to 20, being 8 master's dissertations and 6 doctoral theses related to the use of humic matter (SH) as growth promoters of forest species, and 4 dissertations and 2 theses involving the application of SH in mitigating water stress in plant species in general. In the Scopus portfolio, 84 works were found. After applying the filters, 13 works remained, 3 articles on the use of humic substances in the growth of forest species and 10 articles involving SH and water stress in plant metabolism in general. Bibliometric networks indicated Brazil as one of the main countries related to production on the subject and its mutual collaboration with other countries, contributing with frequently cited articles, which in turn collaborate with the science of humic substances and the development of new biostimulants . For mastic, the concentration of 100 mg L-1 of soil SH promoted the greatest growth of mastic roots (4.26cm ±0.03), statistically differing from the control and other concentrations. While for termite mound SH the dose of 200 mg L-1 promoted the greatest root growth, with an average of 5.51 cm (±0.04), for the treatment with filter cake SH the dose-response of 50 mg L1 stands out, with an average root size of 4.56 cm (±0.04). For cambuí, doses of 25 mg L-1 and 100 mg L-1 promoted the greatest growth, with an average of 4.23 cm (±0.09, 0.22), as for the treatment with termite mound HS , concentrations of 25 mg L-1, 50 mg L-1 and 100 mg L-1 obtained the largest root sizes, with growth averages of 4.33 (±0.12), 4.55 (±0. 08) and 4.38 cm (±0.22) and for filter cake SH, the concentration of 50 mg L-1 promoted the greatest growth, with an average of 4.26 cm (±0.13) in length. It is concluded that, regardless of the concentration of humic substances, there is a significant increase in the average root length, demonstrating that these results are promising when compared to the control.