Effect of Various Fractions of an Ultradispersed Humate-Sapropel Suspension on the Growth, Development, and Quality of Basil (Ocimum basilicum L.) Plants As Compared to the Use of Chemical Fertilizers.

The effect of salts of humic (HA) and fulvic (FA) acids extracted from ultradispersed humate-sapropel suspension on the growth and development of four basil varieties used for medicinal purposes, as well as on the content of microelements in the above-ground parts of these plants, was studied under conditions of a complete photoculture and a poor nutrient provision. The experiment included midripening Green Large and early-ripening Emily, Lemona, and Marian basil varieties. Plants were grown in a closed grow box for 50 days. Seeds were sown in a soil mix consisting of vermiculite (50%) and peaty-gley soil (50%). The total content of organic matter and N_total in this soil mix was 30.4 and 1.4%, respectively; the content of labile forms of P₂O₅ and exchange K₂O was 88.0 and 82.0 mg/kg, respectively; pH_KCl was 5.57. The experimental scheme included the following variants: control (1.0 N Knop's solution) and 0.01% solutions of HA or FA salts. The treatment of plants was performed by a single under-root application and a weekly spraying of leaves. According to the performed morphometric and chemical analyses, the best results were shown by var. Lemona plants, whose height and biomass in the treated variant did not differ from the control values (29.75 and 29.00 mg, respectively). Treated plants of this variety also demonstrated insignificant reduction of their photosynthesis efficiency measured by a SPAD optic chlorophyll counter (31.98 relative units on average vs. 35.54 relative units in the control) that indicated the presence of a variety-specific response to the use of such an approach. The least differences between the experimental and control variants observed for the var. Lemona evidenced to the ability of both humic acid fractions to mobilize microelements for the growth of a plant biomass and change of its biochemical composition. [ABSTRACT FROM AUTHOR]