Spectroscopic, Textural and Thermal Characterization Methods of Biostimulants Based on Sodium Humate

Abstract

Plant biostimulants, an emerging class of agricultural inputs, are complex products. The reproducibility of their specific action on plant metabolism and plant physiology, which lead to an enhanced nutrient use efficiency, stress tolerance and edible yield quality, is still a challenge. Development of quality insurance systems for plant biostimulants need complex investigation based on adapted analytical, physico-chemical and chemical methods. The objective of this work was to characterize commercial humate biostimulants through different analytical techniques (Fourier transform infrared spectroscopy - FTIR, thermogravimetric analysis- TGA) and to evaluate their textural and chemical (pH, C, N, humic acids, inorganic components) parameters. The first derivative curve from TG analysis showed decomposition of different compounds, classified according to the results obtained by FTIR. The humic substances determined by TGA method was comparable with the results obtained by gravimetric reference method. The inductively coupled plasma-optical emission spectrometry (ICP-OES) technique was applied to determine the inorganic elements either from the production process of humate or from raw materials, as well as for the control of humate in terms of requirements for safety and quality. Their complementary properties obtaining through different analytical techniques provide essential information on the chemical characteristics of the humate plant biostimulant formulations.

Sustainable Recovery of Anthocyanins and Other Polyphenols from Red Cabbage Byproducts

“…The extraction process is characterized by the following steps: homogenization of the red cabbage byproducts (25 g) in a blender, mixing with 100 mL extraction solvent mixture, followed by ultrasound-assisted extraction (UAE, Fritsch ultrasound bath, Laborette, sound power 2 × 240 W/period) of the plant material for 20 min at 25 ± 5 • C after flushing the flask with nitrogen. The extraction solvents were selected based on the previous experience of the authors [28,29], and the data from the literature [30]. The following aspects were considered: the use of non-toxic solvents, the limitation of organic substances used, the reduction of the extraction time and the generation of products with added value.…”

“…Briefly, a stock solution of 0.3 mM DPPH was prepared in ethanol. The three different reaction systems prepared according to [28] were incubated in the dark for 1 h, and the absorbance was read at 517 nm. A calibration curve was made in the Trolox concentration interval of 0.01-0.05 mg × mL −1 .…”

Humic Substances as Microalgal Biostimulants—Implications for Microalgal Biotechnology

“…Besides the (bio)chemical priming and activation of the tolerance against oxidative stress, another mechanism is related to the oscillating antioxidant–prooxidant characteristics of HS. The chinone–phenol moieties of HS have context-dependent redox characteristics [ 54 ]. In the “crowded” cellular environment with a high level of reactive oxygen species, HA exert antioxidant activity.…”

“…One illustrative example is the synergic interaction between hydrophobic and hydrophilic moieties in water-holding in arid soil, according to relative humidity. Another feature related to HS system complexity is the context-dependent characteristics, such as redox properties [ 54 ]. Due to this intrinsic complexity, combined methods are needed to characterize the HS used as plant biostimulants [ 55 ].…”

The Effect of Wheatgrass Juice Administration on Physiological State and Oxidative Stress in Carp

“…After 6-10 days of germination, the resulted sprouts form the so-called wheatgrass [1], the juice being rich in vitamins and provitamins, among which vitamins A, C, B1, B6, B12, E, folic acid and b-carotene, antioxidants, minerals such as iron, calcium, magnesium, iodine, selenium, chromium, zinc and phenolic compounds such as ferulic acid, gallic acid, caffeic acid, syringic acid and pcummaric acid [2] and many enzymes and aminoacids [3], which give the wheatgrass juice significant nutritional and medical values [4,5].…”