Effects of Sewage Sludge Amendments on the Growth and Physiology of Sweet Basil

Abstract

Currently, wastewater treatment plants produce large amounts of sewage sludge. Due to the rich content of organic matter and minerals, sewage sludge can be used as soil amendments for eroded soils. The aim of this work was to assess sewage sludge (SS) in combination with an eroded soil (ES) collected from the North Eastern Romania as growth substrate for sweet basil, and their effect on basil growth and physiology. The experiment was conducted in a greenhouse under controlled environment conditions. The tested substrates were: (1) eroded soil, ES; (2) mixture of eroded soil (15%) + sewage sludge, ES + SS (85%); and (3) sewage sludge, SS (100%). Three types of parameters were studied: morphological traits, physiological, and biochemical parameters. The maximum quantum yield of Photosystem II Fv/Fm was reduced in basil leaves grown on eroded soil (0.80) and was close to the normal value in ES + SS (0.83). Chlorophyll a and the carotenoids content were higher for plants grown on SS and significantly higher for those grown in ES + SS compared with the one of plants grown on ES. The fresh biomass yield and height of basil increased with 44% and 34.5% under ES + SS over ES. Total phenolic content was higher in plants grown on ES (7.34 mg/g dry weight Gallic acid equivalent), which also led to an increased antioxidant activity (44.4%) evaluated by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Fourier-Transform Infrared (FT-IR) (4000-400 cm −1 ) spectra of basil did not show significant qualitative differences among the plants from different treatments. The results of this study demonstrated that SS application led to the improvement of the basil morpho-physiological parameters, allowing the growth of basil on ES + SS.

Biochemical, Physiological and Yield Characteristics of Red Basil as Affected by Cultivar and Fertilization

“…Consistently with our findings, previous authors [55,56] reported that the synthesis of phenolic compounds in plants depends upon environmental conditions, cultivar and farming practices; among the latter, the application of microorganisms [30] and fertilizers [57] play a significant role. However, the antioxidant synthesis can be encouraged by different types of fertilization [16] and, indeed, the increased content of polyphenols, flavonoids and anthocyanins recorded in the present study under the unconventional fertilized treatments (biosolids, organic and microorganisms), was presumably due to their stimulation effect on secondary metabolism [58]. Moreover, previous researchers reported an increased content of phenolic compounds in basil plants grown on a substrate with a low nitrogen content [59], as a consequence of the reallocation of nitrogen resources for the synthesis of secondary metabolites at the expense of protein synthesis, according to the carbon/nitrogen balance hypothesis [60].…”

The Effect of Mineral-Based Mixtures Containing Coal Fly Ash and Sewage Sludge on Chlorophyll Fluorescence and Selected Morphological Parameters of Deciduous and Coniferous Trees

“…Sludge containing essential metal ions and high concentrations of plant-available nitrogen and phosphorus increased the content of assimilatory pigments in basil leaves. According to Burducea et al and Pengcheng et al [89,90], these nutrients are essential for chlorophyll synthesis. In the present study, plants grown on the mixture with the highest content of sewage sludge were characterized by the highest assimilatory activity, as demonstrated by high values of the Fv/Fm ratio.…”

“…Plants grown on the above mixture were also characterized by the most rapid growth. Burducea et al [89] analyzed basil plants grown on substrates fertilized with sewage sludge. Sludge containing essential metal ions and high concentrations of plant-available nitrogen and phosphorus increased the content of assimilatory pigments in basil leaves.…”

Optimal Solutions for the Use of Sewage Sludge on Agricultural Lands

“…One of the valid solutions is the use of sludges in agriculture which implies a series of advantages among which natural nutrient intake, soil texture improvement and even water intake, if sludge distribution is performed before its drying. A particularly delicate aspect is that sludges contain, in addition to various beneficial substances, heavy metals, microorganisms, viruses or other pathogens which represent a potential hazard to human and animal health and to the quality of ecosystems, in case they are used as a fertilizer [21][22][23][24][25][26][27][28][29][30].…”