Kalousek P. a kol. The effect of chelating agents on the Zn-phytoextraction potential of hemp and soil microbial activity. Chemical and Biological technologies in agriculture Vol 11(1). 2024 DOI10.1186/s40538-024-00544-6.
Background Hemp (Cannabis sativa) is a crop with a wide range of uses, from the production of fiber and seeds to the secondary metabolites for medicinal purposes. In addition, it is characterized by high biomass yield and the ability to accumulate heavy metals, which makes this plant convenient for phytoremediation purposes. In this study, the effect of applying exogenous biodegradable chelating agents, citric acid (CA) and nitrilotriacetic acid (NTA), to zinc-contaminated soil on zinc (Zn) uptake by two industrial hemp varieties 'Felina 32' and 'Monoica' was studied. The effect of CA and NTA on available Zn in soils was investigated using an 'in pot' experiment under controlled conditions. The effect of both tested compounds on soil microbial activity was simultaneously evaluated. Results After the application of NTA at a concentration of 5 mmol L-1, a > threefold increased accumulation of Zn in the above-ground parts was recorded in the 'Felina 32' variety. In the 'Monoica' variety, the levels of Zn in the above-ground parts were increased > twofold. NTA affected the soil microbiome negatively, causing decreased enzyme activity (in 'Monoica' planted soil) and induced respiration (in 'Monoica' and especially in 'Felina 32' planted soil). On the other hand, CA application did not lead to significantly increased Zn levels in any of the studied hemp varieties. Together with CA's negative effects on some soil enzymes, CA enhanced urease activity, dehydrogenase and several respiration types for the 'Felina 32' variety and exerted less detrimental effect on the soil microbiome. No toxic effects from increased Zn uptake and accumulation in experimental plants were detected, accounting for the unchanged physiological stress markers (levels of photosynthetic pigments and proline in leaves, chlorophyll fluorescence parameters) and selected growth traits of the above-ground organs and root system. Conclusions From the studied varieties, 'Felina 32' seems to be more suitable for Zn-phytoextraction because of its higher tolerance to increased Zn levels, higher biomass production and Zn accumulation capacity. Our results indicate the potential of using the 'Felina 32' variety in NTA-assisted Zn phytoextraction from contaminated soils.
Kintl A. a kol. Mixed cropping system of maize and bean as a local source of N-substances for the nutrition of farm animals. European journal of agronomy. vol 154, 2024. DOI 10.1016/j.eja.2023.127059. In this study, we investigated the quality of mixed cropping system (MCS) composed of maize and bean in comparison with maize grown as monoculture. Experimental stands were established using the precision vacuum seeding machine during a single crossing of the plot. Inter-row distance was 0.375 m, and regularly alternating experimental crops were maize (Zea mays L.) and common bean (Phaseolus vulgaris L.). Experimental variants included maize alone (M) in an amount of 80,000 seeds per hectare and maize (M-MCS) with bean (B-MCS) in a 1:1 ratio (80,000: 80,000 individuals) in MCS. Average yield of N-substances (t/ha) in the biomass obtained from individual variants was 2.36 t/ha in the pure maize culture and 3.09 t/ha in the mixed culture (by 30.9% more). The difference was statistically significant. On the other hand, differences in the content of N-substances (protein) were not found. Results of the experiment for the whole period from 2020-2022 also indicated that the presence of bean in the mixed crop statistically significantly increased contents of acid detergent fibre and crude fibre. On the other hand, compared with the biomass of maize monoculture, bean reduced contents of starch and lipids in the maize biomass. The measured results indicate that biomass from mixed cropping systems has a higher potential to fix more N than biomass from the maize monoculture which is important for digestibility of fodder in livestock production.