Biological effectiveness of quillay (Quillaja saponaria) extracts for the control of yellow aphids (Melanaphis sacchari) in sorghum

Objective: To evaluate and define a plant extract for the control of the yellow aphid in order to prevent environmental contamination and improve crop profitability. Design/Methodology/Approach: In a sorghum plot —located in the municipality of Jantetelco, Morelos— with a high incidence of yellow aphids, three doses —2-, 4-, and 6-mL L-1 of water of Quillaja saponaria extract, 0.2-mL L-1 of water of Imidacloprid, and 10-mL L-1 of water of calcium polysulfide—, as well as an absolute control, were evaluated. The applications were carried out using a 15-L manual spray backpack, which had been previously calibrated and had a fan nozzle. A randomized block experimental design—with six treatments and four repetitions— was used. The experimental unit was made up of five 5-m long rows with 0.70 m between rows, resulting in a 17.5 m2 total area per experimental unit. The three central furrows were the useful plot, leaving 0.5 m at each end of the furrow. The total size of the experimental plot was 420 m2. Results: The biological effectiveness during the samplings was as follows: both the Quillaja saponaria (6-, 4- and 2-mL L-1 water doses) and Imidacloprid treatments had a 100% effectiveness. Study limitations/implications: This study was carried out in sorghum crops. Findings/conclusions: Treatments based on Quillaja saponaria extracts on M. sacchari in sorghum crops showed 100% biological effectiveness from the first application and no phytotoxicity was observed in any treatment

Feasibility of Remediation Lead, Nickel, Zinc, Copper, and Cadmium-Contaminated Groundwater by Calcium Sulfide

Metal contamination in groundwater often occurs in various industrial processes. Studies have confirmed that polysulfide could reduce hexavalent chromium to trivalent chromium, achieving the effect of in situ stabilization. For other metal contamination in groundwater, whether polysulfide also had a stabilizing ability to achieve in situ remediation. This research focused on metals in addition to chromium that often contaminated groundwater, including lead, nickel, zinc, copper, and cadmium, to explore the feasibility of using calcium polysulfide (CaSx) as an in situ stabilization technology for these metals’ contamination of groundwater. Results showed that CaSx had a great removal efficiency for metals lead, nickel, zinc, copper, and cadmium. However, for nickel, zinc, copper, and cadmium, when CaSx was added excessively, complexes would be formed, causing the result of re-dissolution, in turn reducing the removal efficiency. As it is difficult to accurately control the dosage of agents for in situ groundwater remediation, the concentration of re-dissolved nickel, zinc, copper, and cadmium may not be able to meet the groundwater control standards. CaSx had high lead removal efficiency and for a concentration of 100 mg/L, the dose of calcium polysulfide was more than the amount of 1/1200 (volume ratio of CaSx to groundwater). In addition, the removal rate was almost 100% and it would not cause re-dissolution due to excessive CaSx dosing. CaSx can be used as an in situ stabilization technique for lead-contaminated groundwater.

Cyclic drying and wetting tests on combined remediation of chromium-contaminated soil by calcium polysulfide, synthetic zeolite and cement

Using calcium polysulfide as the reducing agent, synthetic zeolite as the adsorbent, and cement as the curing agent, the dual-index orthogonal test method was used to determine the best remediation dosage of chromium-contaminated soil. On this basis, through the dry–wet cycle test, the durability of the chromium-contaminated soil after repair is analyzed from the perspectives of unconfined compressive strength, toxic leaching concentration, quality loss, and microscopic characterization. Test results showed that the optimal ratio for the joint repair of chromium-contaminated soil was 3 times the amount of CaS5, 15% synthetic zeolite, and 20% cement. With the increase in the number of wet–dry cycles, the unconfined compressive strength of the composite preparation combined to repair chromium-contaminated soil was first increased and then reduced, and the concentration of Cr(VI) and total chromium in the leachate was first decreased and then increased. The higher the chromium content of the contaminated soil was, the lower the unconfined compressive strength, and the higher the leaching concentration of Cr(VI) and total chromium were. With the increase in cycle times, the cumulative mass-loss rate of composite preparations for repairing chromium-contaminated soil gradually increased, and the higher the chromium content was, the higher the cumulative mass-loss rate, which was less than 2%, reflecting the combination of composite preparations for repairing chromium-contaminated soil to have good durability. Microscopic and macroscopic results are consistent with each other.

The effect of treatments with a preparation based on calcium polysulfide on seed germination and yield of wheat plants

For the further intensification of the processes of agricultural crop production, the permanent development of new preparations with effective growth-regulating activity in relation to crops and exhibit the ability to suppress phytopathogens and improve the quality of economically valuable products is required. The purpose of the investigation was to study the effect of pre-sowing treatment of wheat seeds with calcium polysulfide (CaS4) preparations on germination, plant productivity parameters, and grain quality. Methods. In laboratory conditions, the effect of calcium polysulfide on the germination of wheat plants was investigated. 0.1; 0.5 and 1 % of CaS4 solutions for incubating the seeds during 1, 2 and 3 hours were used. Fresh and dry mass, shoot and root lengths, as well as the rate of formation of superoxide anion and hydrogen peroxide content, were determined, peroxidase and catalase activity and malondialdehyde (MDA) concentration ware detected. Infield studies seeds were treated with CaS4 solution at a rate of 0.6 l/t, followed by determination of the number of seedlings affected by root rot. Results. As a result of one-hour presowing treatment of seeds with a 0.1% solution in six-day-old seedlings, an increase in leaf length was observed, as well as a beneficial effect of the drug on the redox system of root tissues. The use of CaS4 solution for pre-sowing treatment and during heading in the field increased the yield by 3 quintals/ha and increased the protein content in wheat seeds by 8–9 %. A conclusion is drawn on the effect of calcium polysulfide on the germination of wheat seeds depending on the concentration and time of pre-sowing treatment.