Influence of water quality on Zethamaxx's agronomic efficiency

• Grant number: 20/16451-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2021
• End date: February 28, 2022
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Pedro Luis da Costa Aguiar Alves
• Grantee: Carolina Pires da Silva
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

Water can negatively influence the biological efficiency of herbicides and, therefore, the use of clean water for agrochemical applications is prioritized. However, the use of clean water is not always possible. Water can be withdrawn from superficial regions, such as rivers and reservoirs, and from subsurface regions, which are from artesian wells and semi-artesian wells; Waters from open reservoirs are commonly inappropriate for use in the application of pesticides, as they are generally subject to the influence of rainwater, presenting mainly clay and organic particles in suspension. To this end, six experiments will be carried out in a greenhouse to assess the influence of water quality on the agronomic efficiency of the herbicide Zethamaxx (in two doses: bulla and half of this) in the control of bitter grass (Digitaria insularis), grass -brachiaria (Brachiaria decumbens), and razor grass (Paspalum virgatum). Each experiment will correspond to a conditioning factor for water quality, namely: calcium content, carbonate content, magnesium content, pH levels, iron content and clay content. A completely randomized experimental design will be used, with the experimental treatments arranged in a 2 x C + T factorial scheme, in which the two concentrations of the herbicide will be the main factors, associated with the n concentrations of the conditioning factors, with a control without application, all in 4 repetitions. Symptoms of intoxication in target plants will be characterized and evaluated by treatments at 3, 5, 7, 14, 21 and 28 days after application (DAA), accompanied by photographic records. At 28 DAA, in the remaining plants in each pot, the relative content of total chlorophyll and the fluorescence of chlorophyll a - Fv / Fm will be determined. Then, these plants will be cut close to the substrate surface and placed to dry in an oven with forced air circulation at 60ºC for 96 hours, after which the mass on a precision scale will be determined. For each species, the results obtained in each experiment will be subjected to analysis of variance by the F test and the averages will be compared by the Tukey test at the 5% probability level, when relevant, and subjected to regression analysis, in order to determine the critical concentration.