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Ensitivity of Nitrospirillum amazonense to pre-emergent herbicides used in pre-sprouted sugarcane seedlings

Grant number: 20/03715-4
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): October 01, 2020
Effective date (End): September 30, 2021
Field of knowledge:Agronomical Sciences - Agronomy - Crop Science
Principal Investigator:Patrícia Andrea Monquero
Grantee:Luana Carolina Gomes Jonck
Home Institution: Centro de Ciências Agrárias (CCA). Universidade Federal de São Carlos (UFSCAR). Araras , SP, Brazil

Abstract

Plant Growth Promoting Rhizobacteria (RPCP) can benefit agricultural crops directly or indirectly and are being adopted in the sugarcane production system. Therefore, the objective of this work will be: to evaluate the compatibility of the commercial product Aprinza (Nitrospirillum amazonense) to the herbicides imazapic and indaziflam, and to evaluate the sensitivity of pre-sprouted sugarcane seedlings inoculated with Aprinza to herbicidal treatments. In the first experiment, the "in vitro" compatibility of N. amazonense bacteria to herbicides will be observed. For this purpose, the minimum inhibitory concentration technique will be used. The liquid inoculant Aprinza (Nitrospirillum amazonense) and two herbicides registered for sugar cane (imazapic and indaziflam) will be used in this test. 5 doses of the herbicides will be evaluated: commercial dose (DC), double (2DC), one and a half of the commercial dose (1.5 DC), half (½DC) and a quarter (1/4DC) and control treatment, without the use of the herbicide. The test will be carried out in triplicate in a nutrient broth culture medium, and the growth of the bacteria will be evaluated through the turbidity of the liquid medium with the absorbance measurement in a spectrophotometer. In the second experiment, the resistance of N. amazonense to the application of the same herbicides to the soil will be evaluated. The soil used will be autoclaved, disposed in sterile trays, and will receive the inoculant at a dose of 1.5 L ha-1. The design will be completely randomized in a 2 x 2 factorial scheme, with two herbicides, in the presence and absence of the inoculant, with four replications, in addition to controls (without herbicide and / or without inoculant). The commercial dosages used for the herbicides will be: imazapic (200 g a.i. ha-1) and indaziflam (100 g a.i. ha-1). At the end of the soil incubation, a 10 g sample will be collected from each treatment and will be plated to determine the number of UFC.g-1 of soil. In the third experiment, sugarcane will be planted using pre-sprouted seedlings (MBPs). The experimental design will be completely randomized with 5 replications, using a 6 x 2 factorial scheme, with five herbicidal treatments (indaziflan, imazapic, clomazone, tebuthiuron, sulfentrazone) + control, in the presence and absence of the inoculant Aprinza. Phytotoxicity assessments will be performed at 7, 14, 28 and 56 days after herbicide application (DAA). At 56 DAA the plants will be evaluated for height (cm), leaf area (cm2), dry shoot biomass (g), length (cm) and dry root biomass (g).