Banca de QUALIFICAÇÃO: VANICE CONCEIÇÃO DO NASCIMENTO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : VANICE CONCEIÇÃO DO NASCIMENTO
DATE: 30/04/2025
TIME: 09:00
LOCAL: Sala 02 do PPGF
TITLE:

Tolerance of plant growth-promoting bacteria to herbicides and their influence on maize growth promotion

KEY WORDS:

Plant growth-promoting bacteria; Microorganism-herbicide interaction; Zea mays

PAGES: 35
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SPECIALTY: Matologia
SUMMARY:

The use of beneficial microorganisms and herbicides are essential strategies to increase productivity and sustainability in maize cultivation. Considering the importance of plant growth-promoting bacteria (PGPB) and the use of herbicides in weed management, research has been conducted to understand the basis of inconsistencies in the interaction between microorganisms and herbicides. In this context, the objective was to evaluate the tolerance of PGPB strains to herbicides commonly used in maize cultivation, as well as the influence of these bacteria on maize growth promotion. The study was conducted in three stages. In Stage I, the following PGPB strains were selected: Azospirillum baldaniorum Sp 245, Herbaspirillum seropedicae ZAE 94, Nitrospirillum amazonense CBAmC, Bacillus thuringiensis S76, Commercial Inoculant (A. brasilense Abv5 + Abv6), Paraburkholderia silvatlantica NRB142, and CNPAB Mix (A. argentinense NRB085 + NRB214). The strains were exposed to the herbicides atrazine (500; 750; 1,000; 2,000 g/L a.i.), s-metolachlor (960; 1,440; 1,920; 3,840 g/L a.i.), mesotrione (480; 720; 960; 1,920 g/L a.i.), tembotrione (420; 630; 840; 1,680 g/L a.i.), nicosulfuron (40; 60; 80; 1,600 g/L a.i.), glyphosate (720; 1,080; 1,440; 2,880 g ha⁻¹ a.e.), atrazine + mesotrione (550; 825; 1,110; 2,200 g/L a.i.), and Calaris (400; 600; 800; 1,600 g/L a.i.) in a completely randomized design (CRD) with seven replicates. In Stage II, maize plants were inoculated with H. seropedicae ZAE 94, P. silvatlantica NRB142, and the Commercial Inoculant (A. brasilense Abv5 + Abv6) under the application of atrazine (pre-emergence) at 500 g/L a.i. and glyphosate at 720 g/L a.i., also in a CRD with five replicates. Data were subjected to ANOVA (p ≤ 0.05), and when significant differences were found, means were compared using the Scott-Knott test at 5% probability.

In Stage I, B. thuringiensis S76 showed halo of inhibition at a dose of 2,000 g/L a.i. of atrazine (pre-emergence) and at 1,600 g/L a.i. of nicosulfuron, while the Commercial Inoculant (A. brasilense Abv5 + Abv6) showed inhibition halos at all doses of nicosulfuron and at the highest and double doses of atrazine (pre-emergence) and s-metolachlor. In Stage II, the highest superoxide dismutase (SOD) activity occurred in treatments with the Commercial Inoculant + glyphosate and without herbicide, as well as H. seropedicae ZAE 94 + atrazine (pre-emergence), while the lowest SOD activities were observed in P. silvatlantica NRB142 + atrazine (pre-emergence) and glyphosate, and in the Commercial Inoculant + atrazine (pre-emergence) and in the non-inoculated + atrazine (pre-emergence) treatments. Catalase (CAT) activity was highest in P. silvatlantica NRB142 + glyphosate and absent in the Commercial Inoculant + atrazine and glyphosate. Ascorbate peroxidase (APX) was most active in H. seropedicae ZAE 94 without herbicide and in the Commercial Inoculant + glyphosate and atrazine. For foliar nitrogen content, the Commercial Inoculant + atrazine (pre-emergence), H. seropedicae ZAE 94 + atrazine (pre-emergence), and P. silvatlantica NRB142 + glyphosate treatments showed higher nitrogen content (g/plant). Regarding fluorescence at 1 DAA (day after application), all treatments with bacterial inoculants + Calaris showed a significant reduction in the PIABS parameter (photosynthetic performance index) compared to the control. This compromised performance persisted until 7 DAA, with recovery observed at 14 DAA. However, at 21 and 28 DAA, a new drop in the index was recorded. For the PITOTAL parameter (performance index on an absorption basis) at 1 DAA, the treatments P. silvatlantica NRB142 + atrazine + glyphosate, nicosulfuron, the Commercial Inoculant + atrazine + glyphosate, nicosulfuron, and the non-inoculated + atrazine treatment did not show signs of systemic damage to the electron transport chain, maintaining relative stability until 21 DAA. Nevertheless, by 28 DAA, all treatments exhibited systemic impairment. In the agronomic analysis, the leaf area index was higher in the non-inoculated + Calaris and non-inoculated + nicosulfuron, H. seropedicae ZAE 94 + glyphosate, and Commercial Inoculant + nicosulfuron treatments. Root volume was greatest in plants inoculated with the Commercial Inoculant + atrazine. Shoot dry mass was higher in plants from the non-inoculated + nicosulfuron and Calaris treatments, as well as in the Commercial Inoculant + no herbicide and atrazine treatments. Root dry mass was highest in P. silvatlantica NRB142 + Calaris and glyphosate, and in the non-inoculated + atrazine treatments. The results indicate that B. thuringiensis S76 and A. brasilense Abv5 + Abv6 exhibit variable sensitivity to herbicides, while bacterial inoculation can mitigate the negative effects of herbicides on maize, favoring plant growth.

COMMITTEE MEMBERS:
Presidente - 1905333 - AROLDO FERREIRA LOPES MACHADO
Externo ao Programa - 2626406 - LEANDRO AZEVEDO SANTOS - UFRRJExterna à Instituição - GABRIELA DE SOUZA DA SILVA - UFRRJ
Externa à Instituição - MARCIA SOARES VIDAL - EMBRAPA