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Abstract

An efficient application of phytosanitary products depends, among other factors, on a good selection of nozzles and the application volume rate of the solution used. Thus, the objective of this work was to evaluate the efficiency of different models of hydraulic tips and application volume rates on spray coverage on targets positioned in the upper, middle and lower thirds of corn plants. The application volume rates evaluated were: 50 l · ha −1; 100 l · ha −1; 150 l · ha −1; 200 l · ha −1; 300 l · ha −1 and 400 l · ha −1. The following nozzles were used: TT 11001, TTJ60 11002, TXA 8003, 30HCX 12, GRD120 02 and GAT11002. Applications were carried out in phenological stages V6–V7 of corn plants. There was a directly proportional relationship between an increase in application volume rate and the levels of spray coverage and droplet density in the three thirds of corn plants. The application volume rate evaluated, except for 50 l · ha −1 in the lower third, provided a number of droplets compatible with the literature recommendations for the application of systemic fungicides. All tips evaluated provided a number of droplets compatible with the recommendations in the literature for the application of systemic fungicides, therefore, they can be recommended for use in spraying on corn crops.
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Authors and Affiliations

Roxana Stefane Mendes Nascimento
1
ORCID: ORCID
Douglas Ferreira Parreira
2
Juliana Souza Milagres
3
Danilo Felipe Afonso
3
Pedro Luid de Sousa Oliveira
4
Rafael Guimarães Silva Moraes
4

  1. Fitotecnia, Universidade Federal de Viçosa, Viçosa, Brazil
  2. Fitopatologia, Universidade Federal de Viçosa, Viçosa, Brazil
  3. Agronomia, Universidade Federal de Viçosa, Viçosa, Brazil
  4. Agronomia, Universidade Estadual da Região Tocantina do Maranhão, Imperatriz, Brazil
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Abstract

Nutrient deficiency (ND) stands as a prominent environmental factor that significantly impacts global plant growth and productivity. While numerous methods have been employed for detecting nutrient deficiencies in plants, many of them are invasive, time-consuming, and costly. In contrast, chlorophyll fluorescence (ChlF) signals have emerged as a non-destructive tool for the identification of specific nutrient deficiencies, such as nitrogen (N), phosphorus (P), and potassium (K), across various plant species. In this pioneering study, ChlF measurements were employed for the first time to detect a combination of nutrient deficiencies, including deficiencies in nitrogen and phosphorus (–NP), nitrogen and potassium (–NK), potassium and phosphorus (–KP), and a complete NPK deficiency (–NPK). The experiment was conducted using wheat (Triticum aestivum) and maize ( Zea mays) plants, which were grown under controlled laboratory conditions. An optimal hydroponic system was established to facilitate eight experimental conditions, namely: control, –N, –P, –K, –NP, –NK, –KP, and –NPK. Measurements were systematically collected at two-day intervals over a span of 24 days. Our findings demonstrate that chlorophyll fluorescence signals can enable the differentiation of various nutrient deficiencies even prior to the onset of observable symptoms. Furthermore, the examination of chlorophyll fluorescence parameters enables us not only to identify a singular macronutrient deficiency but also to detect multiple macronutrient deficiencies concurrently in a plant.
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Authors and Affiliations

Zuzanna Malwina Jaszczuk
1
ORCID: ORCID
Wojciech Bąba
2
ORCID: ORCID

  1. Warsaw University of Life Sciences SGGW, Faculty of Agriculture and Ecology, Warsaw, Poland
  2. Institute of Technology and Life Sciences – National Research Institute, Falenty, 3 Hrabska Ave, 05-090, Raszyn, Poland
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Abstract

The evaluation of effect of the grass and broadleaf weed control of different mixture rates of mesotrione plus pethoxamid and terbuthylazine applied postemergence in maize was conducted in the field experiments during the 2005 and 2006 growing seasons. There was no phytotoxicity observed on maize after herbicide treatments. Herbicide mixture provided higher levels of Echinochloa crus-galii (L.) Beauv. control than mesotrione used alone. In the postemergence trials, the broadleaf weeds, except Chenopodium album L., were not well controlled by the mesotrione-alone treatment. The addition of pethoxamid plus terbuthylazine to mesotrione significantly improved the control of broadleaf weeds. Mesotrione and mesotrione plus pethoxamid and terbuthylazine treated plots were always among the highest yielding as compared to untreated plots. Any reductions in cob and grain yield were always associated with high weed fresh matter yields indicating that it was the weed competition that led to reduced yield and not herbicide phytotoxicity.

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Authors and Affiliations

Grzegorz. A. Skrzypczak
Jerzy A. Pudełko
Wojciech Waniorek

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