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Leaf gas exchange and chlorophyll a fluorescence in soybean leaves infected by Phakopsora pachyrhizi
Author(s) -
Rios Vinícius Souza,
Rios Jonas Alberto,
AuciquePérez Carlos Eduardo,
Silveira Patrícia Ricardino,
Barros Aline Vieira,
Rodrigues Fabrício Ávila
Publication year - 2018
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/jph.12663
Subject(s) - phakopsora pachyrhizi , chlorophyll fluorescence , photosystem ii , stomatal conductance , photosynthesis , biology , transpiration , horticulture , chlorophyll , quantum yield , botany , fungicide , fluorescence , physics , quantum mechanics
Asian soybean rust ( ASR ), caused by Phakopsora pachyrhizi , is one of the most important foliar diseases affecting soybean production worldwide. This study aimed to investigate the photosynthetic performance (leaf gas exchange, chlorophyll (Chl) a fluorescence images and photosynthetic pigment pools) of soybean plants sprayed with Acibenzolar‐S‐Methyl ( ASM ) and the fungicide epoxiconazole + pyraclostrobin (Epo+Pyr) and further inoculated with P. pachyrhizi . The ASR symptoms progressed much faster on the leaves of plants from the control treatment (water spray) in comparison with the ASM and Epo+Pyr treatments. In general, the values for the leaf gas exchange parameters net carbon assimilation rate ( A ), stomatal conductance to water vapour ( g s ), internal CO 2 concentration ( C i ) and transpiration rate ( E ) increased for the infected plants sprayed with ASM or Epo+Pyr in comparison with plants from the control treatment. The values for the initial fluorescence ( F o ), maximal fluorescence ( F m ), maximal photosystem II quantum efficiency ( F v / F m ), effective photosystem II quantum yield (Y( II )) and quantum yield of regulated energy dissipation (Y( NPQ )) were consistently higher for the ASM and Epo+Pyr treatments in comparison with the control treatment at advanced stages of fungal infection. By contrast, the values for quantum yield of non‐regulated energy dissipation (Y( NO ) were significantly lower for the ASM and Epo+Pyr treatments. The concentrations of total Chl a + b and carotenoids significantly increased for infected plants sprayed with ASM and Epo+Pyr in comparison with plants from the control treatment. The results of this study demonstrated that the spray of soybean plants with either ASM or Epo+Pyr contributed to reduce the negative effect of ASR on the photosynthesis of soybean plants.

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