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Hydrogen Sulfide: Effects on the Physiology of Rice Plants and Relation to Straighthead Disease. M. M. Joshi, Department of Plant Pathology, Louisiana State University, Baton Rouge 70803; I. K. A. Ibrahim(2), and J. P. Hollis(3). (2)(3)Department of Plant Pathology, Louisiana State University, Baton Rouge 70803. Phytopathology 65:1165-1170. Accepted for publication 16 May 1975. DOI: 10.1094/Phyto-65-1165.

Rapid techniques were used for measurements of oxygen release and nutrient uptake of several rice cultivars, and these variables were correlated with plant responses to straighthead and akagare diseases. Straighthead-resistant cultivars had higher oxygen release and lower nutrient absorption, whereas the susceptible cultivars had lower oxygen release and higher nutrient absorption. Oxygen release from three-week-old seedlings of six rice cultivars was inhibited by 0.2, 5.0, and 10.0 µg/ml H2S. Straighthead-resistant cultivars released more oxygen than the straighthead-susceptible cultivars. Hydrogen sulfide at 0.05 µg/ml caused reductions in nutrient uptake of cultivars Dawn and Zenith, whereas cultivars Bluebelle and Saturn were significantly stimulated by this concentration and were unaffected by 0.1 and 0.2 µg/ml H2S. Radiophosphorus uptake of the four cultivars was inhibited by pretreatment with 1.0, 5.0, and 10.0 µg/ml H2S and differentiated in descending order of resistance: Bluebelle, Saturn, Dawn, and Zenith by 0.1 µg/ml H2S. The sulfide theory of straighthead and mild sulfide disease is supported; nutrient uptake and oxygen release by rice seedlings are new tools for evaluating sulfide responses of rice breeding lines.

Additional keywords: akiochi, citrus, conductivity.