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Physiological and Morphological Adaptations in Two Rice Varieties Cultivated Under Ammonium and Light Deficiency

Grazinoli Garrido Rodrigo نويسنده , de S.R.G. Garrido Fabiola نويسنده , Regina de Souza Sonia نويسنده , Silvestre Fernandes Manlio نويسنده

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In this study, two rice varieties were evaluated: Piaui and IAC-47. Piaui is adapted to Humid Tropic environmental conditions, where there is N deficiency and low light since rice is planted. IAC-47 is an improved variety. This research aimed to characterize physiological and morphological adaptations observed during vegetative growth under low ammonium-N nutrition and low light in both varieties. To analyze it, developmental parameters, soluble sugars content, amino-N, NH/, total-N and pigments were compared between varieties. The assay was carried out in controlled growth chamber conditions, at 24°C and 12/12 h light/dark periods (200 JlE m-2 sec"). Rice plants were grown in nutrient solution until 26 Days After Germination with a modified Hoagland and Amon. All plants received two treatments with NH/-N 0.1 and 1.0 mM, pH 5.5. Under these conditions, Piaui plants presented longer roots, chlorophyll a+b enhances, soluble sugars levels reduction and free amino-N content increases, what would be important for its adaptation to low N and low light environments, found in Humid Tropic rice culture. In spite of this, IAC-47, selected for high nutrient and light availability, presented typical senescence symptoms.

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