Journal of Stress Physiology & Biochemistry, Vol. 13 No. 1 2017, pp. 35-43 ISSN 1997-0838
Original Text Copyright (cc) 2017 by  Alvarado-Sanabria, Garces-Varon and Restrepo-Diaz

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Physiological Response of Rice Seedlings (Oryza sativa L.) Subjected to Different Periods of Two Night Temperatures

Oscar Alvarado-Sanabria1, Gabriel Garces-Varon2, Hermann Restrepo-Diaz1*

1 Departamento de Agronomia, Facultad de Ciencias Agrarias, Universidad Nacional de Colombia. Carrera 30 No 45-03, Bogota D.C., Colombia.
2 Seccional Saldana, Federacion Nacional de Arroceros (Fedearroz). Carrera 18 # 23-112, Saldana, Colombia.


Received December 8, 2016

Night temperatures have shown an increase in rice-growing regions due to climate change in Colombia in recent years, causing a reduction in grain yield. The objective of this research was to study the effect of four different periods of exposure to two night temperatures (24°C vs. 30°C) on the physiological behavior of an Indica rice cultivar widely grown in Colombia. Fedearroz 60 (ʻF60ʼ) were grown under greenhouse conditions for forty-five days. After this period, 12 plants in each treatment was established in a growth chamber at 30°C from 18:00 to 24:00 to carry out the duration of the different periods of heat nighttime stress (4, 8, 12, and 16 days respectively). The control plants were kept in a greenhouse at 24°C. The results showed that leaf photosynthesis, carboxylation efficiency, and pigment content decreased in rice seedlings subjected to 30°C. Also, dark respiration and intercellular CO2 concentration increased. These reductions in the variables as mentioned above were more severe during the first four days of exposure to 30°C than 24°C. In conclusion, these results suggest that these physiological variables may be useful to assess the tolerance of rice plants to high nighttime temperatures in plant breeding programs.

Key words:    Chlorophyll fluorescence, Leaf photosynthesis, leaf respiration, Photosynthetic pigments

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