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Journal of Applied Sciences
  Year: 2003 | Volume: 3 | Issue: 10 | Page No.: 650-658
DOI: 10.3923/jas.2003.650.658
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Diurnal Variations in Net Photosynthesis and Other Gas Exchange Parameters of Spring Wheat under Saline Conditions

Rana Muhammad Iqbal

A hydroponic experiment was carried out to see the effects of salinity by using a randomized complete block design with 4 salinity treatments and 5 replicates. The salinity levels tested were 0, 50, 100 and 150 mol m-3 NaCl. CaCl2 was also applied to the salinity treatments. Leaf temperature was significantly increased by salinity during noon and afternoon whereas the results for the morning were inconsistent. Transpiration rate (E) showed no obvious diurnal variation but was significantly decreased by salinity during morning and noon but the trends with salinity levels were inconsistent. Net photosynthesis (Pn) was not significantly affected by salinity during the morning. During noon and afternoon, Pn was significantly higher at 150 mol m-3 NaCl than at 50 mol m-3 NaCl whereas the difference between other treatments was not significant. Pn was lower at 50 mol m-3 NaCl than in other treatments at all sampling times. There were no consistent trends of Pn due to diurnal variation. Stomatal conductance (gs) was higher in the morning than in the noon and afternoon. Sub-stomatal CO2 level (Ci) decreased with salinity and was significantly higher at 0 mol m-3 NaCl than at 100 and 150 mol m-3 NaCl during noon and afternoon but not for 100 mol m-3 NaCl during morning. Variation in light intensity due to clouds during measurements and absence of any equilibration prior to measurements made it difficult to detect whether the effects of salinity on gas exchange varied according to time of day.
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How to cite this article:

Rana Muhammad Iqbal , 2003. Diurnal Variations in Net Photosynthesis and Other Gas Exchange Parameters of Spring Wheat under Saline Conditions. Journal of Applied Sciences, 3: 650-658.

DOI: 10.3923/jas.2003.650.658






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