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| DOI：10.13522/j.cnki.ggps.2017.0473 |
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| Effects of Alternate Fresh and Brackish Water Irrigation on the Diurnal Variation of Photosynthesis of Summer Maize |
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MIN Yong， ZHU Chengli， SHU Muchen， ZHAI Yaming， HUANG Mingyi， MU Hui
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College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China; Key Laboratory of Efficient Irrigation-drainage and Agricultural Soil-water Environment in Southern China Ministry of Education, Nanjing 210098, China; Geological Survey of Jiangsu Province, Nanjing 210018, China
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| Abstract: |
| 【Objective】 Investigate the effects of alternate irrigation with fresh and brackish water on diurnal variation of photosynthesis of summer maize (Zea mays L.) in different growth periods.【Method】 A pot experiment was carried out with three alternate fresh and brackish water irrigation methods. The various levels brackish waters were irrigated respectively at the seedling stage (i.e. BFF1: 1 g/L NaCl, BFF3: 3 g/L NaCl and BFF5: 5 g/L NaCl), the jointing and tasseling stage (i.e. FBF1: 1 g/L NaCl, FBF3: 3 g/L NaCl and FBF5: 5 g/L NaCl), and the filling stage (i.e. FFB1: 1 g/L NaCl, FFB3: 3 g/L NaCl and FFB5: 5 g/L NaCl). The control treatment (CK) was set with fresh water (0.08 g/L NaCl) irrigation throughout the whole growth period. 【Result】 The net photosynthetic rate (Pn) under BFF1, BFF3, BFF5 and CK treatments charged with double peak curves，and the majority of peaks appeared at 12:00 and 16:00. The similar trends were found in FFB1, FFB3 and FFB5 treatments while the majority of peaks appeared at 10:00 and 12:00 in advance. Diurnal variation of Pn was expressed as a single peak at 10:00 in FBF1, FBF3 and FBF5 treatments. The Pn, transpiration rate (Tr) and water use efficiency (WUE) of maize with brackish water treatments were reduced in different degree compared with the control treatment which resulting in decrease of photosynthesis. Moreover, these reductions were found in stomatal conductance (Gs) and intercellular CO2 concentration (Ci) (increase in BFF3, BFF5, FBF1, FBF3 and FBF5 treatments) which causing decrease of photosynthesis by stomatal and non-stomatal factors. 【Conclusion】 The effect of brackish water irrigation on diurnal variation of photosynthetic of maize is the most significant in the jointing and tasseling stage, followed by the seedling stage, while the effect is the minimum in the filling stage. So, summer maize is seriously sensitive to brackish water irrigation in the jointing and tasseling stage. Fresh water should be applied in the jointing and tasseling stage and brackish water can be irrigated in the filling stage. |
| Key words: brackish water; alternate irrigation; summer maize; diurnal variation of photosynthesis |
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