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| DOI：10.13522/j.cnki.ggps.2019408 |
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| Effects of Water-salt Regulation on Tomato Growth and Quality under Drip Irrigation with Brackish Water in Coastal Saline-alkali Soil |
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LI Dan, WAN Shuqin, KANG Yuehu, LI Xiaobin
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1.Key Laboratory of Water Cycle and Related Land Surface Processes,Institute of Geographical Sciences and Natural Resources Research, CAS, Beijing 100101, China;2. College of Resources and Environment, University of Chinese Academy of Sciences, UCAS, Beijing 100049, China
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| Abstract: |
| 【Background】 With the growing demand for agricultural products and the increasing shortage of agricultural freshwater resources in coastal areas, the development of drip irrigation with brackish water can play a crucial role in relieving the pressure of agricultural water supply. Because most of the soil in coastal areas have a heavy texture and high salinity, and therefore crop growth is challenging. Previous studies have shown that brackish water irrigation can significantly change soil moisture, salinity distribution, and crop quality. However, few studies have conducted systematic experiments to analyze the effects of drip irrigation with brackish water on the crop qualities under water-salt regulation methods. Thus, we introduced drip irrigation and a water-salt regulation method into tomato planting to bridge this gap. This study has potential contributions to urban eco-environment construction, green agricultural development, and exploitation of brackish water, especially in coastal areas with a large amount of brackish water available in shallow groundwater. 【Objective】 This study aims to investigate the feasibility and safety of green agricultural production under drip irrigation with brackish water in coastal saline-alkali soil. 【Method】 To research the effect of brackish water irrigation on tomato growth, yield, quality characteristics, and salinity distribution of the soil profile, we used the conductivity of deep underground water( 0.7 dS/m) as a control check and conducted four tomato treatments with brackish water of different conductivity (3.2 dS/m, 4.7 dS/m, 6.2 dS/m, 7.8 dS/m). The tomatoes were subjected to saline drip irrigation and ridge cultivation using a water-salt regulation method. 【Result】The salinity of the entire soil did not increase significantly, whereas the salinity of the soil profile was redistributed when tomatoes were irrigated with brackish water of 3.2 to 7.8 dS/m. There was an apparent salt leaching zone in the area 10 cm wide and 0~60 cm deep from the dripper. The salinity was mainly washed down to a depth of 70 cm and the surface of ridges and ditches (0~20 cm) that were 20~40 cm away from the dripper. With the increase of irrigation water electrical conductivity (ECi), LAI, fresh weight, and dry weight increase and then decreased, while the plant height and stem thickness gradually decreased. Moreover, all indicators reduced significantly compared with fresh water treatment(0.7 dS/m) when the conductivity exceeded 4.7 dS/m. No significant difference in chlorophyll, malondialdehyde (MDA), carotenoid, and proline content under different treatments, while brackish water irrigation significantly reduced the content of soluble sugar in the leaves. With the increase of ECi, the contents of soluble solids, reducing sugar, and organic acid in tomato fruits gradually increased, whereas the sugar-acid ratio and yield gradually decreased. Besides, when ECi exceeded 1.4 dS/m, for every 1 dS/m increase of ECi, the yield decreased by approximately 9.7% employing formula fitting. 【Conclusion】 In summary, the brackish water irrigation with a conductivity of 4.7 dS/m or less can be used to irrigation in coastal saline-alkali soil where freshwater scarce. Although the yield was reduced, over 300 mm of the water can be saved compared to freshwater irrigation and the quality of tomatoes was also improved, and the salinity balance across the soil profile can be maintained. |
| Key words: brackish water; drip irrigation; growth indicator; physiological indicator; fruit quality; tomato |
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