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| DOI：10.13522/j.cnki.ggps.2025082 |
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| Effects of water and nitrogen regulation on photosynthesis andyield of pigmented marigolds |
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YANG Meixia, YU Shouchao, ZHOU Chenli, ZHANG Hengjia
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1. College of Water Resources and Hydropower Engineering, Gansu Agricultural University, Lanzhou 730070, China;
2. College of Agriculture and Biology, Liaocheng University, Liaocheng 252059, China
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| Abstract: |
| 【Objective】Pigmented marigold (Tagetes erecta) is widely cultivated for its rich natural pigment content. In arid and semi-arid regions such as the oasis zones of Northwestern China, optimizing water and nitrogen management is critical to improving photosynthetic efficiency and yield of pigmented marigold. This paper studies the effects of various irrigation methods and nitrogen fertilizations on photosynthesis and yield of pigmented marigold under drip irrigation.【Method】An experiment was conducted from May to September 2024 at the Yimin Irrigation Experimental Station in Minle County, Gansu Province. Irrigation treatments were to keep soil moisture at key crop growth during stages - seedling, bud, early flowering and full flowering - 55%-65% (W1), 65%-75% (W2) and 75%-85% (W3) of the field capacity. Each irrigation treatment had three fertilizations by applying 120 (N1), 180 (N2) and 240 kg/hm2 (N3) of nitrogen fertilizer. The control is sufficient irrigation and local fertilization that applies 300 kg/hm2 of nitrogen fertilizer (CK). In the experiment, we measured net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr) during reproductive stage of the crop, as well as the crop yield. The TOPSIS method was used to optimize irrigation and fertilization.【Result】Irrigation and nitrogen application significantly affected all measured photosynthetic traits (P＜0.05). Photosynthetic efficiency increased with nitrogen application up to a moderate level and then declined when nitrogen application exceeded the optimal threshold. Yield varied significantly among treatments. The second crop of pigment marigold had the highest yield, with the highest-yielding treatment being W3N2 (16.26 t/hm2); the third crop had the lowest yield, and the lowest-yielding treatment was W1N1 (7.67 t/hm2). Moderate nitrogen application (N2) increased yield by 32.21% and 22.76%, compared to low (N1) and high (N3) nitrogen application, respectively. TOPSIS analysis showed W3N2 as the optimal irrigation-fertilization combination. 【Conclusion】Maintaining soil moisture at 75%-85% of the field capacity combined with a nitrogen application of 180 kg/hm2 (W3N2) is optimal for maximizing photosynthetic efficiency and yield of pigmented marigold under drip irrigation in oasis regions of Northwestern China. |
| Key words: water-nitrogen regulation; photosynthesis; yield; comprehensive evaluation; pigmented marigolds |
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