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| DOI：10.13522/j.cnki.ggps.2020105 |
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| The Effect of Deficit Drip Irrigation on Photosynthetic Characteristics of Kiwifruit |
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ZHENG Shunsheng, CUI Ningbo, ZHAO Lu, ZHANG Yixuan, GONG Daozhi, HU Xiaotao, FENG Yu
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1. State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China；2. Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China; 3. State Engineering Laboratory for Efficient Water Use and Disaster Loss Reduction of Crops, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agriculture Science, Beijing 100081, China
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| Abstract: |
| 【Objective】This paper aims to unveil the effect of regulated deficit drip irrigation on photosynthetic characteristics of kiwifruit at its earlier growth stage by comparative experiments in attempts to provide a guidance for constructing water-saving and high-yield kiwifruit production in seasonally arid areas in southern China. 【Method】 The experiment compared five irrigation levels: sufficient irrigation (CK), and four other irrigations using 85% (LD), 75% (MD2), 65% (MD1) and 55% (SD) of the water used in the CK respectively. We took the variety of Jinyan as our model plant and the deficit irrigations were introduced at bud burst - leafing stage (I) or flowering - fruit set stage (II) respectively. Overall, we had eight treatments, excluding the CK. In all treatments and CK, we measured the photosynthetic indices.【Result】Deficit irrigations reduced net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (gs) of the kiwifruit significantly. All these reductions increased with water deficit, despite Tr and gs decreasing faster than Pn. Compared to CK, I-MD1 and II-MD2 reduced Pn by 16.3% and 6.5% respectively, while increased the instantaneous water use efficiency (WUEi) and intrinsic water use efficiency (WUEn) at leaf level by 7.7% and 15.6%, and 8.1% and 18.2% (P<0.05) respectively. Irrigation after a period of drying significantly increased Pn for the kiwifruit leaves and compared to CK, I-LD increased Pn by 4.2% to 5.94 μmol/(m2·s) (P<0.05), indicating the rewetting could overcompensate the loss during the dry period. Both Tr and gs varied with the vapor pressure difference (Δe) quadratically, with Tr increasing significantly with Δe when the vapor pressure difference (Δe) was less than 25×102 Pa. In contract, gs was significantly reduced when Δe was higher than 17×102 Pa.【Conclusion】 The I-LD treatment increased Pn of the kiwifruit by 4.2% while in the meantime saving 15% of water in bud burst - leafing stage, compared to the CK. The II-MD2 saved 25% of water in the flowering - fruit set stage while in the meantime increasing WUEi and WUEn of the kiwifruit by 8.1% and 18.2% respectively. As such, II-MD2 is the optimal deficit drip irrigation at the earlier growth stage of the kiwifruit growing in the seasonally arid areas in southern China. |
| Key words: drip irrigation; water deficit; kiwifruit; photosynthetic characteristic; water use efficiency |
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