Chinese Journal of Agrometeorology ›› 2020, Vol. 41 ›› Issue (09): 552-563.doi: 10.3969/j.issn.1000-6362.2020.09.002

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 Regulating Effect of Air Humidity on Tomato Growth and Root Exudates during Flowering Period under High Temperature Condition

 XU Chao,YANG Zai-qiang,WANG Ming-tian,HAN Wei,WEI Ting-ting   

  1.  1. Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China; 2. Binjiang College of Nanjing University of Information Science and Technology, Wuxi 214000; 3. Sichuan Meteorological Observatory, Chengdu 610091; 4. Water-Saving Agriculture in Southern Hill Area Key Laboratory of Sichuan Province, Chengdu 610091
  • Online:2020-09-20 Published:2020-09-13
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Abstract:  Increasing air humidity to relieve high temperature stress is one of the common measures in greenhouse management. To study the regulation mechanism of air relative humidity on tomato growth and disaster recovery in high temperature conditions, the tomato variety "Jinguan 5" was used as the experimental material. This experiment was carried out at the Agricultural Experimental Station of Nanjing University of Information Science and Technology from September 2018 to January 2019. Two dynamic temperature (T) levels (daily maximum temperature/daily minimum temperature such as 32℃/22℃ and 38℃/28℃), three relative humidity (RH) levels (50%±5pp, 70%±5pp and 90%±5pp) and four stress days (3d, 6d, 9d and 12d) were set, and 25℃/15℃ and 50%±5pp were taken as control (CK). The net photosynthetic rate (Pn), total dry weigh t(Wtotal), root dry weight (Wroot), root activity (Rv), and the type and concentration of low molecular weight organic acids(LMWOAs) in root soil were measured at 0, 7, 14, 21 and 28d after treatment. The results showed that: (1) Pn and RV decreased, but root shoot ratio and LMWOAs increased significantly under high temperature, and each index value under 32℃ treatment was significantly higher than 38℃, RH increased to 70%, Pn, Wroot and root shoot ratio increased significantly. (2) At flowering stage, tomato mainly secreted oxalic acid and succinic acid. At high temperature, oxalic acid, malic acid, lactic acid, acetic acid and propionic acid increased, while tartaric acid and formic acid decreased. (3) T and RH were negatively correlated with LMWOAs, and Pn, Wroot, Wtotal and Rv were significantly positively correlated with LMWOAs. (4) Increasing RH to 70% at high temperature condition could increase Pn and Wroot and promote the root system to secrete LMWOAs, which was conducive to the recovery and growth of tomato after disaster. However, when RH reached to 90%, Pn and Wroot would be reduced, which will aggravate the damage of high temperature to plants and is not conducive to the recovery after disaster. Therefore, about 70% air humidity can alleviate the high temperature disaster to a certain extent.

Key words:  High temperature and high humidity, Tomato, Photosynthesis, Low molecular weight organic acids, Recovery

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