Chinese Journal of Agrometeorology ›› 2017, Vol. 38 ›› Issue (10): 672-678.doi: 10.3969/j.issn.1000-6362.2017.10.006

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Heat Flux Changes at Junction between Root Zone Matrix and Soil Ridge of Sweet Pepper

LI Zong-geng, FU Guo-hai, LIU Wen-ke   

  1. Institute of Environment and Sustainable Development in Agricultural, Chinese Academy of Agricultural Sciences/Key Laboratory of Energy Conservation and Waste Management of Agricultural Structures, Ministry of Agriculture, Beijing 100081, China
  • Received:2017-03-11 Online:2017-10-20 Published:2017-10-10

Abstract: A novel soil-ridged substrate-embedded cultivation (SSC) method was used to cultivate sweet peppers in Chinese solar greenhouse. Five treatments, including soil ridge (SR), normal ridge (NR), narrow normal ridge (NRn), short normal ridge (NRs) and the double plant density of the normal ridge (NRd), were set to observe diurnal heat flux changes of east and west horizontal directions and the vertical direction of the root zone by using heat flux plates, and select a kind of ridge which was most suitable for vegetables winter production in Chinese solar greenhouse. The results showed that soil heat flux of each treatment presented unimodal curve diurnal changes synchronously, but the time of heat absorption and heat release were different. For east horizontal direction of ridges, the root zones of SR, NR, NRn and NRd absorbed heat at 9:00-14:00 on sunny days, and the time of heat absorbing delayed 2 hours on cloudy days. NRs absorbed heat at 23:00-14:00 on sunny days, and NRs absorbed heat all day when it was cloudy. For west horizontal direction of ridges, NRs absorbed heat all the time, and the rest four treatments absorbed heat at 9:00-17:00. In the vertical direction of root zone, heat flux changes showed that SR, NR, NRn and NRd absorbed heat at 11:00-18:00 in sunny days and 12:00-17:00 in cloudy days. Release heat time of NRs was 2-3 hours later than other treatments. Difference of heat absorption and release of five treatments changed with different locations on horizontal directions of east and west and vertical direction of root zone. Each treatment primarily absorbed heat on the horizontal direction of east side and vertical direction of root zone, but released heat on the horizontal direction of west side. In the junction between east and west lateral soil of ridge and matrix of root zone, the heat absorbed by the root zone of NRs was larger than that of the exothermic heat, while that of NRd was much less than released. So NRd treatment could maintain well root zone temperature in winter, it had a better application prospect in vegetables production in winter and early spring in Chinese solar greenhouse.

Key words: Chinese solar greenhouse, SSC, Sweet pepper, Heat flux