| Simulation of tomato transpiration with nutrient substrate bag-cultivation in solar greenhouse during winter in the cold region of Northern China |
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| DOI：10.7606/j.issn.1000-7601.2019.04.06 |
| Key Words: the northern cold region solar greenhouse tomato nutrient substrate bag-cultivation transpiration soil heat flux |
| Author Name | Affiliation | | LUO Xin-lan | College of Agronomy，Shenyang Agricultural University, Shenyang, Liaoning 110866, China | | WANG Miao | College of Agronomy，Shenyang Agricultural University, Shenyang, Liaoning 110866, China
Jinzhou Meterological Bureau, Jinzhou, Liaoning 121000, China | | TONG Guo-hong | College of Water Conservancy, Shenyang Agricultural University, Shenyang, Liaoning 110866, China | | ZHANG Han-qi | College of Agronomy，Shenyang Agricultural University, Shenyang, Liaoning 110866, China | | LI Ying-ge | College of Agronomy，Shenyang Agricultural University, Shenyang, Liaoning 110866, China | | YIN Jia-qi | College of Agronomy，Shenyang Agricultural University, Shenyang, Liaoning 110866, China | | YANG Li-tao | Inner Mongolia Climate Center, Huhhot, Inner Mongolia 010051, China |
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| Abstract: |
| Crop production in solar greenhouse (CSG) in the cold region of northern China is usually performed under the environment of no ventilation, low light intensity, high humidity, and low temperature. Thus, the crop transpiration is different from those in other kind of greenhouses and in ventilated CSGs. Tomato is the most common crop grown in greenhouses. In this study, a tomato transpiration model based on the Penman-Monteith (P-M) equation, aerodynamic resistance, average stomatal resistance, soil heat flux, and other parameters for the particular environment was used to estimate the transpiration rate of a tomato (Lycopersicon esculentum Mill) and validated by experiments. In this model, aerodynamic resistance model was based on free convection and the stomatal average resistance model was inversed by measured transpiration rate and P-M equation. Heat conduction transfer into soil deep was taken as 0.35 times of net radiation during the daytime and 0.13 times during the nighttime. A sensitivity analysis was conducted for the influence of different soil heat flux on tomato transpiration rates. Based on this model, the study revealed the daily variations of transpiration rate, net radiation, and saturation vapor pressure as well as the quantitative relationship between transpiration rate and net radiation above single plant. The results showed that, during experiment period from December 11, 2017 to January 3, 2018, with a maximum daily solar radiation of 367 W·m-2, near 100% relative humidity at night and during cloudy day, nearly 0 m/s air velocity, for single plant, the aerodynamic resistance changes ranged from 147 s·m-1 to 438 s·m-1 during clear days and from 211 s·m-1 to 365 s·m-1 in cloudy days; the average resistance of stomatal was from 69 s·m-1 to 1 506 s·m-1 during clear days and from 132 s·m-1 to 1 151 s·m-1 in cloudy days. The average transpiration rate of single tomato simulated by the P-M equation was 0.06 mm·h-1 at noon on a sunny day and 0.02 mm·h-1 at noon on a cloudy day, with about 10% of the Mean Relative Error of simulated values. The results also showed that 43.5% of the net radiation above plant was transformed into latent heat by transpiration and the changes of soil heat flux had insignificant influence on the transpiration rate under current experiment conditions. Thus, the transpiration rate simulation model could be used to estimate single tomato transpiration in winter in the cold region of northern China and also give indication for water management inside CSG. |
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