北方寒区日光温室冬季基质袋培番茄蒸腾量模拟

Simulation of tomato transpiration with nutrient substrate bag-cultivation in solar greenhouse during winter in the cold region of Northern China

北方寒区日光温室冬季生产基本无通风,为了探寻室内弱光、高湿、低温及低风速环境下的番茄蒸腾量模拟模型,基于Penman-Monteith(P-M)方程及适应此特定环境的边界层空气动力学阻力、气孔平均阻力、土壤热通量等参数模拟了温室长季节栽培番茄( Lycopersicon esculentum Mill)单株的蒸腾速率并进行了试验验证,揭示了蒸腾速率与净辐射、饱和水汽压差的日变化规律,确定了蒸腾速率与植株上方净辐射的定量关系,检验了土壤热通量取值对蒸腾速率的影响。结果显示:2017-12-11—2018-01-03室内太阳总辐射最大值367 W·m ^-2 、夜晚及阴天相对湿度接近100%、室内风速接近0 m·s^-1 的情况下,单株植株边界层空气动力学阻力变化范围晴天为147~438 s·m^-1 ,阴天为 211~365 s·m^-1;气孔平均阻力晴天69~1 506 s·m^-1 ,阴天132~1 151 s·m^-1;P-M方程模拟的单株番茄逐时蒸腾速率在晴天、阴天中午的平均值分别为0.06、0.02 mm·h ^-1 ,模拟值与实测值比较,平均相对误差约为10%。研究还表明,单株番茄上方净辐射量的43.5%通过蒸腾作用转化为潜热;试验环境下,土壤热通量的取值变化对蒸腾速率影响不大。研究确定的蒸腾速率估算模型可为北方寒区冬季日光温室基质袋培番茄蒸腾量估算以及水分管理提供参考。

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.