日光温室CO_2浓度变化规律研究

Variation of CO_2 concentration in solar greenhouse in Northern China.

研究了日光温室内CO2 浓度的时空变化规律 .结果表明 ,日光温室CO2 浓度日变化曲线通常呈不规则“U”形 ,有时呈不规则“W”形 .冬春栽培过程中日最高CO2 浓度逐渐减小 ,日最低浓度和昼平均浓度先降后升 ,CO2 亏缺时间逐渐延长 .温室内CO2 空间分布特点通常是早晨和傍晚为前部 >中部 >后部 ,近地面层 >作物冠层 >顶层 ;中午前后为前部 <中部 <后部 ,近地面层 >顶层 >作物冠层 .影响日光温室CO2 浓度变化的主要环境因素是光照度 ,通风不能阻止温室内高浓度CO2 外逸和避免CO2 亏缺 .幼苗期群体光合较弱、土壤呼吸旺盛 ,温室CO2 浓度较高 ;结果期群体光合旺盛、土壤呼吸衰竭 ,CO2

The variation of CO 2 concentration in winter spring cultivated solar greenhouse in northern China was studied. The diurnal change of CO 2 concentration showed an irregular 'U' shape in most case, the maximum value appeared prior to unveiling straw mat in the morning, and the minimum between 12∶00 and 14∶00 PM. Sometimes, an irregular 'W' shape curve with two valleys was also observed, with the first one appeared prior to the ventilation at noon, and the second occurred between 15∶00～16∶30 PM. During the period of winter spring cultivation, the daily maximum concentration of CO 2 in solar greenhouse decreased gradually, while the daily minimum concentration and daytime average concentration dropped first, then went up. At the same time, the time of CO 2 depletion lasted longer and longer. In December, CO 2 depletion happened 2.1～3.1 hours after morning unveiling. In the next March, however, it moved up to 0.6～1.1 hours after unveiling in the morning. At daytime, both during and after ventilation, solar greenhouse often showed CO 2 depletion. The period of CO 2 depletion extended from 4～5.8 hours per day in December to 8～8.5 hours per day in March of next year. The spacial distribution of CO 2 concentrations within the greenhouse showed that in the morning and in the evening, the order was the front>the middle>the back, and the ground>the canopy>the upper, and at midday, the order was the front <the middle<the back, and the ground>the upper>the canopy. Photon flux density was the most important environmental factor affecting CO 2 concentration in greenhouse. Ventilation did not avoided CO 2 depletion. Canopy photosynthetic rate and soil respiratory rate were measured at different growth stages of tomato. At seedling stage, CO 2 concentration in greenhouse was higher than that outside, due to the vigorous soil respiration and lower canopy photosynthetic rate. But at fruiting stage, severe CO 2 depletion occurred because of stronger canopy photosynthesis and weak soil respiration.