摘要
灰霾天气导致到达地面的太阳总辐射下降及散射辐射比例增加,从而影响作物生长和产量。为研究灰霾导致的太阳辐射变化对作物的影响,设计了田间开放式灰霾模拟装置。以空气质量等级做为灰霾严重程度的标准,根据不同程度灰霾条件下太阳辐射变化情况,确定了轻度、中度、重度霾下太阳总辐射和散射辐射比例。测定不同聚乙烯(PE)塑料薄膜的光学特性(透光率和散射特性及其覆盖下不同光质的光占总可见光比例的空间分布),选择光学特性满足模拟不同程度灰霾条件下太阳辐射状况的PE塑料薄膜作为覆盖材料。根据作物生长季节太阳高度角和方位角变化范围,确定了保证上午10:00到下午14:00遮荫面积达到4 m2的最小处理小区面积为20 m2,南北向边长为4 m,东西向边长为5 m。在2013-2014年水稻生长季利用所设计的试验装置进行田间模拟不同程度灰霾导致的太阳辐射变化处理试验,对太阳辐射和冠层微气候进行了持续观测。结果表明:该研究设计的灰霾模拟装置可以模拟中度及重度灰霾导致的太阳辐射变化情况。灰霾模拟装置在改变辐射状况的同时,保持了不同光质的光占总可见光比例的空间分布与自然灰霾条件相比没有显著变化。并且处理与对照小区的作物冠层温度及环境温湿度没有显著差异。该研究所设计装置可以较好地模拟不同程度灰霾条件下的太阳辐射变化,为研究灰霾对作物生长和产量的影响提供了有效的田间试验手段和技术支持。
The decrease of solar radiation and increase of diffuse radiation proportion caused by haze affect crop productivity. To investigate the impacts of changed radiation by haze on the crop growth, a device that simulating haze-caused radiation changes was designed and tested in an open field during 2013 and 2014. Based on air quality index(AQI), haze is classified into three levels: mild, moderate and heavy haze. The changes of solar radiation under each level of haze condition are determined based on the relationship between AQI and radiation conditions. Global radiation decreases by 11%-21%, 22%-32%, 33%-54% under mild, moderate, heavy haze while corresponding diffuse radiation proportion are 51%-59%, 60%-68%, 69%-87%, respectively. The optical properties(transmittance, scattering and spatial distribution of visible spectrum) of different thickness and layers of PE film used in the device were experimentally tested as covering materials to simulate radiation conditions under the moderate and heavy haze conditions. Based on the solar height and azimuth angles during crop growing season, the minimum plot area was determined as 20 m^2 to secure 4 m^2 shading area in a plot from 10:00 to 14:00. The haze simulator was designed as a cuboid with 5 m(east-west)×4 m(north-south) × 2 m(above the ground) with the cover material installed on top and without obstacle at the 4 sides to allow free air flow and heat exchange. The device was applied and tested in rice paddy field during two rice growing seasons(2013 and 2014). Solar radiation and other microclimate factors were automatically monitored and 30 minutes average values were recorded during the experiments. The results showed that the changes of total radiation and diffuse radiation proportion under different treatments matched the change scopes of solar radiation under moderate and heavy levels of haze. The spatial distribution of visible spectrum under treatment conditions was not significantly different from that under natural haze conditions. The differences of air, water and soil temperature between shading treatments and control were less than ±0.5℃ in most of the time, and the differences of air humidity between shading treatments and control were 4%-5%. The canopy thermal image showed no significant difference between shading treatment and control at rice heading stage in 2014. These results indicated that the device designed in this study can be used to simulate haze-caused radiation conditions in open field and has the potential to provide effective field experimental means for investigating the effects of haze on crops.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2015年第13期199-206,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家公益性行业(农业)科研专项(200903003)
关键词
太阳辐射
作物
气候变化
灰霾
田间开放式灰霾模拟装置
散射辐射比例
可见光谱空间分布比例
冠层微气候
solar radiation
crops
climate change
haze
field haze simulator in open field
diffuse radiation proportion
spatial distribution of visible spectrum
canopy microclimate