大豆叶片呼吸与植被指数和叶片性状的关系

Relationships Between the Leaf Respiration of Soybean and Vegetation Indexes and Leaf Characteristics

为研究大豆叶片呼吸与植被指数和叶片性状的关系,设置田间试验,观测不同生长阶段的大豆顶1叶、顶2叶、顶3叶叶片呼吸及呼吸系数,并观测归一化植被指数(NDVI)、差值植被指数(DVI)、比值植被指数(RVI)、增强植被指数(EVI)、光化学植被指数(PRI)、红边叶绿素指数(RECI)6种高光谱植被指数以及叶绿素相对含量(SPAD)值、叶片鲜重、叶片干重、含水量、叶面积、比叶面积、氮含量。结果表明:大豆单片叶片呼吸及呼吸系数存在明显的季节变化规律,顶1叶、顶2叶、顶3叶单片叶片呼吸季节平均值分别为(0.157±0.019),(0.162±0.014)和(0.142±0.010)mg·d^(-1),其呼吸系数季节平均值分别为(0.638±0.072),(0.678±0.082)和(0.642±0.076)mg·g^(-1)·d^(-1),顶1叶、顶2叶、顶3叶季节平均单片叶片呼吸及呼吸系数均无显著(p>0.05)差异。不同植被指数的季节动态之间存在差异,RVI,EVI,PRI和RECI在生长季中期的数值相对更大,RVI,EVI,PRI和RECI表现为单峰曲线的变化规律。除大豆生长初期外,随着叶片位置下降,SPAD值、鲜重、干重、叶面积均逐渐下降。叶片含水量随着叶片生长呈现出下降的规律。单片叶片呼吸与气温、PRI存在极显著(p<0.01)相关关系,与RECI、氮含量存在显著(p<0.05)相关关系,基于这4个因子的模型可模拟单片叶片呼吸60.4%的季节变异。呼吸系数与干重、比叶面积存在极显著(p<0.01)相关关系,与气温、SPAD值存在显著(p<0.05)相关关系,基于这4个因子的模型可模拟叶片呼吸系数72.4%的季节变异。本研究显示,大豆叶片呼吸与高光谱植被指数和叶片性状存在内在联系,采用高光谱植被指数可有效模拟不同位置叶片呼吸及呼吸系数的季节变异。

A field experiment was performed to investigate the relationships between the leaf respiration of soybean and vegetation indexes and leaf characteristics.The respiration and respiration coefficient of the first,second and third leaves from the top at the different growth stages were measured.The normalized difference vegetation index(NDVI),difference vegetation index(DVI),ratio index(RVI),enhanced vegetation index(EVI),photochemical reflectance index(PRI)and red edge chlorophyll indexes(RECI)were obtained from the hyperspectral method as well as the leaf characteristics of chlorophyll SPAD value,fresh mass,dried mass,water content,leaf area,specific leaf area and nitrogen content were also determined.The results showed that the respiration of a single leaf and respiration coefficient had obvious seasonal patterns.The seasonal mean respiration of the single first,second or third leaf from the top was(0.157±0.019),(0.162±0.014)and(0.142±0.010)mg·d^(-1),respectively.The seasonal mean respiration coefficient of the first,second or third leaf from the top was(0.638±0.072),(0.678±0.082),(0.642±0.076)mg·g^(-1)·d^(-1),respectively.There were no significant(p>0.05)differences in the seasonal mean leaf respiration and respiration coefficient between the first,second or third leaf from the top.There were significant(p<0.05)differences in the seasonal patterns between the different vegetation indexes.The relatively high RVI,EVI,PRI and RECI appeared mid-growth stages.The seasonal patterns of RVI,EVI,PRI and RECI showed a single unimodal curve.The SPAD value,fresh mass,dried mass and leaf area decreased with the decrease in leaf position except for at the beginning growth stages.The leaf water content decreased with the growth of leaf growth.The respiration of a single leaf was highly significantly(p<0.01)correlated with the RECI and nitrogen content.The respiration of a single leaf was significantly(p<0.05)correlated with the air temperature and PRI.A model based on these four factors explained 60.4%of the variation in the respiration of a single leaf.The respiration coefficient was highly significantly(p<0.01)correlated with thedried mass and specific leaf area.The respiration coefficient was significantly(p<0.01)correlated with the air temperature and SPAD.A model based on these four factors explained 72.4%of the variation in the respiration coefficient.The present study showed that the leaf respiration of soybean could be linked with the hyperspectral vegetation indexes and the leaf characteristics.The seasonal variations in the leaf respiration and leaf respiration coefficient in the different positions could be effectively modeled with the hyperspectral vegetation indexes.