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ARS Home » Plains Area » Lincoln, Nebraska » Agroecosystem Management Research » Research » Publications at this Location » Publication #243754
Title: Vertical Profile and Temporal Variation of Chlorophyll in Maize Canopy: Quantitative "Crop Vigor" Indicator by Means of Reflectance-Based Techniques

Author
item CIGANDA, VERONICA - UNIVERSITY OF NEBRASKA
item GITELSON, ANATOLY - UNIVERSITY OF NEBRASKA
item SCHEPERS, JAMES - RETIRED ARS EMPLOYEE

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2008
Publication Date: 9/8/2008
Citation: Ciganda, V.S., Gitelson, A., Schepers, J.S. 2008. Vertical Profile and Temporal Variation of Chlorophyll in Maize Canopy: Quantitative "Crop Vigor" Indicator by Means of Reflectance-Based Techniques. Agronomy Journal. 100:1409-1417.

Interpretive Summary: Physiological status of a crop is commonly characterized through the LAI, defined as the total leaf area per unit area of ground beneath them, or the green LAI, defined as the green area of leaves per unit area of ground beneath them. These biophysical characteristics have been considered basic to growth analysis and important in current estimates of crop canopies’ potential photosynthesis. Specifically for the case of maize leaf area and the vertical leaf area profile influence the interception and utilization of solar radiation and, consequently, drive dry matter accumulation and grain yield. The objective of this study was to quantify and characterize the temporal variation of chlorophyll (Chl) content in the vertical profile le of maize canopies across a range of agronomic growing conditions using a reflectance based, nondestructive technique. Using a fast and nondestructive reflectance-based technique, more than 2000 maize leaves were measured for reflectance and total and green area during a growing season. It was possible to quantify and characterize the temporal variation in the vertical profile of maize Chl content. Vertical distributions of leaf area index (LAI), green LAI, and Chl were characterized by a bell- shaped function regardless of hybrid or crop growth stage. While similar bell-shaped distributions for green LAI have also been reported in the literature, to the best of our knowledge, this is the first report on vertical distribution of Chl in a maize canopy. The parameters and coefficients of bell-shape functions were

Technical Abstract: Chlorophyll (Chl) content is among the most important crop biophysical characteristics. Chlorophyll can be related to photosynthetic capacity, thus, productivity, developmental stage, and canopy stresses. The objective of this study was to quantify and characterize the temporal variation of Chl content in the vertical profile of maize (Zea mays L.) canopies by means of a reflectance-based, nondestructive methodology. A recently developed technique that relates leaf reflectance with leaf pigment content has been used for accurate leaf Chl estimation. The technique employs reflectance in two spectral bands: in the red edge (720–730 nm) and in the near infrared (770–800 nm). More than 2000 maize leaves were measured for reflectance and total and green area during a growing season. A bell-shaped curve showed a very good fit for the vertical distribution of Chl content regardless of crop growth stage. The parameters and coefficients of the bell-shape function were found to be very useful to interpret temporal changes in the vertical profile of each variable. Comparisons among Chl, leaf area index (LAI) and green LAI showed that Chl content was more sensitive to changes in the physiological status of maize than other biophysical characteristics. The quantification of Chl content in canopy should be seen as a useful tool to complement the information on green LAI or LAI. Its applicability will help to improve the understanding of the crop ecophysiology, productivity, the radiation use efficiency and the interplant competition.