ISHS Acta Horticulturae 507: III International Workshop on Models for Plant Growth and Control of the Shoot and Root Environments in Greenhouses
USING CHLOROPHYLL FLUORESCENCE TO MODEL LEAF PHOTOSYNTHESIS IN GREENHOUSE PEPPER AND TOMATO |
| Authors: | D.H. Willits, M.M. Peet |
| Keywords: | Lycopersicon esculentum Mill., Capsicum annuum, fluorescence yield, carbon fixation, carbon assimilation |
| Abstract:
Photosynthesis and chlorophyll fluorescence yield were measured under laboratory conditions in an effort to determine the feasibility of using fluorescence to model leaf photosynthesis in tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum). The plants tested were grown in the greenhouse in pots and transported to the laboratory on the day of testing. Illumination in the laboratory was provided by high-pressure sodium lights. A portable photosynthesis system (LI-6400) was used to measure gas exchange while CO2, vapor pressure deficit between the leaf and air, and leaf temperature were varied. Chlorophyll fluorescence yield was measured simultaneously with gas exchange using a modulated fluorometer (OS-500) and fluorescence probe adapter attached to the LI-6400 cuvette. Fluorescence yield was used to calculate photosynthesis using the procedure of He and Edwards (1996, Plant, Cell and Environment 19:1272–1280). The resulting values were compared to photosynthesis determined directly from gas exchange measurements. Agreement between the two methods was very good when the actual measured conductances were used in the CO2 fixation model, and only slightly less good when the conductances were modeled. | |
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