Comparison of photosynthetic rates, transpiration rates, and total conductance of greenhouse-grown tomato plants measured with two open chambers with different ventilation rates

Abstract

A real-time monitoring system was developed and applied to monitor the time course of photosynthesis and transpiration in fully-grown tomato plants in a semi-commercial greenhouse. The system was based on an open chamber method in which the ventilator airflow rate is an important parameter affecting the environmental factors in the chamber and physiological response of plants enclosed inside the chamber. So, we assumed that the effects of this parameter on these responses should be evaluated for an agricultural production site. In this study, we investigated differences in the environmental factors in the chamber and physiological response of whole-tomato plants obtained from two chambers) implemented with a single ventilator (SV, 0.36 m 3 min -1) or double ventilators (DV, 0.72 m 3 min -1 ). The relative humidity and vapor pressure deficit inside the SV chamber were about 10% higher and 0.5 kPa lower than those inside the DV chamber because of the difference in air exchange rates. However, we found no significant effect of airflow rate on net photosynthetic rate, transpiration rate and total conductance of the plants in the SV and DV chambers by analyzing with weighted Deming regression. This simultaneous monitoring method, undertaken in multiple chambers, and weighted Deming regression analysis can be used to check whether measurement conditions are appropriate for on-site monitoring.

Using a Real-Time Photosynthesis and Transpiration Monitoring System to Develop Random Forests Models for Predicting Cherry Tomato Yield in a Commercial Greenhouse

“…Real-time and high-time-resolution measurements of whole-plant photosynthetic and transpiration rates in a greenhouse have been achieved recently. Shimomoto et al (2020Shimomoto et al ( , 2021 developed the "real-time photosynthesis and transpiration monitoring system" that has an open-bottom chamber design. This system comprises a transparent openbottom enclosure made of plastic film, two ventilation fans on top of the enclosure to extract air from the inside, and two infrared gas analyzers (IRGAs) (LI-6400; LI-COR, Lincoln, USA) to measure the CO 2 and H 2 O concentrations of the inlet and outlet air simultaneously.…”