Abstract
Greenhouse production of vegetables is widely used throughout the world. Elevated carbon dioxide (CO2) concentrations in these closed environments can increase net photosynthesis and yield. The objective of this study was to determine the effects of atmospheric CO2 enrichment and water supply on the growth of potted bell pepper (Capsicum annuum L.) plants, cultivated under controlled environmental conditions. CO2 was applied daily, and its distribution was monitored above plant rows through micro pipes located at 3.0 m height. A drip irrigation system with one dripper per plant was used to irrigate the plants. Different volumes of irrigation water, representing fractions of the water volume (Vet) consumed by pot plants growing under no water stress conditions (0.5Vet, 0.65Vet, 1.0Vet, and 1.35Vet) with four replications, were evaluated under four different CO2 levels (atmospheric concentration of 367, 600, 800, and 1000 mumol mol-1). Total fresh fruit mass, average number of fruits, and water use efficiency were recorded. For the water deficit treatments, the greatest fresh fruit mass was obtained for the highest CO2 level environment. However, for treatments that received water volumes equal or greater than the evapotranspiration rate, the greatest total fresh fruit mass was observed at the 600 mumol mol-1 of CO2 environment. The yield increase due to CO2 was represented by increase in fruit weight and not in fruit number. Water use efficiency increased in relation to the amount of water applied and it was highest at 600 mumol mol-1 CO2 concentration.
Highlights
The use of carbon dioxide to enrich the atmosphere in greenhouses has been studied since the beginning of the 20th century
Total fresh fruit Total fresh fruit mass increased as water volume applied increased and when CO concentration 2 increased (Table 1)
For the two lowest water volumes applied, there was no difference at the 5% level in relation to the total fresh fruit mass between the C4 and C2 environments
Summary
The use of carbon dioxide to enrich the atmosphere in greenhouses has been studied since the beginning of the 20th century. According to Schaffer et al (1999), due to the global carbon dioxide emissions, the atmospheric CO concentration is expected to reach. This level will affect agriculture in a near future. Due to higher net assimilation rate, atmospheric CO enrichment, in most 2 cases, increases biomass production mainly for C plants. Photosynthetic efficiency is affected by air temperature, and there is an optimum temperature range for each species. Temperatures above this optimum cause a rapid reduction of the photosynthesis process
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