Effects of CO2 Enrichment on Growth and Development of Impatiens hawkeri

Received Sep 8, 2011; Accepted Oct 31, 2011

1. Introduction

Atmospheric concentrations of greenhouse gases such as CO₂, N₂O, and CH₄ are increasing quickly since the beginning of the industrial revolution, which results in a rise in ground-level air temperatures [1–4]. These global climate changes will have produced profound effects on plant physiology and growth, structure and function of plant populations, and species distributions [2–4]. Among these factors, CO₂ is one of the raw materials of photosynthesis and has great influences on plant growth and development. The current atmospheric CO₂ concentration is about 380 μmol·mol⁻¹, which is far below the optimum concentration of plant photosynthesis [5], especially for those plants such as ornamentals grown in greenhouse where ventilation is so limited to supplement the CO₂ consumed by plant photosynthesis, thus seriously affecting the growth, development, yield, and visual value of greenhouse-grown ornamentals [6, 7].

Over the past three decades, a large number of studies have focused on the effects of CO₂ enrichment (elevated CO₂) on the growth and development of plants. Generally, plants grown at elevated CO₂ relative to those grown at ambient CO₂ often exhibit increased growth and photosynthesis, lower transpiration, inhibited respiration, improved water use efficiency, decreased mineral nutrient concentrations, increased plant hormones contents, reduced stomatal density and conductance, and so forth [8–11]. However, most of these studies are focused on trees, steppe plants, crop plants, and greenhouse-grown vegetables, but substantial knowledge about potential influences of CO₂ enrichment on greenhouse-grown ornamentals is lacking [12]. Besides, available studies on greenhouse-grown ornamentals are usually focused on the morphology, photosynthesis, yield, and visual value of plants [7], few of them have investigated the impacts of CO₂ enrichment on antioxidant enzyme system and leaf ultrastructure, which are very important for an integrative understanding of plant responses to elevated CO₂.

Impatiens hawkeri or Impatiens New Guinea is a perennial species with rich colors and long flowering period, which has become a popular and important potted flowering plant throughout the world in recent years [13]. According to our knowledge, a study concentrating on the responses of Impatiens New Guinea to CO₂ enrichment has not been...

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