Estimating Daily Water Use of Two Petunia Cultivars Based on Plant and Environmental Factors

Abstract

<jats:p>Many ornamental plant growers water excessively to reduce the risk of drought stress. Scheduling irrigation in greenhouses is challenging because there is little quantitative information about ornamental plant water requirements and how water use changes when plants are grown in varying greenhouse environmental conditions. Models to estimate the daily water use (DWU) of greenhouse crops may provide a useful tool to conserve irrigation water. Our objective was to develop a model to predict DWU based on plant age and easily acquirable environmental data. Two petunia (<jats:italic>Petunia</jats:italic> ×<jats:italic>hybrida</jats:italic>) cultivars, Single Dreams Pink and Prostrate Easy Wave Pink, were grown in different sized containers (diameter = 10, 12.5, and 15 cm) to quantify their DWU for 6 weeks. The substrate water content (θ, v/v) was maintained at 0.40 m<jats:sup>3</jats:sup>·m<jats:sup>−3</jats:sup> using an automated irrigation system with capacitance soil moisture sensors. Every irrigation event was recorded by a data logger, and this information was used to calculate the DWU of the plants. On overcast days early in the experiment, plants used only 4.8 to 13.8 mL·d<jats:sup>−1</jats:sup>. The maximum DWU of ‘Single Dreams Pink’ was 63, 96, and 109 mL·d<jats:sup>−1</jats:sup> in 10-, 12.5-, and 15-cm containers, respectively. Late in the experiment, ‘Prostrate Easy Wave Pink’ petunia used more water than ‘Single Dreams Pink’ because of their more vigorous growth habit. DWU was modeled as a function of days after planting (DAP), daily light integral (DLI), vapor pressure deficit (VPD), temperature, container size, and interactions between these factors and DAP (<jats:italic>R</jats:italic><jats:sup>2</jats:sup> = 0.93 and 0.91 for ‘Single Dreams Pink’ and ‘Prostrate Easy Wave Pink’, respectively). Days after planting and container size were the most important factors affecting DWU and are indicative of plant size. Daily light integral was the most important environmental factor affecting DWU. These models, describing the DWU as a function of the DAP and environmental conditions, may be used as guidelines for accurately watering petunias in greenhouses and may improve irrigation scheduling.</jats:p>

Influence of Substrate Water Content and Daily Light Integral on Photosynthesis, Water Use Efficiency, and Morphology of Heuchera americana

“…This corroborates the findings of van Iersel et al (2010), who observed that daily fluctuations in irrigation demand were strongly correlated with DLI. Kim et al (2011) found that DLI was the most important environmental factor in predicting plant water use and proposed a model for predicting daily water use in greenhouse settings based on plant age and DLI. In that study, other environmental factors such as temperature and vapor pressure deficit improved the model fit less than DLI.…”

Uptake Efficiency of Phosphorus in Different Light Environments by Zinnia (Zinnia elegans) and Vinca (Catharanthus roseus)

“…Reduction of incoming radiation and corresponding cooler conditions reduces water use in plants as well. In fact, Kim et al (2011) found that DLI was the most significant correlation with water use. Additionally, Garland et al (2012) found that DLI was strongly correlated to water use in plants, attributable in large part to larger plants and more leaf area in treatments receiving greater DLI.…”

Advancing Wireless Sensor Networks for Irrigation Management of Ornamental Crops: An Overview

“…This enables predictive feed-forward management of water use with plant and environmental water-use models. Kim et al (2011) demonstrated that the measured daily plant evapotranspiration of petunia (Petunia ·hybrida) can be precisely modeled in greenhouse production with measurements of crop growth (days after planting, daily light integral, vapor pressure deficit, and air temperature). Kim and van Iersel's empirical modeling approach demonstrates the sensitivity of plant water use to these four easily measured variables.…”