Retail environments for marketing floriculture crops have a wide range of light levels and temperature. One common characteristic is that irrigation is almost never optimum as a result of untrained personnel or understaffing. Watering practices at retail venues may be indiscriminate, i.e., all plants are watered on the same time schedule regardless of their need resulting in some plants being overwatered and some underwatered. Conversely, watering may be limited, i.e., plants are allowed to wilt before they are watered. Either watering regimen is detrimental to plant health and hastens their decline in postharvest quality and shelf life at the retail level.
Hardening off, or toning, at the end of the greenhouse production cycle by reducing fertilizer rate, temperature, light intensity, and soil moisture levels is a practice that has long been known to increase shelf life of floriculture crops such as chrysanthemum (Chrysanthemum indicum), poinsettia (Euphorbia pulcherrima), and other bedding plants (Jones, 2002). Reduced end-of-production fertilization resulted in higher quality ratings for an additional week for bracteantha (Bracteantha bracteata), nemesia (Nemesia ×hybrida), and sutera (Sutera hybrida) and extended flower retention for two argyanthemum (Argyranthemum frutescens ‘Comet White’ and ‘Sunlight’) cultivars during simulated retail (Beach et al., 2009).
Reducing irrigation volume during the entire greenhouse production cycle rather than only at the end of production may serve to acclimate floriculture crops to drought stress during marketing. For example, when irrigation was withheld in salvia (Salvia splendens) and vinca (Catharanthus roseus) until wilting for two consecutive drying cycles, both species had a higher water use efficiency (WUE) during the second drying cycle compared with the first, indicating a physiological acclimation of the plants (Nemali and van Iersel, 2004). By comparing four water levels applied throughout production of two cultivars of potted miniature roses (Rosa ×hybrida ‘Charming’ and ‘Bianca Parade’), it was found plants were better able to survive periods of inadequate water during postproduction when water consumption was lower during production (Williams et al., 2000). Rose plants watered at the highest water level had higher water contents but tended to wilt sooner than plants grown with reduced water.
Petunias (Petunia ×hybrida) grown at three irrigation frequencies during production and then evaluated in three postproduction temperatures (10/10, 20/20, or 30/20 °C day/night) declined in quality most rapidly and had the greatest number of senesced flowers in the moderate and warm postproduction environments when they had been irrigated at the highest frequency. Conversely, plants irrigated less frequently had slower flower development but had reduced number of senesced flowers, greater dry weight, and an overall better visual quality regardless of postproduction temperature to plants irrigated more frequently (Armitage and Kowalski, 1983).
Greenhouse irrigation systems have become more efficient in water conservation while still maintaining floriculture crop quality. Constant SMC was reliably maintained for impatiens (Impatiens walleriana), petunia, salvia, and vinca for an extended period of time despite varying plant sizes with little to no runoff and wastage of water (Nemali and van Iersel, 2006). By maintaining SMC, the irrigation system effectively replaced the water that was lost by evapotranspiration, thus creating a plant-driven system (Burnett and van Iersel, 2008). This type of irrigation system could make it easier for growers to limit water during production to only that needed by the plant to maintain quality and plant health that is sustainable throughout the market channels.
The objective of the present research was to determine the effect of four levels of constant SMC during greenhouse production followed by one of two postproduction irrigation regimens during simulated retail: 1) indiscriminate (all plants watered the same); or 2) limited (plants allowed to wilt before watering) on growth and subsequent shelf life of angelonia (Angelonia angustifolia) ‘Angelface Blue’. Our hypothesis was that lower, constant SMC during greenhouse production would acclimate or “condition” plants for the two simulated retail watering regimens while conserving irrigation, fertilization, and plant quality during production and marketing.
Álvarez, S., Navarro, A., Bañón, S. & Sánchez-Blanco, M.J. 2009 Regulated deficit irrigation in potted Dianthus plants: Effects of severe and moderate water stress on growth and physiological responses Sci. Hort. 122 579 585
Armitage, A.M. & Kowalski, T. 1983 Effect of irrigation frequency during greenhouse production on the postproduction quality of Petunia hybrida Vilm J. Amer. Soc. Hort. Sci. 108 118 121
Beach, S.E., Starman, T.W., Eixmann, K.L., Pemberton, H.B. & Heinz, K.M. 2009 Reduced end-of-production fertilization rate increased postproduction shelf life of containerized vegetative annuals HortTechnology 19 158 167
Burnett, E. & van Iersel, M. 2008 Morphology and irrigation efficiency of Gaura lindheimeri grown with capacitance sensor-controlled irrigation HortScience 43 1555 1560
Eakes, D.J., Wright, R.D. & Seiler, J.R. 1991 Moisture stress conditioning effects on Salvia splendens ‘Bonfire’ J. Amer. Soc. Hort. Sci. 116 716 719
Hansen, C.W., Petersen, K.K. & Larsen, A.K. 2005 Effects of reduced nutrient and water availability on plant growth and post-production quality of Hibiscus rosa-sinensis Acta Hort. 669 269 274
Jones, M.L. 2002 Postproduction care and handling. Ohio Florists’ Assoc. Bul. 872
Klamkowski, K. & Treder, W. 2006 Morphological and physiological responses of strawberry plants to water stress Agr. Conspec. Sci. 71 159 165
Markwell, J.M., Osterman, J.C. & Mitchell, J.L. 1995 Calibration of the Minolta SPAD-505 leaf chlorophyll meter Photosynth. Res. 46 467 472
Nell, T.A. 1993 Flowering potted plants: Prolonging shelf life performance. Ball Publishing, Batavia, IL
Nemali, S. & van Iersel, M. 2004 Moisture stress for growth control: Physiological responses of salvia (Salvia splendens) and vinca (Catharanthus roseus). SNA Res. Conf. 49:618–623
Nemali, S. & van Iersel, M. 2005 A novel automated system for irrigation and plants simulating drought stress in potted plants. SNA Res. Conf. 50:690–695
Nemali, S. & van Iersel, M. 2006 An automated system for controlling drought stress and irrigation in potted plants Sci. Hort. 110 292 297
Starman, T.W. & Lombardini, L. 2006 Growth, gas exchange, and chlorophyll fluorescence of four ornamental herbaceous perennials during water deficit conditions J. Amer. Soc. Hort. Sci. 131 469 475
Williams, M.A., Rosenqvist, E. & Buchhave, M. 1999 Response of potted miniature roses (Rosa × hybrida) to reduced water availability during production J. Hort. Sci. Biotechnol. 74 301 308
Williams, M.H., Rosenqvist, E. & Buchhave, M. 2000 The effect of reducing production water availability on the post-production quality of potted miniature roses (Rosa × hybrida) Postharvest Biol. Technol. 18 143 150