Developing a Water-stress Index for Potted Poinsettia Production

Abstract

<jats:p>Potted poinsettia (<jats:italic>Euphorbia pulcherrima</jats:italic>) is an important commercial commodity for the U.S. floriculture industry. The production of poinsettia demands intensively managed light control, heat, fertilizer, and water; inhibiting elongation with plant growth regulators, and protecting plants from diseases and pests with pesticide applications. Excessive irrigation creates pollution, promotes disease, and is expensive. Sensor-based control systems can optimize irrigation schedules. Irrigation management is crucial in nursery production of poinsettias because water is a limited resource and agricultural runoff is monitored in many states across the United States. By pairing environmental sensors with sensors that continuously monitor plant transpiration, we can determine how plant water use and water stress fluctuate with environmental and physiological demands. We hypothesized that continual measurements of sap flow could be correlated with environmental sensors to develop a new water stress index (WSI), which can deliver the benefits of detecting water stress that might affect the quality of potted poinsettias. To test this hypothesis, rooted cuttings of poinsettia (<jats:italic>E. pulcherrima</jats:italic> cv. Prestige Red) were individually potted into twelve 11-L black plastic nursery pots. Potted plants were grown in a naturally illuminated temperature-controlled glasshouse. The 12 plants were randomly assigned one of three watering treatments: weekly, biweekly, and triweekly irrigation. From the data collected, we were able to create a WSI that correlated available soil moisture with the difference between the expected transpiration with actual transpiration rates. Our results suggest that the plants in the weekly treatment group did not experience water stress until 0.3 m<jats:sup>3</jats:sup>·m<jats:sup>–3</jats:sup> volume water content indicated by &lt;0.2 WSI. These results support previous research that found 0.1 to 0.3 m<jats:sup>3</jats:sup>·m<jats:sup>–3</jats:sup> can be stressful soil moisture conditions for greenhouse-grown crops. Results also show that for substrates with similar substrates that irrigation set points can be reduced to 0.2 m<jats:sup>3</jats:sup>·m<jats:sup>–3</jats:sup> for improved irrigation efficiency.</jats:p>

Investigating the Benefits of Tectonite Dust as an Amendment for Bark Substrates and Dryland Crops

“…This hypothesis could be validated by additional studies that incorporate soil moisture sensors into long-term growth studies. Future studies might consider integrating soil moisture sensors for long-term assessment of water holding capacity [ 20 , 21 ], as well as remote sensing of stand establishment of wheat to compare early season growth and late season density.…”

“…This hypothesis could be validated by additional studies that incorporate soil moisture sensors into longterm growth studies. Future studies might consider integrating soil moisture sensors for long-term assessment of water holding capacity [20,21], as well as remote sensing of stand establishment of wheat to compare early season growth and late season density. Some potential mechanisms, by which improve soil health and crop yields include improving soil structure, increasing nutrient availability, and enhancing water-holding capacity.…”

Biochemical, Physiological, and Molecular Aspects of Ornamental Plants Adaptation to Deficit Irrigation

“…Growth reduction is one of the first manifestations that plants are subjected to with water stress. For example, the application of water stress for one, two, or three weeks decreased the growth of poinsettia (Euphorbia pulcherrima) in terms of plant height (67.4, 57.0, and 49.0 cm, respectively) and leaf area (2.91, 1.22, and 0.93 cm 2 , respectively) [18]. In addition, Rosa damascena Mill., a rose from Damascus which is widespread all over the world for its perfume and use in cosmetics and medicine, was subjected for 90 days to 100% of field capacity (FC), moderate water stress (50% FC), and severe water stress (25% FC) [10].…”

“…For this Horticulturae 2021, 7, 107 2 of 23 purpose, genetic studies are based on breeding and genetic engineering of model plants, such as Arabidopsis thaliana [1,15,16], so that the obtained responses could be extrapolated to other crops such as staple food, medicinal, aromatic, and fiber plants. The efficient use of water is a crucial point in cultivating ornamental plants which have to respond to different needs, e.g., moderate use of natural resources, climate change, environmental pollution, increasing production costs, and maximizing profits [17,18]. Unfortunately, there is still no standard protocol for the irrigation of ornamental species, and water requirements of plants are covered based on growers' personal experience [14,19].…”

Principles and Practices of Plant-based Irrigation Management

“…SAP FLOW. Sap flow sensors have been used in many horticultural production systems to provide continuous monitoring of plant transpiration (Nackley et al, 2020;Pearsall et al, 2014;Qiu et al, 2015;Shackel et al, 1992). Sap flow methods calculate the velocity of a short pulse of heat carried by convection in the transpirational stream (Fig.…”