Irrigation Frequency during Container Production Alters Rhododendron Growth, Nutrient Uptake, and Flowering after Transplanting into a Landscape

Abstract

<jats:p>One deciduous cultivar of <jats:italic>Rhododendron</jats:italic> L., Gibraltar (AZ), and two evergreen cultivars, P.J.M. Compact (PJM) and English Roseum (ER), were grown in containers for 1 year to determine the effects of irrigation frequency during container production on plant performance the next spring when the plants were transplanted into the landscape. While in the containers, each cultivar was irrigated once or twice daily, using the same amount of water per day, and fertilized with complete nutrient solutions containing 0, 35, 70, or 140 mg·L<jats:sup>−1</jats:sup> nitrogen (N). Three months after transplanting into the landscape, nutrient uptake, growth, and flowering were evaluated. In general, the effects of irrigation frequency in containers on performance in the landscape differed between the deciduous cultivar and the evergreen cultivars. In AZ, less frequent irrigation in containers had a pre-conditioning effect that resulted in greater vegetative growth in the landscape but less reproductive growth. In contrast, less frequent irrigation reduced vegetative growth of evergreen cultivars in the landscape and improved flowering. Different growth responses to irrigation frequency between deciduous and evergreen cultivars appeared to be related to differences in timing of nutrient uptake and mobilization. In the deciduous cultivar, less frequent irrigation increased nutrient reserves and improved the ability of the plants to absorb and use nutrients after transplanting, but in the evergreen cultivars, it generally decreased nutrient uptake after transplanting. Less frequent irrigation also altered plant attributes that are important to consumers, including developing a sparser canopy in ER and a fuller canopy in PJM, and producing more but smaller inflorescences in both cultivars. Landscape performance was related to plant nutrition in containers; however, irrigation frequency in containers disrupted relationships between nutrition and performance in all three cultivars. Our results indicate that irrigation frequency during container production of <jats:italic>Rhododendron</jats:italic> results in a tradeoff between vegetative and reproductive growth the next spring when the plants are in the landscape.</jats:p>

Nitrogen Rate, Irrigation Frequency and Volume Differentially Influence Growth, Flowering, and Nutrient Uptake of Container-Grown Rhododendron during the Following Growing Season

“…Improved growth in the first year was also associated with greater concentrations of several nutrients other than N, indicating that better N status in container production enhances the ability of plants to absorb other nutrients. Similar results were found in previous studies on Rhododendron [20,28]. In the current study, the effects of the N rate on plant nutrient status in containers were positively correlated with plant growth and nutrient uptake the following year, suggesting that nutrient status was a primary driver of improved plant performance after transplanting.…”

“…Irrigation that allows substrates to dry to 40-75% of container capacity (CC) can produce plants of acceptable consumer quality [7,[24][25][26]. Although with some species, drought treatments during nursery production can increase nutrient accumulation [23], others report that decreasing irrigation may negatively influence plant nutrient reserves that are essential for growth the following year [27,28]. There is little information on how limiting water during container production of Rhododendron alters plant nutrition and subsequent long-term plant performance once the plants leave the nursery.…”

“…Irrigation frequency alters the uptake and transfer of water from roots to shoots by altering biomass allocation (root-to-shoot ratios) and stem structure (shoot xylem:leaf area ratios) [23,29]. More frequent irrigation in containers can also improve nutrient use efficiency and net uptake of several nutrients, even when altering irrigation has little influence on plant biomass, and can alter performance (nutrient uptake and flowering) after the plants are transplanted into the landscape [28]; however, little is known about how irrigation frequency alters the performance of Rhododendron after transplanting.…”

Daily irrigation attenuates xylem abscisic acid concentration and increases leaf water potential of Pelargonium × hortorum compared with infrequent irrigation

“…These strategies involve delaying the application of water, typically in an attempt to reduce plant transpiration, limit excessive water losses by evaporation from the soil surface or through leaching below the crop root zone, and to regulate water inputs in situations where growers over-irrigate plants (Wang et al 2001). As relatively few studies have investigated the effects of different irrigation frequencies applied at the same irrigation volume (but see Ertek et al 2004, Abalos et al 2014, Scagel et al 2014, there is a limited understanding of the physiological impacts of irrigation frequency, which may limit accurate implementation of this technique.…”

Effects of continuous versus pulsed drought stress on physiology and growth of wheat

“…However, effects of irrigation frequency on field plant performance can depend on the cultivar (Scagel et al . ). These results indicate that irrigation volume and frequency need to be considered in parallel in studies of drought effects on plant resource allocation and biomass production.…”