Water conservation in nursery systems is an ever-increasing focus, yet there is relatively little guidance for growers producing seedlings intended for restoration regarding how practices such as subirrigation influence plant growth in the nursery and after outplanting. Our study investigated red-flowering currant (Ribes sanguineum Pursh) seedling development and early field performance using different fertilizer treatments under a subirrigation regime. Plants were fertilized with 1) incorporated organic fertilizer, 2) incorporated controlled-release fertilizer, 3) top-dressed controlled-release fertilizer, or 4) water-soluble fertilizer. We found that seedlings grown with organic fertilizer used significantly less water than all other treatments. Media electrical conductivity (EC) levels were significantly greater in the organic fertilizer treatment, and EC values in the top portion of the media were significantly greater than the middle or bottom portions for all fertilizer treatments. The remaining subirrigation water at the end of 22 weeks held 17% of applied nitrogen (N) from the water-soluble fertilizer treatment and less than 1% of applied N from the other fertilizer treatments. We observed no differences in plant morphology among fertilizer treatments. Seedlings were subsequently out-planted into low- and high-competition treatments, where myriad factors indicated reduced growth among high-competition compared with low-competition plots, highlighting that competition for soil water limited seedling performance. These results indicate that a variety of fertilizers can be used to grow red-flowering currant under subirrigation and that postplanting growth is enhanced with control of competing vegetation.
Layla J. Dunlap, Jeremiah R. Pinto and Anthony S. Davis
R. Kasten Dumroese, Jasmine L. Williams, Jeremiah R. Pinto and Peng Zhang
Our objective was to evaluate oxyfluorfen for control of birdseye pearlwort (Sagina procumbens L.) in a bareroot nursery crop of western larch (Larix occidentalis Nutt.) seedlings. Oxyfluorfen applied at rates up to 0.56 kg a.i./ha in a split-plot experiment with combinations and frequencies of pre- and postemergence sprays gave minimal control of birdseye pearlwort. Although preemergence rates 0.42 kg a.i./ha or greater reduced western larch emergence 10% compared with the control, final seedling inventory was similar for rates 0.42 kg a.i./ha or less. Seedlings receiving 0.42 kg a.i./ha or greater grew 30% more biomass than those that received 0.28 kg a.i./ha or less. When applied postemergence, oxyfluorfen reduced the number of larch seedlings at final inventory 9% and those seedlings had 20% less biomass than the control. Oxyfluorfen applied preemergence increased the amount of bare soil (reduced the weed canopy) throughout the production cycle compared with the control but even the most efficacious treatment combinations still had birdseye pearlwort canopy coverage 63% or greater.
Anthony S. Davis, Matthew M. Aghai, Jeremiah R. Pinto and Kent G. Apostol
Because limitations on water used by container nurseries has become commonplace, nursery growers will have to improve irrigation management. Subirrigation systems may provide an alternative to overhead irrigation systems by mitigating groundwater pollution and excessive water consumption. Seedling growth, gas exchange, leaf nitrogen (N) content, and water use were compared between overhead irrigation and subirrigation systems used to produce trembling aspen (Populus tremuloides Michx.) seedlings. After 3 months of nursery culture, subirrigation resulted in a 45% reduction in water use compared with overhead irrigation. At the end of the growing season, subirrigated seedlings had lower net photosynthetic assimilation, stomatal conductance (g S), and leaf area, indicating earlier leaf senescence. However, no significant differences were detected for biomass, leaf N content, height, root-collar diameter, or root volume. Thus, we suggest that subirrigation systems offer promising potential for aspen seedling production when compared with overhead irrigation given the added benefits of water conservation and reduced nutrient runoff. Continuing emphasis on refinement such as determining the plant water requirements based on growth and development as well as container configuration is needed so that the intended benefits of using subirrigation can be realized.