ASHS 2024 Conference

In container nursery production, the potting substrate serves as the foundation of the crop, providing essential nutrients, aeration, and moisture retention. A well-chosen substrate is crucial for optimizing plant health and growth, and ultimately influences a nursery’s economic viability since substrate is estimated to be 13% of the total variable costs of 3-gallon production. Our objective is to determine the cost of common potting substrate components. The study goal is to identify opportunities for nursery producers to reduce costs and increase profits by optimizing their substrate components. Email surveys supplemented by interviews were used to collect data from six Tennessee container nursery producers. All growers were within a 117-mile radius of McMinnville, Tennessee, and provided the prices they paid in the last 12 months for the primary components of their potting substrate. Delivery fees and fuel surcharges were not considered in the cost when these expenses were itemized. However, one producer’s prices included delivery expenses. Participating nursery producers self-identified as having 100 (66.7%) acres in container production. Growers in this case study paid an average of $19.07 (SD=$5.53) per yard3 for pine bark; however, the prices ranged from $14.53 to $29.00 per yard3. In general, smaller producers paid more for pine bark. Sand ranged from $40.50 to $49.95 per yd3. Nursery producers paid $1.12 to 1.32 per pound for controlled release fertilizer (CRF), an input estimated at 5% of total variable costs. Therefore, some growers paid 18% more for CRF than others. Growers paid from $0.01 to $0.11 per pound for lime. Tennessee nursery producers were paying on average $66.79 per cubic yard for wood fiber-based substrate and vermicompost, 250% more than the average cost of pine bark but just 46% of the market price for peat. These preliminary data show 1) individual nurseries pay a range of prices for the same potting substrate components, and 2) the relatively high cost of peat replacements, i.e., wood fiber and vermicompost. The data highlight the range of prices being paid for CRF and its relative expense, underscoring the opportunity for growers to reduce costs by optimizing their use and placement of CRF. Additional research is needed to more broadly sample nurseries for these data and determine the influence of nursery size on substrate component costs. cparwutcakwt8uvpamtb

This study aimed to determine the optimal conditions of UV-B exposure for regulating the growth of tomato grafted seedling in Plant Factory with Artificial Lighting by investigating growth characteristics, rhizosphere development, and chlorophyll fluorescence of seedlings. Tomato scion and rootstock were used in the experiment. UV-B treatment timing was divided into three stages from sowing to grafting. UV-B intensities were set at 1.44, 2.88, and 5.76 kJ·m−2·d−1. Results showed that morphology of plants did not exhibit significant differences up to 2.88 kJ·m−2·d−1 for tomato scion and rootstock. However, side effects such as leaf wilting were observed at 5.76 kJ·m−2·d−1. The length of hypocotyl, which is closely related to scion and rootstock suppression of stem elongation, was shortest when treated with 5.76 kJ·m−2·d−1 during the mid-growth stage across all treatment. Interestingly, rhizosphere characteristics such as root volume, surface area, and average root diameter showed improvement trends regardless of treatment timing when exposed to UV-B at 1.44-2.88 kJ·m−2·d−1. Quality indicators of seedlings showed best when 2.88 kJ·m−2·d−1 during the late-growth stage. Comparisons of chlorophyll fluorescence parameters revealed no significant effects of UV-B treatment on cucumber seedlings and grafting except for PIABS. However, tomato seedlings and grafting exhibited significantly reduced FV/FM and DIO/RC at late-growth stage when exposed to 5.76 kJ·m−2·d−1. Therefore, it is concluded that utilizing UV-B in the range of 1.44-2.88 kJ·m−2·d−1 during cucumber and tomato scion and rootstock production in Plant Factory with Artificial Lighting could minimize plant damage while expecting to suppress grafting effects.

Ceanothus velutinus, commonly known as snowbrush ceanothus, is a nitrogen-fixing species native to North America. It plays a vital role in ecosystem by improving soil fertility through nodulation, a symbiotic process with bacteria that fixes atmospheric nitrogen. The purpose of this study was to identify the effects of various nitrogen concentrations on the nodulation and plant morphological and physiological responses. Ceanothus velutinus seedlings were transplanted in calcined clay and inoculated with 30 mL of soil containing Frankia. Seedlings were treated with 0.0 to 8.4 g·L-1 of controlled released fertilizer (CRF, 15N-3.9P-10K) or a nitrogen-free nutrient solution supplemented with or without 2mM ammonium nitrate (NH4NO3). Plant growth and photosynthesis increased linearly or quadratically along with the increasing CRF application rates with a notable increase observed at 4.2 g of CRF. Nodules were observed only in plants receiving 0.0, 0.3, 0.5, 1.1, or 2.1 g of CRF. However, the number of nodules formed in the treatments was too small to analyze statistically. The study indicates that while CRF significantly boosts C. velutinus growth, nodulation and nitrogen fixing capacity of the plant remains unknown. Further investigation is needed to determine the effect of nitrogen on the nodulation of C. velutinus using peat-based soilless substrate.