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Limited information exists for container production of red maple cultivars. The objective of this study was to evaluate first-year growth of container-grown `October Glory' at 3 locations with disparate climates in Georgia and Alabama (Tifton, Ga., Blairsville, Ga., and Auburn, Ala.). Rooted cuttings were planted in 9.2-L containers in one location in the same substrate in April 1995. Trees were transported to each location in mid-June and irrigated from overhead risers at 1.3 cm/day for 6 months until dormant, then transported to a single location for harvest. Despite weather differences among locations, final heights were not different (Blairsville 59.8 cm; Auburn 53.0 cm; and Tifton 60.2 cm). Shoot diameter increase and shoot dry weight was greatest at Tifton (8.4 mm, 17.5 g), least at Blairsville (6.3 mm, 9.2 g), with Auburn similar to both locations (6.8 mm, 12.2 g). Root dry weight and root: shoot ratio was greater in Tifton (17.2 g, 0.97) than Blairsville 14.9 g, 0.51) and Auburn (7.0 g, 0.64).
A 2001 survey of 102 nurseries that were members of the Georgia Green Industry Association was conducted to assess irrigation practices of container ornamental nurseries. Mean nursery size was 64 acres (26 ha) and mean annual revenue was about $3 million. About 50% of the irrigation water was from wells and the other 50% came from surface sources, such as collection basins. Irrigation in smaller containers, including #1, #3, and #5, was applied primarily by overhead methods, while larger containers (#7, #15, #25) made extensive use of direct application methods, such as drip or spray stakes. Frequency of irrigation in the summer growing months was about three times that of the winter season. Georgia nurseries use irrigation practices suggested in Southern Nursery Association best management practices, including collection of runoff water (48%), cyclic irrigation (44%), watering in the morning (92%), and grass strips between the production beds and drainage areas (60%).
On 1 May 2004, a 4 × 2 split-plot experiment was initiated in Athens, Ga., on Rhododendron ×kurume `Pink Pearl'. The four main-plot treatments were low irradiance, low irradiance May–October, low irradiance November–May, and high irradiance (high and low correspond to average daily PPF of 23.6 and 10.4 mol·m-2·d-1). The two subplot fall fertigation treatments were 75 mg·L-1 of nitrogen (N) and 125 mg·L-1 N. Plant stem tissue was harvested monthly from November to March, and analyzed for freeze resistance (LT50). Maximum quantum efficiency of PSII (Fv/Fm) was analyzed monthly with a Mini-pam photosynthesis yield analyzer. No interactions existed between fertilizer application and light intensity and the 125 mg·L-1 N fertilizer treatment reduced freeze resistance of azalea stems throughout the study. Fall fertilization had no effect on fluorescence and no interactions existed between fertilizer and irradiance treatments. In November, plants that received low irradiance May–October were less freeze-resistant than plants from the high-irradiance treatment. However, in January, plants that received low irradiance throughout the study were more freeze-resistant than plants that received the high-irradiance treatment. In November, Fv/Fm was higher in the low irradiance and low irradiance November–May treatments. In February and March, Fv/Fm was lower in the low May–November treatment that received low irradiance during summer than the low November–May treatment that received low winter irradiance. The use of shade to reduce irradiance may delay the acquisition of freeze resistance in fall. However, shade may reduce photosystem damage and increase a plants ability to acquire and maintain greater freeze resistance.
The Southern Extension and Research Activities/Information Exchange Group-27 (SERA/IEG-27) is sponsored by the Southern Association of Agricultural Experiment Station Directors. Thirteen universities and the U.S. National Arboretum cooperate with official representatives from extension and research programs. The objective of the group is to identify, evaluate, select, and disseminate information on superior, environmentally sustainable, landscape plants for nursery crop production and landscape systems in the southeastern U.S. Plants are distributed to members responding to a request from cooperators for plant evaluation. Those who agree to cooperate are expected to grow the selected liner to landscape size, then transplant it in a landscape setting. The plant is rated for insect, disease, and cold damage, heat stress, growth rate, ornamental flowering and fruiting, fall color, commercial production potential, landscape potential, invasiveness potential, and insect disease transmission potential. Growth rate is evaluated annually by recording plant height and width. Initial bloom date is reported followed by bloom duration in days. Following evaluation, the group collectively and individually disseminates information gained from the plant evaluation system to a wide variety of audiences.
Increasing environmental concerns and legislation in many states and in other countries require that we take a more comprehensive sustainable “best management” approach to production techniques in nursery and greenhouse operations. This is particularly important because these production facilities are typically intense users of resources that are applied to relatively small land areas. We have developed an online knowledge center to facilitate the implementation of more sustainable practices within the nursery and greenhouse industry. A web-based knowledge center provides the most cost-effective mechanism for information delivery, as our potential audiences are extremely diverse and widespread. We currently have a registered user database of over 450 educators, growers, and industry professionals, and undergraduate and graduate students. A gateway website provides an overview of the issues and the goals of the project. The associated knowledge center currently has 25 in-depth learning modules, designed in a Moodle learning management framework. These learning modules are designed to actively engage learners in topics on substrate, irrigation, surface water, and nutrient and crop health management, which are integral to formulating farm-specific strategies for more sustainable water and nutrient management practices. Additional modules provide assessment and implementation tools for irrigation audits, irrigation methods and technologies, and water and nutrient management planning. The instructional design of the learning modules was paramount because there can be multiple strategies to improve site-specific production practices, which often require an integration of knowledge from engineering, plant science, and plant pathology disciplines. The assessment and review of current practices, and the decision to change a practice, are often not linear, nor simple. All modules were designed with this process in mind, and include numerous resources [pictures, diagrams, case studies, and assessment tools (e.g., spreadsheets and example calculations)] to enable the learner to fully understand all of the options available and to think critically about his/her decisions. Sixteen of the modules were used to teach an intensive 400-level “Principles of Water and Nutrient Management” course at the University of Maryland during Spring 2008 and 2009. The water and nutrient management planning module also supports the nursery and greenhouse Farmer Training Certification program in Maryland. The Maryland Department of Agriculture provides continuing education credits for all consultants and growers who register and complete any module in the knowledge center. Although these learning resources were developed by faculty in the eastern region of the United States, much of the information is applicable to more widespread audiences.