2007 Annual Report 1a.Objectives (from AD-416) A current problem facing greenhouse growers is distorted terminal growth of pansy, petunia, and gerbera plugs. The problem is thought to be either a boron or calcium deficiency. The occurrence and severity of the problem can vary: from year to year; within a particular period of the season; by stage of plant development; environmental conditions; by geographical; and by cultivar. This research will investigate the mechanisms leading to this problem in pansy, petunia, and gerbera plugs, determine the best management practices to avoid the problem, determine critical tissue levels in plants exhibiting deficiency symptoms, and establish optimal sampling methods to use for measuring boron and calcium levels in tissue. In addition, research will be conducted to determine the symptomology of nutrient deficiencies in floriculture crops including gerbera, cyclamen, and hydrangea. This will aid growers in diagnosing plant problems. 1b.Approach (from AD-416) The current hypothesis is that environmental conditions are a primary component needing investigation in order to determine and correct the cause of distorted growth of the plugs. In addition, a thorough investigation will also require determining the extent in which nutritional factors influence boron and calcium availability. Therefore a number of experiments are proposed. 1) Induce symptoms of boron and calcium deficiency hydroponically for gerbera, pansies, and petunias. 2) Determine the effect of pH on the induction of B deficiency. 3) Determine the effect of changing the bulk density of the substrate on plug B and Ca uptake. 4) Determine the effect of relative humidity on B and Ca uptake. 5) Determine the effect of induced drought stress on plugs and the B and Ca uptake. 6) Determine the effect of calcium interacting with B availability. 7) Determine the effects of leaf temperature and relative humidity on B and Ca uptake. 8) Determine the symptomology of nutrient deficiencies on plant growth and development 3.Progress Report This report documents research conducted under a Specific Cooperative Agreement between ARS and North Carolina State Universityr. Additional details of the research can be found in the report for the parent project 3607-21000-011-00D Develop Improved Technologies for Soilless Greenhouse Plant Production to Minimize Water, Labor, Agrochemical Inputs and Environmental Impacts. An automated irrigation system to conduct the nutrient disorder experiments was built. In this system, the plants are grown with silica sand instead of with a totally hydroponic system. In October 2006, the initial plant species, cyclamen, were installed into the experimental unit. This experiment required five months to complete due to the slow growth of the cyclamen plants and was terminated on March 1, 2007. Disorder symptoms were recorded as they occurred and photographed (Figure 2). Cyclamen plants appear to be very sensitive to iron (Fe) and nitrogen (N) deficiencies based on the relative speed of the onset of symptoms. Plants were moderately sensitive to phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), calcium (Ca), zinc (Zn), and boron (B) deficiencies. Symptoms of the micronutrients copper (Cu) and manganese (Mn) did not appear, which might be due to sufficient nutrient reserves being present in the corm of the seedlings. Tissue analysis will follow. These accomplishments address NP-305, Component I, Problem Statement C. The ADODR monitored activities regularly through telephone conferences and interacted through the exchange of plant tissues for analysis.