2022-2025 SCBG-UK-Vegetable Nutrient Disorders: Characterizing Nutrient Disorders and Developing a Multi-access Compendium for Vegetable Transplants

In 2019, commercial vegetable and bedding plant growers producing young vegetable transplants for commercial sales and open field production, consumer gardens, and protected culture (controlled environments) represented 48% (162) of all Kentucky horticulture specialty operations (337) with a combined value and production area of $5.9 million and 257 acres, respectively. Most often, vegetable transplants can be produced in 21 to 35 days, but quality and production time is significantly affected by propagation environmental conditions (light and temperature) and cultural practices (irrigation and fertility). Transplants are extremely susceptible to macro- and micronutrient deficiencies and/or toxicities. Nutrient disorders can manifest rapidly (~3 to 7 days) during transplant production and are often observed as stunted and/or distorted growth; chlorosis (yellowing), interveinal chlorosis, and necrosis (death) of plant parts; and/or overall plant loss. Laboratory analysis of plant tissue is the primary method to quantify nutrient concentrations of at least 11 essential elements. Most plant nutrient analysis reports provide general or sufficiency ranges, which are not often species-specific. Growers must turn to published literature to determine if nutritional concentrations are sufficient or critical (deficient or toxic). However, only 4% (6 of 146) of vegetable plants listed in Bryson and Mills (2014) plant analysis handbook, containing the largest collection of nutritional leaf tissue values, were listed as transplants and are survey measurements. These reported values are not reliable; for instance, Veazie et al. (2020) characterized nutrient disorders of bok choy (Brassica rapa var. chinensis) transplants and found critical leaf tissue values of all 11 nutrient concentrations to be within the optimal survey range reported by Bryson and Mills (2014). Therefore, this demonstrates survey measurements do not accurately represent the nutritional status nor sufficiency ranges of vegetable transplants grown by commercial vegetable or greenhouse operations, thus research-based information is warranted. This project seeks to (1) characterize nutrient disorders of popular vegetable genera and cultivars grown in Kentucky; (2) develop a mutli-access online diagnostics key; and (3) prepare an all-in-one nutrient disorder compendium to assist growers in identifying and mitigating nutrient disorders in vegetable transplants destined for production fields, gardens, high tunnels, or greenhouses. To strengthen the Kentucky vegetable transplant industry, 7 genera will be investigated including (1) cabbage (B. oleracea), (2) eggplant (Solanum melongena), (3) lettuce (Lactuca sativa), (4) pepper (Capsicum annuum), (5) pumpkin and (6) summer squash/zucchini (Cucurbita pepo), and (7) tomato (S. lycopersicum). Cucumber (Cucumis sativus) will be characterized in a previously funded KY SCBG awarded to Owen (PI). Cultivars of each genus will be selected from an industry survey of growers and county Extension agents. Young plants will be grown in silica sand and provided with hydroponic nutrient solutions devoid of a single element, thus inducing nutrient disorders under controlled environmental research conditions. Nutritional disorder photographs and symptomology descriptions will be documented and whole plants sampled for nutrient analysis. This information and data will produce a total of 86 grower resources including 72 full color genera- and nutrient-specific guides, an online diagnostic key, and a compendium. For beginning to experienced growers and Extension personnel, trainings will be hosted to provide education of nutrient disorders, identification, corrective procedures, and to disseminate resources developer herein. Collectively, this research will benefit growers, Extension personnel, analytical labs, and researchers by characterizing nutrient disorders and establishing leaf tissue nutrient concentrations for production of high-quality healthy vegetable transplants.