Incorporation of specific vitamins such as thiamin to the rooting media has been reported to stimulate root and shoot growth. Thiamin is involved in the Kreps cycle decarboxylation of pyruvate to citrate as a coenzyme in the pyruvate decarboxylase enzyme complex. Axenic and soil glasshouse studies were conducted to determine the tissue nutrient concentrations (ICP analysis), especially Ca, in response to low application rates of thiamin. In a 50 d axenic “Grand Rapids” lettuce study, thiamin (5 mg mL-1 0.5 N Hoagland's) stimulated shoot length (25%), root length (23%), Ca (8%), K (14%), and P uptake (18%) compared with control values (no thiamin added). Soil glasshouse “Grand Rapids” lettuce studies showed that thiamin (6 mg kg-1 soil) stimulated N (72%), Ca (58%). K (12%), and P uptake (11%) compared with control values. Additional glasshouse-soil-thiamin form studies with “Black seeded Simpson” lettuce (20 mg each form kg-i soil) showed thiamin compounds increased Ca tissue levels from 3 to 10% and organic C content from 5 to 30%. The prospect of using these compounds to reduce tipburn in lettuce is being investigated in follow-up studies.
If the inline PDF is not rendering correctly, you can download the PDF file here.