Control of transplant height in tomato using plant growth regulator prohexadione calcium

Abstract

The role of plant growth regulators has become important in modulating physiological responses that will eventually lead to producing high quality seedlings. The objective of the current experiment was to investigate the effects of prohexadione-calcium (Pro-Ca) concentrations (0, 25, 50, 75, and 100 mg L-1) and application methods (foliar spray and soil drench), on growth and quality of tomato (Lycopersicon esculentum Mill. 'BT H2274') transplants. Plant growth measurements of the 5-week-old tomato transplants included transplant height, internode length, stem diameter, number of true leaves, leaf area, root length, shoot fresh and dry weights, root fresh and dry weights, and relative leaf chlorophyll content. Application of Pro-Ca caused an immediate vegetative growth reduction, most dramatically demonstrated by a reduction in transplant height (up to 60%) and internode length (up to 52%), compared with the control treatment. There were significant differences in tomato transplant height in response to application methods and Pro-Ca concentrations. The soil drench application method resulted in shorter tomato transplants up to 27% compared to the foliar spray. These results indicate that lower Pro-Ca concentrations (25 and 50 mg L-1) can be used to control excessive elongation growth and to produce short tomato transplants. The higher application rates may provide excessive suppression in growth which may lead to a delay in flowering and harvesting. © 2020 International Society for Horticultural Science. All rights reserved.