CONTROLLING VEGETABLE TRANSPLANT HEIGHT USING OSMOTICALLY ACTIVE COMPOUNDS
Controlling height of bedding plants enables successful marketing over a longer period of time. Compact vegetable transplants usually establish easier with less shock and are more productive as mature plants. Chemical growth inhibitors maintain bedding plant height for commercial sale, although some have long lasting effects, reducing growth well after transplanting. Natural compounds are needed for controlling plant height for organic production. Dilute osmotic solutions were investigated for their ability to temporarily slow growth of tomato (Lycopersicum esculentum) and kale (Brassica oleracea Acephala Group) plants grown one seedling per cell in trays filled with soilless growing mix. Starting 7 to 10 d (two-true-leaf stage) after emergence, seedlings received weekly treatments with 50 ml per cell of 0, 25, 50, or 75 mM sucrose or a single treatment with 50 mM sucrose and water thereafter. Other treatments included weekly 50 ml of polyethylene glycol 8000 (-5.3 bar) or a 2% beeswax extract solution (-3.5 bar). Seedlings were uniformly sprinkler irrigated by hand or with an automated watering system. Polyethylene glycol solutions increased both tomato and kale plant height. Beeswax reduced tomato transplant height but had no effect on kale. Sucrose inhibited kale height but not tomato. Although some results were promising, managed osmotic stress must be further tested using different types of osmotica, varied growing conditions, and more species.
Faltenovich, S. and Welbaum, G.E. (2008). CONTROLLING VEGETABLE TRANSPLANT HEIGHT USING OSMOTICALLY ACTIVE COMPOUNDS. Acta Hortic. 782, 293-298
bedding plants, tomato, kale, water stress, organic transplants