Use of cold water for irrigation reduces stem elongation of plug-grown tomato and cabbage seedlings

Seedlings of tomato (Lycopersicon esculentnm Mill,) and cabbage (Brassica o leracea L. var. Capitata) were planted in 240-cell plug trays in the greenh ouse and subjected to irrigation with water at different temperatures once a day. Irrigation with cold (5 to 15 degrees C) water reduced stem length o f tomato by 28% to 32% in comparison with irrigation with water at room tem perature (27.5 to 30.5 degrees C), Use of water at 10 degrees C did not aff ect total shoot dry weight but increased the shoot dry weight per centimete r of stem. Irrigation with water at 5 degrees C reduced stem length of cabb age seedlings 40%, but use of water at 10 and 15 degrees C did not. Both sh oot and root dry weights mere increased by irrigation with water at 10 degr ees C, These results demonstrate that irrigation with cold water provides a n effective method for improving the quality of plug-grown seedlings.