Abstract:

The two main problems of substrate culture are the handling of waste caused by substrate mats and the high yearly cost.Rockwool has been proven worldwide to be an excellent growing medium，but it involved some problems，i. e. a relatively short useful life（2 - 3 years max.）and difficulties in disposal of a large amount of waste per year（60 - 80 m3 / hm2）. Recent investigations by environmentalists and governments have led to the
demands for environmentally sound and reusable substrates.
A five-year old PUR was compared with new rockwool and cocovita slabs in cultivation of tomato plants in this trial. The aim of this experiment is to determine the effect of different substrates on the root rhizosphere environment，growth，development and yield of glasshouse tomato，also to determine whether PUR is a satisfactory substrate for hydroponics tomato cultivation and to provide recommendations on management to maximise crop
productivity. In terms of EC，pH，it is clear that PUR provides a more stable rhizosphere condition than rockwool and cocovita. Productivity in terms of fruit number，average weight，total weight and fruit quality from plants grown on PUR 94 was as good as rockwool，though less satisfactory than those from cocovita. Over the period of the trial there was no less yield or worse fruit quality attributed to the reuse of PUR，compared to traditional rockwool
substrate. It might be concluded that PUR could be an environmentally and economically sound substrate for glasshouse tomato plant.

Key words: polyurethane ether foam（PUR）, rockwool, cocovita, environmentally and economically sound substrate, tomato