Studies on the Hot-water Heating of Ridge. II

The purpose of this paper is to investigate the patterns of root system formation in a plant (tobacco) affected by the soil temperature conditions in a ridge. The experiments were made in (i) unmulched ridge, (ii) mulched ridge and (iii) heated ridge in which heating equipment was buried.The conclusion from the results of the experiments was as follows:(1) Root systems in heated ridge had a lot of hard and thick roots and penetrated deep in the soil.(2) Root systems in unmulched ridge consisted of soft roots and spread over the whole of ridge.(3) Root system formation in mulched ridge lay between those in heated and unmulched ridges. Thick roots in mulched ridge were seen beneath the surface of the ridge.(4) Soft and thick roots grew when the temperature in a ridge was low and high respectively.(5) The patterns of root system were formed in response to the distribution of soil temperature in a ridge.