Studies on the Ecological Characteristics of Horticultural Plants

Abstract

Cucumber seedlings were grown at various intensities of blue and red lights at the constant temperature of 25°C in a phytotron and the hypocotyl length and the distortions in cotyledons were observed.Spring-cucumbers of South Chinese type except‘Ochiai’form showed a remarkable distortion and were more sensitive to blue light than other groups in hypocotyl elongation, although their hypocotyl length itself was shorter than other groups′.Summer-cucumbers of South Chinese type showed a slight distortion and their hypocotyl was longer than that of Spring-cucumbers. Summer-cucumbers of North Chinese type except‘Sanjaku’cucumbers showed a slight cotyledon distortion and their hypocotyl was longer than that of Spring-cucumbers of South Chinese type.Both summer-, and Spring-cucumbers of Cross-bred type in this experiment showed a slight distortion. They had longer hypocotyl than Spring-cucumbers of South Chinese type and were not so sensitive to blue light in hypocotyl elongation as Spring-cucumbers of South Chinese type.In‘Ao-fushinari’strain belonging to Spring-cucumber of South Chinese type, cultivars of‘Ochiai’form showed a slight distortion, although those of‘Ao-fushinari’and ‘Hyuga’forms had a remarkable distortion.‘Sanjaku’cucumbers of North Chinese type showed a remarkable distortion. They had a shorter hypocotyl than other cucumbers of that and were sensitive to blue light in hypocotyl elongation as Spring-cucumbers of South Chinese type.Considered these from the standpoint of cucumber pedigree, it is suggested that cultivars belonging to‘Ao-fushinari’and‘Hyuga’forms and to‘Sanjaku’cucumbers owe their character of remarkable distortion in cotyledon and of sensitiveness to blue light in hypocotyl elongation to‘Hanjiro’strain of Spring-cucumbers of South Chinese type.