Effect of mycorrhizal infection on the early growth of protocorm in Habenaria radiata 'Aoba' and 'Gyokuryuka'

Abstract

To compare the stimulative effects of mycorrhizal infection on the early growth of Habenaria radiata, protocorms of 'Aoba' and 'Gyokuryuka' grown from seeds were inoculated with fungal isolate No. 931202A. The protocorm of 'Gyokuryuka' (2n=64) enlarged faster than those of 'Aoba' (2n=32). The difference is attributed to the following factors: (1) Protocorms of 'Gyokuryuka' were infected more easily; (2), the conductive tissue in the protocorm of 'Gyokuryuka' differentiated and functioned earlier; and (3) the degree of invasion of the fungus into the protocorm of 'Gyokuryaka' as measured by the staining intensity of Trypan Blue is much greater. Through these observations, we conclude that the interaction between the infectivity by the different isolate of mycorrhizal fungus and the susceptibility of different cultivars of Habenaria radiata are decisive factors affecting early seedling growth.