Effect of putrescine and alginate oligosaccharide applied to the soil on vesicular-arbuscular mycorrhizal formation in the roots of passionfruit and avocado.

AIKAWA, JIRO¹, TAKAAKI ISHII², KENSAKU OGATA¹, LEONALD SAMITA WAMOCHO², ISAO MATSUMOTO¹ & KAZUOMI KADOYA¹.

¹Fac. Agri., Ehime Univiversity, JAPAN. ²Fac. Educ., Ehime University, JAPAN.

We reported that vesicular-arbuscular mycorrhizal (VAM) formation in citrus roots was stimulated by putrescine, a kind of polyamine, and alginate oligosaccharide applied to the soil (Ishii et al., 1996). In this study, we report the effect of these two chemical compounds on VAM formation in the roots of passionfruit cuttings and avocado seedlings.

Rooted passionfruit cuttings and avocado seedlings which were cultivated in sterile media were individually transplanted in plastic pots. And then the passionfruit cuttings were inoculated with a soil containing about 60 spores of Gigaspora ramisporophora (Gr), 300 spores of Glomus fasciculatum (Gf) and 300 spores of Glomus sp. (R-10) (Gs). The avocado seedlings received similar amounts of the inoculants of Gr and Gf. Both the passion fruit cuttings and the avocado seedlings were treated with 100ml of 0.0005M of putrescine and 100ppm of alginate oligosaccharide solution each per week for 4 weeks.

Our data indicate that there were no distinct differences among plant growth. However, VAM formation in the roots was highly increased in all the treatments for both fruit types, compared with the controls. In particular, VAM formation in the Gr + alginate oligosaccharide plot for passionfruit was the highest with colonization of 40.5%, which was the highest value among all the treatments.