Effect of water stress and mixed types of the genus Arbuscular Mycorrhizal Fungi from cocoa roots on spore propagation and root colonization used corn as the host

Abstract

Biofertilizer with Arbuscular Mycorrhizal Fungi (AMF) as the inoculants is needed in organic cocoa cultivation on smallholder plantations in Indonesia. AMF biofertilizer requires a sufficient number of spore inoculants, so it is necessary to multiply isolated spores. Research objective was determining the effect of water stress and mixed types of AMF genus from cocoa roots on spore propagation and root colonization used corn as the host plant. The study used a 2-factors randomized block design and 3 replications. The first factor was water stress consisting of 3 levels (without water stress as a control, soil moisture content 100% of field capacity; light water stress, soil moisture content 70% of field capacity; and heavy water stress, soil moisture content 40% of field capacity), while the second factor was mixed types of AMF genus also consisting of 3 levels (inoculant of genus Glomus only, mixed inoculants of the genus Glomus + Acaulospora, and mixed inoculants of the genus Glomus + Scutelospora. Result of research showed, the interaction of water stress and mixed types of the AMF genus had no significantly affect on the number of spores reproduced, root colonization and host plant growth. The best way of propagation of AMF spores was by heavy water stress treatment with a soil moisture content of 40% of field capacity producing 6,713.40 spores or an increase of 13,326.82%. Mixed inoculants of the genus Glomus + Scutelospora gave the highest number of spores after propagation (6,263.40 pieces) or an increase of 12,427.77%.