Evaluation of Different Compost Amendments with AM Fungal Inoculum for Optimal Growth of Chives

Abstract

In alternative agronomical practices, the choice of an organic amendment is critical if it is to be used in conjunction with the root colonizing, arbuscular mycorrhizal fungi (AMF). This is because of certain unknown inhibitory moieties which may be present in the organic amendment that deleteriously affect the AMF's ontogenic cycle. The present work tries to address this issue using chive (Allium schoenoprasum L. cv Prague, Sperling), a major herb crop cultivated organically in Israel. Root colonization rates were significantly lower in the sand medium when amended with 10, 30 or 100% compost. In subsequent experiments, three different compost substrates commonly available on-farm were chosen and applied at rate of 15% (V:V) to dune sand. These were, orange peels (OP) plus separated cow manure (SCM, 1:1 V:V) compost, grape marc (GM) plus SCM (1:1 V:V) compost and wheat straw (WS) plus SCM (1:2 V:V) compost. To mimic conventional agricultural practices, sand based substrate (100% dune sand) amended with varying levels of phosphorus (P at 0.15 mg kg−1 & 1.5 mg kg−1) while other nutrients were applied at equal levels. The mycorrhizae tested were mixtures of Glomus intraradices + Glomus mosseae (“Mix-1”) and Glomus macrocarpum + G. mosseae (“Mix-2”). To rule out any deleterious effect of the organic matter on AMF on-togenic development, the chive seedlings were preinoculated with AMF prior to transplanting. For uninoculated plants, the effect of the composts (15%, V:V) on biomass production was insignificant and the highest biomass production was seen in the P (1.5 mg kg−1) amended substrate. However, in combination with AMF, WS plus SCM (1:2 V:V) compost, in conjunction with Mix-1, and OP plus SCM (1:1 V:V) compost in conjunction with Mix-2, could fully replace added P. The results of this study demonstrate that, in order to derive maximal yields from organic based farming with AMF technology, a careful selection of an organic amendment and AMF is very critical.