Indo-3-acetic acid (IAA) and cytokinin-like activity in municipal excess activated sewage sludge: effect on rooting of mung bean (Vigna radiata (L.) Wilcz.) cuttings

A common use for land treatment of municipal sewage sludges is their application in agriculture. Sludges are well known to contain high levels of organic and inorganic materials but can also affect plant growth by supplying growth hormones. We tested the hormonal effect of sewage sludge from the Municipal Sewage Sludge Management Center in Herzliyya, Israel, on rooting of mung bean cuttings. Sewage sludge induces the formation of adventitious roots on mung bean cuttings, in a way similar to the promotion by IBA, the most common treatment for root initiation. Moreover, sewage sludge quadrupled the root elongation rates as compared with the effect of IBA and it seems that at least Herzelia source of municipal se~age sludge comprises a very promotive growth medium for root development. Significant amount of IAA was identified in sewage sludge by GC-MS. The sludge exhibits also cytokinin-like activity. The data of this study and particularly the effect of the sludge on the development of the adventitious roots in mung bean cuttings suggest that in addition to the auxin influence of sewage sludge some other factors are involved.