Impact of castor meal on root-knot and free-living nematodes

Abstract

Soil amendment may enhance soil quality as well as reduce plant-parasitic nematode. Despite the many applications already undertaken using castor meal, its efficiency in controlling root-knot nematodes (RKN, Meloidogyne incognita) when applied to melon (Cucumis melo) is still not clear. Three different amounts of castor meal (Ricinus communis) applied were evaluated in microplots planted with melon either with or without RKN. The impact of castor meal on soil free-living nematode communities was also determined. Total nematode genera richness was estimated as 37 for the entire set of microplots sampled across both sampling dates. Rarefaction analysis resulted in 12 collector's curves out of the total of 30 that reached the horizontal asymptote. Univariate ANOVA with two factors yielded differences (p ≤ 0.05) only with regard to the time factor. Simpson, Shannon, Evenness and Equitability indices showed a trend toward moderate increases by the end of the experiment, while the other indices were higher for tomato in pre-transplant sampling compared to harvest. Nematode community and diversity changed during the course of the experiment, although there was substantial confounding heterogeneity within and between the factorial combinations from the beginning. Root knot population was not reduced by the castor meal but increased throughout the period, regardless of treatment. RKN reduced melon yield, number and weight of melon.

Plants with known antagonistic properties against pests: how they influence non-target free-living soil fauna?

“…Up to now the results have confirmed the antagonistic properties of some plant extracts in relation to different nematode species known to be plant parasites causing high losses in plant production (Grewal 1989, Wuyts et al 2006, Thoden et al 2007, Seenivasan 2011, El-Nagdi and Youssef 2013, Chałańska et al 2013. So far, there is scarce information on the effects of plant extracts on non-target organisms such as free-living nematodes (Akhtar and Mahmood 1993, Seenivasan et al 2013, Ritzinger et al 2014 or other representatives of soil fauna (e.g. earthworms and potworms) which play an important role in the soil environment and the processes taking place there.…”

“…On the other hand Ritzinger et al (2014) explained the increase of the numbers of bacterial-feeding nematodes in soil in response to the high N content in the castor meal by the fact that the formation, release and accumulation of toxic to soil nematodes compounds takes time. Taking into account the length of their experiment (3 months), one might assume that in our experiment a similar mechanism could be also probable.…”

“…However there is scarce information about the effects of plant extracts on non-target organisms e.g. freeliving nematodes (Akhtar and Mahmood 1993, Seenivasan et al 2013, Ritzinger et al 2014 or other representatives of soil fauna (e.g. earthworms and potworms), which play an important role in the soil environment and the processes taking place there…”