Interaction of Vesicular Arbuscular Mycorrhiza, nematode and phytonematicides on growth and nutritional content of Cleome gynandra

Abstract

Cleome gynandra is increasingly becoming an important strategy for achieving food and nutrition security among rural households in many developing countries. Root-knot (Meloidogyne species) nematodes, with limited nematode management strategies, limit the successful production of this vegetable crop. Nemafric-BL and Nemarioc-AL phytonematicides are separately being developed in South Africa for sustainable crop production systems. However, the two products have not been simultaneously tested for managing the notorious Meloidogyne species and absorption of phosphorus, with a combination of Vesicular arbuscular mycorrhiza (VAM). The objective of this study therefore was to determine the interactive effects of VAM and each of the two phytonematicides on nutrient content, growth of C. gynandra. A 2 × 2 × 2 factorial experiment, with the first, second and third factors being VAM (V), nematode (N) and Nemafric-BL phytonematicide (P). The eight treatments included (1) untreated control (V0N0P0), (2) nematodes alone (V0N1P0), (3) VAM alone (V1N0P0) (4) Nemarioc-AL phytonematicide alone (V0N0P1), (5) V1N1P0, (6) V0N1P1, (7) V1N0P1 and (8) V1N1P1, were laid out in a randomised complete block design, with ten replications. The same layout experiment was done for the Nemarioc-AL phytonematicide trial which had a similar layout. Seedlings were irrigated with 250 ml chloride-free tapwater every other day for 56 days. Multifeed and NPK (2:3:2(22) fertilisers were applied at transplanting. The second order interaction (V1N1P1), was highly significant (P ≤ 0.01) for plant height contributing 54% in TTV (Total Treatment Variation) of the variable. Among the main factors (N, P and V), only nematode had highly significant effects on stem diameter. All interactions of VAM, nematode and Nemarioc-AL phytonematicide and main factors each had no significant effect on Cleome. The second order (V1N1P1) and the first order interaction (V1N1P1) did not have significant effects on the three nutrient elements except for the first order interaction (V1N0P1) which was significant on foliar Zn contributing 42% in TTV of the variable. Also nematode had highly significant effect on foliar K and significant effect on foliar Zn contributing 49 and 31% in TTV of the respective variables. Using the two-way table, VAM and Nemafric-BL phytonematicide each increased foliar Zn by 27% and 29%, respectively. The second and first order interactions of VAM, N and Nemarioc-AL phytonematicide and the main factors did not have significant effect on foliar K, Fe and Zn. The second order interaction of VAM, nematode and Nemafric-BL phytonematicide had significant effects on gall rating, contributing 2% in TTV of the variable. VAM, nematode and Nemarioc-AL phytonematicide showed that the second and first order interaction except for V1N0P1 interaction on gall rating, were not significant for nematode variables. The V1N0P1 interaction contributed 20% in TTV of gall rating. Using a two-way table, VAM and phytonematicide each increased root galls by 7% and 74%, respectively. Combined, VAM and phytonematicide reduced root galls by 64%. The innovative products interacted together and that Nemafric-BL and Nemarioc-AL phytonematicides and VAM alone could be used in managing nematodes.