Screening of the indigenous African vegetable, Corchorus olitorius, against root-knot nematodes

Abstract

Corchorus olitorius (Jute mallow) belongs to the genus of about 40-100 species of flowering plants in the family Malvaceae. Jute mallow is an important food for many families. It is famous for its sturdy natural fibre in the Middle East, Africa and Asia. The leaves are a rich source of iron, protein, calcium, thiamin, riboflavin, niacin, folate and dietary fibre. The yield and productivity of C. olitorius are plagued by poor cropping systems, poor soil health and pests or disease incidence. Information on the impact of root-knot nematodes (Meloidogyne incognita) on Jute mallow is scant. Hence, the objectives of the study were to: (i) test the host-status and host-sensitivity of Corchorus olitorius accessions to Meloidogyne incognita and (ii) determine the potential nematicidal effects of Maerua angolensis on population densities of M. incognita and yield of C. olitorius accessions. The two experiments were conducted under greenhouse conditions, in a randomized complete block design (RCBD), with five replications with two C. olitorius vegetable accessions, Manguzi 2 and Manguzi 3. First objective treatments were exposed to eight M. incognita eggs and J2 levels, namely, 0, 25, 50, 100, 200, 400, 800, 1600 and 3200 and for the second objective the treatments consisted of three levels of M. angolensis leaf meal powders, 5, 10 and 15 g plus a standard synthetic, commercial nematicide, Ne macur 10GR at a rate of 5 g per plant, as well as an untreated control. The results for objective 1 showed that both cv. Corchorus olitorius accessions had reproductive factor (RF) greater than 1, while nematode levels did not affect plant variables, except the dry root mass of Manguzi 2. For objective 2, Maerua angolensis decreased the total nematode population found in roots and soil for both cv. Corchorus olitorius accessions. In conclusion, both accessions of C. olitorius were tolerant to M. incognita because plant variables were not damaged by the infestation and M. angolensis managed to reduce the nematode population densities on both cv.. C. olitorius accessions, however, the plant extracts had no significant effect on the plant growth variables.