Climate smart clove production for sustainable livelihoods: intervention for root knot nematode control

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Date

2021

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Journal ISSN

Volume Title

Publisher

Sokoine University of Agriculture

Abstract

Cloves is one of the important spices produced by small holder farmers in East Usambara Mountain (EUM). Previously, the farmers in EUM reported wilting and drying of crops to be associated with biotic and abiotic factors. Plant parasitic nematodes (PPN) particularly root knot nematode has been reported to cause yield reduction in cloves and are considered of highly economic importance. In the same area, climate smart agricultural practices (CSA) had been introduced to enhance use of soil micro-organism such as arbuscular mycorrhizal Fungi (AMF) to combat RKN. However the influence of CSA in the association of RKN and AMF remains largely unknown. The aim was to evaluate the association between indigenous AMF and plant parasitic nematode under CSA practices. The first chapter of this dissertation contains general introduction, the second chapter contains literature review describing cloves, PPN, AMF and Climate smart agricultural practices, the third, fourth and fifth chapters comprise manuscripts in the form of publishable papers while the sixth chapter covers general conclusion and recommendation. Chapter 3 reports on survey conducted in EUM to assess perception and awareness of root knot nematode (RKN) among the farmers. The survey revealed that majority (89.1%) of the farmers were not aware of RKN. Most of them practiced mixed cropping and reported that they faced other constraints such insect pests and diseases that might have contribute to wilting of their clove crop. In Chapter 4 abundance of AMF and plant parasitic nematodes (PPN) in the clove fields was evaluated in CSA and NCSA. The study revealed existence of mycorrhizal colonization in clove roots (86 to 100%) and that Rotylenchulus spp. and Glomus spp. were the most abundant genera. There was no significant difference between PPN and AMF abundance under different farming practices. However, there was positive association between AMF and PPN in both farming practices. The studies showed that there was no significant association between soil properties and arbuscular mycorrhizal fungi but there was positive association between nitrogen and PPN abundance. There was no significant relationship between AMF and PPN abundance in clove fields. In Chapter 5, Pathogenicity of RKN in clove roots was studied. The findings showed that no observable galling symptoms were seen in 300 clove plants in EUM. Thus cloves were not affected by RKN. In screen house experiments clove seedling that were inoculated with second stage juvenile (J2) nematode showed no galling symptoms and reproduction factor was less than 1 indicating that clove plants were not hosts of root knot nematode. Thus RKN was not the cause of the wilting of clove plants reported in the study area. Further research should focus on other causes leading to the problem.

Description

Dissertation

Keywords

Climate, Smart clove production, Sustainable livelihoods, Root knot nematode control, Plant parasitic nematodes (PPN)

Citation