Influence of crop management practices and organic amendments on nematodes population and diversity in banana orchards in Embu county

Abstract

Bananas (Musa spp) play an important role as a source of food and income for many households in Kenya. However production of this fruit crop has not been easy due to pests and disease among other challenges. The objective of this study was to determine the diversity of parasitic nematodes in banana production under varying crop management practices, identify the main soil factors that influence nematode communities in banana production systems and assess the effect of organic amendments on nematode communities. A research was conducted in Runyenjes, Embu County in three agro-ecological zones namely upper midland zone 2, upper midland zone 1 and lower highland zone whereby a questionnaire was administered to farmers to get information on importance and challenges of banana production. Soil and root samples were taken from 30 farm fields from three agroecological zones for determination of nematodes occurrence and diversity. Soil samples were also analyzed for organic carbon, Potassium, soil pH, Nitrogen and Phosphorous as the main soil fertility elements. Field trials were then conducted in farmers’ fields in the 3 agroecological zones in three replicates. The experiment was laid using Randomized Complete Block Design (RCBD) with 3 replicates for two seasons. Treatments used were cow manure, goat manure, chicken manure, fertilizer and a control. Soil and roots samples were collected before treatment application, after six weeks and twelve weeks after treatment application. The same procedure was repeated for season two. Nematodes were extracted and identified to genus level from the soil and roots samples. The genera found were eight and they were Pratylenchus, Meloidogyne Radopholus, Tylenchus, Helicotylenchus, Filenchus and, Scuttelonema. There was no significant different in total number of nematodes. The results showed that the nematodes population is diverse across the three agro-ecological zones. The results also showed that agronomic practices affect the level of nematodes population. In addition, there was a strong negative correlation between parasitic nematodes and soil xvi fertility elements. Moreover, soil amendment reduced the population of parasitic nematodes in the soil and roots but had no effect on free living nematodes. From the study, it was concluded that different agronomic practices affect the population of banana parasitic nematodes and this can be incorporated with other management practices to manage the nematodes. Increase of soil elements such as Nitrogen, pH, organic carbon, Phosphorous and Potassium reduces the population of banana parasitic nematodes. Finally it was also confirmed that addition of organic amendments in the soil reduces the level of nematodes’ population. The general conclusion from this research work is that variations in climate, agronomic activities and soil type, as a result of altitude variation influence the population and diversity of plant parasitic nematodes affecting bananas.