SOIL INOCULUM LEVEL OF ROOT ROT PATHOGENS IN LEGUMES AND MANAGEMENT USING DIFFERENT SEED DRESSING APPLICATIONS IN NANDI SOUTH

ANNE KADAARI A56/80093/2012MSC. CROP PROTECTIONSUPERVISOR: DR.MUTHOMI

INTRODUCTION

Legumes are among the most important food crops in

Kenya

They play an important role on farms, human diet and

sustainability of agriculture.

Mostly grown as risk reducing crop

However, yield decline has been reported due to their

susceptibility to environmental stress, diseases, pests and

low soil fertility.

Problem statement and justification

Root rot diseases are a major limiting factor in legume production

Several factorsfavor their establishment in a crop

Root rot diseases suppress seedling germination and cause

emergency damping off resulting in poor yield of legumes

Major losses have been reported in western Kenya

This study will be carried out to determine the soil inoculum levels of

root rot pathogens with appropriate seed dressing application as a

management tool

Objective

Broad objective

To determine soil inoculum levels of legume root rot pathogens and their

management using different seed dressing applications

Specific objectives

1.Determination of the level of root rot pathogen of legumes

2.To evaluate different seed dressing application on the management of root

rot pathogens of legumes using different regimes

Materials and methods

1. Determination of the level of root rot pathogen of legumes

Study sites

The sites will be in Nandi South; Kapkerer, Kiptaruswo and

Koibem.

Each site will consist of 3 farms selected randomly

Experimental design The design will be a complete split plot with 3 replications Grain legumes to be used include common beans, dolichos

lablab, groundnuts, soy beans, field peas & cow peas. Each legume will consist of 3 varieties.

Materials and methods cont..

The legume species will form the main plot while the varieties form the sub plot.

The plot will be 2x2m size. The legume varieties will be planted in 3 rows per sub plot. 3 seeds per legume species will be sown 5cm deep and 10-30cm

spacing within plants. The experiment will be carried out for two rainy seasons. 18 treatments

Sample collection and isolation 100g of soil will be collected randomly on each plot before the onset

of rainy season, at planting time and prior to harvesting A composite will be made from soil sample collected from one site

and labeled appropriately.

Materials and methodology cont..

Isolations of root rot pathogens & identificationSoil sample will be grounded and soil suspension made from each of the 3 composite samples per site.Serial dilutions will be made by diluting 10g to 100ml sterile distilled water1ml of 10-4 to 10-6 dilutions will be plated and replicated thrice on petridishes containing PDA and incubated for 5-7days at 250c

Colony numbers will recorded and total number of colony forming units per grams in soil calculated.

Hyphal tip transfer will be done and sub cultured to PDA at 26-280C for 5 days . Fungal isolates from the pure culture will be identified by morphological and cultural features

Materials and methodology cont..

Assessment of root rot incidenceAll legumes species showing root rot disease symptoms per plot will be counted in the 2nd ,4th ,6th and 8th week after seedling emergence and total incidence determined by calculating the total no of plants showing disease symptoms over total no. of plants in a plot.

To determine nodulation ,yield , growth and yield parametersNodules will be determined by washing the harvested plants roots and the total no. of nodules counted on entire root system.Growth parameters will consist of biomass and root mass measurements.Individual legume species will be selected randomly ;roots and shoots will be separated from the plant , washed and blot dried.Fresh weight will be determined by weighing freshly harvested plant and weights recorded.The roots and shoot will be dried in an oven at 1000c for 48hrs and weighed to determine dry weight and total biomass calculated.

Materials and methodology cont..

Yield: calculating individual plant yield on each harvesting date by dividing total yield per plot by no.of plants in each plot

Yield parameters will constitute mature pods and seeds. Total no. of pods and seeds per pod at harvest time from randomly selected plants will be recorded and weighed and total no. of seeds per pod recorded.

2. To evaluate different seed dressing application on the management of root rot pathogens of legumes using different regimes

Study area , experimental design and treatments There will be two experiments; a field experiment in Nandi south and

a greenhouse experiment at the University of Nairobi, Upper Kabete Field Station

The experiments will be complete split plot design with 3 replications. Main plot will consist of legumes species and subplot consist of 3

legumes varieties.

Materials and methodology cont..

Treatments will include seeds dressed in portassium sorbate, Neem extract, a mixture of potassium sorbate and neem and a control.

Greenhouse experiment Legumes exhibiting root rot symptoms will be collected, roots will be

cut into small portions which will be washed in running water and surface sterilized using 1% Naocl ,rinse in distilled water thrice and blot dried.

Aseptically the root segments will be plated on PDA and incubated for 7-14 days at 250c and identification will be by morphological and cultural features.

Pure culture will be obtained by hyphal tip transfer into fresh PDA. Inoculum will be prepared whereby colonies will be flooded with

sterile distilled water and gently scraped off from the surface of the media to make a slurry. Sterile soil on each set of plastic pots will then be inoculated with the inoculum through spraying.

Materials and methodology cont…

Chemical seed dressing and botanical seed dressingPrior to seed dressing seeds will be surface sterilized using 1%Naocl and rinsed three times.Sterilized seeds (3) of all legume species will be individually soaked separately for 1hr in potassium sorbate solution and Neem extract concentration at varying concentrations then sown in sterile soil in a set of arranged plastic pots.Seeds will be soaked in a mixture of potassium sorbate and neem extract solutions will be planted.Field experimentA field experiment will be carried out consisting of the 6 legume species on a 2x2m plots in a complete split plot design. 3 Seeds dressed with potassium sorbate and Neem extract at varying concentration and in a mixture of the two applications will be sown on each plot. Untreated seeds will be planted as controls.Assessment of root rot incidenceAll legumes species showing root rot disease symptoms per plot will be counted in the 2nd ,4th ,6th and 8th week after seedling emergence and total incidence determined by calculating the total no of plants showing disease symptoms over total no. of plants in a plot.

Materials and Methodology cont…

To determine nodulation ,yield , growth and yield parametersNodules will be determined by washing the harvested plants roots and the total no. of nodules counted on entire root system.Growth parameters will consist of biomass and root mass.Individual legume species will be selected randomly ;roots and shoots will be separated from the plant , washed and blot dry.Fresh weight will be determined by weighing freshly harvested plant.The roots and shoot will be dried in an oven at 1000c for 48hrs and weighed to determine dry weight and total biomass calculated.Yield: calculating individual plant yield on each harvesting date by dividing total yield per plot by no.of plants in each plot.Yield parameters : Total no. of pods and seeds per pod at harvest time from randomly selected plants will be recorded and weighed and total no. of seeds per pod recorded.Statistical AnalysisData will be analyzed using analysis of variance (ANOVA) Genstat software and means distinguished using Tukey LSD test at 5%

Expected results

Soil inoculum level of root rot pathogens in legumes will be determined.

Seed treatments as a suppression method of root rot pathogens in legumes will be incorporated as management tool

Increase in yield due to seed treatments. Msc. Thesis Publication in scientific journal.

Work plan

Activity 2013 2014

Jun

e

July Aug-

Oct

Sep-

Dec

Jan-

Feb

Mar-

April

May- June

Proposal

development

Planting and

sample collection

Pathogen

isolation and

identification

Data Analysis

Thesis Write up

and submission

BudgetItem Cost (K sh)

Sample collections 20,000

Laboratory analysis 70,000

Variety evaluations 60,000

Thesis development 20,000

publication 20,000

Total 190,000

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