1. Oliver, O., Muthomi, J., Narla, R., Ojiem, J., Nderitu, J
mechanisms contributing to poor crop emergence and establishment of common beans after lablab incorporation
Oliver, O., Muthomi, J., Narla, R., Ojiem, J., Nderitu, J
University of Nairobi

2. Introduction
Green manuring is practice of ploughing or turning into the soil undecomposed green plant tissues for the purpose of improving soil fertility
However, undecomposed plants residues have been reported to reduce crop establishment and increase incidences of pests and diseases.
Reduced emergence of about % have been reported
Decomposition of plant residues results in metabolites that are toxic to other plants. Thee chemicals can either be inhibitory or stimulatory to crop growth, yield and microorganisms in the soil
The chemicals released alter the plant surrounding which may result in either poor crop germination or reduced growth
Therefore, there is need to determine the mechanism that may contribute to poor crop establishment.

3. MATERIALS AND METHODS
Treatments – extracts from lablab, bean, soybean and groundnut
Compost preparation – legume resides chopped and piled in a container with small layer of soil added to obtain microorganism for decomposition
Extracts preparation –fresh legume residues were macerated with sterile distilled water and ethanol (80%) ratio 1:10 to obtain crude extracts
Solvent (ethanol) was evaporated at lower temperature under reduced pressure in rotary flash evaporator to get the crude extracts
Both fresh and compost extracts were tested on bean germination, mycelial growth, spore germination and bacterial growth
Data collected - % germination, % spore germination, mycelial growth inhibition

4. MATERIALS AND METHODS
Percentage germination = Seeds germinated in extracts Seeds used in bioassay ×100,
Percentage spore germination= germinated spores total of spores ×100
Saprophytic fungi were tested for antagonistic activities against root rot pathogens
Percent inhibition of radial growth (PIRG)
PIRG = Radius in control −Radius of fungi in the direction of antagonists Radius in control ×100

5. RESULTS - Effect of different legume extracts on germination of common beans
Seeds treated with lablab extracts had the lowest germination percentage while the maximum was recorded with seeds treated with aqueous groundnut extracts (85%) ( Fig 1)
Seeds treated with lablab ethanol extracts had the lowest germination percentage while maximum was recorded with seeds treated with soybean ethanol extracts (Fig 2)
Seeds treated with sterile distilled water had highest germination percentage
Fig. 1: effect of aqueous extracts on germination
Fig. 2: effect of ethanol extracts on germination

6. Ethanol extracts had strong antifungal activity
Effect of different legume extracts on radial growth of Fusarium oxysporum
The inhibition of mycelial growth varies from legume to legume and with extraction medium used.
Ethanol extracts had strong antifungal activity
The extracts of soybean and groundnut showed a high antifungal activity after four days
lablab extracts showed the least antifungal activity against Fusarium oxysporum
Fig. 3: effect of aqueous extracts on mycelial growth
Fig. 4: effect of ethanol extracts on mycelial growth

7. Effect of different legume extracts on spore germination of Fusarium oxysporum
Among the tested extracts, ethanol legume extracts showed near complete inhibition of spore germination
The lowest conidial germination was recorded in spores treated with lablab extracts while the highest inhibition was recorded with groundnut extracts
Lablab aqueous extracts seemed less inhibitory against Fusarium oxysporum
Fig. 5: effect of aqueous extracts on spore germination
Fig. 6: effect of ethanol extracts on spore germination

8. Effect of different legume extracts on germtube elongation of spores of Fusarium oxysporum
Among the tested extracts, ethanol extracts showed near complete inhibition of germtube elongation germination
The shortest germtube length was recorded in spores treated with beans and groundnuts extracts while the longest germtube length was recorded with lablab extracts
Lablab aqueous extracts seemed very stimulatory against Fusarium oxysporum
Fig. 7: effect of aqueous extracts on germtube elongation
Fig. 8: effect of aqueous extracts on germtube elongation

9. C. Lablab ethanol fresh extracts D. Soybean fresh extracts
Figure 9: Germinated spores of Fusarium after 24 hours of incubation on different legume extracts.
A. Lablab fresh extract,
B. Bean fresh extracts
C. Lablab ethanol fresh extracts
D. Soybean fresh extracts B B C D

10. Effect of saprophytic fungi against activities of root rot pathogens of common beans
All antagonists inhibited mycelial growth with varying efficiencies for different pathogens
The radial growth values ranged from 26mm to 39mm
Trichoderma and Paecelomyces were significantly the best in terms of inhibiting root rot pathogen growth

11. CONCLUSION
The plant extract of lablab origin exhibited effect on Fusarium oxysporum spores causing increase in the size of germtube and rate of sporogenesis
Incorporation of lablab extracts stimulates the population of root rot pathogens through enhanced mycelial growth and through germtube elongation
Lablab extracts
Plant extracts with a good antifungal activity generally have high concentrations of total polyphenolic content and are able to inhibit pathogens
The effective use of this green manure wherein planting within plots incorporated with green manure could affect the growth of the economically viable plants through reduced germination and establishment .

12. Acknowledgement

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