MICROORGANISMS

This study was designed to evaluate the microorganisms associated with soursop seeds obtained from New Benin market, Benin City. The objectives of the study were to ascertain the percentage of infection of microorganism associated with soursop seeds; isolate and identify microorganisms associated with soursop seeds, and determine the microbial diversity associated with soursop seeds. The experiment was carried out in the Department of Crop Science Laboratory, Faculty of Agriculture, University of Benin, Edo State. The Incubation Technique (Agar plate method) was employed during the course of the study. Soursop seeds
(seedcoat and endosperm) were chopped into tiny bits, surface sterilized, and placed on filter paper to drain off moisture, and cultured with Potato Dextrose Agar and nutrient agar (PDA and NA). Microbial identifications were done using morphological and biochemical tests for bacteria, while microscopic features examination was carried out for fungi. During the course of the study which lasted for 9 weeks, three (3) bacteria species (Proteus sp., Streptococcus sp., and Bacillus sp.) and three (3) fungi species (Aspergillus sp., Phoma sp., and Yeast cell) were isolated from the seed of soursop. Results of the study showed that Aspergillus sp. Phoma sp. Yeast cell, Proteus sp. streptococcus sp. and Bacillus sp., known to be pathogenic, were disseminated predominantly by seeds, and was observed that the level of bacteria infection was higher in seed coat when compared to endosperm while the level of fungi infection was higher in the endosperm when compared to the seed coat. The incidence of bacteria and fungal organisms on the seed parts of soursop has been demonstrated by this study. High incidence of some of these organisms can result in far reaching consequences such as total crop failure. It was therefore recommended to carry out seed tests by agar plate method (Incubation Technique). This is because the agar plate method provides an efficient tool for the quick identification of specific seed infections; plant pathogen management should be carried out in form of plant products (plant extract) that show
good bioactivity against bacterial and fungal isolates associated with soursop seed or other related crops.

Annona muricata also known as soursop, is a plant in the Annonaceae family. Soursop grows in a variety of soil types of soil, which provides a habitat that supports the growth of soil organisms. One of the most important factors influencing microbial activity and diversity in soil is the availability of water. The objective of this study was to identify microorganisms in soil subjected to treatment with Trichoderma sp and planted with soursop under varying watering regimes. The experiment was conducted in the department of Crop Science Laboratory, Faculty of Agriculture; University of Benin, Benin city. The study investigated the influence of watering regime, soil media and soil incubation duration on the growth of Soursop. The experiment was laid out in a Completely Randomized Design (CRD) with two replications and were separated using Student-Newman-Keul test. The results of this experiment showed the presence of four fungal isolates (Mucor mucedo, Trichoderma sp, Aspergillus niger, and Rhizopus arrhizus) and four bacterial isolates (Escherichia coli, Bacillus subtilis, Bacillus pumilus, and Klebsiella oxytoca) in soil cultivated with soursop under different watering regimes. The identification of Trichoderma sp reaffirms the efficacy of the treatment while the diverse fungi and bacterial species suggest a complex soil ecosystem. It was observed that the varying watering regimes (Watering every day, watering every 3 days, watering every 5 days and Watering every 7 days) showed different degrees of microbial population and diversity, with the highest occurring (12.4 x 10 6 cfu/g and 16.9 x 10 6 cfu/g) in Watering every day while soil-seed treatment; Untreated seed-Untreated soil had the highest microbial population (12.9 x 10 6 cfu/g and 16.4 x 10 6 cfu/g). From the results obtained, the soil and seed treatment, watering regime and soil incubation duration had effect on the microbial population. On the basis of these findings, it is recommended that soil watered daily should be used when growing soursop for optimum growth.