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Characterization of germplasm is important for crop improvement. An investigation was carried out with twelve guava germplasm to investigate morphological characters viz. leaf qualitative and fruit qualitative and quantitative characters. The single factor experiment was conducted in randomized complete block design (RCBD) with three replications. Maximum fruit length was found in Chiangmai long (9.37 cm) and minimum was found in Sawadi (4.43 cm). The highest number of seeds was observed in Chiangmai round (352.80). Number of Seed was lesser in Kanchan Nagar (196.40) and in BAU-5 (200.80). Analysis of variance for different characters showed high degree of variation among the germplasm. Among the germplasm BAU-1, BAU-5, Chiangmai long, Chiangmai round, Mukundapuri and Poly guava were found superior according to size, taste, sweetness and so on. The variability in these characters generated valuable information could be used for choice of parents for advance guava breeding programme.

Effects of the water-soluble extracts (dry leaf powder of Azadirachta indica, Datura stramonium and Acanthus ilicifolius) were studied on the behavioral pattern and mortality of Artemia species. The extracts of all the plants brought significant change in the behavioral pattern of Artemia. The Artemia become agitated just offer exposure to the extract and started to move upwards and downwards vigorously. The Artemia exposed to the various concentration of water-soluble plant extracts were unable to maintain dorso-ventral position and dropped to the bottom finally. The mortality rates recorded after 24 h exposure to the extract Azadirachta indica were 30% at 1500 mg/L and 70% at 3000 mg/L. Similarly, after 24 h exposure to the extracts of Datura stremonium, the mortality rates were 40% at 2000 mg/L and 75% at 3500 mg/L. Again, after 24 h has exposure to the extracts of Acanthus ilicifolius, the mortality rates were 35% at 2500 mg/L and rose to 80% at 4000 mg/L. The 24 h LC50 values of the water-soluble extracts of Neem, Datura and Acanthus were 2331.930, 2357.948 and 2922.957. Artemia was more sensitive to the water-soluble extract of Neem than Datura and Acanthus.

Antagonist microorganisms, such as Trichoderma spp. have long been recognized as biological agents, for the control of plant disease and for their ability to increase root growth and development, crop productivity, resistance to abiotic stresses, and uptake and use of nutrients. An attempt was made to evaluate the in vitro biocontrol of branch canker (Macrophoma theicola) of tea plants by Trichoderma spp. Isolation of Trichoderma spp. and M. theiocola was done carefully. Pure culture of Trichoderma spp. and M. theiocola and their morphological characteristics were studied at different intervals. Five M. theiocola and five Trichoderma isolates were collected from mature tea plants and tea soils respectively of Bangladesh Tea Research Institute (BTRI) main farm area. The cultural morphology and antagonistic potentiality of Trichoderma spp. against branch canker pathogen (M. theiocola) were taken into consideration. Trichoderma spp. controls the growth of M. theiocola at different intervals. After 24 hour growth rate of Trichoderma was 9.3% and M. theiocola was 0.88%. The antagonistic potentialities of isolated Trichoderma against pathogens (M. theiocola) were observed at different intervals (24-120 hrs) and the percentage of inhibition was 82% which were observed after five days (120 hours) of inoculation. The Trichoderma spp. antagonizes the pathogens by several mechanisms such as antibiosis, competition, mycoparasitism or other form of direct exploitation. From this study it was revealed that, the Trichoderma spp. was highly effective to control the isolates of M. theiocola that is responsible for branch canker in tea cultivation.

The present study was carried out to assess the efficacy of an integrated management strategy for Fusarium wilt of chickpea that combined the use of microbial antagonist, botanical extract and fungicide. Before setting the experiment in field micro plots, a series of in vitro and in vivo experiments were conducted to select a virulent isolate of F. oxysporum f. sp. ciceris, an effective antagonistic isolate of Trichoderma harzianum, a fungitoxic botanical extract and an appropriate fungicide. The isolate FS1 of F. oxysporum f. sp. ciceris appeared to be most virulent to chickpea cultivar BU-Chola-1 and selected as test pathogen. Among the 20 isolates screened, T. harzianum isolate T-75 showed the highest (75.89%) inhibition of the radial growth of F. oxysporum f. sp. ciceris in dual culture assay on PDA. Absolute inhibition (100.00%) of colony growth of F. oxysporum f. sp. ciceris was observed where fungicide Provax-200 at 100 ppm was used. Azadirachta indica leaf extract gave maximum inhibition (55.19%) of radial growth of F. oxysporum f. sp. ciceris at all concentrations. The integration of soil treatment with T. harzianum isolate T-75 and Az. indica leaf extract and seed treatment with Provax-200 appeared to be significantly superior in reducing Fusarium wilt and in improving seed yield of chickpea compared to any single or dual application of them in the field. The results of this study exhibit the importance of integrating selective microbial antagonist, botanical extract and fungicide to achieve appropriate management of Fusarium wilt and increase of seed yield in chickpea in Bangladesh.

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