ABSTRACT
Three crop fields namely, paddy, sugarcane and tomato exposed to bavistin [Methyl (1H-benzimidazol-2-yl) carbomate], monocrotophos [Dimethyl (E)-1-methyl-2-(methyl-carbamoyl) vinyl phosphate] and kinado plus [(EZ)-2-chloro-3-dimethoxyphosphinoyloxy- X1, X1-diethylbut-2-enamide], respectively were chosen for the present investigation to know the bacterial population and degradation of pesticides. The chemical nature of the soil and water samples from the pesticide contaminated fields was analysed along with counting of the total heterotrophic bacteria (THB), Staphylococci and Enterococcci population. Mean calcium, phosphate and biological oxygen demand were maximum in tomato field water. Field water recorded maximum phophate and silicate content, whereas, sugarcane field water elicited maximum dissolved oxygen content. On the other hand, available phosphate and exchangeable potassium were maximum is sugarcane field soil. Significant variations in the bacterial population were evident between the treatments in sugarcane field soil and tomato field water exposed to monocrotophos and kinado plus, respectively. In addition, significant variations between THB, Staphlyococci and Enterococci population were also evinced in both the sugarcane and tomato fields. The dominant pesticide resistant bacteria, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeuroginosa harboured plasmids and the resistant trait observed were found to be plasmid borne.
ABSTRACT
A reliable and reproducible protocol for contamination free plant recovery system from alginated encapsulated uninodal microcuttings of micropropagated Bacopa monnieri L.have been developed after storage at 18oC for 45 days. Node segments excised from freshly micropropagated plants were encapsulated as single explant beads with 3.0 % sodium alginate and 80 mM CaCl2 2 H2O. To find out the optimal concentration of fungicide bavistin for efficient plant recovery, different concentrations of bavistin (1.0 - 15 mg l-1) were incorporated in to the encapsulation medium. 3.0 mg l-1 bavistin showed no reduction in plant conversion and generated maximum number of shoots (45.6 ± 1.69) at high frequency with out any contamination after storage up to 45 days at 18oC. At high concentrations (13 and 15 mg l-1), rupturing of calcium alginate coats after 8 - 9 days and gradual decline in the number of shoots indicates the toxic effect of bavistin on plant conversion. Encapsulated node cuttings stored up to 45 days regenerated shoots (5.2) and multiple shoots (45.6) in MS basal and hormone medium respectively. Maximum shoot length (8.2 ± 0.37 cm) was observed from encapsulsted node cuttings incorporated with 3.0 mg l-1 bavistin on MS basal medium. 90 % of the recovered plantlets were hardened off and successfully established in soil.
ABSTRACT
This study was conducted to identify the Colletotrichum species causing anthracnose disease of strawberry in Balgladesh and to evaluate in vitro activity of commercial fungicides it. Based on morphological and cultural characteristics, all 22 isolates were identified as Colletotrichum gloeosporioides. They developed white or glittery colonies with grey to dark grey reverse colony colors and they produced cylindrical conidia. The efficacy of five commercial fungicides, Bavistin DF, Dithane M-45, Sulcox 50 WP, Corzim 50 WP and Rovral 50 WP, were tested against the fungus. Bavistin inhibited radial growth completely and was followed in efficacy by Dithane M-45. In Bavistin DF treated media, the fungus did not produce conidia. The percent inhibition of radial growth of the fungus was increased with the increasing concentrations of fungicide.