Ma Ali

Plumieride fromAllamanda catharticaas an inhibitory compound to plant pathogenic fungi

Allamanda leaf extract (Allamanda cathertica) was made in water at room temperature (25 ± 2 °C) as well as in a number of less polar to highly polar solvents like methylene chloride, benzene, chloroform and ethyl acetate at their boiling point, that means, at refluxing temperature (40 ± 2 °C). Methylene chloride, benzene, chloroform, ethyl acetate and water extracts were applied to determine their growth inhibition against Phomopsis vexans, Phytophthora capsici, Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii. Results of these extracts showed that refluxing methanol, ethanol and ethyl acetate extracts of Allamanda were statistically similar for inhibition of mycelial growth of all fungi tested. But effect of 50% ethanol extract is different; it inhibited 100% mycelial growth of P. vexans, P. capsici and F. oxysporum; 83.33% of R. solani and 88.63% of S. rolfsii. Effort was also made to find out the compound in Allamanda to be responsible for such antifungal activity. Thin layer chromatography (TLC) of Allamanda extracts showed the presence of a number of compounds having polarity very high to low. The Rf values of compounds in 37–42 fractions were calculated and from these six fractions, crystals were separated. These crystals were more or less white. Melting point of these crystals was determined by ordinary and digital melting point apparatus that ranged from 145.5–162 C. Structural determination of the compound was done by Infra-red (IR) spectral study. The finger print region was 700–1400 cm−1. The strong band at 1612.4, 1633.6, 1693.4, 1655 and 2850.6 cm−1 indicated the presence of conjugated double bond (–C=C–C=C–), non-conjugated double-bond (–C=C–C–C–C=C–), carbonyl group attached to carbon–carbon double (–CO–C=C), ester (–COOR) and C–H stretching, respectively. Mass spectra of separated compounds gave molecular weight 470. All these characters are typical to pumieride as described previously. Again, In vitro screening of plumieride against P. vexans, P. capsici, F. oxysporum, R. solani and S. rolfsii were found effective in inhibiting radial mycelial growth of these fungi at 1:2 w/v concentration.

Genetic diversity of the bacterial wilt pathogen Ralstonia solanacearum using a RAPD marker

Bacterial wilt caused by Ralstonia solanacearum is a destructive disease of many economically important crop species. A significant variation in wilt incidence and severity in eggplant and potato was observed among the growing areas surveyed. R. solanacearum isolates obtained both from eggplant and potato belong to biovar III, while isolates from eggplant belong to race 1 and isolates obtained from potato belong to race 3. Random amplified polymorphic DNA (RAPD) technique was used as a tool for assessing genetic variation and relationship among seven isolate groups of R. solanacearum viz., RsB-1, RsB-2, RsB-3, RsP-1, RsP-2, RsP-3 and RsP-4, consisting in a total of 28 isolates. Out of the RAPD markers used, amplification with four decamer primers produced 70 bands with sizes ranging from 100 to 1400 bp. Out of 70 bands, 68 bands (97.06%) were polymorphic and two bands (2.94%) were monomorphic amongst the seven R. solanacearum isolates group. The Unweighted Pair Group Method of Arithmetic Means (UPGMA) dendrogram constructed from Neis genetic distance produced two main clusters of the seven isolates of R. solanacearum. The isolates RsB-1, RsB-2, RsB-3 and R-4 grouped in cluster І, while RsP-2, RsP-3 and RsP-4 grouped in cluster ІІ. The highest intra-variety similarity index (Si) was found in RsB-1 isolate (86.35%) and the lowest one in RsP-2 (56.59%). The results indicated that relatively higher and lower levels of genetic variation were found in RsP-3 and RsB-3, respectively. The coefficient of gene differentiation (G(st)) was 0.5487, reflecting the existence of a high level of genetic variations among seven isolates of R. solanacearum. Comparatively higher genetic distance (0.4293) and lower genetic identity (0.6510) were observed between RsB-2 and RsP-4 combinations. The lowest genetic distance (0.0357) and highest genetic identity (0.9650) were found in RsB-1 vs. RsB-2 pair. Thus, RAPD offers a potentially simple, rapid and reliable method to evaluate genetic diversity analysis in R. solanacearum.

Survival and transmission of Xanthomonas oryzae pv. oryzae in rice seeds

Xanthomonas oryzae pv. oryzae is a major pathogen of rice that causes bacterial leaf blight (BLB) disease and is a great threat to rice production worldwide. Transmission of X. oryzae pv. oryzae from seed to seed is remain in enigma. In this study, seed transmission was investigated to detect and identified X. oryzae pv. oryzae in rice seeds of BR11 collected from the naturally BLB infected field and the transmission of X. oryzae pv. oryzae from seed to plant to seed during November, 2014 to November, 2015 at Seed Pathology Centre, Bangladesh Agricultural University, Mymensingh. The results indicated the survival ability of X. oryzae pv. oryzae for one season to another for at least 10 months but the survivability of the bacterium decreased with the increasing of storage time. The transmission of X. oryzae pv. oryzae was carried out through transplanting of the seedlings raised from the infected seeds. X. oryzae pv. oryzae was then detected in the seeds harvested from the infected plants raised from the seedlings produced from the previously harvested BLB infected seeds. These results clearly indicated the transmission of X. oryzae pv. oryzae from seed to plant to seed carryover at least from one season to another.

Management of jute yellow mosaic virus disease through cultural practices

A field experiment was conducted to investigate the effect of some management practices to minimise jute yellow mosaic virus disease. The management practices were employed at natural condition and placed randomly with four replications. The treatments were spraying malathion 57 EC, rouging and field sanitation, top dressing of nitrogenous fertiliser, mulching with straw and untreated control. The highest percentage of mosaic incidence was recorded in control and the lowest incidence was recorded in top dressing of nitrogenous fertiliser. Among the treatments, top dressing of nitrogenous fertiliser showed the best performance in terms of increasing yield (3.05 t/ha). The second highest was obtained in rouging and field sanitation which was statistically similar to spraying malathion 57 EC. The best gross margin (

Digital image analysis to estimate the live weight of broiler

379.02/ha) and increase of gross margin (63.00%) compared to control were achieved in top dressing of nitrogenous fertiliser with the highest benefit-cost ratio (4.84). However, the treatments were found significantly profitable compared to the control indicating the usefulness of the cultural practices in integrated disease management programme for healthy and profitable jute cultivation.