Khajista Jabeen

Antifungal compounds from Melia azedarach leaves for management of Ascochyta rabiei, the cause of chickpea blight

The antifungal activity of Melia azedarach L. leaves was investigated against Ascochyta rabiei (Pass.) Lab., the cause of destructive blight disease of chickpea (Cicer arietinum L.). Bioassay guided fractionation revealed that the chloroform fraction of the methanolic extract of M. azedarach leaves was highly effective against A. rabiei. Six compounds, namely β-sitosterol (1), β-amyrin (2), ursolic acid (3), benzoic acid (4), 3,5 dimethoxybenzoic acid (5) and maesol (6) were isolated from the chloroform fraction through column chromatography. The in vitro antifungal activity of compounds 2–5 was evaluated against A. rabiei. A commercial fungicide, mancozeb, was used as a positive control. Different concentrations of mancozeb and the isolated compounds, ranging from 0.0039 to 4 mg mL−1, were used in the antifungal bioassay, and data regarding minimum inhibitory concentration (MIC) was recorded 24, 48 and 72 h after incubation. All concentrations of mancozeb inhibited the fungal spore germination at all three incubation periods. The tested compounds exhibited variable antifungal activity against the target fungal pathogens. All compounds showed their highest antifungal activity after 24 h of incubation. Compound 2 was found to be the most effective, with an MIC of 0.0156 mg mL−1, followed by compounds 3, 4 and 5, with MIC values of 0.0312, 0.25 and 0.125 mg mL−1, respectively.

Antifungal activity of Syzygium cumini against Ascochyta rabiei–the cause of chickpea blight

Aqueous, ethanol and n-hexane extracts from leaves, fruit, root-bark and stem-bark of Syzygium cumini (L.) Skeels were tested for their antifungal activity against Ascochyta rabiei (Pass.) Lab., the cause of blight disease of the chickpea (Cicer arietinum L.). Different concentrations, namely 1, 2, …, 5% of both aqueous and the two organic solvent extracts were used in this study. Aqueous extracts of all the four test plant parts, namely leaves, fruit, stem-bark and root-bark, showed significant antifungal activity resulting in 7–30%, 22–59%, 23–39% and 21–64% reduction in fungal growth, respectively. Similarly, n-hexane stem-bark extract, and ethanol root- and stem-bark extracts also significantly suppressed the growth of target fungal species, resulting in 17–39%, 24–30% and 12–32% suppression in fungal growth.

Management of parthenium weed by extracts and residue of wheat

This study was carried out to investigate the prospects of using methanolic extracts and residue of wheat ( Triticum aestivum L.) for the management of parthenium ( Parthenium hysterophorus L.), one of the world’s worst weeds. In a laboratory bioassay, the effect of methanol extracts of 1, 2, 3, 4 and 5% (w/v) concentrations of four wheat varieties namely: AS 2002, Inqalab 91, Ufaq and Uqab was studied against the germination and seedling growth of parthenium. Extracts of all the four wheat varieties suppressed germination as well as root and shoot growth of the seedlings. In soil amendment bioassay, dried and chopped wheat straw of the four test wheat varieties was thoroughly mixed in pot soil at 0.5, 1.0 and 1.5% (w/w). Pots were irrigated with tap water and left for one week followed by sowing of seeds in these pots. The effect of residue incorporation of all the wheat cultivars was insignificant on germination of parthenium seeds. However, all the residue incorporation treatments significantly reduced the survival percentage of the parthenium seedlings. Root and shoot growth in terms of length, and fresh and dry biomass were also significantly suppressed by residues of all the four test wheat cultivars. This study concludes that parthenium weed can effectively be managed by amending the soil with wheat residue. Key words : Non-chemical weed control, parthenium, wheat residue.

BIOPESTICIDAL ACTIVITY OF Calotropis procera L. AGAINST Macrophomina phaseolina

Background: Mungbean [Vigna radiata (L.) Wilczek] is an important pulse crop globally. This imperative crop is severely affected by charcoal rot disease caused by Macrophomina phaseolina (Tassi) Goid. In the present study, the leaves of Calotropis procera L. were tested for their antifungal potential against M. phaseolina. Materials and Methods: Various concentrations i.e. 1%, 2.5%, 4%, 5.5% and 7% of methanolic extract of C. procera leaves were prepared and their in vitro bioactivity was examined against the test fungus. Methnolic leaf extract was partitioned using n-hexane, chloroform, ethyl acetate and n-butanol and antifungal activity of each fraction was evaluated. n-Hexane fraction was subjected to GC-MS analysis. Results: The higher concentration of methanolic leaf extract (7%) caused maximum inhibition in the diameter of M. phaseolina i.e. 38%. The n-hexane fraction of methanolic leaf extract was found to be the most effective against M. phaseolina. Seven compounds belonging to classes of chlorocarbon, aromatic hydrocarbon, azocompounds, aromatic carboxylic acids and fatty acids were identified in GC-MS analysis of n-hexane fraction. Conclusion: Antifungal activity of the methanolic leaf extract of C. procera might be due to the presence of the identified compounds in n-hexane fraction of methanolic leaf extract.