Mohd Yaqub Bhat

Bio-activity of fungal culture filtrates against root-knot nematode egg hatch and juvenile motility and their effects on growth of mung bean (Vigna radiata L. Wilczek) infected with the root-knot nematode, Meloidogyne incognita

Culture filtrates of selected soil fungi, namely Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium oxysporum, Penicillium vermiculatum and Rhizopus nigricans exhibited variable response to egg hatching and mortality of the root-knot nematode, Meloidogyne incognita. Higher concentrations of the culture filtrates of all the fungi inhibited egg hatching and proved to be toxic to the juveniles of M. incognita. In addition, development of the gall and multiplication of M. incognita were also found adversely affected in varying degrees on all the plants of Vigna radiata treated with the filtrates. The culture filtrate of A. niger showed highest toxicity to the nematode than those of any other fungus tested. Soil drench application of the culture filtrates gave better seedling growth and least nematode multiplication in comparison to seed soaking treatment.

Preparation, characterization and antifungal activity of iron oxide nanoparticles

Iron oxide nanoparticles with particle size 10-30 nm were prepared by a green approach using tannic acid as reducing and capping agent. These nanoparticles were characterized by X-ray diffractometry (XRD), high resolution field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The prepared iron oxide nanoparticles were also evaluated for their antifungal activity against Trichothecium roseum, Cladosporium herbarum, Penicillium chrysogenum, Alternaria alternata and Aspergillus niger. The antifungal activity was observed as inhibition in spore germination and by determining the zone of inhibition of fungal pathogens caused by different concentrations of iron oxide nanoparticles on culture media. It was observed from the present study that Fe2O3 nanoparticles showed significant antimycotic activity against all the tested fungal pathogens. Highest inhibition in spore germination was caused against T. roseum (87.74%) followed by C. herbarum (84.89%). The highest zone of inhibition by iron oxide nanoparticles was reported against P. chrysogenum (28.67 mm) followed by A. niger (26.33 mm), T. roseum (22.67 mm), A. alternata (21.33 mm) and least against C. herbarum (18.00 mm). Activity index was recorded highest against P. chrysogenum (0.81). The MIC value of Fe2O3 NP varies between 0.063 and 0.016 mg/ml for different fungal pathogens that is comparable with the MIC value shown by the standard, revealing the efficacy of iron oxide NPs against different fungal pathogens.

First report of Penicillium glaucum Link causing Penicillium rot of pear fruits Pyrus communis L. in Jammu and Kashmir, India

Pears Pyrus communis L. collected from different sites of Kashmir Valley were found infected with Penicillium glaucum causing Penicillium rot. The diseased fruits appears light tan to dark brown. The decayed tissue becomes soft, watery and the lesion has a very sharp margin between diseased and healthy tissues. Decayed fruit has an earthy, musty odor. The pathogen was isolated and cultured on PDA medium for further fungal morphological observation and confirming its pathogenicity according to Koch’s postulates. Results of morphological data and pathogenicity test showed that the pears were infected by Penicillium glaucum Link resulting in Penicillium rot of pears. To our knowledge, it is the first report of pear fruit rot caused by P. glaucum in India. Study was also undertaken for the management of Penicillium rot of pear with some fungicides. It was revealed from the study that different concentration of fungicides brought about significant reduction in the mycelial growth and spore germination of Penicillium glaucum under in vitro conditions. Amongst the tested fungicides, carbendazim proved highly effective in inhibiting the mycelial growth and spore germination of Penicillium glaucum followed by hexaconozole, bitertanol and myclobutanil respectively. Higher concentration proved effective than lower concentrations.

The effect of Meloidogyne incognita on the histopathology of Momordica charantia roots

Bitter gourd (Momordica charantia L.) was inoculated with root-knot nematode Meloidogyne incognita to investigate the anatomical abnormalities in the affected roots. Soon after inoculation the second-stage juveniles (J2) entered at or near the root caps and migrated intercellularly towards the zone of vascular differentiation. Discrete giant cells were observed after three days of inoculation. The nematode induced hypertrophy and hyperplasia near the giant cells. After six days, the juveniles moulted to their third stage (J3). At the same, time giant cell size and density of giant cell cytoplasm increased. The continuity of vascular strands remained unaffected. Between 12 and 24 days of inoculation the giant cells enlarged several times and became multinucleate and enclosed dense and granular cytoplasm. The nematodes became almost pyriform 18 days after inoculation. The orientation of vascular strands changed, due to hypertrophy, hyperplasia and enlargement of the nematode. After 30 days of inoculation the nematodes developed into mature females and started egg laying. A large amount of parenchyma transformed into abnormal xylem.