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Nidiry E.S.J.,Indian Institute of Horticultural Research
Magnetic Resonance in Chemistry | Year: 2012

Octadecyl p-coumarates undergo E-Z isomerization in daylight. Although 1H NMR, 13C NMR and 1H-1H COSY gave indications about this isomerization, the overlapping of some signals in the 1H NMR of aromatic region prevented the delineation of signals of the individual isomers. However, heteronuclear spin quantum coupling correlation (HSQC) with the unique feature of two sets of nearby δC- δH correlations gave conclusive evidence for this isomerization and helped in the delineation of 1H NMR and 13C NMR signals of E-octadecyl p-coumarate and Z-octadecyl p-coumarate. Copyright © 2012 John Wiley & Sons, Ltd.

The study was undertaken with a view to unravel the source of bacterial colony growth observed in a section of micropropagated triploid watermelon cultures that were supposedly cleansed of the associated endophytic bacteria through antibiotic treatment, and thereafter maintained under stringent sterility checks to prevent lateral intrusion of contaminants. Five different bacteria were retrieved from colony growth-displaying watermelon cultures that were previously treated with gentamycin and five isolates from cefazolin-treated stocks with the organisms showing tolerance to the respective antibiotic. These watermelon cultures were in degeneration phase (over 6 months after the previous sub-culturing), while the actively maintained counterpart stocks appeared healthy with no colony growth on different bacteriological media during tissue-screenings. The latter cultures, however, revealed abundant motile, tetrazolium-stained bacterial cells in microscopy, suggesting tissue colonization by non-culturable endophytes. PCR screening on healthy cultures endorsed tissue colonization by different bacterial phylogenic groups. A few organisms could be activated to cultivation from healthy watermelon stocks through host tissue extract supplementation, which also enhanced the growth of all the organisms. The study indicated that a fraction of antibiotic-tolerant bacteria survived intra-tissue in non-culturable form during the preceding cleansing activity, multiplied to substantial numbers thereafter, and turned cultivable in degenerating cultures contributed by tissue breakdown products. This study brings out the existence of a deep endophyte association in tissue cultures which is not easily dissociable. It also signifies the utility of in vitro system for investigations into plant-endophyte association and to bring normally non-culturable novel organisms to cultivation facilitating their future exploitation. © 2011 Springer-Verlag.

Mohapatra S.,Indian Institute of Horticultural Research
Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes | Year: 2014

The persistence and dissipation kinetics of trifloxystrobin and tebuconazole on onion were studied after application of their combination formulation at a standard and double dose of 75 + 150 and 150 + 300 g a.i. ha-1. The fungicides were extracted with acetone, cleaned-up using activated charcoal (trifloxystrobin) and neutral alumina (tebuconazole). Analysis was carried out by gas chromatograph (GC) and confirmed by gas chromatograph mass spectrometry (GC-MS). The recovery was above 80% and limit of quantification (LOQ) 0.05 mg kg-1 for both fungicides. Initial residue deposits of trifloxystrobin were 0.68 and 1.01 mg kg-1 and tebuconazole 0.673 and 1.95 mg kg-1 from standard and double dose treatments, respectively. Dissipation of the fungicides followed first-order kinetics and the half life of degradation was 6-6.6 days. Matured onion bulb (and field soil) harvested after 30 days was free from fungicide residues. These findings suggest recommended safe pre-harvest interval (PHI) of 14 and 25 days for spring onion consumption after treatment of Nativo 75 WG at the standard and double doses, respectively. Matured onion bulbs at harvest were free from fungicide residues. © 2014 Copyright © Taylor & Francis Group, LLC.

Mohapatra S.,Indian Institute of Horticultural Research
Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes | Year: 2011

Flubendiamide is a new insecticide that has been found to give excellent control of lepidopterous pests of tomato. This study has been undertaken to develop an improved method for analysis of flubendiamide and its metabolite des-iodo flubendiamide and determine residue retention in tomato and soil. The analytical method developed involved extraction of flubendiamide and its metabolite des-iodo flubendiamide with acetonitrile, liquid-liquid partitioning into hexane-ethyl acetate mixture (6:4, v v 1) and cleanup with activated neutral alumina. Finally the residues were dissolved in gradient high pressure liquid chromatography (HPLC) grade acetonitrile for analysis by HPLC. The mobile phase, acetonitrile-water at 60:40 (v v 1) proportion and the wavelength of 235 nm gave maximum peak resolution. Using the above method and HPLC parameters described, nearly 100 % recovery of both insecticides were obtained. There was no matrix interference and the limit of quantification (LOQ) of the method was 0.01 mg kg 1. Initial residue deposits of flubendiamide on field-treated tomato from treatments @ 48 and 96 g active ingredient hectare 1 were 0.83 and 1.68 mg kg 1, respectively. The residues of flubendiamide dissipated at the half-life of 3.9 and 4.4 days from treatments @ 48 and 96 g a.i. ha 1, respectively and persisted for 15 days from both the treatments. Des-iodo flubendiamide was not detected in tomato fruits at any time during the study period. Residues of flubendiamide and des-iodo flubendiamide in soil from treatment @ 48 and 96 g a.i. ha 1 were below detectable level (BDL, < 0.01 mg kg 1) after 20 days. Flubendiamide completely dissipated from tomato within 20 days when the 480 SC formulation was applied at doses recommended for protection against lepidopterous pests.

Mohandas S.,Indian Institute of Horticultural Research
Scientia Horticulturae | Year: 2012

The rhizospheres of three year old-mango (Mangifera indica L.) rootstocks namely, Vellakulamban, Bappakai, Olour, Chandrakaran, Necker, Peach, Totapuri and Vellakulamban were studied for the spore load of arbuscular mycorrhizal (AM) fungi and root colonization at 15. cm, and 30. cm depths. Mycorrhizal spores were highest in Totapuri followed by Bappakai, Olour and Peach and Vellakulamban at 15. cm depth. Spores belonged to the genera Glomus and Acaulospora and few other genera, the predominant ones being Glomus fasciculatum and Glomus mosseae as identified by their morphology. The colonization of the root was higher in Vellakullamban and Totapuri rootstocks. Frequently occurring AM species were initially multiplied on finger millet (Eleucine coracona L.) in paper cups filled with soilrite and then in 12. in. pots that contained 1:1 sand soil mixture. The rootstock cultivars predominantly used for grafting mango scions in southern India were screened for their response to AM inoculation in pot culture. All the rootstock seedlings responded to mycorrhizal inoculations showed varied intensity of root colonization and improved plant height, growth and nutrient content compared to non-mycorrhizal in pot culture. Under field conditions, rootstock cv Totapuri inoculated with AM fungi and scions of mango hybrids Arka Aruna and Arka Puneeth grafted on them produced shoots earlier compared to non-mycorrhizal plants. Within two years of application of AM fungi yearly, clear difference in growth performance of mycorrhizal and nonmycorrhizal plants was observed. Plant growth studied in terms of number of branches, available soil P, leaf P, Zn and Cu improved significantly in AM colonized plants compared to uninoculated plants. This trend continued in the 8th year of sampling. The root acid and alkaline phosphatase activity was higher in six month old Arka Puneeth grafted on AM colonized Totapuri rootstock. Mycorrhizal inoculums can be easily multiplied on-farm on finger millet and applied yearly for desired results. © 2012 Elsevier B.V.

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