Volume 82, Issue 3
September 1975, pages 77-125
pp 77-91 September 1975
Filtrates from cultures of 5Pyricularia spp. from different graminaceous hosts and, isolates ofP. oryzae from rice belonging to 10 races were analysed for phytotoxic components by thin-layer chromatography and bioassay techniques. A number of phytotoxic components including pyriculol was detected. A component which was apparently the reduced form of pyriculol was also detected in some of the toxic eluates of the chromatograms. The components could be distinguished by their characteristic UV absorption spectra. Most of the components appeared to be unsaturated and phenolic in nature. The number and nature of the components varied with the isolate, medium and cultural condition.
pp 92-99 September 1975
Four unnamed species of the subgenusEusimulium Roubaud are described and illustrated, thus bringing the number of species from nine to thirteen in the Darjeeling area of India. A key to the species of the subgenus occurring in the area is provided here.
pp 100-107 September 1975
Pueruli of the spiny lobsterPanulirus polyphagus are being reported for the first time from the western part of the Bay of Bengal, along the east coast of India. Diagnostic characters and a revised key to the identification of the known pueruli of the Indo-West Pacific species ofPanulirus are given.
pp 108-116 September 1975
Changes in the stomatal aperture and the rate of transpiration under foliar application with triazine (atrazine) urea (diuron), amide (alachlor, butachlor) and thiocarbamate (EPTC and Molinate) type of herbicides onAmaranthus viridis L.;Digera arvensis Forsk;Boerhaavia diffusa L.;B. repanda Willd.;Commelina benghalensis L.;Cyperus rotundus L.;Pisum sativum L.; andPennisetum typhoides Stapf and Hubb; were studied. It was observed that the triazine and urea herbicides have caused an appreciable stimulation of stomatal opening within two hours of chemical contact, while the amides possessed a contrasting behaviour in as much as they have brought a rapid closure of the open stomata. Thiocarbamates on the other hand have exhibited a differential response characteristically relating to the C3 or C4 type plants. The general trend observed with the thiocarbamates was that they were stimulatory for the C3 and inhibitory for the C4 plants in respect of stomatal opening.
A definite correlation of the rate of the transpiration with the stomatal response to the herbicide was found. The present study suggests that the resistance or susceptibility of the plants is determined by the selective stomatal behaviour towards different herbicides.
pp 117-125 September 1975
Three new species of strigeoid cercariae,viz., Cercariae indicae LXIII, LXIV and LXV are described.C. indicae LXIII and LXIV are pharyngeate, distomate, longifurcate furcocercous cercariae with respectively six and eight pairs of flame cells in the body.C. indicae LXV is a pharyngeate, monostomate, longifurcate furcocercous cercaria with eight pairs of flame cells in the body.C. kumaunensis, a cyathocotylid cercaria, is reported from Andhra Pradesh also. Suppression of the various sub-groups of cyathocotylid cercariae, which neither have any taxonomic validity nor indicate any phylogenetic relationship, is advocated.