• Volume 76, Issue 3

      September 1972,   pages  85-132

    • Observations on comparative propensities for carp fry destruction by adults and last instar preimaginal stages of predatory aquatic insects

      G A Shirgur H G Kewalramani

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      1. Studies on comparative propensities for carp fry destruction by preimaginals and imaginals of both Heteroptera and Coleoptera and Odonatan nymphs, have been made under laboratory conditions.

      2. It was seen that Coleopterans, especially theCybister larvae, have been the most predaceous of all the insects, whereas the Odonatan nymphs, the least.

      3. An interesting feature has been observed in case of the preimaginals of Coleoptera and Heteroptera. The preimaginals display more carp fry destructive tendency than their respective adults.

    • Nodulation of lucerne (Medicago sativa L.) under the influence of chlorides of magnesium and potassium

      C S Singh M Lakshmi-Kumari Amita Biswas N S Subba Rao

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      In experiments conducted under bacteriologically controlled conditions using aseptic plant culture method on agar slopes, the effects of chlorides of magnesium and potassium on nodulation of lucerne (Medicago sativa L.) were studied. Simultaneously, the effect of these salts on growth of five species of rhizobia includingR. meliloti which is effective on lucerne, was also studied with the object of finding out the effects of these salts on the bacterial and host components of a symbiotic system not excluding the effects on nodulation where both the symbionts interact. The results demonstrated that the degree of salinity conductive for optimum nodulation is definitely different from the limits of salt tolerance either ofRhizobium or the host. Further, it was noted that the host is more sensitive to KCl and MgCl2 thanRhizobium, a fact to be borne in mind in agricultural programmes on the establishment of legumes in saline soils.

    • Thyroxine and hypothalamic neurosecretory system in chick embryos

      Kamalaveni Chandrasekhar

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      Thyroxinisation of chick embryos brings about the appearance of stainable neuro-secretory material a day earlier than what is found in the control embryos. The Gomori-positive granules are found to appear first in the lateral group of neurons of the supra-optic nucleus. This is so in the treated as well as in the control embryos.

      It is observed that in the thyroxinised as well as control embryos, the fuchsinophil granules appeared much later in the paraventricular nucleus but in the thyroxinised embryos, the granules appeared consistently a day earlier than in the controls.

      The interesting phenomenon observed is that when the supra-optic nucleus got depleted of the stainable granules, the pericapillary part of the median eminence got deposited with the Gomori-positive granules. Similarly when the paraventricular nucleus got depleted, the neural lobe was seen getting filled with the fuchsinophil granules.

      In all the cases, the depletion and deposition of the stainable granules took place a day in advance in the thyroxinised embryos than in the controls. The purpose of this precocious appearance of the stainable granules in the thyroxinised embryos is inexplicable without further experimentation.

    • Studies on the inheritance of leaf blast resistance in rice

      G C Rath S Y Padmanabhan

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      Studies on the inheritance of leaf blast resistance in seven differential varieties of rice tested against two Indian isolates of the international races IA-11 add ID-1 ofPyricularia oryzae Cav. under standardized experimental conditions revealed the presence of three dominant genes, one each in Zenith. Tetep and Ginga conferring resistance to IA-11 and two, one each in Zenith and Tetep, to the race ID-1. The genes of Zenith were independent of those of Tetep. C.l. 5309 possessed inhibitory genes inhibiting the resistance of Zenith but not of Telep. Mode of segregation of resistance o Norin 20 to the race IA-11 was found to be anamolous. Studies on the crosses among susecptible varieties showed the existence of dominant genes conferring susceptibility, two each in P.I. 180061 and Yakeiko. This is a new feature of the present studies and its utility in evolving homozygous recessive resistant varieties have been pointed out.

    • Foliicolous lichens from the Palni and Nilgiri Hills, India

      Dharani Dhar Awasthi Krishna Pal Singh

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      The paper deals with 29 species of the foliicolous lichens from the Palni and Nilgiri Hills in peninsular India. Two genera—Tapellaria andByssolecania and 17 species are reported from India for the first time. Short descriptions and/or diagnostic characters are provided for each.

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