• Volume 81, Issue 5

      May 1975,   pages  187-227

    • Studies in cyperaceae - XIII. Novelties inCyperus L. subgen.Pycreus (Beauv.) C. B. Clarke

      E Govindarajalu

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      Four novelties belonging to the genusCyperus are described and illustrated from South India. Out of them two species come under the sectionFlavescentes and the other two under the sectionsPropinqui andLatespicati respectively.

    • The leaf structure inPodocarpus brevifolius (Stapf.) Foxw.

      S B Kausik

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      The family Podocarpaceae (Order Coniferales) is of great interest; its members display a wide range of morphological and structural features in their leaves. In the present study of one of the members,Podocarpus brevifolius (Stapf.) Foxw., the occurrence and characteristics of the transfusion and accessory transfusion tissues are dealt with in some detail and brief notes on stomata are included. The transfusion tissue appears in the form of lateral wing-like extensions on either side of the vascular bundle; the accessory transfusion tissue is a special structural feature extending from the midrib to the margins of the leaf. Both these tissues consist of two types of component cells, the parenchyma cells and the tracheids. They are somewhat isodiametric in the transfusion tissue, while they are long and disposed at right angles to the midrib in the accessory transfusion tissue. The tracheids of the transfusion tissue have bordered pits with circular borders and circular apertures, although oval borders with oval apertures are not uncommon; on the other hand, the tracheids of the accessory transfusion tissue show bordered pits with oval eccentric borders and oval apertures.

      The stomata are haplocheilic as in most gymnosperms and amphicyclic. Typically each stoma has four subsidiary cells of which two are lateral and two polar, but this number may often be more than four formed by divisions of the original cells. Some interesting features displayed by the stomata are described and commented upon in the paper.

    • Ecological aspects of zooplankton production off Visakhapatnam (bay of Bengal)

      K V Ramanamurty P N Ganapati

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      The quantitative distribution of zooplankton off Visakhapatnam was investigated during the period March 1968 to February 1970. The seasonal data on the parameters like surface water temperature, salinity and oxygen were recorded. The seasonal abundance of zooplankton was estimated by volume, dry weight and numerical estimation. In general, a similarity was observed in the trend of the numbers, volume and dry weight values. Peak periods of zooplankton occurred during March–April, July–August, and November–December. In general, the major and minor peaks of abundance coincided with the south-west monsoon and north-east monsoon respectively. The major fluctuations in the numbers of total zooplankters were largely due to fluctuations in the numbers of copepods. Considering the higher turnover rate consequent on higher rate of metabolism and the occurrence of several broods in a year the standing crop of zooplankton in tropical waters may be actually more than in temperate waters. The factors which may be responsible for the variation in the quantitative abundance of the zooplankton, during the two monsoon currents, in the present area are discussed.

    • Effect of leaf diseases on grain yields of some varieties of sorghum

      H C Sharma N K Jain

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      Correlation and regression studies on intensity of leaf diseases and grain yields have been carried out in 5 varieties of sorghum. A negative correlation existed between disease intensity and grain yields. The lowest negative regression coefficient was found in variety CK 60 B 1·63, 0·198 followed by 302 4·27, 1·01; Pila amla 5·7; PJ 4 K 10, 0·77; and Vidisha 60-1 25; in increasing order. The maximum loss sustaining ability was exhibited by 302 (55 and 37·96%), followed by Pila amla (31·01%), PJ 4K (26·46 and 19·28%), CK 60 B (23·10 and 20·16%) and Vidisha 60-1 (12·20%) in decreasing order.


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