• Volume 91, Issue 3

      June 1982,   pages  175-280

    • Photoperiodic control of extension growth, bud dormancy and flowering ofNerium indicum Mill. andThevetia peruviana Schum.

      Kushal Singh Surinder Kumar K K Nanda

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      Plants ofN. indicum andT. peruviana grew taller and produced more leaves underld than undernd condition. WhileT. peruviana plants were taller and had more leaves undernd than undersd, those ofN. indicum did not differ under the two photoperiods. In both caseslds delayed the onset of bud dormancy but hastened the initiation of floral buds. While inT. peruviana floral buds were not formed undersd condition, inN. indicum floral buds were formed but they did not develop into flowers. While inN. indicum more flowers were produced underld than undernd condition, inT. peruviana the number produced was higher undernd than underld condition.

    • Interaction of kinetin with B group vitamins on the seedling growth of green gram (Phaseolus radiatus L.)

      P Gopala Rao J Kodandaramaiah

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      Kinetin (50 and 100 mg 1−1) inhibited both the shoot and the root growth. Inhibition of root growth by kinetin is considered to be mainly due to inhibition of protein synthesis. Vitamins of the B groupviz., riboflavin, thiamin, niacin and pantothenic acid are found to be antagonistic to kinetin in reversing the inhibition of protein synthesis of the root. Vitamins, probably by acting as inducers of protein synthesis, antagonized the action of kinetin. The response of kinetin to shoot protein content is different from that of the root.

    • Leaf architecture of Apocynaceae

      J S S Mohan J A Inamdar

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      Leaf architecture including venation pattern has been studied in 19 genera and 29 species of the Apocynaceae. The leaves are simple, alternate, opposite or whorled with entire margin and a simple midrib. The major venation pattern conforms to pinnate camptodromous type with festooned brochidodromous secondaries. The qualitative and quantitative features are charted. The leaf size, areole size, number of vein endings entering the areoles and number of vein terminations entering the areoles vary from species to species even within the same species. The highest degree of vein order is observed up to 7°. Isolated tracheids, isolated vein endings, isolated free vein endings and tracheoidal elements are noticed. Bundle sheath cells ensheaths all category of veins.

    • Impact of extension growth and flowering on the cambial activity ofDelonix regia Rafin.

      A K M Ghouse Shamima Hashmi

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      Shoot growth inDelonix regia takes place in three distinct flushes, the first commencing in mid-March, the second in late May and the third in October. The cambial reactivation starts in April after the initiation of the first flush of shoot growth, but the addition of new vascular derivatives does not take place until the second flush of shoot growth has occurred. Heavy flowering which ensues following first flush of shoot growth seems to delay cell divisions in cambial initials in April. Once the formation of cambial derivatives starts, it continues till mid-November whence the cambium enters the dormant phase. Xylogenesis begins from July and the formation of phloem in October, while the precursor phloem differentiates in early April.

    • Pharmacognostic studies on the flower ofMesua ferrea L.

      Usha Shome Shanta Mehrotra H P Sharma

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      Stamens ofMesua ferrea L. constitute the genuine ‘Nagkeshara’ of Ayurveda, a drug considered to be astringent, stomachic and expectorant. The present communication deals with detailed pharmacognosy of the drug and includes morphological, anatomical as well as certain phytochemical characters of the floral parts ofMesua ferrea. Some of the distinguishing characters are: cortical fibbres, numerous resin canals and calcium oxalate crystals in the cortex and pith of the pedicel; anamocytic, anisocytic or paracytic stomata on sepals and petals; and 3-(4-) zonocolporate pollen grains with reticulate exine surface. Fluorescence analysis, behaviour of the drug with certain chemical reagents and thin layer chromatography were also carried out.

    • Effect of CO2 in ovecroming self-incompatibility barriers inBrassica campestris L. var. toria

      A S Dhaliwal C P Malik

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      CO2 mediated induction of pollen adhesion, germination, tube penetration, tube growth through the stylar tissue and seed set was studied inBrassica campestris L. var. toria following incompatible pollination. This report stresses the effect of CO2 not at a single step but at various levels which normally prevent and/or hinder successful fertilization and seed set. The possible role of CO2 in overcoming these barriers is discussed.

    • Pharmacognosy of the stems ofPortulaca quadrifida L. andPortulaca oleracea L.

      J Lal A M Khan

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      Pharmacognostic details of the stems ofP. quadrifida L. andP. oleracea I are reported to distinguish one from the other.

    • Structure and function of a sub-tropical humid forest of Meghalaya I. Vegetation, biomass and its nutrients

      Jasbir Singh P S Ramakrishnan

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      The peripheral disturbed zone of a 50-year old stand of the forest at Lailad was dominated byDendrocalamus hamiltonii, an early successional bamboo characteristic of a secondary successional fallow of not more than 20–25 years while the central undisturbed zone hadSchima wallichii, Castanopsis indica andShorea robusta as important components. The biomass of the forest was computed as 137×108 kg/ha of which 64.7% was in the central zone. The contribution by different species both in the central and peripheral zone of the forest was worked out. Linear relationship betweendbh/d2h and biomass was worked out for different species. The standing crop had: N, 953; P, 284; K, 600; Ca, 2281; and Mg, 450 kg/ha, of which 60% was in the central zone of the forest.

    • Structure and function of a sub-tropical humid forest of meghalaya II. Litter dynamics and nutrient cycling

      Jasbir Singh P S Ramakrishnan

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      The litter production in a 50 year old humid sub-tropical forest at Lailad was found to be 5.5 t/ha/yr, 77% of which was through leaf and the remainder through wood. Litter production was more in the peripheral disturbed zone compared to the undisturbed central zone which is related to the successional status of the community. Species differences in the rate of decomposition of litter was noted. Besides litter production and decomposition pattern were related to seasonal differences in temperature and humidity. The present results have been discussed in the light of the data from other studies done elswhere.

    • Structure and function of a sub-tropical humid forest of Meghalaya III. Nutrient flow through water

      Jasbir Singh P S Ramakrishnan

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      This paper deals with water and nutrient flow through incident rainfall, throughfall and stemflow through a 50-year old stand of forest at Lailad. A larger proportion of water was accounted as throughfall and stemflow in March-April and was related to canopy density and this was inversely related to interception loss which was maximum in December. Many of the nutrient concentrations like that of N, K, Ca, etc. increased with the maturation of the leaves during October–November. Though concentration of nutrients was higher in stemflow, the total quantity was morevia throughfall because of larger quantity of water passing through this compartment. More of Ca and K was lost through run-off and percolation due to greater release of these nutrients through litter. The significance of these results have been discussed in the context of secondary succession after slash and burn agriculture (jhum) of which this forms a later stage of community development.

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