• Volume 78, Issue 5

      November 1973,   pages  195-239

    • Dichotomous venation and anastomosis in the corolla of an orchid—Habenaria dentata (SW.) Schltr

      K Subramanyam N C Nair

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      The lip of the corolla inHabenaria dentata (Sw.) Schltr. is tripartite. The lateral lobes show dichotomously branched veins. While the majority of the vein-endings are related to crenulation in the corolla and terminate at the tip, others end blindly. Usually each crenulation receives one vein. In exceptional cases two veins enter a crenulation. Cases of veins ending beneath an incision (sinus) separating two crenulations have been observed. Sinus vein dichotomies are present. Nine types of anastomoses are described. In Type I, two branches of a single vein-dichotomy remain united. Type II is characterized by the union of adjacent branches of two vein dichotomies and their separation. Type III is similar to Type II but the branches do not separate after confluence. In Type IV an arcuate vein unites with the branch of contiguous vein dichotomy and then separates. Type V is similar to Type IV but the fused branches do not separate. Type VI is formed by the union of the outer branch of a second order vein-dichotomy and the outer branch of a first order vein-dichotomy. In Type VII one outer branch each of two adjacent second order vein-dichotomies unite and separate. Type VIII is similar to Type VII but the branches do not separate after confluence. In Type IX the outer branch of a third order vein-dichotomy and the outer branch of a second order vein-dichotomy unite and separate after a short area of confluence. Cases of vein-approximations also have been observed.

    • Biometrical studies on the length-height relationship in two species of wood-boring pholads of east coast of India

      V V Srinivasan

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      A comparative study of the length-height relationship in the woodboring pholadsMartesia striata andMartesia fragilis occurring at the harbour and the open coast has been made.

      In both the species in the burrowing phase, the length-height relationship is linear and the rate of enange of height per nnit length does not differ appreciably. In the resting stages, while there is approximately a proportional increase in height of the shell per unit increase in length inMartesia fragilis, it was noted that there is no uniform rate of increase inMartesia striata. The rate of increase of height diminishes for greater lengths of the shell.

    • Individual behaviour of some legumes in monocultures related to growth rate

      P S Ramakrishnan

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      The three leguminous species under consideration here, whilst having a number of common behavioural features in monocultures also show differences with regard to mortality, plasticity and productivity which could be related to the growth rate of the species concerned. Thus it is seen that the density-induced mortality is much higher in fast growing species as compared to the one with slower growth rate with the result that in the former species there was an ultimate reduction in population size at very high densities. Not only was the dry weight yield different at low and high nutrient levels in the soil for all the species, but in the case of the fast growing species likeCassia the dry weight yield/m2 declined significantly at very high densities whereas in the case of the slow-growing one it tended to level off. The seed output/m2 tended to decline at very high density in all the species but this decline was most pronounced in the case of the fast-growing species. The significance of these results are discussed.

    • Effect of various trace elements on the growth and sporulation ofClaviceps Microcephala andMicroxyphiella hibiscifolia

      K S Thind Mira Madan

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      Out of fifteen trace elements tested, Fe, Zn, Mn and Cu were found to be essential for the growth as well as sporulation ofClaviceps microcephala andMicroxyphiella hibiscifolia; Mo forC. microcephala but not forM. hibiscifolia; Ca forM. hibiscifolia but not forC. microcephala. No other trace element was found to be essential for either of these fungi. Optimum concentrations in ppm of essential trace elements were found to be as follows:C. microcephala, Fe 0·2, Zn 0·1, Mn 1·0, Cu 0·01 (0·01–0·1) and Mo 1·0;M. hibiscifolia, Fe 0·01 (0·01–0·1), Zn 10·0, Mn 1·0, Cu 10·0 and Ca 10·0. Concentrations higher than the optimum were progressively inhibitory to the respective fungi.

    • Studies on incidence of anthracnose of soybean in a fertility inoculumvarietal trial

      M L Verma A R Upadhyay

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      Anthracnose disease of soybean [Glycine max(Linn.) Merrill] caused byColletotrichum dematium var.trauncatum (Schw.) V. Arx. was observed to cause leaf spot, stem die-back and pod blight and seed rot at Raipur inKharif (1968). The incidence of pod blight and stem die-back was recorded to be more in Clark-63 than Bragg variety under different doses of rhizobium culture, nitrogen and phosphorus application. However, the differences due to the varying doses of nitrogen and phosphorus were nonsignificant. Seed infection was 15·2 to 81·0 per cent. The weight of the diseased seed was reduced by 22·4 to 61·7 per cent.

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