• Karan Singh

      Articles written in Proceedings – Plant Sciences

    • Some histochemical observations on leaf abscission zone inCapsicum annuum L.

      Karan Singh Y S Murty

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      The present observations were conducted on NP 46-A and Pusa jwala varieties ofCapsicum annuum L. Investigations on changes in cell wall components of the cells of leaf abscission zone associated with the process of abscission were based on specific qualitative histochemical staining procedures. It was observed that the loss of pectic and cellulosic substances preceded the separation phase of abscission from middle lamella and cell walls of the cells of separation layer of abscission zone. The abscission zone was characterized by thin cutin deposition on epidermal cells and poor lignification in vascular elements of this region. Separation of senescent part of petiole was followed by deposition of suberin in cells of some outer layers of abscission zone and by the deposition of lignin in cells of the remaining layers of abscission zone to form a protection layer on exposed part of petiole stump. Development of tyloses, tannins and calcium oxalate crystals was not found associated with abscission in the present plant material.

    • Petiolar abscission responses to hormonal treatments inCapsicum annuum L. varieties

      Karan Singh Y S Murty

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      Debladed petioles of pot cultured plants, entrained into one-stemmed habit and two-stemmed habit of PN-46-A and Pusa jwala varieties of Chilli (Capsicum annuum L.) were treated with lanolin+growth hormone emulsion. It was observed that morphactin, cytokinin and auxin retarded petiolar abscission in both the varieties and methods while ethylene, gibberellin, abscisic acid and ascorbic acid accelerated the abscission of all the petioles tested for the purpose. Relative merits and demerits of the methods used are discussed in relation to alternate leaf arrangement in the present experimental plant material.

    • Abscission responses of petiolar explants ofCapsicum varieties to treatments with growth substances and their combinations

      Karan Singh Y S Murty

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      The abscission responses of petiolar explants of NP 46-A and Pusa jwala cultivars of chilli (Capsicum annuum L) to proximal and distal applications of growth substances were investigated. Ethephon, abscisic acid and ascorbic acid proved to be accelerants of abscission irrespective of age of explants and site of application. The synthetic auxin (naphthalene acetic acid) retarded abscission in younger explants regardless of the site of application but in the older explants proximal application of the auxin promoted abscission while distal application retarded the process. Gibberellic acid showed effects opposite to those caused by the auxin. The proximal application of gibberellic acid retarded abscission irrespective of age of explants while distal application effectively accelerated abscission. The cytokinin (benzyl adenine) and morphactin delayed abscission of petiolar explants on distal as well as proximal applications. The abscission responses to combinations of growth substances were highly variable depending on the age of explants, site of applications and varietal source of experimental material. The morphactin and benzyl adenine exhibited additive interaction in retarding the abscission up to such extent that ethephon and abscisic acid could only partially counteract their effects in combination of two growth substances. The auxin and gibberellin showed irregular and mixed interactions with other bioregulants studied.

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