Volume 95, Issue 6
December 1985, pages 357-459
pp 357-363 December 1985
InArachis hypogaea (Papilionoideae, Leguminosae), the stigma is of the dry papillate type. The papillae are multicellular and multiseriate. They are covered with a thin lining of pellicle which responds for proteins, non-specific esterases and acid phosphatases. The style is 3–6 cm long and hollow throughout its length. The stylar canal is bordered by a layer of canal cells. The canal cells in most of the stylar region are not glandular, they are vacuolate with scant cytoplasm. The canal cells at the base of the style, however, are glandular with dense cytoplasm and prominent nuclei. The structural features of the pistil ofArachis are discussed with those of other Papilionoideae.
pp 365-371 December 1985
Plagiochasma intermedium grows commonly in various parts of the country with minor local variations. A critical assessment of the taxonomically significant characteristics show that the plants growing in western Himalaya, central India and peninsular India, with elaters devoid of thickening bands, are all referable to this species. Thesem details of the spore also confirm this conclusion.
pp 373-377 December 1985
Sonchus oleraceous Linn. The cytological study of a few of the collections ofSonchus oleraceous has been carried out. All the collections ofSonchus oleraceous showed 2n=32 chromosomes. ‘Chromosome mosaics’ is noticed in one of the root tip studies. There is a wide range in variation with regard to the position of centromeres in the chromosomes of the somatic complement. Sixteen bivalents are counted at diakinesis. Occurrence of ‘chromosome mosaics’ has been discussed.
pp 379-387 December 1985
The development of gametophytes, initiation of integuments and embryogeny are described inMicrostylis cylindrostachya. The anther wall consists of an epidermis, fibrous endothecium, one middle layer and secretory tapetum with uninucleate cells. Its development corresponds to the Monocotyledonous type. Cytokinesis is simultaneous. The microspore tetrads are decussate, isobilateral and tetrahedral. At shedding, the pollinia are 2-celled. The ovules are anatropous, bitegmic and tenuinucellate. Both the integuments are dermal in origin. Development of the female gametophyte is of the Monosporic type. Double fertilization occurs. The primary endosperm nucleus degenerates. Development of the embryo corresponds to the Asterad type. The mature embryo is undifferentiated. The seed is non-endospermic and the seed coat is formed entirely by the outer layer of the outer integument.
pp 389-403 December 1985
The paper examines the effect of water stress and clipping treatments on growth behaviour and nutrient value of 4 grasses, viz.,Lolium perenne, Poa pratensis (both C3 plants),Chloris gayana andPanicum coloratum (both C4 plants).
Biomass, net production, relative growth rates were affected more markedly and adversely in the two C4 species due to water stress. The effect of clipping varied with species and was generally more marked and adverse in two C4 species. The C3 plants developed higher R:S ratio under water stress. Water stress resulted in a greater decline of total non-structural carbohydrate and protein content in the two C4 species. Clipping affected adversely the nonstructural carbohydrate content and again the effect was more marked in the two C4 species. On the other hand, protein content in shoots of all plants increased due to clipping.
pp 405-407 December 1985
Disruption of leaf cell membranes was studied after the foliar application of isoproturon [N-(4-isopropyl phenyl)-N,N-dimethyl urea] through the parameters of electrolyte leakage and the quantity of efflux in ions. Differential activity of isoproturon, on leaf cell membranes ofSida acuta, cleome viscosa andAmaranthus viridis was observed. A high degree of correlation of resistance or susceptibility of a particular plant to the herbicide with appropriate change in electrolyte leakage and efflux of ions was observed.
pp 409-415 December 1985
Decomposition of 3 leaf litter species, viz,Datura inoxia, Solanum sysimbrifolium and mixed grass were studied. Within 150 days, about 90% ofDatura, 66% ofSolanum and 51% of mixed grass litter disappeared. Mean relative decomposition rate was higher during rainy season for all the 3 litter species. From the stepwise multiple regression analysis it was concluded that in arid to semi-arid locality decomposition process is mainly controlled by soil moisture.
pp 417-427 December 1985
Acquired resistance to the antibiotic cycloheximide developed byNeurospora crassa andSclerotium rolfsii was studied. Both the fungi gained certain level of tolerance to the antibiotic just after a single exposure and by serial transfers could adapt to the several-fold initial inhibitory dosage. Cycloheximide-resistance in both the cases was not a stable characteristic and was lost gradually on serial transfers in fungicide-free media. The resistant strains of both the fungi showed poor growth and decreased sporulation or sclerotia formation in fungicide-free media.Sclerotium rolfsii developed cross-resistance to Difolatan but not to Polyoxin-D, Hinosan and Bayleton. The cycloheximide-resistance inSclerotium rolfsii was probably due to the conversion of cycloheximide into isocycloheximide which is a less toxic structural analog, as revealed by thin layer chromatographic studies of culture filtrates of resistant and sensitive strains. The resistant strain ofSclerotium rolfsii retained its pathogenicity to tomato, mustard and chilli seedlings. However, the loss of sclerotia forming capacity and the instability of the acquired resistance trait may prove to be of ecological disadvantage to the resistant strain.
pp 429-436 December 1985
The palmately compound leaf ofTabebuia pentaphylla is initiated by periclinal division in the hypodermal layer at the flank of the maximal shoot apex, which lacks cytohistological zonation. The growth of the leaf primordium is diffuse until it reaches a height of 50–60 μm after which an adaxial meristem makes it conspicuously thick at the basal region. The first pair of lateral leaflets arise about 50 μm below the tip of the leaf primordium when the latter is about 150 μm high and before the differentiation of a well defined marginal meristem. The second pair of leaflets arises subsequently below the first. The terminal portion becomes the central leaflet. The sites of leaflet initiation are the terminal endings of acropetally differentiating procambial strands. The 6-layered plate meristem of the leaflet lamina arises from a marginal meristem whose submarginal initial is wedge shaped. Leaflet venation is comptodromous and the ultimate areoles lack free vein endings.
pp 437-440 December 1985
The thermotropic phase transition temperature in the Chloroplast envelope membrane ofMimosa pudica has been measured using a fluorescent probe pyrene, for the first time. RCA1-induced agglutination does not change the fluidity picture in general but reduces the fluidity uniformly throughout the whole range of temperature (15°–55°C). The turbidimetric assay of this agglutination reveals that this is less in case of membrane than in liposome, for which several explanations are discussed. Also, we have shown that divalent cations, like Ca2+ and Mg2+ do not affect the lectin-induced agglutination.
pp 441-451 December 1985
Seeds of kail collected from 10 localities in the western Himalaya were germinated at 4 temperatures viz 20°, 28°, 34° and 40°C after storage in dry cold conditions in freezer. The seed lots representing different localities differed in the capacity and rate of germination. At lower temperature of incubation (20°C) most of the seed lots exhibited varying degree of dormancy. This dormancy could be revoked by chilling imbibed seeds for 2 weeks at 3–5°C. At higher temperatures of incubation the seed lots did not exhibit dormancy, although the optimum conditions for germination were provided by a combination of prechilling and higher temperatures of incubation (28° and 34°C). Treatments such as prolonging the stratification period up to 38 days, soaking in GA 100 mg/litre, with or without prechilling, and in 1% H2O2, did not have any significant effect on germination. The study revealed seed source variation in the degree of dormancy at low temperature of incubation.
pp 453-459 December 1985 Review
Endogenous levels of phytohormones like auxin, gibberellin, cytokinin, abscisic acid and ethylene appear to determine the fate of flower sex primordia. Higher levels of auxins, cytokinins and ethylene have been found to be correlated with female sex expression whereas a greater amount of gibberellins favours the differentiation of male sex organs. It appears that the phenotypic expression of flower sex is controlled by a balance between male-promoting and female-promoting hormones. Variations occurring with regard to amino acids, proteins and enzymes/isozymes during the reproductive phase may also have a prominent role in determining the nature of the flower sex.