Volume 90, Issue 5
October 1981, pages 389-497
pp 389-393 October 1981
Sporulation of fivePyricularia spp. on detached and injured leaf bits, and on media with leaf extracts ofCommelina benghalensis, was enhanced considerably by the leaf bits and extracts. Of the many substrates and substances reported for stimulating sporulation inPyricularia spp., detached and injured leaf bits, or leaf extracts ofC. benghalensis are commended.
pp 395-400 October 1981
Chlorflurenol (2-Chloro-9-hydroxyfluorono-9-carboxylic acid) applied at 50, 100 and 200 ppm to male plants ofMorus nigra produced intersex and female flowers. Various transitional stages of male floral primordia into intersex and female flowers were observed. However, the fruits formed by inflorescences with such flowers were abnormal in shape, size and appearance. Frequent drying of inflorescences and fruits occurred at higher concentrations and, as a result, only a few fruits ripened.
pp 401-411 October 1981
The ontogeny of the embryoids arising from a variety of somatic and male gametophytic tissues has been compared to that of a zygote embryo; it has often been stressed that a free cellrecapitulates the ontogenetic sequence of stages that are seen in the development of a zygote into an embryo. An embryoid significantly lacks a polarised ontogenetic pattern throughout the gamut of differentiation; it lacks typical centres of polar organization like the hypophysis and the epiphysis in early ontogeny; the protoderm formation is belated and also incomplete; the organization of tap root is suppressed. In spite of assuming exomorphic contours comparable with those of the gross developmental stages recognized in embryogenesis consequential to sexual fusion, the embryoid is devoid of internal differentiation both in degree and pattern. Under these circumstances the ontogeny of an embryoid never stands comparison with that of a zygotic embryo. From the morphological standpoint an embryoid is more closely related to a shoot bud.
pp 413-423 October 1981
Growth, development and carbohydrate distribution in successively developing shoots and underground parts of purple nutsedge (Cyperus rotundus L.) are described on the basis of three consecutive years of experiments in pot culture. Emphasis has been laid on the contribution of successively developing aerial shoots to the overall process of tuber development in this weed plant. Tuber development is primarily dependent on the growth and development of aerial shoots to which the tubers directly belong. Results of carbohydrate analyses together with growth and developmental pattern of aerial shoots suggest early and frequent application of herbicides if tuber formation in this plant is to be prevented in any control programme.
pp 425-433 October 1981
The wood ofBridelia retusa of the family Euphorbiaceae is nonstoried and diffuse porous. The axial parenchyma is vasicentric. Ray parenchyma is heterocellular and uniseriate or multiseriate. Fibres are enucleate and septate. The sapwood is light yellow and heartwood is greyish. The innermost sapwood is the transition zone. All the constituent cells of the heartwood are dead. Nucleus is present in both axial and ray parenchyma cells of the sapwood and transition zone. Tyloses are absent in the vessels of sapwood but are frequent in the transition zone and heartwood. Parenchyma cells and some vessels in the heartwood show accumulation of extractives. Starch and lipids are present in both axial and ray parenchyma cells of the sapwood. Peroxidase activity is detected in the xylem near the cambial zone. Acid phosphatase activity is prominent in the middle sapwood. Succinate dehydrogenase activity is maximum in the outermost sapwood.
pp 435-441 October 1981
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.
pp 443-450 October 1981
A few collections made from hill stations of Tamil Nadu are not only found to be without a name but preclude the possibility of placing this under any one of the existing sections ofFimbristylis. Therefore this situation has necessitated the creation of a new sectionIndofimbristylis in order to accommodate the new species. The anatomical data of this novelty shows an agreement with that of the genus as a whole.
pp 451-455 October 1981
The amino acid composition of the blue-green algaSpirulina platensis was determined and compared with other algal, vegetable and animal protein sources. The alga with 58·5% protein is rich in lysine and tryptophan, but deficient in sulphur containing amino acids. Of the three species ofSpirulina, S. platensis has a higher content of sulphur containing amino acids. The PER of this alga is much higher than that of other algae likeChlorella andScenedesmus.
pp 457-463 October 1981
The node in 7 species of Umbellifers is multilacunar multitrace. The number of traces increases from the lower foliar nodes reaching a maximum at the node bearing the largest foliage leaf, and then decreases gradually till the node vearing the inflorescence, which is trilacunar three trace. The vasculature of the primary rachis has many traces which anastomose to form a diaphragm at the ‘node’ where secondary rachii arise. From the diaphragm three traces go to the next distal ‘internode’ of the primary rachis but become five due to division of the lateral traces.
pp 465-470 October 1981
Age of sorghum plants is important in the development of downy mildew disease incited byPeronosclerospora sorghi. Plants inoculated just after emergence and up to 4–5 leaf stage are highly susceptible. In plants inoculated after 6–7 leaf stage, systemic symptoms were not observed but only local lesions appeared. Conidial concentration of 40/seedling brings about 100% infection if the host seedlings are inoculated through root. Systemic infection occurs in 10 and 22 days depending upon the conidial concentration. Roots of the seedlings inoculated with 1000 conidia/seedling get infected earlier. Mature conidia are highly infective compared to immature or old conidia. Soil and seed-borne inoculum can initiate both systemic and local lesion type of symptoms at any growth stage of the host plant in addition to air-borne conidia. Late expression of systemic infection can result both from air-borne conidia and oospore present in the soil or seed.
pp 471-475 October 1981
Diagnostic features of the genusLeucoscypha Boud. emend. Rifai are given and the present position of its species previously known from India but described under different genera is ascertained.L. rutilans (Fr.) Dennis and Rifai is described in detail based on collections made from the North Western Himalayas while annotated notes are included for other species. A key to separate the known species ofLeucoscypha is given.
pp 477-483 October 1981
Arundinella mesophylla n=8 andA. purpurea n=10 of the Poaceae, endemic species of South India are studied for their mode of reproduction. Meiosis in microsporocytes of these two diploid taxa is regular and produces normal spore tetrads. Development and organization of the female gametophyte conform to the monosporic Polygonum type. However,A. mesophylla produces aposporous embryo sacs in about 10% of the ovules. Occasionally two archesporial cells function and develop into embryo sacs inA. purpurea.
pp 485-497 October 1981
The structure and ontogeny of stomata on the vegetative and floral organs in nine species ofVerbena are described. The data on stomatal index, density and size and epidermal cell density and size are also tabulated. Nine types of stomata occur side by side on the same surface in different combinations. The stomatal ontogeny is mesogenous, mesoperigenous and perigenous. Stomata with common subsidiary cells, cytoplasmic connections, cuticular striations, unequal guard cells, one guard cell and contiguous stomata are but sparingly observed. An increase in the number of subsidiary cells takes place by wall formation or the neighbouring perigenes assuming their shapes. Epidermal cells with inward projections are observed in the limb region of petals in all species. The taxonomic significance of stomata is also indicated.