Volume 89, Issue 1
January 1980, pages 1-78
pp 1- January 1980
pp 1-6 January 1980
The present paper reviews the relationship between the procambium and the vascular cambium. It is suggested that the procambium is not a pre-requisite for the formation of vascular cambium, even in the stems, as is claimed by several morphologists.
pp 7-13 January 1980
Development of the shoot apex inSesamum indicum Linn, andEruca sativa Mill, was followed from the mature embryo to early reproductive stages. The shoot apex shows an age-related increase in size until the reproductive phase sets in. In both species, the epicotyl apex is flat with a single tunica layer covering a homogeneous corpus. InSesamum the 3-day old seedling apex shows the early stages in the establishment of cytohistological zonation in the corpus leading to well-established zonation in the dome-shaped 4-day old seedling apex. InEruca the maximal stage of the 3-day old seedling apex is a low dome and zonation in the corpus is well established in the 4-day old apex. Establishment of zonation seems to be related to the size of the apex in the first place and probably to the shape also as applied to particular species. The sequence of establishment of zones is, the peripheral zone first followed by the corpus mother cells and pith meristem zones almost simultaneously.
pp 15-22 January 1980
34 spore types were caught on cylinders exposed to air over cotton field throughout the season. Deuteromycetes dominated the air-spora. The total air-spora gave a peak in September. 11 pathogens of cotton were caught which, mainly includedAlternaria tenuis, Alternaria macrospora, Rhizoctonia bataticola, and Aspergilli. Sclerotia ofR.bataticola were also caught and their concentration increased in August and declined later. Days on which highest counts of individual spore types obtained, were restricted to August-September.
pp 23-28 January 1980
The ontogeny and structure of stomata have been studied in the fruit wall ofBrassica oleracea var.botrytis Linn, andEruca sativa Mill. They are of mesogenous trilabrate type. Ontogeny resembles stomata of vegetative parts. Sometimes, the number of subsidiary cells gets increased due to cell division in spiral of three subsidiaries. Stomata are absent on inner epidermis of pericarp. In both the plants, contiguous and incompletely developed stcmata are also present.
pp 29-35 January 1980
The paper describes the ontogeny of the shoot apical meristem inBotrychium lanuginosum Wall. In young plants the apical activity is governed by a single inverted pyramidal apical initial, discernible in the middle of the superficial layer. In plants of prime youth, though an apical initial has been recognised, it attains a rectangular shape and cuts cells even from its basal side. Adult plants do not possess any prominent cell which can be demarcated as apical initial. The apical activity is governed by a group of cells forming a discrete layer. In general, the meristem in adult plants consists of a superficial layer covering an inner tissue. On the basis of stainable contents and size of the cells, the inner tissue can be further divided into three zones, i.e. a central zone, a lateral zone and a peripheral zone.
pp 37-41 January 1980
A case of translocation between A and B chromosomes was recorded in the B-chromosome carrying material of pearl millet. This was induced through chemical treatment with EMS. The B-chromosomes never pair with A-chromosomes, but pair among themselves to form bivalents and multivalcnts. In the experimental material under study at pachytene and diakinesis stages in PMCs, A and B chromosome associations were observed.
pp 43-46 January 1980
The build-up index of the lance nematode (Hoplolaimus indicus) was 6·88, 6·23, 3·72, 2·76 and 2·28 respectively at harvest of the rice varietyPadma when inoculated with 900 females and 100 males at 10, 30,50,70 and 90 days age of plants. The high build-up in the inoculations at 10 or 30 days age of plants was due to the rapid multiplication of the nematode in successive generations which resulted in yield losses of 25·11 and 19·11% respectively. The susceptibility of the plant, however, was not affected by the age of the plant at inoculation time, but on the availability of the root system.
pp 47-55 January 1980
The tuber arises from the hypocotyl due to intensive unilateral activity of the primary thickening msristem. The resulting growth thrust produces a tuber apex, which consists of a drawn-out dome of this meristem, covered by secondary cortex and having a core of conjunctive parenchyma with vascular bundles. The tuber undergoes axiate and thickening growth by activity of the primary thickening meristem in the subapical and lateral regions. The tubercle, formed by the hypocotyl plus the first internode of plumular shoot and the hypopodia of successive aerial shoots of a sympodium, undergoes secondary growth by the primary thickening meristem, initiating in the hypocotyl. Morphologically, the tuber is an integral appendage of the hypocotyl secondary body, whereas the tubercle is a sympodial rootstcck, the two together forming a perennial organ through activity of the same primary thickening meristem.
pp 57-60 January 1980
The translation of Southern sunnhemp mosaic virus (SSMV) in its primary hostCrotalaria juncea was studied by local lesion assay. The systemic spread of the virus was rapid and efficient; 24 hr after inoculation of the primary leaves, the virus could be recovered from the developing stem and leaves as well as the hypocotyls showing movement and multiplication of the virus in the stem axis in both directions of the primary node. In the roots, the multiplication of Southern sunnhemp mosaic virus was delayed but the titre reached a ligh level by the fifth day. The pattern of movement of Southern sunnhemp mosaic virusin viva differed from those of TMV and other plant viruses.
pp 61-65 January 1980
Seed germination of 11 species and four ecotypes of one species ofPotentilla, collected from Himalayan alpine and temperate climates has been studied under light and temperature conditions. Germination is generally favoured by high temperature and continuous light but the magnitude of response varies from one species to another. The ecotypic variations or the parental environment does not influence germination.
pp 67-72 January 1980
Fortnightly collections of bark samples of 3 consecutive calendar years revealed that the main bulk of secondary phloem formation inDelonix regia takes place late in a calendar year during October and November. About 30 to 40 layers of phloem cells measuring about 400 to 500 μm in depth, are produced during this period. A narrow strip of 4 to 5 layers of new phloem cells (precursor type) also differentiates in late April from the over wintered phloem mother cells. The October-November phloem functions for about 10 to 11 months and the precursor type for about 8 months.
pp 73-77 January 1980
The effect of certain proanthocyanidins and catechins isolated from different plant sources was studied on the growth ofLemna paucicostata Hegelm. Each compound was tested at five levels of concentration, i.e. 0·01 ppm,0·05ppm, 0·1 ppm, 0·5 ppm and 1·0 ppm. The growth was estimated in terms of fresh weight and total number of plants in each flask at the end of a growth period of 10 days. All the compounds tested proved to be growth-promoting, the proanthocyanidin isolated fromPhoenix sylvestris Roxb. causing maximum growth. Proanthocyanidin fromDichrostachys cinera Wright and Arn. and Epigallocatechin stimulated the growth to a lesser extent. However, at higher levels of concentrations, some compounds decreased the growth.
pp 78-78 January 1980 Erratum