Volume 89, Issue 5
October 1980, pages 323-427
pp 323-330 October 1980
Separation of the outer bract enclosing the flower bud and spike axis results in the stimulation of amylase synthesis in the petals of gladiolus. Light is implicated in this process. Amylase production is localised in the petal epidermis (which is free of starch) and not generalised in the ground parenchyma (which contains abundant starch). Depletion of starch in the petal is strictly basipetal. It is proposed that the reducing sugars released from hydrolysis of starch in the ground parenchyma cause osmotic water intake, leading to petal expansion and flower opening.
pp 331-345 October 1980
The morphological and anatomical studies of the floral galls ofPongamia glabra reveal the involvement of the entire floral primordia, telescoping of the internodes of the peduncle resulting in the agglomeration of galls, morphogenetic phenomena of hypertrophy, hyperplasia, dediffsrentiation and redifferentiation, lack of polarity of certain cells and tissues as shown by the concentric, plicate and reticulate types of arrangement of vessels of the reaction xylem, development of irrigating strands and sclerosed cells towards the larval cavities and formation of crystals and tanniniferous idioblasts. The nutritive tissue around the larval cavity is rich in starch grains. The short vessels of the normal and reaction xyla with simple porous perforations and minute alternate lateral wall pittings indicate an advanced level of specialisation of secondary xylem, despite the modifications of the flowers due to galling.
pp 347-359 October 1980
A topographic survey of the laminae ofGarrya has revealed that sclereids are present only in 14 taxa and they conform to polymorphic, groupings. The usefulness of sclereids in the provisional identification, nomenclatural changes and taxonomic status has been discussed.
pp 361-367 October 1980
Embryology ofEleutherine plicata Herb. andBelamanda chinensis Lem. has been studied. Anther wall shows epidermis, fibrous endothecium, 3–4 middle layers and secretory tapetum. Pollen mother cells divide successively or simultaneously. Tetrahedral, isobilateral, decussate, linear and T-shaped tetrads are present. Embryo sac development is of polygonum type. Fertilisation is porogamous. An obturator is present. Embryo development inE. plicata confines to Muscari Variation of Asterad type. Occurrence of polyembryony is also recorded.
pp 369-374 October 1980
The pericarp ofSolanum tuberosum is 30–40 layers thick. It is a multilayered region of the fruit made up of outer epidermis and the periclinally divided cells of the outer hypodermal layers. The mesocarp is developed from the middle layers and partly from the outer hypodermal cell layers of the ovary. The increment in number of cell layers of endocarp is only upto 0·3·0·8 cm size of the fruit. There are no endocarpic outgrowths. The small chambers are formed by the placental outgrowths surrounding individual seeds. The outgrowths develop further and contact the innermost layer of endocarp or the septa of the fruit.
pp 375-379 October 1980
Treatment of 20-day-old soybean (Glycine max L.) seedlings with morphactin caused sprouting of all lateral buds, but when the application was supplemented with a specific cytokinin synthesis inhibitor (hadacidin) the effect entirely disappeared. The data show that the augmentation of cytokinins following morphactin application is responsible for lifting the apical dominance and not the effect of newly ensued bud growth.
pp 381-393 October 1980
The growing apex of the rhizome ofMicrolepia speluncae has a tetrahedral apical cell crowning a pad of meristematic cells located on the dorsal surface behind a semicircular dorsiventral leading ledge at the tip. Leaf initials are formed anterior to the apical cell and the youngest 2 or 3 leaves are anterior to the meristem. Each leaf initial is associated with 4 primary roots two of which are anterior and two posterior to the apical cell; root initials are superficial at origin. Provascular tissue is formed associated with leaves and roots only. Leaf trace is channel-shaped and gets connected to vasculature of the primary roots, which in turn gets connected secondarily to the vasculature of the next older leaf; young region of rhizome, thus, has a channel-like stele open ventrally but the margins get connected later by secondary provascular tissue formed from intervening parenchyma. Leaf traces and stele of younger regions are highly dissected; the parenchyma in the perforations, transforms into provascular tissue as the rhizome matures, rendering leaf traces and stele intact. The rhizome branches after every 3rd leaf; branch initial is an apical cell formed away from the apical cell of the rhizome. Vasculature of branch is associated with the leaves produced by the branch apex and gets connected to the main stele on its dorsal side. The rhizome is interpreted as a fusion product of leaf bases.
pp 395-400 October 1980
Application of 3-amino-1, 2, 4-triazole (amitrole) causes chlorosis inCanna edulis. The contents of chlorophyll, carotenoids, µ-carotene and plastoquinone are reduced drastically in young leaves, whilst that of aged leaves are not affected. Photosynthetic O2 evolution by isolated mesophyll cells of amitrole-treated young leaf is drastically inhibited when compared to that of aged leaf. The turnover of pigment synthesis is implicated in the specific inhibition of chloroplast development by amitrole in the young leaves ofCanna.
pp 401-406 October 1980
Numerical analysis has been conducted to assess the relationships between fifteen operational taxonomic units inSetaria (L.) Beauv. representing ten species belonging to two sub-genera,Ptychophyllum (A. Braun) Hitchcock andSetaria (L.) Beauv. Data were recorded for twenty-four characters. Coefficients of associations were calculated on the basis of characters studied.
pp 407-413 October 1980
The karyotaxonomy ofLimnophyton obtusifolium (L.) Miq. has been critically interpreted. The karyotype is essentially asymmetric in character. This appears to be substantiated by the fairly high disparity index of chromosomes, being as much as 65%. The 24-chromosome form is presumably a karyo-ecotype and tetrasomic derivative from the 22-chromosome form, specially adapted to helophytic environment. Interestingly enough, while the 22-chromosome form shows only one pair of satellited chromosomes in its karyotype, the present type invariably shows two such pairs, nearly identical with the single pair in the other form. From the standpoint of karyotaxonomy,Limnophyton is a blend of primitive and advanced characters. The high value of recombination index suggests the incapacity of this taxon for outcrossing and enlarging itself beyond the status of a tritypic genus.
pp 415-420 October 1980
Potassium deficiency effects on growth, nitrogen and carbohydrate fractions and minerals were studied in 30 day-old peanut plants. Reduced stem length, tap root length and reduced number of leaves and primary laterals were noticed in K+ deficient plants. In addition, decreased levels of total protein and soluble nitrogen fractions were observed. However, high amounts of starch and total sugars were found in all the three component parts of the plant under K+ deficiency. K+ deficiency also decreased the levels of potassium and calcium but increased the level of total phosphorus in peanut plants. The relevance of these changes has been discussed.
pp 421-427 October 1980
The present study reveals a variety of competitive interactions between the two species ofEuphorbia—Euphorbia hirta andEuphorbia thymifolia depending upon the calcium status of the soil. In general,Euphorbia thymifolia suffered high mortality in low calcium soils as compared toEuphorbia hirta. The former, however, showed better survival in high calcium soils. This was more pronounced in mixtures than in pure stands. A similar pattern of behaviour though not so pronounced was also recognised with respect to the growth performance of the two Species in low and high calcium soils. The significance of these results is discussed.