Volume 87, Issue 11
November 1978, pages 255-360
pp 255-270 November 1978
Calendula officinalis L. bears a short main axis and branches of several orders. The upper axillary branches grow vigorously whereas the lower branches remain arrested at different levels. Foliar application of gibberellic acid (GA3) stimulated the elongation of the main shoot and of the upper few primary axillary branches (PAB’s). The length of the main axis nearly doubled 10 days after application. The endogenous level of GA3 is probably sub-optimal, since external application enhances stem growth. However, treatment caused varying degrees of stimulation of the arrested branches. Whereas all the concentration of GA3 were equally effective in promoting the growth of the first six primary axillary branches after 60 days of application, in plants treated with 500 ppm, the lower primary axillary branches failed to develop. Since the lower axillaries remained inhibited, it is presumed that 500 ppm of GA3 is supra-optimal. At 100 and 250 ppm, however, the growth of the arrested branches at the base was significantly increased.
Thirty days after application, GA3 promoted growth and augmented the number of secondary axillary branches. Curiously at 100 ppm GA3 markedly inhibited the length of the secondary axillary branches of PAB3 to PAB6.
These studies show that a complex mechanism of apical dominance operates inCalendula officinalis.
pp 271-276 November 1978
Amongst twelve different spray schedules tested, the best control of apple scab [Venturia inaequalis (Cooke) Winter] in Kashmir Valley was obtained with Captafol 80 WDP (Difolatan) sprayed at 2 g per litre of water at green tip stage, pink bud stage and 15 g in 18 litres of water applied at 10% petal fall followed by four cover sprays two of which were given at three week intervals with 15 and 10 g of Captafol in 18 litres of water respectively and 2 more at 10 g of Captafol in 18 litres of water at an interval of 1 month each, depending on the rainfall. The total amount of Captafol sprayed in this treatment was 73·12 g. The residues in the fruit varied from 1·22 ppm to 1·64 ppm. Even at the highest dose of 137 g of Captafol per plant, the residues did not exceed 2·75 ppm, which is lower than the tolerance limit of 3 ppm fixed by FAO/WHO.
pp 277-282 November 1978
A trilacunar, three traced stipulate node is observed in 36 species studied representing all the six genera of Trifolieae. Most of the species ofTrifolium agree in the splitting of the median at the base into three, in the presence of five bundles at the base of the petiole and in their formation. Thus they appear to be distinct from others.
pp 283-291 November 1978
Root apical organisation inAnnona squamosa, Artabotrys odoratissimus,Polyalthia longifolia, Nigella sativa, Ranunculus sceleratus, Clematis triloba andMichelia champaca falls into two types: Type I—Annona,Artabotrys, Polyalthia,Michelia andNigella, show a common group of initials around which the derivatives differentiate into the root cap, epidermis, cortex and central cylinder. Type II—Ranunculus andClematis, show discrete initials for the plerome, periblem, dermocalyptrogen and columella. The arboreal species investigated show a common group of initials and the herbaceous ones (exceptNigella) discrete initials at the root apex. This may be of phylogenetic significance.
pp 293-298 November 1978
The growth pattern, leaf morphology and flower development were studied inLycopersicon esculentum Mill. With the increase in concentration of morphactin the height of the plants and the length of the petiole reduced and leaflets of young primordial leaves gradually fused to form simple leaves. The length of the inflorescence axis gets reduced and leads to the formation of composite flowers due to a gradual condensation with the increase in the concentration of this growth regulator. The shedding of flowers, a common phenomenon in tomato plants during first flowering was checked and considerable increase in the number of fruits was observed by lower concentration of morphactin treatment.
pp 299-302 November 1978
Rhizosphere effect of twenty varieties of wheat, two of maize and three of sorghum on nitrogen fixing bacteria was measured. The rhizosphere effect of wheat with regard toClostridium- like anaerobes was higher than those of maize and sorghum. The reverse was true with regard toAzotobacter chroococcum.
pp 303-308 November 1978
The inflorescence and mature seeds of sorghum plants infected bySclerospora sorghi were subjected to histological studies. The mycelia of the pathogen were detected in the inflorescence axis, ovary wall, anther wall and endosperm of the seed. Infected anthers contained shrunken pollen grains. Oospores were detected in the glumes and pericarp of mature seeds. However, there was no trace of the pathogen in the embryo either as mycelium or as oospores. Upto 80% of the seedlings showed systemic infection when samples of seeds with glumes from systemically infected plants were sown in sterile soil. 1–4% infection was observed in seeds sown without the glumes, probably because the oospores contained in them were eliminated. Although mycelium and oospores were found in the seeds, in proper sun-dried seeds they may not remain viable.
pp 309-317 November 1978
Spore concentration profiles along a vertical line passing through and above a growing sugarcane crop were studied using a suction-line apparatus. Two tests were conducted at monthly intervals for about 8 months with a uniform set-up consisting of six miniature suction traps located at 4 ft apart from ground to 20 ft. The seasonal changes in the vertical profiles of smut spores, conidia ofCladosporium, Nigrospora, Lacellinopsis and total airspora are presented graphically on a log-log scale. Spore concentrations are always found to be greater within the crop than above and the variations in the shapes of profiles at any time in a day or in the season appear to be closely related to source height, crop height, availability of suitable substrate and the prevailing weather. The effects of abnormal weather conditions and the agronomic practices on spore profiles are also presented.
pp 319-324 November 1978
Morphactin (100 ppm) treated plants of soybean (Glycine max L. Cv. Bragg) were studied for morphological, anatomical changes and for the endogenous levels of cytokinins. The reduction in internodal length was drastic and almost all the lateral buds of the treated plants were released from apical dominance. Some reduction in root length of treated plants was also observed. A conspicuous anatomical change was the increased breadth of stem meristematic cells. The cell number per unit area (208·32µ) in root and stem meristematic zones declined significantly. The increase in the levels of three species of cytokinins viz. zeatin, zeatin riboside and zeatin ribotide was significant while an unknown species maintained its level in treated and control plants. Another natural cytokinin, 2 iP could not be detected.
pp 325-333 November 1978
Evolution was in the beginning applied to the species. When genetics established the independent inheritance of characters, evolution also began to be analysed in terms of characters or organs, each considered independent in its evolutionary trend. Subsequently, however, this rule of independence began to be violated in the attempts to determine evolutionary status by correlation. Furthermore, the circumscription of an organ for evolutionary correlation is equivocal. With regard to the vegetative and floral morphology of the angiosperms, the concepts of old formal morphology in terms of fundamental organs were more definite and evolution has not been able to offer anything better. Many of the concepts of formal morphology havein toto been transferred to evolution.
The principles laid down by Carlquist, in what he has proposed to be a function oriented approach to angiosperm morphology, appear to be based on undue assumptions with a mixing up of homology and evolution. The decline of evolution as the directive force behind plant morphology necessitates new approaches that could impart dynamism to this basic discipline of botanical study.
pp 335-346 November 1978
Morphology of vessel members in 7 species ofMarsilea is described. The roots in all species examined possess vessels with scalariform (original), scalariform-porous and simple (specialised state) perforation plates; these variables are recorded in the different regions of the same root. Vessels of distinct morphology are also recorded for the first time in the rhizome-root-petiole juncture. Their origin and evolution in roots, and their absence in the internodal parts of the rhizome and petiole are discussed. Past comparison betweenMarsilea andPteridium vessels is reviewed.
pp 347-353 November 1978
Cytological observations in amphidiploids of the F1sH.acetosella (2n=72) ×H. cannabinus (2n = 36) andH. radiatus (2n=72) ×H. cannabinus (2n=36) and backcrosses of these F1s withH. acetosella andH. cannabinus, showed highly irregular chromosomal behaviour. These meiotic irregularities are considered as the probable causes for different degrees of the sterility exhibited by these plants. Perenniality and branching habit, wilt resistance, high fibre yield, inH. acetosella andH. radiatus appeared to be due to factors present in its B genome. The possibilities of transferring these factors toH. cannabinus, the cultivated types have been explored.
pp 355-360 November 1978
A preliminary cytological screening of 19 grasses of coastal Orissa revealed three new records of chromosome numbers and nine variations from earlier reports. These variations are due to polyploidy and aneuploid gains and losses. Interestingly only seven species have chromosomes conforming to the earlier reports. Nine seems to be the commonest basic number. This report incidentally is the first ever cytological study of Poaceae of this coastal belt.