Volume 36, Issue 6
December 1952, pages 223-257
pp 223-228 December 1952
pp 229-233 December 1952
A study of the germination of micro- and macro-conidia ofFusarium vasinfectum introduced into the wilt infected soils amended with microelements was made employing modified Cholodny’s slide technique.
Statistical analysis of the results showed the micro-elements, concentrations, incubation periods and the interacting factors to be highly significant from the point of view of retardation of conidial germination.
Percentage germination of the conidia in all the amended soil samples, excepting manganese 50 p.p.m., was much lower than that of the unamended control soil. Zinc, molybdenum, lithium, aluminium, nickel, boron, cobalt and manganese were correspondingly inhibitive in the order mentioned.
pp 234-242 December 1952
In the experiment conducted to study the response of cotton plants to micro-element soil amendments zinc and manganese were found to be beneficial for the growth of cotton plants. Boron, lithium and molybdenum were toxic.
Cent per cent. germination of cotton seeds was recorded in the control and all the treated soils except in the case of boron treatments. When the seeds were soaked in micro-element solutions prior to sowing in soil, only the nickel-treated seeds showed scanty germination.
Studies on the pathogenic potentialities ofFusarium vasinfectum on a susceptible variety of cotton showed that zinc was effective in reducing the wilt incidence, whereas manganese aggravated the incidence of wilt.
pp 243-248 December 1952
The morphological, cultural and physiological characters of strains ofNocardia corallina andNocardia rubra isolated from coconut oil and the alimentary canal of the earthworm are described. Deeply staining granules in the cytoplasm pf theNocardia when grown on Ashby’s nitrogen-free. medium have been reported,N. corallina showed bipolar granules whileN. rubra showed subcentrally situated granules. The observations are substantiated with photomicrographic illustrations. The need for further study of the cytology and nutrition of theNocardia is emphasised.
pp 249-257 December 1952
A comparative account of some aspects of the embryology in three members of the Dipsacaceæ,viz., Dipsacus leschenaultii, Scabiosa caucasica andCephalaria ambrosioides is presented. In all the three species the flowers are borne on globose capitula. InCephalaria the outermost flowers in the capitula are functionally male, since the ovule does not develop beyond the initial stages.
The wall of the anther is made up of the epidermis, endothecium, middle layer and tapetum. The cells of the tapetum soon become multinucleate and at a later stage form a periplasmodium. The mature pollen grain is tricolpate with a tube nucleus and two male cells.
In the pendulous tenuinucellate ovule the vascular strand traverses the single massive integument right up to the micropylar end of the ovule. The hypodermal archesporium directly functions as the megaspore mother cell. Double megaspore mother cells are found inScabiosa andCephalaria, and double dyads are seen in the latter. Megasporogenesis proceeds normally and the development of the embryo sac follows the Polygonum type.
The antipodals are organised as cells and inCephalaria they become binucleate.
Surrounding the narrow chalazal end of the embryo sac there is a prominent radiating tissue.