Volume 33, Issue 2
February 1951, pages 49-100
pp 49-68 February 1951
A number of distinctly varyingFusarium strains were isolated during the course of the study, from wilt-sick soils (Coimbatore) and from infested host material (wilted plants from Coimbatore and the laboratory experimental plot). Comparative cultural studies with the type cultureF. udum and the isolates revealed that the Coimbatore strains were more closely allied to the identified strain.
Pathogenicity tests withF. udum and isolates indicated that Strain I (F. udum) and Strains II and III were more virulent than the other strains. Pre-emergence wilt was mainly caused by Strains V and VI.
A greater protection to seedling emergence in wilt-infested soils was obtained by the addition of micro-nutrient solutions of boron, manganese and zinc (especially at levels of 20, 40 and 80 p.p.m.). This beneficial effect was further seen in the increase of plant vigour, early flowering and production of better type of seeds with higher germination capacity. The pre-soaking of seeds in various concentrations of the micro-elements also induced early germination and better seedling vigour.
The colonization of Fusaria on host stubble was temporarily retarded by the addition of the micro-nutrient solutions, especially in the presence of zinc.
The survival and persistence ofF. udum was conditioned by the presence of micro-nutrient elements in the soil, zinc being responsible for the most rapid disappearance of the fungus.
pp 69-91 February 1951
pp 92-99 February 1951
Studies were made on the distribution and seasonal variation of salinity, dissolved oxygen and nutrients in the surface waters of the Bay of Bengal in the vicinity of Madras during 1948–49. The various constituents show marked seasonal fluctuations. The variations of phosphates and nitrates during the period appear to be more regular than those of silicates. The influx of fresh water at a certain season during the year is offered as an explanation for this phenomenon.
pp 100-100 February 1951 Erratum