Volume 37, Issue 1
January 1953, pages 1-32
pp 1-13 January 1953
Greater accumulations of fungi, bacteria and actinomycetes in the rhizosphere than in the control soils were recorded.
A decreasing order of ‘rhizosphere effect’ as follows was noticed: bacteria > fungi > actinomycetes.
Maximum ‘rhizosphere effect’ on bacteria was noticed during the time of flowering. Increase in fungal numbers after flowering was recorded.
Changes in the total fungal numbers correspond with the changes in numbers of Aspergilli and Penicillia, both in the dilution plates and the root platings.
The absence of certain predominant fungi likeFusarium spp.,Macrophomina phaseoli, Neocosmospora vasinfecta in the rhizosphere dilutions emphasizes the necessity of assessing the physiological state in which they are extant in the rhizosphere.
Sorghum stands unique in that its rhizosphere had highest numbers of fungi among the non-legumes and highest numbers of actinomycetes among all the plants studied. The potential root pathogens so often encountered in the rhizosphere of other plants were absent in the case ofSorghum.
pp 14-21 January 1953
Maleic hydrazide treatments in suitable concentrations can advantageously be utilized to prevent premature and undesirable bolting in onions and thus help in increasing the yield and quality of bulbs.
pp 22-26 January 1953
A convenient and rapid routine method for estimation of nicotine in tobaccos has been developed. The method is applicable to nicotine concentrations as low as 1 p.p.m. within · 2% error. The method will have a special bearing for studying the biogenesis of nicotine in plant tissues. Thanks are due to Mr. T. R. Srinivasan for verifying some of the results.
pp 27-32 January 1953
The occurrence of tetraploidy in yeasts reported by us several years back finds confirmation in some recent reports regarding the existence of tetraploidSaccharomyces. Tetraploidy furnishes the possibility of an array of genetic combinations ignored up till now by Winge and Lindegren.
Photomicrographs are presented to illustrate normal and abnormal mitoses in a tetraploid. The origin of diploids, triploids, pentaploids and hexaploids are described.
Abnormal mitoses common in tetraploid yeasts offer possibilities regarding the origin of new types. Lindegren’s belated admission that triploid and tetraploid yeasts do occur is a tacit admission of the accuracy of our criticism that since he and Winge analysed segregation in yeasts ignoring the possibility of polyploidy, their work was based on a fundamentally erroneous assumption.