Volume 16, Issue 3
September 1942, pages 49-90
pp 49-66 September 1942
The autecology ofScytonema ocellatum Lyngb. formaminor Bharadwaja has been studied, especially with respect to its soil requirements.
The alga has been found to grow throughout the year and hence it is considered to be a perennial form.
The seasonal distribution of the plant is governed by the necessary moisture in the soil. A prolific growth takes place at a moisture of 20–40% of the water-holding capacity of the soil.
The growth of the alga is not affected by differences in the organic content of the substratum; but, on the other hand, it is the balance between carbon and nitrogen,i.e., C/N ratio of the soil which is the controlling factor.
The pH range varies between 6–4 and 7–4, but maximum growth results at higher pH values provided the redox potential is fairly high.
The oxidation-reduction potential varies between 410 and 456 m.V. (E7 values), and at higher values there is an increase in growth.
The ammonium-thiocyanate and diphenylamine tests show that the soil samples characterising the growth of the alga indicate intense oxidation intensity.
It is concluded that, on the whole, the plant enjoys an oxidising nature of the substratum.
In conclusion, I have much pleasure in expressing my great indebtedness to Professor Y. Bharadwaja for the kind guidance and criticism throughout the course of this investigation.
pp 67-71 September 1942
pp 72-78 September 1942
The Giant Star grass grows very rapidly and has a good soil binding effect.
The HCN content of the Giant Star grass varies from 0·003 to 0·053 per cent, while that ofhariali (Cynodon dactylon) varies from 0·001 to 0·039 per cent.
Feeding trials carried out on bullock, buffalo, pony and sheep showed no stock-poisoning effect.
Animals fed on Giant Star grass have not relished the grass.
Under irrigated conditions Guinea grass (Panicum maximum) has yielded 76·5 per cent, more than Giant Star grass.
The proportion of stem is greater than leaf in the Giant Star grass as compared tohariali (C.dactylon) in which the proportion is very nearly equal.
pp 79-85 September 1942
An account of the life-history and biology ofPseudococcus saccharicola Takh. is given in this paper.
Reproduction takes place both by amphigony and parthenogenesis.
About 230 eggs are laid by the gravid female in 12 days. The incubation period of the eggs is very short.
The male has five stages in its life-history and moults four times. The female moults three times and there are four stages in its life-cycle. Distinguishing characters of the various stages are set forth in the text.
Some of the predators and parasites ofP. saccharicola are mentioned.
pp 86-90 September 1942