Volume 49, Issue 4
April 1959, pages 207-279
pp 207-216 April 1959
Studies on the nutrition of rice plant (Oryza sativa L.) - Part III.Partial efficiency of nitrogen absorbed by rice plant at different stages of growth in relation to yield of rice (O. Sativa var.Indica)
Rice plant of medium duration, grown under low nitrogen supply (10 p.p.m.), shows two peak periods ofpartial efficiency for nitrogen, when nitrogen taken up by the plant is most efficiently utilized in increasing grain yield. First such period occurs at the tillering stage and the second at flowering, between the boot and milk stages.
Nitrogen taken up by the plant between tillering and ear-initiation plays role in increasing tiller and panicle number per plant. During panicle development, from ear-initiation to flowering, nitrogen taken up increases number of filled grains per panicle and, after flowering, it increases effective 1,000 grain weight. The first period of maximumpartial efficiency is, therefore, for increasing tiller number and the second for increase of panicle weight,
If, however, the plant is grown at high levels of nitrogen (60 p.p.m.) from the start, nitrogen taken up during the vegetative stage, up to ear-initiation, is stored in the body of the plant and is used in the later growth and development, even if nitrogen supply is cut off later. High nitrogen supply, after ear-initiation, has detrimental effect on growth and decreases grain yield because of decrease in number of filled grains per panicle and 1,000 grain weight. Chaffiness of panicle, under this condition, also markedly increases and plant becomes more susceptible to neck infection due to blast.
The authors are indebted to Mr. R. L. M. Ghose, Director, Central Rice Research Institute, Cuttack, for suggestions and improvement in the text of the paper.
pp 217-226 April 1959
pp 227-238 April 1959
pp 239-244 April 1959
The paper deals with the chromosome numbers of 13 plants of medicinal value. The chromosome counts of 10 species have been reported for the first time.
pp 245-263 April 1959
Succession of marine algæ on a fresh substratum—a concrete boulder with the top surface paved with coral stones—was studied. The algæ colonizing the boulder were identified; the pioneer communities, succession, biotic factors, growth rate and reproductive phases of some of the forms, chemical factors, other dynamic factors and relation of the surrounding flora on the colonization over a period of 18 months were noted.
I am grateful to Dr. N. K. Panikkar and Dr. S. Jones for the kind interest they have shown in this work. To Dr. (Mrs.) F. Thivy for her valuable suggestions, and to Shri K. G. Nambiar for taking the photographs, special gratitude is due.
pp 264-270 April 1959
The effect of insulin injection on the protein-bound amino acids (except tryptophane) of the pituitary ofOphicephalus striatus has been studied chromatographically at intervals of 0·5, 1·0, 1·5, 2·0 and 2·5 hours. It is found that all the protein-bound amino acids are affected quantitatively. Leucines, valine, tyrosine, aspartic acid and alanine disappear completely for sometime as a result of insulin injection. The other amino acids show varying degree of reduction. The recovery of all amino acids expecting tyrosine is not complete even after 2·5 hours. The degree and duration of recovery varies for different amino acids.
pp 271-279 April 1959
1. Measurements of the penetration of daylight of different wavelengths have been carried out in the coastal waters of Porto Novo using photoelectric cells.
2. Nearly 50 per cent. of solar radiation at near ultra-violet region is absorbed by the first one meter of sea-water.
3. Longer wavelengths, especially red light, is heavily absorbed by the surface layer.
4. Selective scattering in the wavelengths 475–590 mµ has been observed in the coastal waters at Porto Novo.