B N Singh
Articles written in Proceedings – Section B
Volume 1 Issue 8 February 1935 pp 435-451
Volume 1 Issue 9 March 1935 pp 471-495
Volume 1 Issue 9 March 1935 pp 496-518
Volume 1 Issue 11 May 1935 pp 736-753
The march of assimilation from day to day in a young leaf for twenty days—the period of physiological activity of a radish leaf in the laboratory—is deduced from the separate time-assimilation curves of mature and old leaves.
Under the natural pressure of carbon dioxide in the atmosphere, assimilation of radish leaves increases continuously upto 29°C. more or less in conformity with the Van’t Hoff’s law, the coefficient of increase being 2·26.
The maximum assimilation attainable under the atmospheric conditions of carbon dioxide is reached at 30°C.
From 30 to 34°C. the first observed value of assimilation attained is of the same order but at and beyond 30°C. this initial value of photosynthesis abates in successive hours.
While the first evidence of time factor is available at 30°C. its pronounced influence is manifested not till 37°C. when the disparity between the first and second hourly reading is striking.
At 29°C. it is possible to reach a higher sustained pitch of assimilation in time by increasing the partial pressure of carbon dioxide in the environment.
Assimilatory activity in the radish leaf becomes extinct at a temperature of 47·4°C. and does not commence at a temperature lower than 12·6°C. in these regions. This behaviour is contrasted with that of Cherry Laurel, recorded by Matthaei working in the temperate regions who found the threshold value for photosynthesis to be −6°C., and ascribed to the ecological adaptation of the plants to higher temperatures in these regions.
Volume 1 Issue 11 May 1935 pp 754-762
At the normal atmospheric pressure of carbon dioxide the intensity of assimilation increases measurably with the intensity of illumination upto 68,760 metre candles in radish leaves in the sub-tropics.
At a ten time atmospheric concentration of carbon dioxide the rate of assimilation continues to increase with the intensity of illumination to a slightly higher illumination intensity of 72,197 metre candles.
Depression in the photosynthetic activity of radish leaves appears to occur for the first time at a light intensity more than twice the average sunlight in the winter months in these regions. An appreciable time factor sets in at a light intensity of 1,80,000 metre candles.
This depression in the photosynthetic rate appears to be connected with the inactivation of chloroplasts and is capable of reversal under reduced light intensity provided the exposure to the higher light intensity has not been prolonged.
The threshold light intensity for photosynthesis is in the neighbourhood of 4,000 metre candles for radish leaves in these regions. The minimal and optimal cardinal points herein mentioned though characteristic of the winter season in the sub-tropics should not necessarily apply to the temperate regions where the plants are adapted to lower intensities of light in contrast to the high illumination conditions obtaining in these regions.
Volume 1 Issue 12 June 1935 pp 909-927
Volume 2 Issue 4 October 1935 pp 387-402
On the basis of the observations recorded the population of plants studied is segregated into representatives of two physiologically distinct classe:—
The two classes of plants segregated have a fundamental difference in the drift of the respiratory index of the meristems. In the short-lived plants there is a characteristic decrease in values from an early phase of growth (young stage) and the rate of fall becomes more pronounced before the initiation of the reproductive organs, while in the long-lived species the respiratory index maintains more or less a level value for a considerably long time after germination and shows a decline only towards the end of growth cycle.
The gradient of energy release will govern the period of life-cycle—the steeper the gradient, the briefer the life span and the less steep the gradient, the longer will be the life duration and
Longevity is proportional to the initial respiratory energy with which the young organism starts its life, as well as the average rate maintained during the course of the life-cycle. The higher the average rate, the more rapid the expenditure of energy and consumption of materials and briefer the life span; and the lower the rate, the more restricted the release of energy and consumption of materials, the longer will be the duration of life.
The meristematic tissue, in general, has a high initial rate relatively independent of external factors and gives an idea of the genetic constitution of the plant.
On the basis of experimental findings the view is held that apart from inheriting the potentiality for morphological characteristics, an organism also may exhibit a potentiality for a certain rate of metabolism and thereby for a specific duration of life.
Volume 2 Issue 5 November 1935 pp 437-456
Volume 3 Issue 3 March 1936 pp 238-245
The paper deals with the effect of varying concentrations of oxygen on the production of dry matter in plants. The following conclusions are the outcome of the present investigation:—
The dry matter produced is more or less proportional to the concentration of oxygen. With increasing percentages the curve merges into a stationary and later a decline phase.
The increased growth at higher concentrations of oxygen is explained on the basis of increase in the intensity of both respiration and assimilation. Suggestion is made that the former controls the production of dry materials probably by a control over the supply of energy, while the latter by controlling the development of the photosynthetic machinery.
The deviations in the concentration of Oxygen near about those of the atmosphere do not affect the dry matter production to any great extent, proving thereby that growth is not ordinarily limited by the concentration of oxygen under natural conditions of the plains and the critical concentration for the growth of wheat plants lies near about 15%.
The dry matter production at any stage appears to be a function of the interaction between two variables, the age-factor and the factor for oxygen. An increase in any one of these factors at any stage brings about increased growth showing thereby that under the conditions of experimentation growth in plants at any stage of the life-cycle is not limited by one factor alone but by as many as two factors,
Volume 4 Issue 5 November 1936 pp 376-402
Volume 7 Issue 3 March 1938 pp 143-160
Volume 8 Issue 4 October 1938 pp 301-308
An attempt has been made in this paper to study the photosynthetic activity of a number of plant species under optimum yet identical conditions of factor-intensity and to trace the relationship, if any, between the organic materials subsequently formed and the assimilatory influx of carbon dioxide.
Different plant species have different photosynthetic rates, the range of variation from species to species becoming more and more pronounced with advance in age of plants. Such variations under otherwise constant external conditions are discussed with special reference to internal factors.
The water-content of the experimental material no doubt differs from plant to plant but does not follow the same gradation as that maintained by assimilation rate. The chlorophyll content too shows no correlation with the assimilatory efficiency.
There seems to be a fair degree of correlation between the products economised in leaves during their photosynthetic activity and the products stored by the same species towards the close of the life-cycle. Plants economising sugars, proteins, starches and fats in assimilating leaves also store such substances respectively in their storage organs towards the close of their life-cycle.
The photosynthetic rate seems to be related to the nature of the end products accumulating in assimilating leaves. Leaves accumulating simpler sugars have fairly high rates of assimilation while those economising the more complex starches, proteins and fats respectively have to their credit decreasing assimilatory efficiency.
The biochemic constitution of the experimental material as judged by the products economised during assimilation appears to be an important internal factor governing photosynthesis and suggestively explains the phenomenon of photosynthetic specificity in certain groups of crop plants.
Volume 8 Issue 4 October 1938 pp 324-335
The application of chlorine from the very beginning of the life-cycle of wheat, brings about a slight depression in dry matter production and an increase in moisture content during their early stages of growth. With advance in age, however, the dry matter accumulation is markedly increased without any appreciable increase in water content.
Plants supplied with chlorine twenty days after germination have the maximum dry matter yield. Relative growth rate as well as net assimilation rate are also accelerated.
The treated plants do not show any marked effect on their shoot length although the assimilatory surface is increased beyond the control. The roots, on the other hand, in spite of a diminution in length, exhibit a greater lateral ramification and dry matter production.
Chlorine-treated plants have a larger percentage ear formation maximum values being obtained in case where this element is supplied twenty days after germination.
The accumulation of carbohydrates as also the diastatic activity are greater in the treated plants as compared to the control ones.
Growth of plants at successive stages of the life-cycle appears to be determined by both the age and the factor for chlorine a change in either bringing about a variation in dry matter production.
The greatest physiological need and hence the maximum augmentative efficiency of this element is found at the period (twenty days after germination in the present case) when plants are showing active growth and differentiation.
Volume 9 Issue 3 March 1939 pp 133-141
The paper deals with effects of ammonium sulphate (N), potassium sulphate (K) and double superphosphate (P), singly and in combinations (total 8 treatments) on the water retentive force of the soil at different moisture contents.
As the moisture content of the soil decreases the water retentive force of the soil increases. The changes in this force are less at higher moisture percentages while large changes are noted at lower moisture contents.
K has the least effect in reducing the water retentive force as soil is being depleted of its moisture, and P both singly and in combinations has the best effect in as far as it tends to keep the forces steady.
The fertilisers influence both the wilting coefficient and water retentive force of soils (Table III). In general the fertilisers bringing about increase, in wilting coefficient also bring about a corresponding decrease in water retentive force.
The gradient of increase in water retentive force of soils from high to low moisture content is higher in K treated soils and low in P treated soils (P, PN and KPN). This necessarily calls for drastic changes in the osmotic relations of the root cells of plants in K treated soils if the plants have to maintain a proper water balance.
It is concluded that a combination of P and N is the best treatment as far as water relations of plants are concerned for the proper growth and yield of crops under Indian conditions.
Volume 9 Issue 4 April 1939 pp 151-168
The influence of fertilizers upon photosynthesis, chlorophyll content and respiration rate of
When supplied singly potassic and phosphoric fertilizers are much more useful than the nitrogenous in increasing the photosynthetic efficiency of leaves. In all these cases photosynthesis rises with increasing supply of fertilizers upto a certain optimal level, later showing a decline.
In the three fertilizer series the rate of photosynthesis never reaches the same level as that recorded for optimal doses of potash and phosphates applied singly. The association of the three ingredients N2, P2O5 and K2O appears to slacken the rate of CO2 intake by leaves. When one or the other nutritive ingredient is either reduced or completely removed, this deleterious influence is partly overcome and photosynthesis increases.
The influence of fertilizers upon respiration, photosynthesis (both apparent and real) and chlorophyll is practically of the same nature, inasmuch as, augmentation in assimilatory activity in majority of cases is also followed by an increase in chlorophyll content and respiration rate.
Photosynthesis in different series of cultures does not rise with the increase in the chlorophyll content upto a critical limit of 2.0 mgm./fresh weight. Beyond this level, however, increase in chlorophyll is always associated with acceleration in photosynthetic activity.
The variation in assimilation number in different series of experiments indicates that chlorophyll is not the only factor controlling photosynthesis.
Photosynthetic augmentation under the influence of fertilizers may be due to (i) increased chlorophyll formation which in its turn influences carbohydrate metabolism, (ii) direct supply of mineral ingredients, nitrogen, phosphorus and potassium for proper functioning of leaf material and (iii) the increase in respiratory activity of leaves which considerably influences the rate of real assimilation.
Volume 9 Issue 4 April 1939 pp 169-174
The paper deals with the effects of injection of buffer solutions, varying in pH from 4.0 to 8.5, upon the photosynthesis and respiration of leaves of
A close relationship is found to exist between the photosynthetic and respiratory rates and the ‘final’ pH of buffers, although the reaction of the cell-sap is practically constant.
The high concentrations of the buffer solutions are, probably, responsible for depressing the rates below the values of the control, and for causing discoloured areas in the leaves in certain cases.
Volume 9 Issue 6 June 1939 pp 323-330
As the duration of light is increased above the normal the concentration of the total carbohydrates and nitrogen increases resulting in a diminished range of C/N ratio. A concomitant increase in the acidity value of the plant sap is observed with the length of the day. Accumulation of such metabolites appears to play an increasingly significant role in governing the initiation of the reproductive phase, in modifying the nature of the growth curve and thus inducing abnormalities in the organism.
Volume 9 Issue 6 June 1939 pp 331-342
The paper deals with the influence of moisture content on ammonification and nitrification, and of nitrate feeding conditions of moisture and aeration on ammonification.
A method is proposed for measuring ammonification. The proposed method for measuring ammonification based upon the difference in organic nitrogen both before and after the incubation period has been found to give better results for ammonification.
There is a particular range of moisture content, both for optimum ammonification and nitrification, being between 34 and 51 per cent, of the moisture-holding capacity of the soil.
Under saturated conditions nitrification is completely inhibited whereas ammonification continues though at a slower rate.
Nitrates influence the ammonifying organisms to increased activity till a particular concentration is reached beyond which the process is retarded.
The ratardation of ammonification is accompanied by setting in of denitrification.
The ammonifiers seems to be composed of two groups, one aerobic and the other anaerobic in nature, if aerobic they exhibit facultative anaerobism under unfavourable conditions.
Under aerobic conditions the activity of the ammonifying organisms is proportionately higher.
Volume 10 Issue 1 July 1939 pp 27-40
A detailed study has been made to elucidate the after-effects of the addition of certain fertilisers,
Treated plants in general exhibit decided improvement in their growth than the untreated ones. While the height, tiller number and total dry matter accumulation per plant are significantly better in all the fertilised series than the unmanured ones, K78.7 (potassium sulphate) and P66 (superphosphate) applied alone do not show significantly higher increase in the yield of grain and straw as also of the length of earhead or the absolute weight of the grains.
The general effect of the fertilisers is to cut short the water requirement of the treated plants to values much below that obtained for the control ones although with P66 (superphosphate) and N16.5K18P16.5 (potash mixture) the differences are not statistically very significant. The total amount of water necessary for raising a successful crop of wheat is therefore less in certain cases,
Volume 11 Issue 4 April 1940 pp 133-154
Volume 11 Issue 6 June 1940 pp 236-247