Effect of different levels of water salinity on the decomposition of organic manures in a brackish water fish pond soil

Effects of different water salinity levels on the decomposition of the two organic manures cowdung and poultry manure were studied under laboratory condition. Application of the manures increased the free CO₂ content and decreased D.O. levels of water. pH values of soil and water declined slightly on addition of the manures. The amount of nitrogen, released from the organic manures to water and soil phases, increased gradually with the period of incubation but decreased with increase in water salinity levels. NH₄ ⁺ was found to occur in comparatively higher amount than NO₃ ^–, due to prevailing anaerobic environmental conditions. The amount of added organic carbon remaining in the soil decreased gradually as the decomposition proceeded, but recorded slightly higher values with increase in water salinity levels.The results showed that the rates of decomposition of added organic manures were comparatively lower under higher water salinity levels and hence indicated that use of well decomposed manures might be more suitable for use under such water salinities in brackish water fish ponds.This work formed a part of a thesis submitted for the Degree of Doctor of Philosophy to Bidhan Chandra Agricultural University, West Bengal in 1978This work formed a part of a thesis submitted for the Degree of Doctor of Philosophy to Bidhan Chandra Agricultural University, West Bengal in 1978     

Effect of different water salinity levels and organic matter application on the composition of water soluble and exchangeable bases in a brackishwater fish pond soil

Behaviour of different water soluble and exchangeable bases in a brackishwater fish pond soil was studied under four levels of water salinity, in combination with and without organic matter application. The results showed average content of water soluble bases to increase with increase in water salinity. The bases were dominated by Na⁺ followed by Mg⁺⁺, Ca⁺⁺ and K⁺ in decreasing order. SAR values of water increased with increase in water salinity and decreased slightly on organic matter treatment.Total content of exchangeable bases in soils was fairly high and was dominated by Ca⁺⁺ and Mg⁺⁺, followed by Na⁺ and K⁺ respectively. Amount of exchangeable Ca⁺⁺ + Mg⁺⁺ decreased while that of Na⁺ increased with increase in water salinity levels. Amount of exchangeable K⁺ did not show any appreciable change. Application of organic matter tended to increase the exchangeable Ca⁺⁺ + Mg⁺⁺ content and decrease the amount of exchangeable Na⁺ in the soil, while exchangeable K⁺ content remained practically unaffected due to organic matter treatment.Formed part of a Ph.D. thesis submitted to Bidhan Chandra Agricultural University, India in 1978Formed part of a Ph.D. thesis submitted to Bidhan Chandra Agricultural University, India in 1978     

Morphological variation in the sugarcane smut Ustilago scitaminea Syd

Summary A study of the morphological variability among 25 different collections of sugarcane smut fungusUstilago scitaminea from the States of Delhi, Uttar Pradesh, Bihar, Madhya Pradesh, Maharastra, Andhra Pradesh and Madras revealed that considerable variation exists in spore size, colour, spore-wall markings of the isolates. On the basis of statistically significant differences in the spore size, the 25 isolates can be classified into 4 distinct groups. Three types of spore-wall markings viz., verrucose, punctate and echinulate are met within the isolates studied. There is no appreciable difference in the spore wall thickness of the different isolates. Spore colour of the different isolates varied from yellow to brown with several shades in between.Part of a thesis submitted by the senior author in partial fulfilment of the Degree of Doctor of Philosophy, P. G. School, Indian Agricultural Research Institute, New Delhi.     

Respiration of Streptocephalus dichotomus Baird (Crustacea : Anostraca)

Summary The Rate-temperature (R-T) curve for S. dichotomus tends to reach a peak at 30°C in both sexes in all the weight groups. As the temperature increases above 30°C the metabolic rate decreases considerably.The proportionate weight specific rate of oxygen uptake is the same for all sizes.There is no significance in the relationship between oxygen lethal levels and body weight.This work formed part of the thesis submitted for the award of the Degree of Doctor of Philosophy to the University of Madras, in 1970.     

Antixenosis,tolerance and genetic analysis of some rice landraces for resistance to Nilaparvata lugens (Stål.)

Twenty-six rice landraces from West Bengal, India were evaluated for antixenosis and tolerance against brown planthopper (BPH) biotype 4 at the Bidhan Chandra Krishi Viswavidyalaya (BCKV), West Bengal. High levels of resistance were observed in six landraces, namely Badshabhog, Gamra, Haldichuri, Janglijata, Kalabhat and Khara. These phenotypically resistant rice landraces including Ptb33 exhibited lowest feeding rate, fecundity, nymphal and adult preference, survival, plant dry weight loss per mg of BPH dry weight produced (PDWL), and higher functional plant loss index (FPLI), more days to wilt and unhatched eggs compared with the susceptible check Swarna. All the landraces were classified into four major clusters at 10 unit distance by the scale of similarity during genetic diversity analysis through 21 gene-linked SSR markers of BPH resistance. Some phenotypically resistant landraces were gathered under the major cluster I indicating their analogous genetic history, while some were grouped with susceptible landraces exhibiting their genetic variation. The resistant landraces can be used as potential donors in the breeding programme for the development of rice varieties with resistance to BPH.     

The characterization of phosphorus excretion products of a natural population of limnetic zooplankton

The characteristics of phosphorus excretions of zooplankton collected in spring 1974 from Stonehouse Pond, New Hampshire were studied with gel filtration, ultraviolet spectroscopy and seston incorporation. The soluble phosphorus component released from a natural population has a molecular weight the same as orthophosphate and behaves similar to orthophosphate in seston incorporation studies. Approximately 15 percent of the total phosphorus released was organic, but could not be identified by ultraviolet spectroscopy. No evidence of nucleic acid excretion or any hydrolytic degradation product was detected in the ultraviolet spectrum.The experimental work was based on a thesis submitted to the Graduate School of the University of New Hampshire in partial fulfillment of the requirements for the degree of Doctor of Philosophy.     

An ecological study of the macrophytic vegetation of the Doodhadhari Lake,Raipur, M. P., India

Summary Physical factors operating in Doodhadhari Lake were studied periodically during 1967–68. Thermal stratification in the lake was found to be induced by solar radiation during daytime and destroyed by nocturnal cooling and mixing of the lake waters as evidenced by temperature records. Light intensities at different strata were found to be reduced by plant growth. At 0.5 m depth and 1 m depth considerable reduction in light intensities was found. The floating-leaved rooted plants and free-floating sudd communities curtailed the light transmission to 0.0 – 0.1% at 0.5 m depth. Visibility also decreases considerably owing to shading by the plants at different stations.A part of the thesis submitted for the Degree of Doctor of Philosophy.     

Hatching and Postembryonic Development of Streptocephalus Dichotomus Baird (Crustacea : Anostraca)

Summary Hatching and postembryonic development of Streptocephalus dichotomus have been studied. Only dried eggs hatched in the laboratory. Hatching is influenced by desiccation and temperature. Drying for 10 or 20 days and temperature of 30° C seem to be favourable for S. dichotomus eggs to hatch. In S. dichotomus immersion in water up to 120 cm depth has no effect on hatching.Fifteen larval stages are involved in postembryonic development and sex differentiation appears at the eighth larval stages and becomes more pronounced in later stages. S. dichotomus takes 28 days to attain its adult structure in the laboratory at room temperature.This work formed part of the thesis submitted to the University of Madras for the award of the Degree of Doctor of Philosophy in 1970.     

Effect of flooding and cropping on the changes in the inorganic phosphate fractions in some rice soils

Summary Greenhouse experiments were conducted to evaluate the significance to flooded rice of the various forms of inorganic soil phosphate on Aborlan, Luisiana and Pili soils with and without phosphate. Changes in the various inorganic soil phosphate fractions with time under cropped and uncropped conditions were measured. Results showed that the iron phosphate fraction was the most important source of phosphate to the rice plant. It was also evident that phosphate added to the soils was slowly converted into the iron phosphate form. Transformation of soil phosphate seemed to be greatly affected by the presence of plant roots. Changes in the phosphate fractions were marked in the cropped soils.Data presented in this paper form part of Ph.D. dissertation submitted by the first author to the University of the Philippines, College of Agriculture, Los Banos, The Philippines.Professor of Agr. Chemistry, Dept. of Agr. Chemistry, Univ, of the Philippines, College of Agriculture.Rice Agronomist, Univ. of Agr. Sciences, Regional Research Station, Mandaya, Mysore, India.     

Studies on the nutrition of forage legumes

Summary Surface samples of six Ontario soils were selected to provide a range in pH, texture and carbonate content. Phosphorus was added to the soil samples at the rate of 200, and 2000 pounds. P₂O₅ per acre and the inorganic phosphates associated with aluminum (Al-P), iron (Fe-P) and calcium (Ca-P) were analysed 15, 30, and 335 days after treatment. Samples of the check soils were leached with the equivalent of 7 litres of soil-percolated water and then analysed for phosphate fractions. In 5 soils with added phosphorus the Al-P fraction increased at both rates of added phosphorus, Fe-P increased only at the higher rate of added phosphorus and Ca-P did not increase at either rate. In the sixth soil (69.9% CaCO₃ equivalent) Ca-P increased at both rates of added phosphorus, but proportionately less than the water-soluble phosphorus. These changes in phosphorus values existed relatively unchanged for 335 days after the addition of phosphorus. Leaching generally removed phosphorus from all phosphorus fraction. At or below pH 7.1 (soil paste) the Al-P decreased proportionately more than the Fe-P and Ca-P. Above pH 7.1 the Ca-P decreased proportionately more than the other two fractions upon leaching.Contribution from Dept. of Soil Science, O.A.C., Guelph, Canada. Part of thesis submitted by junior author to the Graduate School, University of Toronto, in partial fulfilment of the requirements for the M.S.A. degree.     

The role of zooplankton in the intrabiocoenotic phosphorus cycle and factors affecting phosphorus excretion in a lake

The temporal and spatial excretion rates of specific size groups of limnetic zooplankton were studied by measuring changes in soluble reactive phosphorus following incubation. Animals were collected in the epilimnion and hypolimnion of Stonehouse Pond, New Hampshire from August, 1972 to July, 1973 and separated into > 0.308 and < 0.308 (mm) size groups. Temporal excretion rates varied considerably within groups, however, similar patterns were observed in both strata. Peak excretion rates were observed in the spring and fall with a low in winter months. In addition, smaller animals excreted at higher rates and excretion rates of both size groups in the epilimnion exceeded those in the hypolimnion.The phosphorus uptake of natural seston relative to the amount released by zooplankton is considered using mass balance equations and kinetic analyses. During the spring of 1973 excretion rates increased, however, this increase was offset by an even greater rise in the rate of phosphorus uptake by the seston. This suggests that during this period the phosphorus excretions of zooplankton were not sufficient to meet the amount of phosphorus being removed by the seston.The experimental work was based on a thesis submitted to the Graduate School of the University of New Hampshire in partial fulfillment of the requirements for the degree of Doctor of Philosophy.     

Food,feeding and digestion in streptocephalus dichotomus baird (Crustacea: Anostraca)

Summary Gut analysis of Streptocephalus dichotomus revealed that the main source of food is phytoplankton. S. dichotomus is a non-selective filter feeder, taking in all the food-items carried in the feeding currents and passed through the midventral groove. The feeding currents are produced by the thoracic limbs.Feeding experiments have shown that the time taken for the passage of food is directly proportional to the number of days of starvation. Food intake of males did not significantly differ from that of females when fresh animals were used, as well as animals used after one day of starvation.Fresh males as well as females took in significantly more food than starved animals.The digestive enzymes such as carbohydrases, proteases and lipases are present in the gut. The optimal pH for amylase ranged between, 5.8 to 6.6, for protease 7.4 to 8.0 and for lipase 5.2 to 6.5.This work formed a part of the thesis submitted to the University of Madras, in 1970 for the award of the Degree of Doctor of Philosophy.     

Fluctuations in the relative abundance of the weed fauna of a tropical freshwater fish pond

Summary The macrofauna present in the weed Eichhornia crassipes in a tropical fish pond have been studied for a two year period. Different groups of animals under the phyla Annelida, Arthropoda and Mollusca and their seasonal abundance have been recorded. The method of studying densities of organisms as related to a known volume of plant material was found to give satisfactory results. Aulophorus furcatus and Branchiodrilus hortensis were the two species of Oligochaeta which were associated with the weeds. The Ostracods Stenocypris malcolmsonii and Eucypris capensis showed almost similar seasonal trends. Larvae of the Ephemeropteran, Baetis, five species of Chironomidae and different nymphal instars of Zygoptera and Anisoptera were also encountered. Of the four species of Molluscs, three were pulmonates whose occurrence in the weeds is considered to be favourable for their growth and reproduction in view of their proximity to the water surface. The effect of nutrition on the populations of weed fauna has been discussed. Their maximum abundance during the months of November to March was found to be concurrent with the presence of other favourable environmental factors also.This work formed part of the thesis submitted for the award of the Degree of Doctor of Philosophy to the Calcutta University, in 1964.     

Biochemical composition of Streptocephalus dichotomus Baird Branchinella kugenumaensis (Ishikawa)

Summary Estimations of total nitrogen, non-protein nitrogen protein, amino acids, lipid, carbohydrate, ash and water contents are carried out for the two fairy shrimps Streptocephalus dichotomus and Branchinella kugenumaensis.The mean values for S. dichotomus are: T.N. - 12.13%; N.P.N. - 3.49%; Protein - 54.71%; Lipid - 11.01%; Carbohydrate - 7.43% and ash - 10.44% and for B. kugenumaensis are: T.N. - 12.63%; N.P.N. - 4.92%; Protein - 48.21%; Lipid - 17.14%; Carbohydrate - 8.93% and ash - 9.17% expressed as percentage dry weight.The protein ash contents are higher in S. dichotomus while non-protein nitrogen, lipid and carbohydrate are higher in B. kugenumaensis.These biochemical fractions show no significant difference between males and females in both S. dichotomus and B. kugenumaensis.The work on Streptocephalus dichotomus formed a part of a thesis submitted for the Degree of Doctor of Philosophy to the University of Madras in 1970.     

Seasonal trends in physicochemical factors and plankton of a freshwater fishpond and their role in fish culture

Summary A two year study on seasonal variations of the physicochemical factors and plankton of a freshwater fish pond was made. The importance of these factors in fish culture has been discussed. pH ranging between 7.3 and 8.4 falls within the range considered suitable for fish growth. The amount of dissolved gases at any given time is found to be associated with biological activities taking place in the medium. The relatively high total alkalinity values observed may also help in higher yield of fish. Low phosphate content is attributed to utilisation by phytoplankton. Most plankters exhibit a single annual peak, though individual species have different seasons of maxima. Volume and dry weight values also showed a single peak suggesting a period of maximum production. However, year to year variations observed in total quantity of plankton is likely to affect fish growth and production.This work formed part of the thesis submitted for the award of degree of Doctor of Philosophy to Calcutta University, India in 1964.     

Studies on the bottom fauna in a tropical freshwater fish pond

Summary Quantitative samples of the bottom fauna obtained from a tropical freshwater fish pond during a period of two years were studied with regard to species composition, zonal variation and seasonal fluctuation. Two different zones with differences in faunal composition could be distinguished. The littoral zone was dominated by Mollusca, whereas Oligochaetes were predominant in the profundal zone. Most of the organisms showed their peaks in the months January to April. Breeding activities ofVivipara bengalensis, Digoniostoma cerameopoma, Melanoides granifera andPisidium clarkeanum as evidenced by presence of younger length groups in the populations were also observed during the same period (January to April). The influence of environmental factors as temperature, alkalinity and food were discussed as probable causes for the peaks in abundance. The average number of total organisms per square metre was found to be comparatively high indicating a high standing crop. Differences observed in the total number of organisms present have been attributed to inflow of water resulting in sudden alteration of the nutrient condition of the bottom mud. The seasonal variations of the standing crop of bottom fauna during both the years have been found to be influenced by fluctuations of the bivalve mollusc,Lamellidens corrianus. The availability of sufficient amount of benthic fauna for consumption by bottom feeding fishes has been indicated.This work formed part of a thesis submitted for the Degree of Doctor of Philosophy to the University of Calcutta, India in 1964.     

On the ecology of notholca squamula muller in Loch Leven,Kinross, Scotland

Notholca squamula was rarely found in Loch Leven when the water temperature rose above 10°C. Under favourable temperature conditions its abundance appeared to be closely related to that of Asterionella formosa. In the laboratory the animal was seen to feed on this diatom by breaking open the frustule and ingesting the cell contents.Part of a dissertation for the Degree of Doctor of Philosophy to the Council for National Academic Awards at Paisley College, Scotland, in conjunction with the Institute of Terrestrial Ecology, Edinburgh, Scotland     

The distribution and periodicity of the phytoplankton of three Ceylon lakes

Summary The phytoplankton of three Ceylon lakes, two situated in the warm lowlands and one in the cool mountains has been investigated. Certain similarities and differences in regard to growth, distribution and periodicity of the plankton algae are discussed and related to environmental conditions.The lowland lakes are dominated by Myxophyceae which form 95% and 87% of the phytoplankton respectively, while in the mountain lake, which is temperate rather than tropical, Diatoms form 65% of the phytoplankton. Of the lowland lakes that in the centre of the densely populated city of Colombo has an algal productivity which is two and a half times as great as that situated in a vast area of uncultivated land. The mountain lake, surrounded by cultivated hills, occupies an intermediate position between the low country lakes in regard to productivity.The environmental factors mainly affecting algal growth, distribution and periodicity in these lakes are temperature, rainfall, sunshine, movement of the water, amount of influx of organic matter and nature of the surrounding soil. In assessing the effect of rainfall consideration has been given not only to the total precipitation, but also to its intensity and the occurrence of periods of drought between those of heavy rainfall.Part of thesis (Ceylonese Plankton Algae) approved for the Degree of Doctor of Philosophy in the University of London and lodged in the Library of that University.     

Effect of algal growth on the availability of phosphorus,iron and manganese in rice soils

Summary Laboratory experiments were conducted to study the effect of algal growth on the change of (I) pH, (II) available phosphorus and (III) solubility of iron and manganese content in five waterlogged alluvial rice soils of West Bengal, India. The results showed that the algal growth initially caused an increase in the soil pH, which later declined to the original value in some of the soils. The available phosphorus content decreased upto 90 days of their growth and began to increase towards the later period of incubation. The drastic fall of water soluble plus exchaneable manganese content of the soils due to algal growth was accompanied by similar increase in reducible manganese content. No appreciable change in water soluble plus exchangeable ferrous iron content was encountered but theN-NH₄OAC(pH 3) extractable iron due to algal growth progressively decreased with the progress of the incubation period.     

Rhizophagus in Mycorrhizal Association with Litchi chinensis Sonn

The morphology and the mycotrophic habit of a new species ofRhizophagus in mycorrhizal association with the roots ofLitchi chinensis Sonn a tropical fruit tree, has been described. It belongs to the vesicular-arbuscular group of phycomycetous endophytes and has been namedRhizophagus litchii sp. nov.The endophyte could not be brought into culture in artificial media, the presence of living litchi roots was necessary for its growth and development.Root penetration of the endophyte was through the epidermal cells. Roots hairs were free from infection.Part of the thesis submitted byS. Pandey for the award of the degree of Doctor of Philosophy from Bhagalpur University, Bhagalpur, Bihar (India).