Showing papers by "North Eastern Hill University published in 1984"

Leaf dynamics of tropical trees related to successional status

Abstract: SUMMARY Leaf dynamics of two early successional and two late successional species of a tropical humid forest at Lailad in north-eastern India were studied. Leaves produced during different months were found to have markedly different longevity, for all the species studied. The early successional species showed higher leaf turnover rates, reduced leaf longevity, more uniform production and fall of leaves under forest-grown conditions than in open-grown conditions (though with some fluctuation during the year) and an evergreen or leaf-exchanging pattern of leafiness. The late successional species had slower leaf turnover rates, longer leaf longevity, a peak of leaf production and a deciduous habit. It is concluded that differences in leaf dynamics of early and late species are related to the successional niches they occupy in the forest community.

Herbaceous vegetation development and weed potential in slash and burn agriculture (Jhum) in N. E. India

Abstract: Summary The patterns of herbaceous vegetation development and weed potential following slash and burn clearing after different lengths of time between the cultivation cycles are described. The early stages of secondary succession following burning tended to conform closely to the ‘initial floristic compositione’ model under shorter cycles of 4 and 6 years between cultivation, but the ‘relay floristicse’ model was found to be more applicable to the cycles of 10 and 20 yearse’ duration. Weed population, in terms of density, biomass and germinable seeds present in the soil, was significantly higher after cycles of 4 and 6 years compared to 10- and 20-year cycles. In all the cycles, however, weed population declined sharply after a year of cropping with an effective weeding programme following the burn. Rasuma Evolution des adventices herbacees en culture sur brulis (Jhum) au nord est des Indes Les tendances observees dans le developpement de la vegetation herbacee et de son potential en tant que mauvaises herbes suivant culture sur brulis sont decrites. Les etapes precoces de la succession secondaire apres brulis ressemblaient d'assez pres au modele ‘composition floristique initialee’ dans les cycles plus courts, c'est-a-dire de 4 et 6 ans entre cultures; mais pour les cycles d'une duree de 10 et 20 ans le modele ‘floristique de relaise’ semblait plus approprie. Le peuplement de mauvaises herbes, considere en fonction de la densite, de la biomasse et des graines capables de germer presentes dans le sol, etait significativement superieur apres des cycles de 4 et 6 ans par rapport aux cycles de 10 et 20 ans. Cependant dans tous les cycles le peuplement diminuait rapidement au bout d'un an de culture qui comprenait un desherbage effectif apres le brulis. Zusammenfassung Entwicklung des staudenartigen Pflanzenwuchs und dessen Unkrautspotential in der Brandwirtschaft (Jhum) Nordostindiens Das Bild der Entwicklung von staudenartigen Pflanzen und deren Unkrautspotential in einer Brandwirtschaft werden mit Bezug auf verschiedene Zeitabstande zwischen den Anbauperioden beschrieben. Die fruhen Etappen der sekundaren Sukzession nach dem Brand neigten bei den kurzeren Zeitabstanden mit 4 und 6 Jahren zwischen den Anbauperioden dem Modell ‘floristichen Anfangskompositione’ zu. Das Modell ‘Staffelfloristike’ aber erwies sich als den Zyklen mit 10- und 20-jahrigen Zeitabstanden mehr geeignet. Die Unkrautpopulation, als Dichte. Biomasse und keimfahige Samen im Boden ausgedruckt, lag bedeutend hoher nach 4- und 6-jahrigen, im Vergleich mit 10- und 20-Jahrigen Zeitabstanden. In allen Zyklen aber geschah eine starke Minderung der Unkrautpopulation nach Anbau wahrend eines Jahrs, wo ein erfolgreiches Unkrautbekampfungsprogramm nach dem Brand durchgefuhrt wurde.

The science behind rotational bush fallow agriculture system (jhum)

Abstract: Rotational bush fallow agriculture variously termed as shifting agriculture, slash and burn agriculture are commonly known in India asjhum is a traditional agricultural system of the humid tropics and is extensively practised by the tribes of the north-eastern hill region. There is a renewed interest in this agricultural system as it has so much to offer in terms of concepts and ideas to modern agricultural organization. The science behind jhum is based on intuitive experience of the farmer based on long tradition. This paper looks at the science behind jhum with particular emphasis on the ecological and economic significance of mixed cropping, recycling of resources within the system and between jhum and animal husbandry, the non-weed concept weed potential under different cycles of jhum, and nutrient cycling. The distortions brought about by the shortening of the jhum cycle to 4–5 yr is considered. Alternate strategies for development with jhum as the focal point, with suitable modifications but without the present-day distortions, have been considered.

A convenient method of preparing nickel(II) thiocyanate and its use in synthesis

Abstract: A convenient method for preparing nickel(II) thiocyanate is described. Some new compounds containing nickel thiocyanate and ligands, such as OPPh3, OAsPh3, bipy, Me2NH, Et3N or N2H4 are reported, together with their structures and the nature of the bond between the thiocyanate and the metal, which has been determined by physical and chemical methods.

Study on the vesicular-arbuscular mycorrhiza of three cultivars of potato (Solanum tuberosum L.)

Abstract: The establishment and development of vesicular-arbuscular mycorrhizal (VAM) fungi were studied in three cultivars of potato, which differed in susceptibility to ‘Late blight’, in a field experiment on a lateritic sandy-loam during two growing seasons (1980 and 1981). The cultivars ‘SSC 1174’ (highly resistant) and ‘Kufri Jyoti’ (resistant) showed an earlier establishment and more rapid development of VAM fungi than ‘up-to-date’ (highly susceptible). The first mycorrhizal infection in both ‘SSC 1174’ and ‘Kufri Jyoti’ was observed after 12 days in 1980 and 8 days in 1981, whereas in ‘up-to-date’ it was observed after 19 and 12 days respectively. The mycorrhizal infection increased with the age of the plants in all the three cultivars.

Allelopathic effects of Eupatorium riparium on population regulation of two species of Galinsoga and soil microbes

Abstract: Allelopathic effect ofEupatorium riparium Regel, a dominant ruderal weed at higher altitudes in Meghalaya state in north-eastern India, was studied on two common sympatric annual weeds,Galinsoga ciliata (Raf.) andG. parviflora Cav. and on soil microbes. Seed germination and radicle and plumule growth of both species ofGalinsoga were suppressed by the aqueous extract and leachate ofE. riparium. Although the leaf leachate, leaf and litter extracts and litter bed caused considerable reduction in leaf area and seed and dry matter production in both species ofGalinsoga, the effect was much more pronounced onG. parviflora. The inhibitory effect was directly correlated with the concentration of the extract and leachate. The soil microbial population and growth of theGalinsoga spp. declined considerably in the experimental pots where the soil had earlier received leachate of different plant parts ofE. riparium growing in it. The presence of the partly decomposed litter ofE. riparium in the pots reduced soil microbial population and growth of the two weeds much more strongly as compared to the litter in the advanced stages of decomposition. The study also revealed that the abundance and colony growth of the two test fungiviz. Trichoderma viride andAspergillus flavus were differentially affected by the allelopathy ofE. riparium; T. viride being favoured andA. flavus inhibited.

Photooxidation and electron‐transfer processes in free‐base tetraphenylporphin probed by resonance raman spectroscopy

Abstract: We report here the resonance Raman studies of photooxidation of free base tetraphenylporphin (H2TPP) in the presence of external electron acceptors such as CCl4 and chloranil under selective laser irradiation From the dependence of photooxidation on the concentration of electron acceptors, polarity of solvents, excitation lines and temperatures, we have inferred that a weak triplet exciplex formed between the excited H2TPP and electron acceptor in non-polar solvents serves as transient species and the light-induced intermolecular charge transfer from H2TPP to the electron acceptor is the primary process involved in photooxidation Observation of partial photooxidation in the rigid matrix at low temperatures has been interpreted to be due to long-range quantum mechanical electron tunneling process Almost complete photooxidation is observed in a soft matrix as the donor and acceptor molecules can attain favorable relative orientation and separation for electron transfer during the excited state lifetime of the exciplex

Seasonal fluctuation of different edaphic microarthropod population densities in relation to soil moisture and temperature in a pine, Pinus kesiya Royle plantation ecosystem

Abstract: Seasonal fluctuations of soil and litter microarthropod populations in a pine,Pinus kesiya Royle plantation of North Eastern India were investigated between November 1976 and November 1977. Three major groups were recognized: (a) Collembola, (b) Acarina and (c) miscellaneous. Collembola was the most abundant group and was dominated byIsotoma trispinata (MacGillivray). The total microarthropod density ranged from 26,800 per m2 to 145,200 per m2. Collembola densities ranged from 10,000 to 121,200 per m2, Acarina densities ranged from 8,800 to 41,600 per m2, and the miscellaneous group ranged from 1,200 to 6,400 per m2. Soil moisture was positively correlated with total arthropod, Collembola and Acarina densities. Soil temperature was positively correlated only with Acarina. Densities of Collembola and Acarina were negatively correlated.

Growth and patterns of resource allocation in Eupatorium odoratum L. in the secondary successional environments following slash and burn agriculture (Jhum)

Abstract: Summary Biomass, nitrogen, phosphorus and potassium in Eupatorium odoratum L. (Asteraceae), an abundant early successional perennial weed, were studied in seral stages after slash and burn. Increment in individual biomass and nutrient uptake declined with increasing time after fallow. A higher proportion of the available resources was allocated to the supporting organs but a lower proportion to the photosynthetic organ in the older fields compared to recently fallowed fields. The allocation of biomass to reproduction, and also nutrient content, decreased during seral development. However, cost of reproduction to the plants (considered as the proportion of increment in biomass or nutrient uptake during the current growing season) was much higher in the older fields than the younger ones. Growth was adversely affected by low nutrient availability in soil in the recently fallowed fields but the allocation pattern remained unaffected. Biomass was not allocated in the same manner as nutrients. A higher proportion of nitrogen and phosphorus compared to that of biomass and potassium was devoted to reproduction in all the fields. Rasuma Croissance et distribution des reserves chez Eupatorium odoratum L. dans des environnements de succession secondaire suivant un systeme de culture sur brulis (Jhum) La biomasse, l'azote, le phosphore et le potassium dans des plantes d'Eupatorium odoratum L. (Asteracees), adventice perenne abondante des successions precoces, ont fait l'objet d'une etude aux etapes serales suivant culture sur brulis. L'augmentation de la biomasse, ainsi que l'absorption d'aliments chez des individus, baissait a mesure que l'intervalle depuis la jachere augmentait. Dans les plus vieux champs, une plus grande part des reserves disponibles a ete distribee aux organes de soutien et une moindre part a l'organe de photosynthese que dans les champs plus recemment affriches. La part de la biomasse consacree a la reproduction, ainsi que les reserves alimentaires, a diminue pendant le developpement seral. Cependant, si l'on considere le cout de la reproduction comme la part de l'accroissement en biomasse ou en absorption d'aliments pendant la saison vegetative en cours, il s'est revele beaucoup plus eleve dans les plus vieux champs que dans les plus recents. Le peu d'aliments, disponibles dans les sols des champs recemment affriches a eu un effet defavorable sur la croissance; neanmoins la distribution n'en a pas subi d'influence. La distribution de la biomasse diffeait de celle des aliments. Une plus grande part d'azote et de phosphore, par rapport a la biomasse et au potassium, a ete consacree a la reproduction dans tous les champs. Zusammenfassung Vegetation und Verteilung der Reserven bei Eupatorium odoratum L. in sekundaren Sukzessionsamgebungen nach Brandwirtschaft (Jhum) Es wurden die Biomasse sowie der Stickstoff-, Phosphor- und Kaliumgehalt bei Eupatorium adoratum L. (Asteraceae). einem haufig vorkommenden, mehrjahrigen, fruhen Sukzessionsunkraut in seralen Etappen nach Brandwirtschaft (Jhum) studiert. Der Zuwachs an Biomasse und Nahrstoffaufnahme in einzelnen Pflanzen nahm bei wachsender Zeit nach der Brache ab. Ein starker Anteil der verfugbaren Reserven wurde in alteren Feldern den stutzenden Organen zugeteilt, indem die dem photosynthelisehen Organ zugeteilte Menge kleiner war als in neulich gebrachte Feldern. Die der Vermehrung zugeteilte Biomasse sowie das Nahrstoffgehalt nahmen wahrend der seralen Entwicklung ab. Der Vermehrungspreis abet (als Anteil der Bio-masszunahme oder der erhohten Nahrstoffauf-nahme wahrend der laufenden Vegetationsperiode betrachtet) war viel hoher fur Pflanzen in alten als in neuen Feldern. In den neueren Brachfeldern wurde das Wachstum durch ungenugend verfugbaren Nahrstoff im Boden nachteilig beeinflusst aber das Zuteilungsbild blieb unbeeintrachtigt. Die Biomasse wurde nicht ahnlich wie die Nahrstoffe verteilt. Ein grosserer Anteil Stickstoff und Phosphor als Biomasse und Kalium wurde in allen Feldern der Vermehrung gewidmet.

Nitrogen budget under rotational bush fallow agriculture (jhum) at higher elevations of Meghalaya in north-eastern India

Abstract: The nitrogen budge of ‘rotational bush fallow’ agriculture (jhum) was investigated at higher elevations of Meghalaya in north-eastern India under 15, 10 and 5 year fallow cycles (the intervening fallow period between one or two croppings on the same site). Nitrogen depletion was affected by initial stocks in the soil and vegetation compartment at the time of slash and burn as well as the rate at which this was lost during the subsequent land use. While nitrogen losses due to the burn was more severe under longer cycles compared to the 5 year cycle the losses through sediment and water was more under a 15 year cycle compared to 10 and 5 year cycles. Transfer of nitrogen from soil to the weed biomass increased with shortening of the fallow cycle. The positive role of weeds in conservation of nitrogen in their biomass and subsequent release through organic manure into the agriculture system has been highlighed. Under a short fallow cycle of 5 years, considered on a time scale of 15 years, the soil nitrogen was depleted to a very low level compared to a 15 year cycle, suggesting that a 5 year cycle as prevalent today is not viable from the point of view of nitrogen economy.

Chromosomal Evolution in Indian Murrels (Channiformes: Channidae)

Abstract: SUMMARYThe chromosome complements of five Indian murrels belonging to the Genus Channa viz. C. striatus, C. barca, C. punctata, C. stewartii and C. orientalis have been investigated. The diploid number and chromosome formula for each of these species have been established. The most interesting finding is the existence of two chromosomal variety of C. punctata with 2n number as 34 and 32. Basing on the present findings, a hypothetical line of karyotypic speciation among the different Channa species has also been presented. Robertsonian rearrangements superimposed with pericentric inversion and/or centromeric shift seem to be the underlying factor in chromosomal speciation in Channids.

Influence of pH on Sporulation, Spore Germination and Germling Survival in Blue‐green Algae

Abstract: An investigation is made on the influence of the pH-value in the range of pH = 4.5 to 11.0 on sporulation, germination and germling development of Anabaena fertilissima and Anabaenopsis arnoldii, isolated from the Sambhar Salt Lake, Rajasthan. Maximum rates of germination were obtained with Anabaena at pH = 7.0… 10.5, with Anabaenopsis at pH = 7.0 to 8.5. With both species, sporulation occurs in the same pH-ranges, Anabaena dying without sporulation in the range of pH = 5.5… 6.5 and above pH = 10.5 and Anabaenopsis surviving without sporulation above pH = 9.5. With Anabaena the germling growth steadily increases from pH = 7 to 10.5, whereas Anabaenopsis shows a maximum at pH = 7 and at any other pH-value growth is considerably lower. Moreover, spore germination is bound to an exchange of the medium. In agreement with these experimental findings concerning the cultures, from July to February Anabaenopsis occurs in the Sambhar Lake as a vegetative form with a partial mass development, and from March to June it survives as a spore. Anabaena, however, has only a short vegetative phase in June, and it survives the remaining part of the year as a spore. Thus, the fast germination and sporulation in the range of higher alkalinity is the ecological strategy for Anabaena to resist the competition offered by Anabaenopsis.

The Need to Conserve Silent Valley and Tropical Rain-forest Ecosystems in India

Abstract: The tropical rain-forests of India are restricted to two major geographical zones of the country - the western Ghats of southwestern peninsular India and the northeastern region However, much of these forests have already been irreparably damaged The destruction is chiefly related to: timber extraction on a large scale, conversion for permanent agriculture or plantation crops, and other developmental activities It is in this last context that the relatively undisturbed tropical rain-forest ecosystems of the Silent Valley, in Palghat District (11 degree 5'N, 75 degree 27'E), is important and has gained considerable prominence in the recent past

Diagnostic Features of Rana danieli (Anura: Ranidae) Tadpoles

Abstract: Tadpoles of Rana danieli Pillai and Chanda were collected from temporary rain pools in marshy places at Umling situated at 296 m above sea level (91° 48’ E , 25°58’ N) about 65 km north of Shillong at Meghalaya hills. They are characterised by the keratodont formula 1:1+1/1+2:2, the presence of poison glands on the ventral and lateral abdominal surface, and a lateral line system on head and trunk region. Their structural features confirm the allocation of this species to the subgenus Hylarana.

A note on some Eurotatoria from Panjab State, India

Abstract: Among 35 eurotatorian species presently reported from Panjab State, India, ten species are new records to this region while eight are new records from N. W. India. A new synonym is proposed and biogeographical remarks are made.

Effect of fuel burning on the microbial population of soil

Abstract: An attempt was made to study the effect of different amount of fuel burning on the microbial populations of forest soil. Maximum effect of fire was observed in the surface layer of soil and not much variation was seen in the distribution of soil microflora. However, with increasing amount of fuel burned, the effect became higher, microorganisms being destroyed to a depth of 70 mm. Qualitatively, there was no significant difference in the composition of fungal species in comparison with the control soil. Similar types of fungal species were isolated from all the types of burned soil,Aspergillus, Penicillium, Trichoderma, Fusarium andPhoma being the predominant genera.

Competitive interaction between two leaf morph populations of white clover in relation to soil nitrogen

Abstract: The pure and mixed stands of the two populations of white clover (Trifolium repens L.) differing in leaf character were raised in the experimental pots using de Wits' replacement series. Of the two populations, one is characterized by having white ‘V’-shaped markings on the leaflets (marked population) and the other does not have any such marking (unmarked population). The competitive interaction between the two populations has been studied at two soil nitrogen regimes. The nitrogen requirement of the marked population seems to be higher than that of the unmarked population. The marked population was found to be more competitive as compared to the other population at high N level as shown by their relative yield. The competitiveness of the former was, however, masked to some extent under low soil nitrogen. This confirmed the differential response of the two populations ofT. repens to soil fertility as observed in nature.