Showing papers by "North Eastern Hill University published in 1981"
TL;DR: In this paper, fertility changes in agro-ecosystems where vegetation is removed by slash and burn procedures, the land is planted to crops (cultivated) for one year, and then left to revegetate naturally for upto 50 years (forested fallow, here after referred to as ‘fallow’) before the entire cycle (locally called Jhum) is repeated.
Abstract: The present study deals with fertility changes in agro-ecosystems where vegetation is removed by slash and burn procedures, the land is planted to crops (cultivated) for one year, and then left to revegetate naturally for upto 50 years (forested fallow, here after referred to as ‘fallow’) before the entire cycle (locally called ‘Jhum’) is repeated. A comparison has been made between three jhum cycles of 30, 10 and 5 years. Depletion in soil carbon continued throughout the cropping period of one year and extended upto a 5 year fallow. This could be one of the reasons against a short jhum cycle, alongwith a similar pattern in depletion of nitrogen. Available phosphorus build up in the fallows also starded only beyond a 5 year fallow period with rapid increase in 10, 15 and 50 year fallows. Cationic concentration in the soil also rapidly declined in the early phases of regrowth of vegetation. This decline was most pronounced for potassium due to the fact thatDendrocalamus hamiltonii is a heavy accumulator of this nutrient. Since this bamboo species dominates the fallow upto about 20 years, potassium build up in the soil was observable only at this stage. It is suggested that this species plays an important role in conservation of this nutrient. In a 50 year fallow, low levels of calcium and magnesium were maintained with rapid depletion of both with depth which is in contrast to that of potassium and phosphorus. In general, short jhum cycles of 5 year permit only low levels of soil fertility with very poor recovery during the fallow period. The significance of these results are discussed.
121 citations
TL;DR: Some medicinal plants commonly used by aboriginal people in Meghalaya are reported based upon the information gathered from local people in different parts of the state.
Abstract: Ethnobotany is the study of plants in relation to the inhabitants of an area. Meghalaya, one of the hill states in India, inhabited by aboriginal people, offers unusual opportunity for ethnobotanical studies, as these people largely depend upon the surrounding plants for their existence. In the present paper some medicinal plants commonly used by these people are reported based upon the information gathered from local people in different parts of Meghalaya.
102 citations
TL;DR: All the strains have diverged at morphological, karyotypic and genotypic levels and it is suggested that taro might have originated in the north-eastern India.
Abstract: Karyotypes and electrophoretic pattern of 15 strains of taro were studied. Strains collected from the northeast India hill state, Meghalaya were diploids and triploids whereas those from the plains of south India were diploids and of north India was a triploid. The diploids had 2n=28 and triploids showed 2n=42 chromosomes. The wild taro had the most asymmetrical karyotype. The protein content varied from 4.2 to 11.4 mg/g dry wt. The maximum protein content was found in a triploid strain 8 (11.4 mg/g dry wt) and minimum in the wild taro (4.2 mg/g dry wt). The number of protein bands was 7 in the wild taro (diploid) and 12 in one of the cultivated triploid strain. Meghalaya strains showed great variation with respect to leaf size and tuber shape and size. All the strains have diverged at morphological, karyotypic and genotypic levels. It is suggested that taro might have originated in the north-eastern India.
84 citations
TL;DR: The 30-year jhum cycle has the advantage over the 10 or 5 year cycle apart from higher yields, in that the monetary output/input ratio under a 30 year Jhum cycle is comparatively favourable.
Abstract: Shifting agriculture locally known as jhum is the predominant form of agriculture used by the local tribe of the north-eastern hill region of India. There is also some valley rice cultivation and terrace cultivation. The structure and some functional aspects of these three agro-ecosystem types are discussed and compared. The 30 year jhum cycle has the advantage over the 10 or 5 year cycle apart from higher yields, in that the monetary output/input ratio under a 30 year jhum cycle is comparatively favourable. Further, the 30 year jhum cycle is advantageous over terrace cultivation as the latter needs heavy inputs of fertilizers. The main advantage of settled valley cultivation is the raising of crops consistent in yield year after year from the same site.
71 citations
TL;DR: In this paper, a shortening of the Jhum cycle to 4-5 years does not permit the recovery of soil fertility and has adversely affected the vegetational cover and the biogeochemical and hydrological cycles.
Abstract: Subsequent to slash-and-burn of the forested fallow, and during shifting agriculture (Jhum) in the northeastern hill areas of India, the system loses much of its capacity to hold soil nutrients. Various losses occur through wind-blow of ash and also through runoff and percolating water. The chemistry of the ash, and the amounts of run-off and percolating water, are related to the length of the Jhum cycle owing to the type of vegetation that is slashed and burnt.The runoff and percolation losses of water and sediment during cropping, increased with shortening of the Jhum cycle. As percolation losses are fairly high due to the generally porous soil, terracing of the land in the manner suggested by some as an alternative to Jhum is not considered ecologically sound. Drastic reduction of fertility through losses of sediment and nutrients occurred in both 5- and 10-years' fallows. The shortening of the Jhum cycle to 4 – 5 years does not permit the recovery of soil fertility and has adversely affected the vegetational cover and the biogeochemical and hydrological cycles.
59 citations
TL;DR: Maximum fungal population in burnt site was recorded in July while it was highest in April and May in unburnt site, and Absidia sp.
Abstract: The effect of man-made fire on soil mierobial population in a natural subtropical pine forest eco-system, was studied. A nearly fifty years old pine(Pinus kesiya Royle) forest was cut and burnt in March 1977. Another half of this pine forest was left uncut and unburnt. Microbial population was destroyed completely just after the burning and recolonization occurred after some days. Bacteria and actinomycetes were found to be the first colonizers followed by fungi. Burning initiated better growth and higher population of bacteria after two or three showers. Bacterial population was highest in July in burnt and in May in unburnt forest. Maximum fungal population in burnt site was recorded in July while it was highest in April and May in unburnt site.Penicillium spp.,Cladosporium sp. andTrichoderma sp. were found to be first colonizing fungi just after the burning. In unburnt forest eco-systemAbsidia sp.,Trichoderma sp.,Fusarium sp. andPenicillium spp. were found to be dominant.
16 citations
TL;DR: In this article, a quantum spherical model of spin glass is solved and the solution exhibits the usual spin glass phase transition, but with out any unphysical features at low temperatures, and the entropy vanishes like T 3 as T → 0.
15 citations
13 citations
TL;DR: In this paper, the reduction of an aqueous solution of CrO3 with hydrazine hydrate in the presence of an excess of equimolar amounts of MI OH and 40% HF yields green, crystalline alkali hexafluorochromates(III), MI 3CrF6 (MI= NH4, Na, K or Rb), in very high yield.
Abstract: The reduction of an aqueous solution of CrO3 with hydrazine hydrate in the presence of an excess of equimolar amounts of MI OH and 40% HF yields green, crystalline alkali hexafluorochromates(III), MI 3CrF6 (MI= NH4, Na, K or Rb), in very high yield. The lithium analogue has been prepared by using Li2CO3 instead of lithium hydroxide. The compounds have been characterized by elemental analyses, room temperature magnetic moments, infrared spectra and molar conductivity. Time dependent molar conductivity studies of (NH4)3CrF6 and K3CrF6 suggest that the compounds do not undergo decomposition in water at ambient temperatures.
6 citations
TL;DR: The present study has added 8 taxa as new records to the list of previously recorded brachionid rotifers from N. W. India and one represents a new record from India.
Abstract: This communication deals with an account of 20 species (spread over four genera) belonging to the family Brachionidae, collected from various localities in Panjab State (N. W. India). A number of infraspecific categories (forms and varieties) are also recorded. The present study has added 8 taxa as new records to the list of previously recorded brachionid rotifers from N. W. India and one represents a new record from India.
5 citations
TL;DR: In this article, a saturated solution of KMnO 4 in pyridine in presence of an excess of K 4 reacts with 48% HF to produce K 2 MnF 5 ·H 2 O and MnF 4 ·py H 2 O.
TL;DR: The Transfer of a Self-Instructional Teacher Training Course from Britain to India Programmed Learning and Educational Technology: Vol 18, No 3, pp 136-143 as discussed by the authors.
Abstract: (1981) The Transfer of a Self‐Instructional Teacher‐Training Course from Britain to India Programmed Learning and Educational Technology: Vol 18, No 3, pp 136-143
01 Sep 1981
TL;DR: Deuterobaris intestinalis Mehrotra, 1973 is described in detail and its validity discussed and a key to the species of the genus is provided.
Abstract: Deuterobaris intestinalis Mehrotra, 1973 is described in detail and its validity discussed. A key to the species of the genus is provided. The description ofOctangium takanoi is also supplemented.
TL;DR: Several hitherto untested pyrimidine analogues inhibited germination as well as RNA synthesis in Cicer arietinum seeds, and Cyclic-AMP, adenosine, indole-3-acetic acid (IAA) and folic acid partially reversed the inhibitory effects produced by purine pyrimidine analogues.
TL;DR: The electron impact induced mass spectra of cyclopentadienyl compounds have been studied in this article, showing that an increase in temperature eases the expulsion of ECF2 groups from all the compounds.
Abstract: The electron impact induced mass spectra of [CF3SMn(CO)4]2, [CF3SeMn(CO)4]2, [CF3SFe(CO)3]2, [CF3SeFe(CO)3]2, CF3SeFe(CO)2C5H5 and CF3SCr(NO)2C5H5 are reported. These compounds exhibit weak molecular ion peaks and undergo preferential loss of CO or NO groups. The CO or NO free fragments suffer typical loss of ECF2(E = S, Se) with the simultaneous shift of F from carbon to metal. The ions [FFeC5H5]+ and [FCrC5H5]+ in the spectra of the cyclopentadienyl compounds prefer expulsion of π-cyclopentadienyls. The pyrolysis effects on the spectra of the compounds have been studied. An increase in temperature eases the expulsion of ECF2 groups from all the compounds and favors the formation of [Fe(C5H5)2]+ and [Cr(C5H5)2]+ in the cyclopentadienyl compounds.
TL;DR: The mass spectrum of Mn(CO)5Cl has been studied at 70 eV and at varying inlet temperatures of 20 −250°C as mentioned in this paper, showing the characteristic pattern of Mn2(CO10 which originates from the formation and recombination of the Mn( CO)5 radical.
Abstract: The mass spectrum of Mn(CO)5Cl has been studied at 70 eV and at varying inlet temperatures of 20–250°C. Like the heavier metal carbonyl derivatives, Mn(CO)5Cl exhibits peaks due to carbido fragments. The spectrum run at 100°C shows the characteristic pattern of Mn2(CO)10 which originates from the formation and recombination of the Mn(CO)5 radical. The spectral pattern changes further at an elevated temperature (250°C) showing the formation of Mn2(CO)8Cl2. The effect of pyrolysis has been discussed.
TL;DR: The effect of the inoculum density of vesicular arbuscular mycorrhizal endophytes on growth and development in maize was investigated in sterilized soil under glass-house conditions and the uninoculated plants exhibited the symptoms of chlorosis.
Abstract: The effect of the inoculum density of vesicular arbuscular mycorrhizal endophytes on growth and development in maize was investigated in sterilized soil under glass-house conditions. Mycorrhizal plants grew robust and produced three times more dry weight than non-mycorrhizal plants. 40 or more endophytes per plant produced the highest mycorrhizal association and the maximum growth in maize. The uninoculated plants exhibited the symptoms of chlorosis.
TL;DR: In this paper, a new phonon frequency distribution function for quasi-two-dimensional systems is proposed, and the lattice specific heat of crystalline graphite is calculated and compared with experiment.
01 Dec 1981
TL;DR: The seeds of Duabanga sonneratioides Ham were found to be positively photoblastic and gave fast and maximum germination of 80% in cortinuous light but failed to germinate in the dork.
Abstract: The seeds ofDuabanga sonneratioides Ham. were found to be positively photoblastic and gave fast and maximum germination of 80% in cortinuous light but failed to germinate in the dork. Longer photoperiod favoured germination. Total length of exposure to light rather than the dark period determined the germination of the seeds. Higher temperature favoured germination at a given light exposure treatment. In the field, seeds up to a depth of 2 mm in the soil could germinate. These results have been related to the light demanding nature of this carly suceessional tree species.