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Showing papers by "North Eastern Hill University published in 1975"


Journal ArticleDOI
TL;DR: Nine species belonging to eight genera have been described as new to science in a study of the ostracod fauna in Madurai Area in Southern India.
Abstract: Summary A study of the ostracod fauna has been carried out in Madurai Area in Southern India. Nine species belonging to eight genera have been described as new to science. Comparisons have been made with related temperate and tropical ostracods and the relationships have been discussed.

17 citations


Journal ArticleDOI
TL;DR: It is suggested that stimulation of the crop is related to nitrogen enrichment of the soil due to the nodular bacteria in the root of the weed and in nutrient-rich soils at a given plant density.
Abstract: The behaviour of wheat and Trigonella polycerata L. was studied in pure and mixed stands at two nutrient levels in the soil. Wheat responded to increasing density by extreme plasticity whereas the legume responded both by mortality and plasticity. In mixtures, an increase in the density of T. polycerata resulted in an increased dry weight yield of the crop and only at very high densities of Trigonella was there an adverse effect of the weed on the crop. It is suggested that stimulation of the crop is related to nitrogen enrichment of the soil due to the nodular bacteria in the root of the weed. The legume itself suffered from the presence of the crop. T. polycerata showed considerable interplant variation, the range of variation was greater at low densities and in nutrient-rich soils at a given plant density.

11 citations


Journal ArticleDOI
01 Nov 1975
TL;DR: The interference between maize andEchinochloa colona was studied by growing the two species in pure and mixed stands under varied nutritional levels in the soil and it was shown that the interference from the weed to the crop is a continued risk throughout the life cycle and that longer the period of association between the two, greater the damage done to crop yield.
Abstract: The interference between maize andEchinochloa colona was studied by growing the two species in pure and mixed stands under varied nutritional levels in the soil. Both the species responded to density stress in pure stands by mortality and plasticity. Density dependent mortality was comparatively higher for maize than forE. colona. The higher mortality rate of maize was related to the higher growth rate in this species. The dry matter production was also more sensitive to density stress for maize than forE. colona. The generally higher mortality in the more fertile soil was explained as due to the better expression of genotypic individual differences and the consequent elimination of the weaker individuals by more vigorous ones.

4 citations


Journal ArticleDOI
TL;DR: The increase in the number of secondary malpighian tubules of Chrotogonus trachypterus in its nymphal stages is apparently related to the increased excretory requirement brought about by the growth of the body.
Abstract: The present paper deals with the development of secondary malpighian tubules of Chrotogonus trachypterus in its nymphal stages. There are 12 groups of malpighian tubules in the adult C. trachypterus, each group opening into the alimentary canal at the junction of the midgut and hindgut through an ampulla derived from the hindgut. But, while in the male each group has only 5 tubules, in the female each group has 11 tubules, so that the male has 60 tubules and the female has 132 tubules. The early 1st nymphal instar has only 18 well-developed malpighian tubules in both sexes. Sexual dimorphism starts in the 2nd nymphal instar. In the males, the secondary malpighian tubules are added in the sequence of 6, 12 and 24 tubules in the 1st, 2nd and 3rd numphal instars respectively; in the 4th and 5th instars there is no further addition. In the females, they are added in the sequence of 6, 24, 36, 24 and 24 in the 1st, 2nd, 3rd, 4th and 5th instars respectively. The development of a secondary malpighian tubule comprises successively the phases of initial development, mitosis and cell enlargement. The increase in the number of secondary malpighian tubules is apparently related to the increased excretory requirement brought about by the growth of the body.

1 citations