Volume 80, Issue 3
September 1974, pages 105-161
pp 105-120 September 1974
Four inbreds of pearl millet and their F1 hybrids, obtained by crossing the inbreds in all possible combinations, were grown in two seasons—the stress season and the non-stress season—to study whether there are any differences in the genotype environment interactions between the inbreds and their F1 hybrids. The mean chiasma frequency of the inbreds was lower and the variation of the mean chiasma frequency was more in the stress conditions than in the non-stress conditions. In both seasons the heterozygotes showed limited variation among their means, and larger mean chiasma frequencies when compared to the inbreds. The differences between the inbreds in their interaction with the seasons were significant. Different hybrids interacted with the seasons in a significantly different manner from each other. However, the differences between the inbreds as a group and hybrids as a group interacted with the environment in a large measure. When examined with the means, the significant differences between hybrids and inbreds in their interaction with the seasons showed that the hybrids were relatively stable over seasons as compared to the inbreds. The intercell variation within each plant was also examined as a variable to detect differences if any between genotypes, particularly to find out if the hybrids have a different type of variation as compared to the inbreds. The analysis revealed that the inbreds as a group are having larger means for this variable over hybrids. The hybrids have much less intercell variation within individual plants and nearly twice the buffering capacity of the inbreds. The hybrids and inbreds interacted similarly to the environment for the intercell variation. Diallel analysis carried out to study the genetic nature of heterosis for chiasma frequency revealed average overdominance for this character and the overdominance was shown to be at least partly due to non-allelic gene action.
pp 121-126 September 1974
Immediately after fertilization of the ovum, vigorous cell proliferation commences at the expense of the yolk reserves. The high titre of glycogen, observed both during the initial as well as the final stages of embryogenesis, suggests glycogen to be the main energy reserve which in combination with protein also participates in the chitinization of the newly hatched out larva. The close resemblance in the variation pattern of free sugar content to that of active phosphorylase activity is noteworthy.
The initial total protein concentration inPhilosamia egg (165µg/egg) although declines during early embryonic development, rises again to 149µg/egg on day 6 on the eve of emergence of the first instar larva depicting intensive tissue transformation during the tail end of embryogenesis.
pp 127-133 September 1974
The histochemical constituents, namely, lipids, polysaccharides, reducing sugars and proteins of fresh materials of style, stigma, pollen and pollen tubes were assessed inSetaria italica Beauv.
The style and stigma contain a rich quantity of lipids, and low content of polysaccharides and reducing sugars before pollination. These become very much reduced afterwards. Germinated pollen grains and pollen tubes, on the contrary, contain high concentrations of lipids, polysaccharides and proteins, but not the reducing sugars. The cell wall of the latter shows detectable tinge of polysaccharides and proteins. Lipid nature could be discerned in the pollen wall, but not in the wall of pollen tube.
Based on the present results and previous available data, biochemical composition of, and correlation between the pollen tube and pistillar tissues have been discussed. InSetaria italica nutritional correlation appears to be present initially between the germinating pollen and stigma, but not later—between the pollen tube and style.
pp 134-138 September 1974
Karyotypes and meiosis inScirpus jacobi (2n=28),S. supinus (2n=28),S. lateriflorus (2n=30) andS. juncoides (2n=76) have been investigated. The chromosomes in all these species have been found to possess localized centromeres.
pp 139-146 September 1974
The morphology of a new copepod parasiteLernaea hesaragattensis has been described. The infection appears to be maximum during July and minimum during January. The parasite is found generally attached at the base of the fins of the host fish,Lebistes reticulatus. The adult female parasite measures 6–9 mm, and possesses a pair of ovisacs measuring 2–3·5 mm, with 120–140 eggs in each sac. The abdomen is distinctly 3-jointed and extends posteriorly at an angle from the thorax. The pregenital prominence which marks the posterior end of the thorax is in the form of a large undivided lobe.
pp 147-161 September 1974
The phytal fauna ofUlva fasciata off Visakhapatnam coast were investigated during the period January, 1967 to December, 1968. The standing crop of the alga ranged between 900 g and 1575 g/m2 of rock surface. The maximum growth was observed during July–August in both the years and the minimum in April. The total non-sessile faunal density ranged from 413 to 10166/100 g of alga with the maximum numbers in April–May period and the minimum in January, 1967 and July, 1968. The maximum faunal density occurred when the algal thalli were declining and degenerating and the ambient hydrographical conditions (like salinity and temperature) were steady. Gastropods, bivalves, isopods, amphipods and decapods were abundant when the alga was prolific and while withering, foraminiferans, nematodes, polychaetes, halacarids, chironomids and copepods were high in numbers. The phytal faunal density of the present area compares favourably with those from temperate belt. The primary importance of the algal structure, which determines the degree of sedimentation, the animal composition and the relative abundances of the faunales is discussed.