• V Singh

      Articles written in Proceedings – Plant Sciences

    • Floral anatomy and systematic position ofCyrtandromoea

      V Singh D K Jain

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      The floral anatomy ofCyrtandromoea differs from those of the other taxa of Gesneriaceae in several respects but shows many resemblances with that of Scrophulariaceae. Hence the transfer ofCyrtandromoea from Gesneriaceae to Scrophulariaceae is supported.

    • Floral organogenesis inCassia fistula L. (Caesalpiniaceae)

      V Singh Sunita Sharma

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      The five sepal primordia arise successively in clockwise sequence. Interprimordial growth initiates a short calyx tube. The petal primordia are formed almost simultaneously alternate to the sepal primordia. They are followed by the antesepalous stamen primordia which also appear simultaneously opposite the sepal primordia. The primordia of the antepetalous stamens are formed after the inception of the gynoecium. They are inserted inside the antesepalous stamen primordia. The floral apex grows up into a crescent-shaped gynoecial primordia. In floral developmentCassia differs from members of the Papilionaceae and Mimosaceae. The position of insertion of the leguminous carpel on the floral apex has been discussed and it was concluded that the carpel ofCassia is a terminal structure.

    • Studies in Bignoniaceae—VI. Floral anatomy

      D K Jain V Singh

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      The vascular anatomy of the flower of 18 species of Bignoniaceae is described. The flowers are hermaphrodite, zygomorphic, hypogynous and pentamerous. In many investigated taxa several medullary traces are given from the central vascular cylinder. The calyx shows much variation in its vascular supply in different taxa of the family. It is suggested that one-trace condition of the sepals has arisen by the fusion of the laterals with the median and multitraced condition by amplification of the three traces. Each petal receives a single trace but inTecomaria capensis although there are four petals, five traces differentiate for the corolla. The posterior petal which has two traces seems to have arisen by the incorporation of two petals. A siphonostelic stamen trace has been observed in some taxa and it has been correlated with the large size of the filaments. The vascular supply of each carpel consists of a dorsal bundle, a ventral strand and several carpellary laterals. The Bignoniaceae show an intermediate condition between axile and parietal placentation. The disc is very richly vascularised and derives its vascular supply from more than one source. It is suggested as carpellary in nature.

    • Studies in bignoniaceae. VII. Wood anatomy

      D K Jain V Singh

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      The wood anatomy of 17 species representing 14 genera has been investigated. The wood is diffuse porous. It is composed of vessels, tracheids, fibres, axial parenchyma and rays. The vessels are either scattered solitary or in radial or tangential multiples of two or three or in long radial chains. All the lianas and a few trees studied have two types of vessels with narrow and broad diameter. The vessels usually show a simple perforation plate. Two main types of xylem fibres, the fibre tracheids and the libriform fibres intergrade with each other. The xylem parenchyma is paratracheal, vasicentric and confluent to aliform. The rays are uni- or multiseriate, homogeneous or heterogeneous and their length varies in different species.

    • Phytochemical evaluation ofCassia obtusifolia L. andCassia tora L.

      S K Upadhyaya V Singh

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      Cassia obtusifolia andCassia tora are distinct in several important phytochemical characters. Obtusin, obtusifolin and stigmasterol are confined only toCassia obtusifolia and chrysoobtusin toCassia tora. They also differ in their amino acid constituents. Cyotine y-hydroxyarginine and aspartic acid are present inCassia tora but absent inCassia obtusifolia. Hystidine, which is present inCassia obtusifolia is absent inCassia tora. Also there was no natural hybridization betweenCassia obtusifolia andCassia tora and thus showing complete genetical segregation. This supports their treatment as two distinct species. The presence of 3 additional secondary constituents, stigmasterol, obtusin and obtusifolin inCassia obtusifolia suggest thatCassia tora was derived fromCassia obtusifolia.

    • Growth response ofVigna sinensis to SO2 pollution

      Naresh Kumar V Singh

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      Effects of 0·12, 0·25 and 0·5 ppm SO2 have been studied on growth, yield and carbohydrate contents ofVigna sinensis cv. Pusa Barsati. Bifacial necrotic lesions appeared on the middle and lower leaves exposed to 0·25 and 0·5 ppm SO2. A slight stimulation in plant height, root and shoot lengths was observed in 0·12 ppm SO2 exposure in early stages of plant growth. However, prolonged exposure caused significant reductions in all growth parameters and dry weight fractions and net primary productivity. The root weight reductions were higher than shoot weight. The flowering and first pod maturation were advanced by 1–4 days as a result of SO2 fumigation. Yield and yield attributes recorded a significant decrease. There was ca 50% reduction in seed yield per plant in 0·5 ppm SO2 exposures. Carbohydrate contents also recorded a decrease and leaf carbohydrates were most susceptible to SO2 pollution.

    • Sensitivity ofTriticale hexaploide Cv. Panda-6 to sulphur dioxide

      Subhash Chand V Singh

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      The sensitivity ofTriticale hexaploide cv. Panda-6 to 320 and 667 μg m−3 SO2 has been studied. Plant growth in terms of plant height, shoot and root length, number of leaves, roots and tillers and biomass per plant were reduced significantly in 320 and 667 μg m−3 SO2 respectively. The leaves of 90-day old plants were analysed in terms of leaf area injury per cent, leaf area reduction per cent, absorbic acid, leaf extract pH, phosphorus, sulphur and carbohydrate contents. Appreciable reductions in dry weight fractions and net primary productivity of SO2 treated plants were observed and the effects were concentration dependent. Chlorophylla, chlorophyllb and total chlorophyll contents of leaves were also reduced after 15 days to fumigation. The loss was higher in chlorophylla than chlorophyllb. Flowering and spike maturation were slightly advanced in both concentrations and 667 μg m−3 SO2 caused 22·11% reduction in weight of 100 grains.

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