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About: Pith is a(n) research topic. Over the lifetime, 2011 publication(s) have been published within this topic receiving 32791 citation(s). more


Journal ArticleDOI: 10.1016/J.BIORTECH.2005.12.008
D. Kavitha1, Chinnaiya Namasivayam2Institutions (2)
Abstract: Varying the parameters such as agitation time, dye concentration, adsorbent dose, pH and temperature carried out the potential feasibility of thermally activated coir pith carbon prepared from coconut husk for removal of methylene blue. Greater percentage of dye was removed with decrease in the initial concentration of dye and increase in amount of adsorbent used. Kinetic study showed that the adsorption of dye on coir pith carbon was a gradual process. Lagergren first-order, second-order, intra particle diffusion model and Bangham were used to fit the experimental data. Equilibrium isotherms were analysed by Langmuir, Freundlich, Dubnin-Radushkevich, and Tempkin isotherm. The adsorption capacity was found to be 5.87 mg/g by Langmuir isotherm for the particle size 250-500 microm. The equilibrium time was found to be 30 and 60 min for 10 and 20 mg/L and 100 min for 30, 40 mg/L dye concentrations, respectively. A maximum removal of 97% was obtained at natural pH 6.9 for an adsorbent dose of 100 mg/50 mL and 100% removal was obtained for an adsorbent dose of 600 mg/50 mL of 10 mg/L dye concentration. The pH effect and desorption studies suggest that chemisorption might be the major mode of the adsorption process. The change in entropy (DeltaS0) and heat of adsorption (DeltaH0) of coir pith carbon was estimated as 117.20 J/mol/K and 30.88 kJ/mol, respectively. The high negative value of change in Gibbs free energy indicates the feasible and spontaneous adsorption of methylene blue on coir pith carbon. more

Topics: Freundlich equation (61%), Adsorption (55%), Langmuir adsorption model (55%) more

773 Citations

Open accessJournal ArticleDOI: 10.1105/TPC.9.7.1147
Hiroo Fukuda1Institutions (1)
01 Jul 1997-The Plant Cell
Abstract: Vascular plants, which are adapted for life on land, first appeared in the late Silurian period, some 400 million years ago. Since then they have evolved to fill a diverse range of habitats all over the earth. The vascular systems of land plants are composed of specialized conducting tissues, the xylem and the phloem, which provide both a pathway for water and nutrient transport and mechanical support for slender plants. The vascular system is also an important conduit for signal-transducing molecules. Tracheary elements (TEs), which are the distinctive cells of the xylem, are characterized by the formation of a secondary cell wall with annular, spiral, reticulate, or pitted wall thickenings. In the primary xylem, TEs differentiate from procambial cells, whereas in the secondary xylem, they arise from cells produced by the vascular cambium. As they mature, TEs lose their nuclei and cell contents, leaving hollow dead cells that form vessels or tracheids. The final stage of TE differentiation represents a typical example of programmed cell death in higher plants (see Pennell and Lamb, 1997, in this issue). TEs can also be induced to form in vitro from various types of cells, including cells of the phloem parenchyma and the cortex in roots, the pith parenchyma in shoots, the tuber parenchyma, and the mesophyll and epidermis in leaves (Roberts et al., 1988; Fukuda, 1992). In Zinnia elegans cell cultures, single mesophyll cells transdifferentiate directly into TEs without cell division in response to phytohormones (Fukuda and Komamine, 1980). The Zinnia system has proven to be particularly useful for studies of the sequence of events during TE differentiation. This is largely because differentiation occurs at a high frequency in Zinnia cultures and because the process can be followed in single cells (Chasan, 1994; Fukuda, 1994, 1996). Recently, I presented a general overview of xylogenesis (Fukuda, 1996). In this article, I focus on efforts to elucidate the molecular mechanisms underlying the in vitro differentiation of parenchyma cells into TEs. more

Topics: Vascular cambium (61%), Tracheary element differentiation (60%), Xylem (59%) more

416 Citations

Open accessJournal ArticleDOI: 10.1104/PP.96.2.577
L. M. Lagrimini1Institutions (1)
01 Jun 1991-Plant Physiology
Abstract: Tobacco (Nicotiana tabacum) plants transformed with a chimeric tobacco anionic peroxidase gene have previously been shown to synthesize high levels of peroxidase in all tissues throughout the plant. One of several distinguishable phenotypes of transformed plants is the rapid browning of pith tissue upon wounding. Pith tissue from plants expressing high levels of peroxidase browned within 24 hours of wounding, while tissue from control plants did not brown as late as 7 days after wounding. A correlation between peroxidase activity and wound-induced browning was observed, whereas no relationship between polyphenol oxidase activity and browning was found. The purified tobacco anionic peroxidase was subjected to kinetic analysis with substrates which resemble the precursors of lignin or polyphenolic acid. The purified enzyme was found to readily polymerize phenolic acids in the presence of H2O2 via a modified ping-pong mechanism. The percentage of lignin and lignin-related polymers in cell walls was nearly twofold greater in pith tissue isolated from peroxidase-overproducer plants compared to control plants. Lignin deposition in wounded pith tissue from control plants closely followed the induction of peroxidase activity. However, wound-induced lignification occurred 24 to 48 hours sooner in plants overexpressing the anionic peroxidase. This suggests that the availability of peroxidase rather than substrate may delay polyphenol deposition in wounded tissue. more

Topics: Peroxidase (60%), Pith (55%), Nicotiana (54%) more

364 Citations

Open accessJournal ArticleDOI: 10.1046/J.1365-2664.1998.3540596.X
Abstract: Summary Primates dominate lists of pests that damage crops around African parks and reserves. Beyond creating management problems, crop foraging is integral to the ecology of primates inhabiting forest—agriculture ecotones. Twenty-three months of data from four villages around Kibale National Park, Uganda, revealed that redtail monkeys Cercopithecus ascanius, olive baboons Papio cynocephalus and chimpanzees Pan troglodytes selected different crops or plant parts. Baboons took root and tuber crops ignored by other primates, and fed on the greatest variety of crops. All three species preferred maize and/or bananas. Redtails ate only banana fruit, baboons ate banana fruit more frequently than pith, and chimpanzees raided pith and fruit in equal proportions. Each primate showed a distinct monthly pattern of crop foraging, significantly non-random for baboons and redtail monkeys, weakly for chimpanzees. Large inter-monthly variation was observed for all three primates, but was least pronounced in redtails. Raiding frequency on maize peaked approximately 8 weeks after the onset of rains and was strongly correlated between the three primate species. Abundant forest fruit did not diminish primate appetite for maize. Raiding frequency on bananas varied considerably despite continuous availability of fruit and pith. Peaks in banana consumption were unrelated to rainfall or maize raiding, but were associated instead with forest fruit shortages, specifically Mimusops bagshawei. Chimpanzees consumed banana pith more frequently when forest fruits were scarce, whereas baboons targeted more banana fruits. The use of banana pith by chimpanzees supports the suggestion that energy-rich pith is crucial to chimpanzees during fruit scarcity. Conservation of Mimusops bagshawei and other key forest fruit trees may lessen primate raiding intensity on perennial crops, e.g. bananas. Maize raiding appears unaffected by forest fruit abundance. Such highly palatable crops are best planted > 500 m from the forest edge. Planting agroforestry buffers along park edges creates ideal habitat for crop-raiders. This management strategy is appropriate where human population density is low and crop raiding species are legal game. When dangerous or destructive wildlife species forage amidst densely settled subsistence farmland, managers are challenged to separate forests from agriculture using non-palatable plant barriers or electric fences. more

Topics: Frugivore (53%), Pith (51%)

308 Citations

Book ChapterDOI: 10.1007/978-94-009-4378-0_1
Yaacov Okon1, Yoram Kapulnik1Institutions (1)
01 Feb 1986-Plant and Soil
Abstract: The surface distribution of Azospirillum on inoculated roots of maize and wheat is generally similar to that of other members of the rhizoplane microflora. During the first three days, colonization takes place mainly on the root elongation zone, on the base of root hairs and, to a lesser extent, on the surface of young root hairs. Azospirillum has been found in cortical tissues, in regions of lateral root emergence, along the inner cortex, inside xylem vessels and between pith cells. Inoculation of several cultivars of wheat, corn, sorghum and setaria with several strains of Azospirillum caused morphological changes in root starting immediately after germination. Root length and surface area were differentially affected according to bacterial age and inoculum level. During the first three weeks after germination, the number of root hairs, root hair branches and lateral roots was increased by inoculation, but there was no change in root weight. Root biomass increased at later stages. Cross-sections of inoculated corn and wheat root showed an irregular arrangement of cells in the outer layers of the cortex. These effects on plant morphology may be due to the production of plant growth-promoting substances by the colonizing bacteria or by the plant as a reaction to colonization. Pectic enzymes may also be involved. Morphological changes had a physiological effect on inoculated roots. Specific activities of oxidative enzymes, and lipid and suberin content, were lower in extracts of inoculated roots than in uninoculated controls. This suggests that inoculated roots have a larger proportion of younger roots. The rate of NO 3 - , K+ and H2PO 4 - uptake was greater in inoculated seedlinds. In the field, dry matter, N, P and K accumulated at faster rates, and water content was higher in Azospirillum-inoculated corn, sorghum, wheat and setaria. The above improvements in root development and function lead in many cases to higher crop yield. more

Topics: Lateral root (66%), Root hair (61%), Rhizosphere (54%) more

307 Citations

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