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Effect of legume-based cropping systems on nitrogen mineralization potential of Vertisol (1995)

Wani, S. P. ; Rego, T. J. ; Rajeswari, S. ; [et al.]

Springer

Plant and soil 175 (1995), S. 265-274

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ISSN: 1573-5036

Keywords: cropping system ; legumes ; N mineralization ; N potential ; rotation effects

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract The quantity and patterns of net mineralization of soil nitrogen (N) were studied in Vertisols under different cropping systems in the semi-arid tropical areas. Eight cropping systems were selected; three contained pigeonpea (PP), one contained PP and cowpea (COP), and two contained chickpea (CP) as legume component crops, one included sequence cropping with nonlegumes during the rainy and postrainy seasons, and one system was kept fallow (F) during the rainy season and sown to sorghum (S) during the postrainy season. Cropping systems with PP as a component crop increased mineralizable N(N o ) content two-fold in the soil compared with fallow + sorghum (F+S)−F+S system. The N mineralization rate constant (k) was not significantly affected by previous cropping history of the soil; however, a numerically higher rate constant was observed in the COP/PP intercrop, followed by sequential S+safflower (SF) system as compared to the other soils. Mineral N accumulation curves for six soils were more accurately described by the exponential model than the linear model. The active N fraction (N o /Ntot %) varied between 8 and 16% for different systems and a direct relationship was observed between N o /Ntot and total N for the soils under diverse cropping systems.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00011363

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Studies on Debenzylation and Photolysis of 1-Benzyl- and 1-(β-Phenethyl)-1,2,3,4-tetrahydroisoquinolinesDedicated to the memory of late Prof. Dr. phil. Hans Schmid (1977)

Govindachari, T. R. ; Nagarajan, K. ; Rajeswari, S. ; [et al.]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 60 (1977), S. 2138-2150

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ISSN: 0018-019X

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Debenzylation of 1-(3-benzyloxybenzyl)-1,2,3,4-tetrahydroisoquinolines 1, 6, 7 with hydrochloric acid and ethanol gave the corresponding phenolic isoquinolines 2, 8, 9 and tetrahydroprotoberberines 4, 12, 13. Compounds 2, 8, 9 on photolysis also gave, besides the expected noraporphines 3, 10, 11, the tetrahydroprotoberberines 4, 12, 13 [1-4] (Schemes 1 and 2). 6-Benzyloxy-1-(5-benzyloxy-2-bromo-benzyl)-1,2,3,4-tetrahydroisoquinoline (27a) containing no methoxy or methylenedioxy groups either in ring A or C does not give protoberberine during debenzylation; but 28, the debenzylation product of 27a, on photolysis gives both the noraporphine 29 and the tetrahydroprotoberberine 30 (Scheme 6), proving that during debenzylation of 1-(3-benzyloxybenzyl)-1,2,3,4-tetrahydroisoquinolines containing additional methoxy or methylenedioxy groups, the necessary formaldehyde comes from the latter groups. During photolysis both the methoxy groups (methylenedioxy groups) and the C(3) atom of the tetrahydroisoquinoline moiety provide the formaldehyde. Veratrole under debenzylation and photolytic conditions and tetrahydroisoquinoline under the latter condition also give rise to formaldehyde (Schemes 8 and 10).The novel bromohomoprotoberberine 43 along with 42 was formed during debenzylation of the 1-phenethyl-1,2,3,4-tetrahydroisoquinoline 41. Photolysis of 42 yielded the novel nor-homoaporphine 44, in addition to 43; the latter was debrominated to give the homoberbine 45.