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  • Author or Editor: B. Chandrasekaran x
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In a wet-seeded rice establishment system, it is feasible to raise dhaincha (Sesbania aculeata. W.) in alternate rows as an intercrop using a newly developed joint rice and green manure seeder. Intercropping dhaincha exclusively for in situ green manuring recorded a higher grain yield of rice (with green manure) than sole rice. Besides in situ green manuring, leaving every 20th row for seed production achieved not only the self manuring of the land, but also the self-production of green manure seed (dhaincha). Leaving dhaincha at narrow spacings (10th or 15th row) for seed production affected the growth, development and yield of rice in the adjacent rows. Within the total dose of fertiliser N, split dose of 25, 33, 21 and 21% at 20 days after sowing (DAS), at green manure incorporation (37 DAS), 55 DAS and 70 DAS were found to be the ideal method of N application, alleviating the temporary lock-up of N, if any, upon green manure incorporation. Thus, the sustainability of the green manure intercrop for in situ incorporation in the rice culture and of green manure seed production were proved by the study.

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Field experiments were conducted with rice (ADT-39) during the wet Kharif season (July- October 2001) at two locations, the Tamil Nadu Rice Research Institute (TRRI) farm, Aduthurai (Vertisol) and the Agricultural Research Station (ARS) farm, Pattukkottai (Alfisol), representing the old and new delta areas of the Cauvery, respectively. The same set of treatments was followed in both soils. The treatments consisted of the recommended NPK fertilizer application at 75% and 100% alone, and 10 or 20 kg ha-1 humic acid (HA) in combination with NPK fertilizers as soil application, besides an integrated method involving soil application, root dipping and foliar spraying with humic acid and NPK fertilizers. initial soil samples from the experimental fields were analysed for physical, physico-chemical and chemical properties. Surface soil samples were collected at critical growth stages and analysed for various available nutrients. The results of the field experiments revealed that the application of humic acid along with inorganic fertilizers led to higher soil nutrient availability at all the growth stages of rice. Similar results were obtained in both Vertisol and Alfisol. The present investigation concluded that the best treatment for soil nutrient availability was 10 kg ha-1 HA (soil application) + 0.1% HA foliar spray (twice) + 0.3% HA root dipping + 100% NPK, which was on par with the treatment involving 20 kg ha-1 HA (soil application) + 100% NPK compared to the other treatments.

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A new, rapid, and specific reversed phase high-performance liquid chromatographic (RP-HPLC) method involving precolumn derivatization with benzoyl chloride was developed and validated for the estimation of γ-aminobutyric acid (GABA) in rat brain tissue preparations. The derivatization product of GABA was identified by melting point, infrared, and proton nuclear magnetic resonance (1H NMR) spectroscopy to be n-benzoyl GABA. Various parameters which influenced derivatization and elusion were optimized. The chromatographic system consisted of C-18 column with ultraviolet (UV)—photodiode array detection ranging from 210 to 400 nm. Elution with an isocratic mobile phase consisting of 0.025 M disodium hydrogen phosphate buffer—methanol (65:35, v/v; pH 6) at a flow rate of 1 mL min−1 yielded sharp and specific peak of n-benzoyl GABA within 7 min. The method was validated with respect to the linearity, accuracy, precision, sensitivity, selectivity, and stability, wherein the benzoyl derivative of GABA showed stability for 2 months. The lower limit of detection was 0.5 nmol L−1. This novel derivatization procedure for the estimation of GABA with benzoyl chloride was also applied for rat brain tissue preparations that gave highly specific peak and good component recovery. The results show that the method for the determination of GABA by benzoylation using RP-HPLC has good linearity, accuracy, precision, sensitivity, and specificity and is simple and economical to perform.

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