No abstract

Experiments were conducted for the study of nutrient budget in ten farmer's ponds (0.2-0.5 ha) in Orissa, India with a mean water depth of 1.0-1.2 m. Scampi (Macrobrachium rosenbergii) were stocked in these ponds at stocking density of 3.75-5.0/m(2). The average initial body weight of scampi was 0.02 mg. The culture period was for 4 months. Feed was the main input. Total feed applied to these ponds ranged from 945 to 2261 kg pond/cycle (crop). The feed conversion ratio varied 1.65 to 1.78. In addition to feed, rice straw, urea, and single super phosphate were applied to these ponds in small amounts for plankton production. At harvest time, the average weight of scampi varied from 60-90 g. The budget showed that feed was the major input of nitrogen (N), phosphorus (P), and carbon in these ponds. The inorganic fertilizer (urea and single super phosphate), organic fertilizer (rice straw and yeast extract), and inlet water, either from the initial fills or from rainwater, were the source of all other N, P, and organic carbon (OC) to these ponds. Total N applied to these ponds through all these inputs ranged from 44.45 to 103.98 kg N per crop, 12.23 to 28.79 kg P per crop, and from 381.54 to 905.22 kg OC per crop, respectively. Among all the inputs, feed alone accounted for 95.34 % N, 97.98 % P, and 94.27 % OC, respectively. Recovery of 16.34 to 38.66 kg N (average 29.27 kg), 1.28 to 3.02 kg P (average 2.29 kg), and 63.21 to 149.51 kg OC (average 113.20 kg), respectively, by the scampi harvest were observed in these ponds. Thus, harvest of scampi accounted for recovery of 35.18 to 39.01 (average 36.85%) of added N, 10.09 to 10.97 (average 10.44%) of added P, and 7.57 to 17.12 (average 16.34%) of added OC, respectively.

It is important to understand nutrient budgets of aquaculture practices for efficiency of input resources and to utilize all output nutrient sources. The aim of the present study was to develop a nutrient budget for giant freshwater prawn (Macrobrachium rosenbergii) culture ponds. The study was conducted in farmer's ponds (0.25-0.5 ha) of Odisha, India, and the results showed that feed accounted 97% total nitrogen (N), 98.7% total phosphorus (P) and 90% total organic carbon (OC), respectively. The harvested prawn accounted for recovery of 37% N, 10% P and 15% OC, respectively. The N, P and OC accumulated in sediment were 52%, 76%, and 65%, respectively. Nutrient loads in the effluents were 2.22 ± 0.66 kg inorganic N, 0.40 ± 0.15 kg P, and 21.01 ± 6.4 kg OC per ton of prawn production. The present study implicated that high nutrient values observed in both water and sediment provide important opportunities for nutrient reuse through pond sediment applications to croplands as an organic manure, as well as pond water irrigation to crops as a "liquid fertilizer".

A convenient one‐pot protocol for the synthesis of benzo‐fused and indole‐fused indolizines from Baylis–Hillman acetates was developed. This strategy involves CuBr/tert‐butyl hydroperoxide promoted oxidation, intramolecular cyclization, and aromatization as key steps. The efficacy of this methodology was demonstrated by the formal synthesis of (±)‐crispine A, a biologically active molecule.

A formal total synthesis of platencin from a simple aromatic precursor is described. Transformation of the aromatic compound into reactive spiroepoxycyclohexa-2,4-dienone and intramolecular cycloaddition are the key features of our methodology. 2-Hydroxymethyl-6-(3-hydroxy-hex-5-enyl)-phenol was oxidized with NaIO(4) to give a dimer that, upon a retro-Diels-Alder reaction, generated the spiroepoxycyclohexa-2,4-dienone that underwent intramolecular Diels-Alder reaction to give a tricyclic adduct having a core structure of platencin and appropriately disposed functional groups in a single step. Reduction of the double bond present in the ethano-bridge, manipulation of the oxirane ring and introduction of a double bond in the six-membered ring furnished a tricyclic intermediate which has already been converted into platencin.