Residues ofimidacloprid at 20 g a.i. ha-1 and lambda-cyhalothrin at 15 g a.i. ha-1 were estimated quantitatively by HPLC/GLC in/on brinjal fruits. Initial deposits of insecticides were higher in imidacloprid than lambda-cyhalothrin. Initial deposits of 0.652 mg kg-1 of imidacloprid dissipated to 93.17 per cent on 10 th day. In lambda-cyhalothrin the initial deposits were 0.138 mg kg-1 which dissipated to 92.75 per cent on 10 th day. The degradation of imidacloprid was relatively higher as compared to lambda-cyhalothrin. Both imidacloprid and lambda-cyhalothrin had half-life values of 1.92 and 2.65 days, respectively on brinjal fruits. The safe waiting period for imidacloprid was found 4.70 days. In lambda-cyhalothrin, no waiting period is required after its application as the initial deposits were less than its MRL (0.3 mg kg-1
An attempt has been made to study the toxicity of two commonly used pesticides aldrin (organochlorine) and ethyl‐parathion (organophosphorus) to the fish Colisa fasciatus (Anabantidae) and Notopterus notopterus (Notopteridae).During bioassay studies, the behaviour of the fishes was recorded. The aldrin concentration used lies between 0.021 mg/1 and 0.042 mg/1 for C. fasciatus and 0.00056 mg/1 and 0.00135 mg/1 for N. notopterus. The ethyl‐parathion concentration used lies between 1.8 mg/1 and 3.7 mg/1 for C. fasciatus and 0.49 mg/1 and 1.00 mg/1 for N. notopterus.
The effect of lethal aqueous concentrations of pesticides on the Fishes prior to death are usually manifested by excitation, erratic swimming ability, difficulty in respiration, increasing in ventilation rate, jerky movements of body and fin fast, up‐ and downward movements, convulsions, loss of equilibrium, loss of the original colour of the body skin and the excess secretion of mucus by the gills and the body wall.
the TLm values for 24, 48 and 96 hours of exposition are determined for both species of fish and both pesticides at the following variables:
three levels of temperature,
three levels of dissolved oxygen,
three levels of pH,
three fish sizes.
statistical analysis of variance shows, that all variables have a significant effect on the TLm values of both pesticides for both fish species;
Aldrin (chlorinated hydrocarbon) is more toxic than ethylparathion (organophosphate) at all variables;
Colisa fasciatus is the more resistant species than Notopterus notopterus.
the relationship between the total number of the fishes N0, survival numbers N and time t can be expressed by a mathematical formula as:
the harmless concentration to C. fasciatus ranged from 0.0049 mg/1 to 0.0161 for aldrin, 0.54 mg/1 to 0.99 mg/1 for ethyl‐parathion and to N. notopterus from 0.00012 mg/1 to 0.00045 mg/1 for aldrin, 0.10 mg/1 to 0.21 mg/1 for ethyl‐parathion;
the aldrin should be diluted at least 4000 times and ethyl‐parathion 320 times of its actual concentration.
Drip irrigation technology will undoubtedly plays an important role in the future of the agriculture. A field experiment was conducted to evaluate the performance of drip system with five operating pressure viz. I1 (0.4 kg/ cm2), I2 (0.6 kg/cm2), I3 (0.8 kg/cm2), I4 (1.0 kg/cm2), I5 (1.2 kg/cm2). It was observed that the average discharge of drippers was 1.08 lph, 1.24 lph, 1.50 lph, 1.62 lph and 1.74 lph and emission uniformity was 80.55%, 84.89%, 86.30%, 88.88% and 90.80 in each treatment respectively and coefficient of variation was observed 0.12, 0.13, 0.12, 0.11, and 0.09. Flow component was found 0.450 and the value of k was 0.572 while R2 was observed 0.986.Based on the result it can be concluded that the operation of drip irrigation system at 1.2 kg/cm2 pressure head, gives the maximum efficiency in respect of discharge, emission uniformity and coefficient of variation.
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