Introduction

Pesticides are used extensively to control, a wide array of agricultural pests for growing all most all the crops. However, excessive uses of pesticides produces adverse effects on crop plants and have tendency to penetrate into the tissue of the plants¹.

Application of pesticides have also shown that, they react with cellular constituents producing both physiological, germination changes and also at bio-chemical level^2,3. Some workers have reported severe effects of pesticides on the seed germinations and have concluded that seed dressing in the form of emulsifiable concentrate were phytotoxic to majority of the crops^4,5. Hence, the present study was initiated to investigate the toxic effects of a different concentrations of insecticides Gaucho and fungicide Apron, on percent germination, early growth, Phytotoxicity, chlorophyll and Dry weight of two cultivator varieties of Red gram.

Material and Methods

Certified breeders seed samples of Red gram cultivar variety TTB-7 and HYD-3C were procured from the Department of Pulses of Gandhi Krishi Vidyalaya Kendra (G.K.V.K.) U.A.S. Bangalore, Gaucho (insecticide seed treatment) and Apron (fungicide seed treatment) were obtained from authorised company Bangalore.

The slurry of both the pesticides, recommended dosage of Gaucho – 10 gms/kg and Apron – 6gms/kg of seeds were prepared. In order to observe the variations, 25% of the above recommended, 25% of the below recommended and also incombination of both Gaucho and Apron 50% among recommended were prepared.

Prior to treatment, the seeds of two cultivar varieties were surface sterilized with 0.1% Mercuric chloride for 10 minutes and washed thoroughly with distilled water for 4-5 times. For each treatment 25gms of seeds were taken and replicated for four times. The seeds were mixed thoroughly in all the concentrations of both the pesticidal slurry and kept for 24 hours. Then they were subjected for germination in germinator at 28±2°C using Between paper method.

Table 1 : Effect of presowing seed treatments with Gaucho and Apron on germination, early growth, phytotoxicity, chlorophyll content and Dry weight in pigeon pea cv. TTB-7 and Hyd-3C

Germ : Germination %, RL : Root Length, SL : Shoot Lenght, VI : Vigour Index, TI : Tolerance Index, PP : Percent Phytotoxicity, CHL : Chlorophyll, AM : Arithmetic Mean, SD : Standard Deviation, CV : Cultivar Varieties, BR : Below Recommended dosage, RD : Recommended Dosage, AR : Above Recommended dosage, I+F : Insecticide + Fungicide Values are mean of ± SD based on three determinations According to International Seed Testing Association 1985 on the termination day (6th day for Red gram) of the experiment, percent germination, seedling growth, Radicle length and Plumule length were recorded. Chlorophyll was estimated at 8th day old seedlings⁶, in both the crops, Vigor index⁷, Tolerance index⁸ and percent Phytotoxicity⁹ were calcualted.

All the tabulated data were analysed using Arithmetic mean and standard deviation of three determination^10,11.

Results and Discussion

Germination was severely inhibited at higher concentrations of both the pesticides i.e., 37.67% reduction in Gaucho, 38.34% reduction in Apron and 44.34% reduction of germination percentage at incombination treatment over control of 97.67% in cultivar variety TTB-7. And in case of Hyd-3C 38.5% reduction in Gaucho, 42.5%, reduction in Apron and 51.5% reduction of germination at incombination treatment over control of 89%.

This clearly indicates that the inhibitory action of insecticide and fungicide on the metabolic activities^12,13,14 and gradual decrease in the length of radicle and plumule along with the increase in concentration and incombination treatment of both the pesticides¹⁵. The early growth inhibition of root and shoot at higher concentration indicates the effect on cell division and cell elongation¹⁶.

The Chlorophyll content was greatly reduced at incombination treatments than other concentrations of both the pesticides¹⁷. The percent phytotoxicity and the calculated results of vigor index and Tolerance index were also drecreased with the increase in concentrations and incombination treatments in both the cases¹⁸.

Further when the dry weight was estimated, it has been observed that nearly 75% reduction in Gaucho and 85% reduction in Apron of incombination treatment over higher concentrations and control.

In the present study (as shown in the table), an inhibitory effect has been observed on seed germination, early growth pigment content, percent phytotoxicity and Dry weight of Red gram cv. TTB-7 and Hyd-3C at incombination dosage and higher concentrations of both the pesticides. But below recommended dosage did not affect major change in germination and other parameters in both the cases. The more susceptibility of Hyd-3C has been observed in both Gaucho and Apron, when compare to cv. TTB-7.

Acknowledgement

The authors are grateful to Dr. G.R. Shivamurthy, Prof and Chairman, Dept. of Studies and Research in Botany, University of Mysore for providing necessary facilities to carry out this work.

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