Residue Dynamics of Hydrogen Cyanamide and Ethephon in Apple

Abstract

In the present study, supervised field trials were conducted in Royal delicious variety of apple trees to evaluate the persistence of hydrogen cyanamide and ethephon during 2015-16 at different locations of Himachal Pradesh and Jammu & Kashmir. Standardised analytical methods simulated to the lab conditions were validated and adopted to find out the recoveries of hydrogen cyanamide and ethephon in apple fruits. Residues of hydrogen cyanamide were determined by HPLC-PDA with mobile phase comprising of methanol and water (2:8) following the application of Dormex 49% AS at the rate of 0.5% a.i., 1.0 % a.i. and 2.0 % a.i. during dormant stage of apple trees. Formulation of ethrel 39% SL was applied on fruit bearing trees close to harvest stage were determined as ethylene by head space analysis. Hydrogen Cyanamide residues were not detected in any sample right from walnut stage of apple after 85-111 days of treatment to the final harvesting between 179 -209 days irrespective of any location. It has been observed that spray application of ethephon caused early fruit drop therefore, samples from all the four locations were analysed up to 10 days. Initial deposits of ethephon as ethylene on apple fruits at Matiana and Thanedhar ranges between 2.044 -2.147 mg kg -1 and 4.036 -4.133 mg kg -1 which reduces between 0.056 -0.057 and 0.083 -0.088 mg kg -1 on day 10 due to the single and double dose application, respectively. Harvest time residues of ethephon in Youngora and Lassipors locations of J&K were 0.100 and 0.099 and 0.143 and 0.137 mg kg -1 at single and double dose, respectively. A safe waiting period of 5 days is suggested between ethephon application and fruit harvest to safeguard the consumer's health. No residues of hydrogen cyanamide were detected in fruits and hence, does not pose any threat to the consumers.