Investigating the effects of ethephon (2-chloroethylphosphonic acid) on Persian walnut fruit quality

The darkness of the kernel and the lack of simultaneous ripening of the mesocarp and endocarp are among the most significant challenges in Iranian walnut orchards. The mentioned problems appear more in areas with hot and humid summers. The research focused on the quality of the kernel in terms of colour and marketability, as well as the dry matter of the kernels. Additionally, the ease of mesocarp separation from endocarp was examined. Experimental trials were designed with 27 treatment combinations to address the mentioned issues using varying concentrations of 2-chloroethylphosphonic acid (ethephon) at different harvest dates. In this study, using 1 920 ppm of ethephon on August 22nd resulted in the best quality walnut kernels and mesocarp. Researchers in this project successfully achieved the highest quality of walnut kernels and nuts in a region where over 90% of the harvest consisted of dark-kernel walnuts.