In a glass or stainless steel bowl, layer zucchini slices with salt. Add cool water to cover, cover and let stand at room temperature for 2 hours. Transfer to a colander placed over a sink and drain zucchini. Rinse with cool running water and drain thoroughly.
In a large stainless steel saucepan, combine vinegar, sugar, mustard seeds, celery seeds and turmeric. Bring to a boil over medium-high heat, stirring to dissolve sugar. Reduce heat and boil gently for 5 minutes, until the spices have infused the liquid. Stir in zucchini. Remove from heat, cover and let stand for 1 hour.
Meanwhile, prepare canner, jars and lids.
Return saucepan to medium-high heat and bring zucchini mixture to a boil, stirring occasionally. Reduce heat and boil gently for 5 minutes, until zucchini is heated through.
Pack zucchini into jars to within a generous 1/2 inch of top of jar. Ladle hot picking liquid into jar to cover vegetables leaving 1/2 inch head space. Remove air bubbles and adjust headspace if necessary. Wipe rims, center lid on jar, screw on band until fingertip-tight.
Place jars in canner, ensuring they are completely covered with water. Bring to a boil and then process for 15 minutes.