Relationship between Dormancy and Zeatin Level during Pre- and Postharvest Storage Period of Carrots (Daucus carota L.)

Summary The cytokinin zeatin level was determined in carrots during pre- and postharvest period to assess a potential relationship with dormancy. Samples of the leaves and roots of the F1 carrot cv. ‘Nandor’ were obtained approximately two months before harvest for hormone analysis. After harvest, carrots were stored in 5 kg perforated polyethylene (PE) bags, and placed into the cold stores set at 0 ° and 5 °C, and 85 % to 90 % relative humidity (RH). At monthly intervals in the post-harvest period, all samples were evaluated for their content of the zeatin, rooting ratio and degree and sprouting ratio and degree. Leaves possess a higher zeatin content than roots in the pre harvest period. During growth and development, zeatin content decreased in leaves, but increased in the root tissues. In the post-harvest period, zeatin levels of roots stored at 5 °C increase and then subsequently decline. Rooting and sprouting are observed at the same time when the level of cytokinin reaches its highest value. These data show that increasing levels of zeatin cause dormancy break in carrot tissues, and that levels of cytokinin fall with aging. Zeatin increases in 0 °C treatment beginning of month 4.