Ecophysiology of Plant Growth Regulators In Inducing and Modulating Root Bulking In Cut and Peel Carrots

The Individually Quick Frozen (IQF) carrot industry is expanding in North America. Recently, IQF cut and peel carrots have been developed as a high-value product with a great market potential. Obtaining uniform and highest quality baby-grade roots is critical for optimizing root quality thereby favoring industry expansion. Root grades are under the control of the root bulking process, which is possibly signaled and modulated through endogenous hormonal levels in response to genetic and ecophysiological parameters. Current research on the bulking physiology of cut and peel carrots are limited. Understanding the interrelationships between the hormonal, physiological and environmental factors in the root bulking process would uncover bulking physiology and help to optimize the root grades. It is hypothesized that agro-ecosystem management practices alter endogenous ethylene and polyamine(s) and thereby, the root bulking. Experiments were conducted to quantify endogenous levels of ethylene and polyamines in the roots and shoots as altered by genotypes, crop competition and nitrogen rates. The changes in the root grades as affected by changes in the canopy photosynthesis, ethylene evolution in situ in response to certain agro-ecological factors were determined and the relationship among these factors and root bulking affecting the final root grades are discussed.
Key words: Carrots, root bulking, hormones, ethylene, polyamine and ecophysiology