Light regulation of quality and growth of basil

Quality of fresh products is determined by genotype and environmental practices. Light intensity and spectrum are environmental factors which have significant effects on quality. Light can increase the content of metabolites, such as carbohydrates and antioxidants. To maintain shelf life of fresh products low temperature storage is often used during the postharvest phase as the water loss and metabolic rates slows down which will delay senescence. However, crops of tropical origin are sensitive to temperatures below 10-12 °C. One of such crops is basil (OcimumbasilicumL.). Basil suffers from chilling injury (CI) when stored at low temperature. CI is visible within a few days as dark spots on the leaves. Thus, there is a large potential to improve the chilling tolerance of basil. Chilling tolerance may be improved by an increase in carbohydrates and antioxidants such as phenolic compounds. They may scavenge the reactive oxygen species produced during chilling. In this thesis it was investigated if an increase in light intensity and modification of the light spectrum (i.e. an increase in percentage of blue light) could increase the content of carbohydrates and antioxidants resulting in improved chilling tolerance. Furthermore, it was investigated if the addition of far-red (FR) during cultivation would increase the levels of hormones related to chilling tolerance and in turn improve the postharvest chilling tolerance. Light also affects the morphology which is an important quality parameter. Thus, response of growth and morphology to light intensity and spectra was also studied. In a number of experiments basil was grown in a climate chamber in a vertical farming set-up and the effect of light intensity and spectra on at-harvest and postharvest quality were studied.