Far-red light during cultivation improves postharvest chilling tolerance in basil

Abstract

Basil (Ocimum basilicum L.) is a temperature sensitive plant and suffers from chilling injury (CI), especially during the postharvest storage. We investigated the effect of additional far-red light (FR) during cultivation at two temperatures on postharvest chilling tolerance. Basil was cultivated under red-white Light Emitting Diodes (LED) at 25 °C. During the last 3 weeks before harvest, plants were maintained at a high temperature (25 ºC) or exposed to a low temperature (15 ºC). Furthermore, plants were exposed to additional FR (180 µmol m−2 s−1) for different durations (0, 1 or 3 weeks). After harvest, leaves were stored at 4 and 12 ºC in darkness. Overall visual quality and maximum quantum yield of PS II (Fv/Fm) as indicators of chilling injury were monitored every third day for 15 d. Abscisic acid (ABA) and jasmonic acid (JA), carbohydrates, and antioxidants were measured at harvest and after 9 d of storage at 4 °C. Additional FR improved the chilling tolerance at both cultivation temperatures. Cultivation temperature had no effect on postharvest chilling tolerance. Hormone levels in basil leaves at harvest were not affected by FR. This indicates that ABA and JA are not involved in development of FR-induced chilling tolerance in basil. FR had no effect on the levels of antioxidants at harvest whereas the levels of soluble sugars and starch increased under additional FR. The positive effect of adding FR during cultivation on chilling tolerance in basil may be due to the increase in soluble sugars and starch.