The 2012 ASHS Annual Conference

Vines begin senescence under low temperatures of 4 °C to 10°C during the growing season when double cropping is practiced in Guangxi, China, a sub-tropical grape growing region. Sugar accumulation and acid degradation are reduced, resulting in slow or insufficient fruit ripening for commercial production. Field study demonstrated that Salicylic acid (SA) application 1–2 d prior to a low temperature event was effective in inhibiting leaf senescence and yellowing, and promoting fruit ripening. In 2010, an experiment was conducted to simulate field temperature conditions to determine physiology changes in relation to leaf senescence in Nanning, Guangxi, China. Leaves of one-year-old self-rooted Kyoho grapevines grown in greenhouse were sprayed with water or SA at 0.015% until runoff, incubated at 7 °C for 12 h, and then allowed to recover at 25 °C for l d. Activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in leaf blades were reduced by exposure at 7 °C, recovered during the exposure at 25 °C, but did not restore to levels prior to exposure at 7 °C. Vines treated with SA had higher activity of SOD and POD at both 7 °C and 25 °C. The ratio of bound to free water as well as the contents of free proline, soluble sugars, and soluble proteins was higher, but the content of Malondialdehyde (MDA) and relative electrical conductivity were lower in SA-treated vines after 12 h exposure at 7 °C. The research demonstrated the potential of SA to inhibit leaf senescence and yellowing by maintaining higher SOD and POD activity, higher contents of free proline, soluble sugars, and soluble proteins, as well as reducing MDA accumulation under low temperatures.