Infl uence of lysophosphatidylethanolamine application on fruit quality of Thompson Seedless grapes

The effect of foliar applications of lysophosphatidylethanolamine (LPE) on 'Thompson Seedless' (Vitis vinifera L.) was evaluated to determine the suitability of this plant amendment aid as a management tool in table grape production. LPE at 10 mg L-1 was sprayed on vines at two different stages of berry growth and development. Treatments were: 1) 4 weeks after fruit set; 2) 6 weeks after fruit set; and 3) 4 and 6 weeks after fruit set. Soluble solids content (SSC) of berries at all harvest dates was signifi cantly higher for vines treated with LPE compared to the control. Titratable acidity (TA) gradually decreased during ripening, and by the third harvest, TA of berries from vines treated with LPE was lower than that of control. All the treatments resulted in higher fruit fi rmness when compared to control. However, there were no signifi cant differences in fi rmness of berries from vines given LPE treatment at different stages of growth. LPE treatment increased berry size, although no signifi cant difference in size between single and sequential applications of LPE was observed. These results indicate that LPE may play a role in plant hormone-associated regulation of berry growth and development. Key words: Firmness, plant growth regulators, size, soluble solids content, titratable acidity table grapes. 'Thompson Seedless' is one of the most important table grape cultivars grown worldwide, which is marketed nearly year-round throughout the world. Fruit quality parameters are most important for growers and contribute directly to on-farm income and success of the business. Therefore, in the present study the effects of foliar applied LPE on quality parameters, including soluble solids content (SSC), titratable acidity (TA), fi rmness, and berry size of 'Thompson Seedless' table grapes were investigated. In preliminary small scale experiments, we observed an increase in SSC and fi rmness of grapes indicating that foliar application of LPE might be an ideal management tool to enhance berry quality of 'Thompson seedless' grapes. Materials and methods The study was performed on 8-years old vineyards cv. Thompson Seedless, located at Coltauco, Rancagua, Chile. The experimental design consisted of a randomized block with three replicates of fi ve vines each. Two buffer vines were used between different experimental vines to limit drifting of spray material from adjacent treatments. For single application studies, vines were foliar-sprayed with 10 mg L-1 LPE either 4 or 6 weeks after fruit set (December 29, 2005 and January 11, 2006). For sequential treatment, foliar application with 10 mg L-1 LPE was carried out at 4 weeks after fruit set, followed by 10 mg L-1 LPE at 6 weeks after fruit-set. Clusters for analysis of SSC and TA were harvested on three occasions and at weekly intervals. Berry fi rmness and size were measured only at the third harvest. The fi rst sampling was on February 7, 2006. Three clusters were selected at random from each vine and ten berries were collected from each cluster. For SSC and TA analyses, ten berries without peel were fi rst