2018 ASHS Annual Conference

We examined the hypothesis that the premature floral bud abscission that produces alternate bearing in pistachios is a function of carbohydrate status. This study focused on shoots with and without crop to better characterize the carbohydrate status at the individual branch level. At α=.05 average percent abscission was significantly higher in “on” branches (91.5%), compared to “off” branches (50.1%). Additionally, carbohydrate analysis of individual branches showed a significant difference (p<0.05) between the starch content of one-year-old wood and that of current-year wood of the same branch. Results suggest competition for stored carbohydrates in the new wood of fruit-bearing shoots may initiate a hormonal signal that precipitates bud abscission on current year’s shoot growth.