Biophysical and Hormonal Changes Linked to Postharvest Needle Abscission in Balsam Fir

Potential Roles of Fatty Acids and Lipids in Postharvest Needle Abscission Physiology

“…whereas the decrease in break strength is linked to cell wall breakdown and abscission [22] [46]. Prior research has identified prolonged exposure to ethylene as a mediator of abscission in balsam fir postharvest [47], while [6] additionally suggest key roles for ABA, IAA, and CK, in postharvest needle abscission. Another biophysical change of great interest is needle retention related to clonal variations and cold acclimation.…”

“…The harvesting process places the tree under multiple stresses and it has been found that abscission of needles is a postharvest quality challenge. Wounding creates the initial stress postharvest but the most predominant stress is water deficit or drought, even when the root-detached trees are rehydrated [1] [6] [9]. Dehydration leads to senescence in balsam fir [10], though individual genotypes demonstrate differences in the level of dehydration required to induce an irreversible response [11].…”

“…Ethylene evolution is increased prior to abscission and abscission is delayed with the application of ethylene inhibitors, such as aminoethoxyvinylglycine or 1-methylcyclopropene [5] [22]. Other growth regulators that may be related to abscission are ABA, abscisic acid; AUX, auxins; JA, jasmonic acid; PA, polyamines; BR, brassinosteroids; cytokinins; and GA, gibberellins [6]. Signals from hormones potentially lead to the activation of genes promoting AZ separation, but FA and lipids may also be involved either before or after hormone production [13] [23], but the information is lacking.…”

“…Many biophysical and hormonal changes have been monitored in postharvest balsam fir [6]. whereas the decrease in break strength is linked to cell wall breakdown and abscission [22] [46].…”

“…Another stress response in root detached balsam fir is organ abscission due to the loosening and separation of the cells in the abscission zone, primarily due to the breakdown of the cell wall by the action of enzymes such as cellulose [5]. Abscission generally follows senescence, though senescence is not a prerequisite for postharvest needle abscission [6].…”