Mechanical Shaking and Baling of Balsam Fir Trees Influence Postharvest Needle Senescence and Abscission

Abstract

This study investigated the influence of both shaking duration and number of trees per bale on postharvest needle characteristics such as percentage needle loss, needle retention duration and explored the physiological roles of endogenous ethylene and volatile terpene compounds (VTCs). To accomplish these objectives, 25 six-year-old trees were detached and exposed to a range of shaking durations (0 to 60 sec.), and 30 six-year-old detached trees were exposed to baling treatments from 0 to 5 trees. Response variables measured were percent needle loss, needle retention duration, average water use, ethylene and volatile terpene compound evolution. Trees shaken for 60 seconds lost 16% less needle compared to control, which was consistent with the decrease in percent needle loss with increasing shaking duration. Baled trees lost 13% more needles compared to control, but percent needle loss was observed to decrease with increasing number of trees in a bale. These trends corresponded with increasing ethylene and VTC evolutions, where the longer the shaking duration or larger number of trees in a bale, the higher the ethylene and VTC evolutions. One can therefore draw inference that mechanical perturbation as a result of shaking and baling induce biosynthesis and regulation of ethylene and VTC in balsam fir trees in an effort to regulate postharvest needle abscission.

Forests Phenolic Compounds Instigate Cloud Precipitation

“…The end of this period is called a 'perfume front', whereby wind violently shakes the trees, uttering their leaves, triggering stress mechanism responses, generating heat and stimulating the fresh and clean leaves to release phenolic substances ( Figure 08). Mechanical stress as a consequence of shaking and bundling has been shown to prompt the biosynthesis and adaptation of ethylene and VTCs in balsam r trees (Korankye et al, 2018).…”

Qualitative Assessment of Postharvest Stomata and Chloroplast Degradation in Contrasting Abscission Resistant Balsam Fir (<i>Abies balsamea</i> (L.) Mill.)

“…Postharvest needle abscission is a complex physiological phenomenon that is triggered by root detachment but modified by several factors. Cold acclimation [5], soil nutrition [6], volatile terpenes [7], and a plethora of hormones [8] all affect postharvest abscission. In any case, ethylene biosynthesis is increased while auxins decrease [8] [9], which activates several hydrolytic enzymes that weaken abscission zone cell walls [10].…”