Effect of Height of Primary Scaffold Branch on Freezing Injury of Fig (Ficus carica L.)

Abstract

We investigated the effect of the height of the primary scaffold branch on freezing injury, growth, yield, and fruit quality of the fig (Ficus carica L. 'Masui Dauphine'). The primary scaffold branch was adjusted to 1.8 m with a straight line and horizontal direction of the fruit-bearing shoots, compared with the conventional system of adjusting the primary scaffold branch to a height of 0.6 m with a straight line and vertical direction of the fruit-bearing shoots. The trees of the 1.8-m-high scaffold branch system showed less freezing injury (0% mortality) in spring over the successive two seasons, while those of the conventional 0.6-m-high primary scaffold branch system suffered 100% freezing injury. Fig growth and yield were undermined, but the fruit quality was much improved in the high (1.8 m) primary scaffold branch system relative to that of the conventional system, before freezing injury occurred. One of the reasons for the reduced freezing injury being associated with the new training system may be ascribed to the observation that the high primary scaffold branch can narrow the early morning and daytime temperature difference on the upper surface of the branch. The adoption of the 1.8-m-high scaffold branch is therefore expected to improve fig fruit quality and reduce freezing injury.

Shoot Growth and Fruit Production of ‘Masui Dauphine’ Fig Trees Having High Limb Position with Downward Shoots

“…We have confirmed elsewhere the beneficial effect of the novel training in preventing injury due to freezing, probably because of the smaller temperature differences on the primary scaffold (Mano et al, 2012a). Another benefit is the reduction of animal invasion in the early harvest season when a high market price is expected.…”

“…No reserve nutrient reduction was observed in those studies. For instance, the starch and water soluble sugar content in dormant shoots of novel training was equal to or greater than values in normal training (Mano et al, 2012b). Premature defoliation, disorders in germination, and failure of fruit set in the novel training were not observed in subsequent years.…”

“…This training is distinct from normal straight line training and involves a long trunk and high limb position. We call this the "high limb style" and its advantages were confirmed as preventing freezing injury (Mano et al, 2012a) and animal (raccoon) invasion (unpublished), but the effect on fruit production was unknown. The high position of the limb will force shoots to be elongated on the horizontal trellis or be bent downward from the limb.…”