Experimental study on wind breakage of kiwifruit shoots (Actinidia deliciosa Planch.)

Abstract

SummaryThe broad leaves of kiwifruit (Actinidia deliciosa Planch.) vines may be easily torn or shed by high-speed winds. High-speed winds during the Spring can break the tender young shoots at their point of attachment to the arm. In this study, the threshold winds at which young shoots were broken from their originator bud were investigated experimentally. The experiments were carried out under two different atmospheric boundary layer (ABL) conditions simulated in a wind-tunnel test section. To record the critical wind speed at which the test cane was just broken, movement of the test cane was recorded using a digital video camera. The average threshold wind speeds for the less and more turbulent wind regimes were approx. 20.5 m s–1 and 18.9 m s–1, respectively. Longer, thinner shoots were broken more easily than shorter fatter shoots. In addition, more vertical shoots were less easily broken than those which grew at a more acute angle to the cane.