Use of photo-selective nets for hail protection of kiwifruit vines in southern Italy

Kiwifruit vines are very sensitive to damage caused by hail and wind. For this reason, the use of wind and hail protection systems is recommended for kiwifruit vines in those agricultural areas where windy conditions and hailstorms occur with high frequency. However, the presence of anti-hail nets above the canopy can influence air temperature and humidity and can affect the quantity and/or quality of the light reaching the canopy. Our aim was to study the effect of photo-selective anti-hail nets on the vegetative growth, fertility, and fruit yield of kiwifruit vines, Actinidia deliciosa [(A. Chev.) C.F. Liang et A.R. Ferguson]. The experiment was carried out in a private orchard located in Battipaglia (Southern Italy) on 'Hayward' vines grafted on 'Bruno'. Four knitted photo-selective anti-hail nets (blue, gray, red and white) were placed horizontally above the vines at the beginning of April 2004. Measurements of vegetative and reproductive growth were taken throughout 2004, 2005, and 2006. In this paper, only part of the data collected in 2005 and 2006 is presented. Vines under the blue net exhibited significantly reduced vigor relative to all other covered vines, as well as the uncovered control, whereas the red and gray nets appeared to stimulate vigor. Vine fertility and fruit yield were slightly, albeit significantly decreased under all the nets, but in the covered vines, an increase in fruit size partially compensated for the decreased value of fruit production.