MALE DENSITY AND ARRANGEMENT IN KIWIFRUIT ORCHARDS

In 1988 and 1989, flowers were removed before opening from all pollenizers (male vines) except that closest to the middle of an orchard block 76 m long and 24 m wide, containing 140 vines at 4 m X 4 m spacing. Fruit set decreased from 100% in vines nearest the central male to 17% in 1988 and to only 7% in 1989 in the most distant vines. Mean fruit weight for each vine decreased from 110 to 34 g in 1988 and from 113 to 37 g in 1989, fruit weight decreasing the further the vine was from the pollen source. As a consequence, yield progressively decreased from vines adjacent to the pollenizer (54.9 and 58.9 kg per vine in 1988 and 1989, respectively) to those most distant (3.7 and 1.9 kg per vine in 1988 and 1989, respectively). The area covered by a pollenizer, i.e. the area within which plants produce at least half the number of seeds of those closest to the pollenizer, was 229 m2 in 1988 and 103 m2 in 1989. Since pollen transfer, rather than its availability, is the main factor limiting pollination, to achieve full pollination about 118 pollen sources ha-1 must be provided in kiwifruit orchards, without regard to planting distances and canopy sizes. Male vines occupy too much canopy space and it is suggested that they be eliminated; instead, sectors of female vines at appropriate positions in the orchard should be grafted with male scionwood.