POLLINATION REQUIREMENTS OF 3 HIGHBUSH BLUEBERRY (VACCINIUM-CORYMBOSUM L.) CULTIVARS

The effects of pollination treatments on fruit set and five berry char acteristics [mass, diameter, number of apparently viable seeds (well-d eveloped, plump with dark seed coat), total seed number (includes appa rently viable and partially developed seeds), and harvest date] were e xamined on three highbush blueberry cultivars. Pollination treatments included unpollinated, open pollinated, emasculated, and three hand po llinations that used pollen from the same Bower, from the same cultiva r, or from a different cultivar. Berries matured earliest and were sma llest with the most apparently viable seeds in 'Northland', 'Patriot' had the greatest fruit set and smallest seed number, and 'Bluecrop' ma tured the latest. Fruit set was greater, berry size larger, seed numbe r smaller, and maturation later in 1990 than 1991. For all three culti vars, berries were generally smallest, latest maturing, and had the fe west seeds when pollination was prevented and were largest with the mo st seeds and earliest maturing in open visitation. Emasculation result ed in berries similar to those from unpollinated flowers. For berry ch aracteristics, cross-pollination was of benefit for 'Patriot' and poss ibly 'Northland' but not 'Bluecrop'. Thus, commercial highbush blueber ry planting designs must be based on the pollination requirements of t he particular cultivar. 'Northland' berries almost always had seeds, w hile 'Patriot' showed high levels and 'Bluecrop' low levels of parthen ocarpy.