Critical irrigation threshold and cranberry yield components
Yield components are useful for characterizing the impact of crop management parameters on cranberry yield and are known to be influenced by irrigation management. This study was conducted to evaluate the potential contribution of cranberry yield components to maximizing yield, and the influence of the soil water tension threshold used to initiate irrigation (SWTI) on those components. During the 2011 and 2012 growing seasons, tensiometers were installed at three production sites in Quebec to test SWTI values ranging from 5.5 to 10.0kPa. Sites were cropped to cranberries to evaluate the impact of these irrigation treatments on yield components. The four most important cranberry yield components related to final yields were, in order of importance, the number of marketable berries per quadrat (BM/Q), the number of uprights per quadrat (U/Q), the number of marketable berries per upright (BM/U), and the marketable fruit set (BM/F). Significant reductions in BM/Q, BM/U and BM/F were observed when SWTI varied from 8.5 to 10.0kPa while a reduction in U/Q was associated with a SWTI of 5.5kPa. A SWTI ranging from 7.0 to 8.0kPa significantly improved the principal yield components.
Initial growth and yield structure of selected cultivars of cranberry (Vaccinium macrocarpon Ait.) cultivated on mineral soils
Abstract A study was conducted to evaluate the possibility of cranberry cultivation on mineral soils and to assess the influence of vegetative biomass development, generative growth and yield components on the yielding of three cranberry cultivars originating in the USA (Stevens, Pilgrim and Ben Lear) at two locations in Poland. The key biometrical traits involved in yield formation were taken into account, and the soil and plant chemical conditions were evaluated. All of the measured biometrical characteristics were strongly influenced by the location and the year of cultivation, and varietal differences were also noted. The most important determinants that explained yield variation were: the number of uprights per square meter, floral induction and berry set. However, the participation of each component in yield variation was strongly affected by the location, age of plantation and to a minor extent by the cultivar. The study confirmed the possibility of cranberry cultivation on mineral soils with a low pH. The biggest average yield of the three years was collected from cv. Stevens as cultivated on sandy soil in contrast to the same cultivar grown on sandy loam soil. In the case of sandy loam soil after acidification, cv. Pilgrim appeared to be a relatively better yielding cultivar.
Pollination and Pollen Tube Growth in Relation to Cranberry Fruit Development

Pollination and pollen tube growth were evaluated in two years as potential factors suppressing cranberry (Vaccinium macrocarpon Ait.) fruit set. Supplementing insect pollination with hand pollination increased fruit set from ≈30% to ≈38% in both years. The number of flowers per unit area was an important contributor to fruit set variation in one year. Cranberry uprights exhibited a temporal decline in fruit set when flowers were pollinated sequentially; the first flowers to open had a higher probability of fruit development than flowers opening later. Examination of stigmas indicated flowers receiving low amounts of pollen (<10 tetrads), or pollen that fails to germinate, are more likely to abort. An inadequate number of pollen tubes and lack of subsequent fertilization provides a partial explanation of fruit abortion in cranberry. Cranberry fruit set under existing field conditions appears to be limited, in part by insufficient pollination and pollen tube growth, with the latter apparently the result of intraplant competition for resources. Providing supplemental hand pollination increased cranberry yields in both years, 48% over natural insect pollination when the number of flowering uprights per unit area was high (≈3000/m2). A significant amount of yield variation was explained by the number of flowering uprights per unit area in both years.