Plots of 19 clones of strawberry (Fragaria ×ananassa Duch.) were planted in 1996. Fruit of 16 clones were harvested in 1997 and fruit of 11 of the same clones plus three additional clones in 1998. Individual plots were harvested on three or four dates in 1997 and from three to seven dates in 1998. Fruit firmness was determined with a penetrometer at harvest, and additional samples were processed and frozen for subsequent determination of percentage of drained weight. Clones differed in firmness in both years and in drained weight in 1998, but not in 1997. Drained weight varied considerably from harvest-to-harvest. Correlations between firmness and drained weight were significant (P ≤ 0.01) in both years, but firmness was not a good predictor of drained weight. The correlation between drained weight of fruits in 1997 and those of fruits from the same plots in 1998 was nonsignificant, but that between firmness in 1997 and firmness in 1998 was significant at P ≤ 0.05.
Randomly amplified polymorphic DNA markers (RAPDs) were used to distinguish among seven Pacific Northwest red raspberry (Rubus idaeus L.) cultivars. Random 10-base sequences were used to distinguish among `Chilcotin', `Chilliwack', `Comox', `Meeker', `Qualicum', `Tulameen', and `Willamette'. The seven cultivars could be distinguished even though there is considerable relatedness among the cultivars. `Chilliwack' and `Comox' share `Skeena' as a parent, and `Chilliwack' is a parent of `Qualicum'. `Willamette' is a parent of `Meeker'. This technology shows promise as a means of distinguishing cultivars and developing a genetic map to aid in breeding.
Measuring intact fruit with a colorimeter could be a quick way to estimate anthocyanin concentration and reduce waste disposal. Five fresh fruit from each of 134 plots were measured with a Minolta tristimulus colorimeter in 1994. Samples were frozen and anthocyanins extracted with acidified ethanol and measured with a spectrophotometer. The hue angle and anthocyanin concentration had r2 = 0.51. L*, a*, b* and C* were significantly correlated with anthocyanin concentration with r2 = 0.31, 0.32, 0.42, and 0.34, respectively. In 1995, five fruit from each of 20 plots were measured as before. In 1995, the hue angle and anthocyanin concentration had r2 = 35. A regression equation with hue angle, b* and a* estimated anthocyanin concentration with R2 = 0.62. In 1995, the same 20 samples were also measured with a colorimeter immediately after thawing. The hue angle and anthocyanin concentration had r2 = 0.55. A regression equation with hue angle, b* and L* estimated anthocyanin concentration with R2 = 0.76. It may be possible to estimate anthocyanin concentration by measuring intact fruit with a colorimeter after freezing and thawing the samples.
Cultivated raspberries may include North American red raspberry (Rubus idaeus strigosus Michx), European red raspberry (R. idaeus vulgatus Arrhen.) or black raspberry (R. occidentalis in their pedigrees. Twenty-one raspberry clones were investigated using chloroplast restriction fragment length polymorphisms to determine the cytoplasm type and the amount of cytoplasmic diversity among these selected clones. The raspberry clones were selected representing North American red raspberry, European red raspberry, black raspberry and cultivars with divergent maternal lineages. Total cellular DNA was probed with two 32P-labelled fragments of tomato chloroplast DNA. Probe-restriction enzyme combinations were selected which discriminated between representatives of the two red raspberry subspecies. Raspberry clones were grouped according to the chloroplast restriction fragment patterns. The composition of the groups was compared with their pedigrees.
In our breeding program, harvest data is first collected two years after planting. In order to streamline efforts, some selections are discarded after the first harvest season and attention is concentrated on the remaining selections. Some selections that could become potentially superior cultivars that are slow to establish may be discarded. To test how reliable the first year data is for making decisions, the first year harvest data from five plantings was compared with the second year harvest data. Fruit rot and yield were the least consistent (r = 0.28 and 0.36 respectively) while fruit weight (r=0.76), fruit firmness (r=0.63) and midpoint of harvest (r=0.79) were more consistent. The impacts of decisions based on first year harvest data will be discussed.