Estimation of fruit weight by cane traits for various raspberries (<i>Rubus ideaus</i> L.) cultivars

Abstract

Raspberries are an important commercial fruit crop, widely grown in all temperate regions of the world. The raspberries contain significant amounts of polyphenol antioxidants such as anthocyanin pigments
linked to potential health protection against several human diseases. The aim of this study was to estimate fruit weight by their cane traits (the number of canes, cane height, cane diameter, and cane
yield) for Aksu Red, Canby, Heritage I, Heritage II, Holland Dwarf, Nuburg, Rubin, Summit, Tulameen, and Willamette cultivars grown in Central Anatolia region during 2002 - 2006. For this aim, average fruit
weight (dependent variable) for each cultivar was estimated by independent variables such as the number of cane, cane height, cane diameter, and cane yield using Multiple Regression Analysis (MRA).
The results clearly show that cultivars having the best fit (giving the best R2 values and the lowest RMSE) in MRA were: Holland Dwarf (99.64%), followed by Heritage I (99.06%), Summit (98.6%) Aksu Red
(92.82%), Willamette (92.68%), Heritage I (90.46%), Rubin (90.28%) and Canby (85.45%). Multiple Regression Modeling gave good results for these cultivars. However, R2 values of these cultivars were
found higher (better fit) than those of Nuburg and Tulameen cultivars. It was concluded that the number of canes had significant negative effect on fruit weights of Heritage (P < 0.05) and Summit (P < 0.001)
cultivars, but significant positive effect on only fruit weight of Rubin cultivar (P < 0.05). Cane height had significant positive effect on fruit weights of Aksu Red (P < 0.001), and Summit (P < 0.001) cultivars,
while it had significant negative effect on fruit weights of Canby (P < 0.05) and Heritage I (P < 0.05). Cane diameter had significant positive effect on fruit weights of Aksu Red (P < 0.001), Heritage I (P <
0.001), and Tulameen (P < 0.05) cultivars. Cane yield had significant positive effect on fruit weights of Canby (P < 0.05), Heritage I (P < 0.001), Heritage II (P < 0.05), Holland Dwarf (P < 0.001), Summit
(P<0.001) and Willamette (P < 0.01) cultivars, but significant negative effect on only fruit weight of Aksu Red cultivar (P < 0.01). The effects of cultivar, year, and cultivar by year interaction for fruit weight and
all cane traits were statistically significant (P < 0.001). As a result, cane traits with the positive and negative effect on fruit weight for each cultivar might provide valuable clues for breeding proposes to
improve fruit weight.