Estimation of Fruit Weight by Cane Traits for Eight American Blackberries (Rubus Fructicosus L.) Cultivars

Abstract

The present paper aimed to estimate fruit weight by their cane traits (the number of cane, cane height, cane diameter, and cane yield) for eight American blackberry cultivars (namely, Ness, Cherokee, Arapaho, Chester Thornless, Navaho, Black Satin, Dirksen Thornless and Cv. Jumbo) grown in Central Anatolia during 2002 - 2006. For this aim, average of 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 in Multiple Regression Analysis (MRA). With respect to determination coefficients for each cultivar, it is clear that cultivars having the best fit (giving the best R-2 values) in MRA were found to be Black Satin (99.40%), Ness (99.16%), Navaho (96.46%), Dirksen Thornless (96.22%), Chester Thornless (91.92%), and Cv. Jumbo (91.26%), which meant that most (almost 100%) variation in fruit weight for these cultivars was explained by the number of cane, cane height, cane diameter, and cane yield. However, corresponding values for Arapaho and Cherokee cultivars was estimated as 2.88% and 33.2% of the total variation in fruit weight. It was concluded that number of canes had positive-significant effect on fruit weights of Dirksen Thornless (P < 0.001) and Cv. Jumbo (P < 0.01), but negative-significant effect on that of Black Satin (P < 0.001). Cane height had positive-significant effect on fruit weights of Black Satin (P < 0.001) and Ness (P < 0.001) cultivars, but negative-significant effect on cv. Chester Thornless (P < 0.001) and Dirksen Thornless (P < 0.01). Cane diameter had positive-significant effect on fruit weights of Black Satin (P < 0.001) and Chester Thornless (P < 0.01), Navaho (P < 0.05), Ness (P < 0.01) cultivars, whereas it had negative-significant effect on cv. Jumbo (P < 0.05). Cane yield had positive-significant effect on fruit weight of only Cv. Jumbo, but negative-significant effect on cv. Black Satin (P < 0.001), Chester Thornless (P < 0.01), Dirksen Thornless (P < 0.001), Navaho (P < 0.001) and Ness (P < 0.001). It was concluded that cane traits with the positive and negative effect on fruit weight provide useful clues for breeding proposes to improve fruit weight.