Growth and development of primocane fruiting red raspberry, (Rubus ideaus L.) and influence of nitrogen fertilizer and pruning

Graduation date: 1985A cultivar comparison study was conducted to identify similarities\ud and differences in cane characteristics between 2 primocane fruiting\ud red raspberry cultivars and to determine if the differences and\ud similarities can help determine cultural practices that may improve\ud productivity. The comparison of the cultivars 'Amity1 and 'August\ud Red' showed a difference in vegetative and fruiting characteristics.\ud 'Amity' is much more vigorous having a greater cane length and\ud diameter, greater leaf area and longer distance to the first fruiting\ud node. 'August Red' had a greater number of fruiting sites, more\ud fruits set per cane and a higher percentage fruit set. Both cultivars\ud increased in vigor and productivity over the 2 year period. Cane\ud length, cane diameter and leaf area were positively correlated with\ud fruit numbers for both varieties.\ud A crop response study was conducted to determine the effect of 2\ud nitrogen and 3 pruning methods on earliness of flowering and the\ud subsequent effect on yield and cane characteristics. The treatment\ud effect on the canes self supportiveness was also observed. Time of\ud flowering and the time required for fruit ripening to occur were\ud unaffected by any treatment. The distribution of fruit on the cane\ud was greatest at the basal end fewest at the apical end. The largest\ud fruits were found at the apical end and the smallest at the basal end.\ud High N, 135 kg/ha vs. 67 kg/ha, increased yield late in the harvest\ud season resulting in 14% higher total yield (8.1 vs. 7.0 MT/ha).\ud Pruning back the current season primocane growth to 40 cm above the\ud ground had a detrimental effect on yield per cane but due to an\ud increase in the number of branched canes total yield was greater (not\ud significantly however); 8.0 MT/ha vs. 7.5 or 7.0 MT/ha for dormant\ud cane pruning at 20 cm and 0 cm respectively. None of the pruning\ud treatment improved the self supporting cane characteristic