EFFECT OF FLORICANE NUMBER IN MARION TRAILING BLACKBERRY .2. YIELD COMPONENTS AND DRY MASS PARTITIONING

In Spring 1993 and 1994, mature trailing 'Marion' blackberry (Rubus L, subgenus Rubus Watson) plants mere pruned to 0, 4, 8, and 12 florican es, In 1994, yield per cane was higher for plants with 4 floricanes co mpared to plants with 8 or 12 floricanes, In Summer 1993, there was a trend for lower primocane dry mass with a higher floricane number and a significant reduction in primocane branch dry mass with an increase in floricane number, Total plant, fruit, floricane, and lateral dry ma ss increased linearly with floricane number, Results were similar for floricane components in Summer 1994; however, there mere no treatment effects on primocane or branch dry mass and there was a significant li near increase in crown dry mass With floricane number, By Winter 1994- 95, there were no treatment effects on primocane or crown dry mass, Pl ants without floricanes produced more primocanes per plant than plants with floricanes in 1993 but not in 1994, Plants without floricanes pr oduced primocanes that had a significantly lower percent budbreak the following year (1994) than plants with floricanes, Primocanes produced by plants without floricanes had more nodes per branch and a greater average branch cane length than those from plants with floricanes the previous season, The number of nodes per primocane tended to decrease with an increase in floricane number per plant in 1994 and 1995, There was no significant effect of floricane number per plant the previous season on fruit per lateral, fruit mass, or yield per plant the follow ing season in either treatment year (1993 + 1994), However, in 1994, p lants without floricanes the previous year had the lowest yield per ca ne, Topping primocanes at 30 cm in 1993 and 1994 had few significant e ffects on yield components the following season, Thus,'Marion' blackbe rry can compensate for reduced fruiting cane number through an increas ed percent budbreak on remaining canes, While there were differences i n primocane dry mass among treatments after harvest in 1993, there wer e no differences by mid-winter in either 1993 or 1994, Although plants grown without floricanes in 1993 had more primocanes, these canes had a lower percent budbreak the following season, Consequently, in this study we did not see increased yield in plants grown without floricane s the previous season, This was perhaps because primocanes were not tr ained as they grew, a practice that improves light exposure to the can es and may increase flower bud initiation.