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  • Author or Editor: Jessica M. Cortell x
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Treatments consisting of 0, 4, 8, or 12 floricanes were established in March 1993. An additional treatment was set up with zero floricanes and early primocane pruning. Starting in April and continuing through early November, weekly primocane measurements were taken including: number of nodes, number of primocanes, number of branch canes, length of primocanes, and length of branch canes. Additional plants in each treatment were harvested in August to assess total biomass partitioning. The zero floricane treatment had a significant increase in the number and length of both primocanes and branches. Primocanes grown without competition from floricanes had a 65 % increase in primocane dry weight. Primocane pruning resulted in significantly shorter internodes, an increase in branch dry weight, and a decrease in total length of the primocanes. The increase in total primocane biomass with removal of the floricanes should contribute to higher yields the following season.

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In Spring 1993 and 1994, mature trailing `Marion' blackberries (Rubus L. subgenus Rubus Watson) were pruned to 0, 4, 8, and 12 floricanes/plant. An additional treatment of 0 floricanes with early (30 cm) primocane topping and pruning was included. Primocane length was measured from emergence in April until growth cessation at the end of October on individual canes and for the whole plant. In January 1994 and 1995, cane cold hardiness was evaluated by controlled freezing. In 1993, plants without floricanes produced more primocanes and branches with an increased total length at the end of the season than plants with floricanes. However, there were no significant differences in primocane length among treatments in 1994. In all treatments, the absolute growth rate (AGR), on a length basis, of primocanes occurred in flushes of rapid growth followed by slower growth throughout the season. Plants without floricanes had a significantly greater AGR than plants with floricanes on five dates in 1993. In 1994, there was no effect of floricane number per plant on AGR of primocanes over the season and the growth peaks were not as distinct. When comparing primocane elongation rate at three phenological stages in 1993, plants with no floricanes had a significantly higher total primocane growth per day during fruit production and from harvest to length cessation. The following year, plants with no floricanes had the highest rate of growth before bloom and a trend toward greater growth during fruit production. After fruit production, there were no differences in AGR between the treatments. Plants with floricanes produced a second flush of primocanes, while plants with no floricanes produced only one flush of primocanes. Primocane length of the first flush (averaged for 4-, 8-, and 12-floricane plants) was significantly different from the second flush at all dates during the season except for the final end of season measurement date. Primocanes pruned at 30 cm did not produce significantly more branches than unpruned primocanes on plants without floricanes. Plants without floricanes produced primocanes that were significantly more cold hardy (lower LT50) in 1994 and 1995 than plants with floricanes.

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In Spring 1993 and 1994, mature trailing `Marion' blackberry (Rubus L. subgenus Rubus Watson) plants were pruned to 0, 4, 8, and 12 floricanes. In 1994, yield per cane was higher for plants with 4 floricanes compared 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 mass increased linearly with floricane number. Results were similar for floricane components in Summer 1994; however, there were no treatment effects on primocane or branch dry mass and there was a significant linear increase in crown dry mass with floricane number. By Winter 1994-95, there were no treatment effects on primocane or crown dry mass. Plants without floricanes produced more primocanes per plant than plants with floricanes in 1993 but not in 1994. Plants without floricanes produced 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 following season in either treatment year (1993 + 1994). However, in 1994, plants without floricanes the previous year had the lowest yield per cane. Topping primocanes at 30 cm in 1993 and 1994 had few significant effects on yield components the following season. Thus, `Marion' blackberry can compensate for reduced fruiting cane number through an increased percent budbreak on remaining canes. While there were differences in primocane dry mass among treatments after harvest in 1993, there were 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 floricanes the previous season. This was perhaps because primocanes were not trained as they grew, a practice that improves light exposure to the canes and may increase flower bud initiation.

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Nitrogen is one of the most important nutrition factors affecting grapevine growth performance and berry quality. Leaf pigments contents and leaf areas are the important indicators of grapevine nitrogen status and plant performance. In order to find a efficient way to nondestructively measure leaf nitrogen and pigments status, the SPAD meter, CCM-200 and CM-1000 chlorophyll meter in comparisons with FOSS NIR system were used in measuring leaf nitrogen, leaf chlorophyll, carotenoids, flavonoids and anthocyanins in 7-year-old Pinot Noir grape with different rate of N treatments. The results indicate that the reading of all these meters have a good relationship with leaf N, leaf chlorophyll and leaf area. But the accuracy among these meters was different, in which the accuracy of FOSS NIR is better than that of the SPAD meter, CCM-200 and CM-1000. There is the good relationship between leaf nitrogen contents, leaf area, leaf chlorophyll and carotenoids contents. Flavonoids and anthocyanins have the inverse relationship with leaf N contents and leaf area. FOSS NIR system can be use for nondestructive assessing nitrogen, leaf chlorophyll, carotenoids, flavonoids and anthocyanins whereas the other meters can only used for nondestructive assessing leaf nitrogen and leaf chlorophyll. These results indicate it is possible to use nondestructive spectral methods as the precision viticulture tools to manage vineyards nitrogen fertilization and grapevine performance.

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