mutation-breeding processes. Also, raspberry cultivars can be divided into two types according to the characteristics of fruit sets, floricane (FC)-fruiting, and primocane (PC)-fruiting ( Heide and Sønsteby, 2011 ). PC-fruiting cultivars go through the
Saki Toshima, Marika Fujii, Momoko Hidaka, Soya Nakagawa, Tomonari Hirano, and Hisato Kunitak
Javier Fernandez-Salvador, Bernadine C. Strik, and David R. Bryla
, 1986 ). Recommended rates of N application in conventional plantings vary with age and cultivar of blackberry grown, ranging from 25 to 70 lb/acre N ( Bushway et al., 2008 ; Hart et al., 2006 ). In blackberry, primocane leaf nutrient concentration
of the above acreage is under multi-bay tunnels and the vast majority of the raspberries produced are from primocane-bearing cultivars. In states mostly in the upper-midwestern and northeastern United States, single-bay tunnels are more commonly used
Jessica M. Cortell and Bernadine C. Strik
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.
Gina E. Fernandez and Marvin P. Pritts
The objective of this experiment was to determine the effects that altering the probable source-sink relationships would have on subsequent growth and yield components under field conditions. The balance between vegetative and reproductive growth was altered by imposing light stress (shading) on various growth phases, or removing primocanes, floricanes or fruit. Removal of primocanes significantly increased yield the year of removal. However, if primocane removal coincided with canopy shading, this increase in yield was not achieved. Overall, a significant negative correlation existed between 1991 and 1992 yields. Treatments with high yields in 1991 had low yields in 1992, and visa verca. This evidence-suggests that: 1) primocanes and floricanes are competing for light, not photosynthates during the flowering and fruiting period and 2) altering the balance of vegetative and reproductive growth one year had a significant effect on growth the subsequent year.
Maria E. Cramer, Kathleen Demchak, Richard Marini, and Tracy Leskey
relocated, so there were three replicates of all six treatments. Two primocane-fruiting red raspberry cultivars, Josephine and Polka, were used in 2016 and 2017. These cultivars were double-cropped and were chosen for their ability to provide fruit
G. Fernandez and M. Pritts
Seasonal changes in growth, photosynthetic rates, temperature, and light response curves of `Titan' red raspberry (Rubus idaeus L.) were obtained from potted plants grown under field conditions. Primocane dry weight accumulation underwent two phases of linear growth at the beginning and the end of the season, but growth slowed during fruiting. This slower rate of dry weight accumulation also coincided with an increase in root dry weight. Primocane NAR and SLA were highest early in the season. Light response curves differed depending on cane type and time of year. Floricane photosynthetic rates (A) were high during the fruiting period, while primocane A rates remained steady throughout the season. Both primocane and floricane leaflets displayed a midday drop in A rate, with a partial recovery in late afternoon. Photosynthetic rates of both primocane and floricane leaves were very sensitive to high temperatures. Temporal convergence of sink demand from fruit, primocanes, and roots occurs when plants experience high temperatures. This may account for low realized yields in raspberry and the high level of yield component compensation typical of source-limited plants.
Gina E. Fernandez and Marvin P. Pritts
Seasonal changes in growth, mean maximal photosynthetic rates, and the temperature and light response curves of `Titan' red raspberry (Rubus idaeus L.) were obtained from potted plants grown under field conditions. Primocane dry weight accumulation increased steadily at the beginning and the end of the season, but growth slowed midseason during fruiting. The slower midseason dry-weight accumulation rate coincided with an increase in root dry weight. Primocane net assimilation rate (NAR) was highest early in the season. Floricane photosynthetic rates (A) were highest during the fruiting period, while primocane A remained steady throughout the season. Primocane and floricane leaflets displayed a midday depression in A under field conditions, with a partial recovery in the late afternoon. Photosynthetic rates of primocane and floricane leaves were very sensitive to temperature, exhibiting a decline from 15 to 40C. Light-response curves differed depending on cane type and time of year. A temporal convergence of sink demand from fruit, primocanes, and roots occurs when plants experience high temperatures. These factors may account for low red raspberry yield.
Stanley R. Nehrbas and Marvin P. Pritts
Effects of annual pruning, alternate-year mowing, and primocane suppression on yield and its components for ‘Titan’ and ‘Royalty’ summer-bearing raspberries (Rubus idaeus and R. neglectus) were measured for 2 consecutive years. Cumulative yield was highest for primocane suppression and lowest for alternate-year mowing. Path analysis revealed that cane number per plant and number of fruitful laterals per cane were the most important yield components for both cultivars. Alternate-year mowing plots had higher cane numbers per plant than other treatments, but fewer fruitful laterals in the bottom and middle thirds of the canes. Annual primocane suppression increased numbers of fruitful laterals in the bottom and middle thirds of canes, resulting in increased yield compared to other treatments. Productivity was related to the amount of photosynthetically active radiation entering the canopy.
NAA at 0.25% to 1.0% applied in late May on the basal portion of thornless blackberry (Rubus, subgenus Eubatus) primocanes inhibited lateral shoot growth in the treated area and reduced the number of primocanes. However, regrowth occurred near or below ground from axillary buds not contacted by NAA. Rates of (0.25% and 0.12570 NAA did not affect the terminal or lateral growth above the treated area. The reduced number of basal lateral shoots facilitated machine harvesting. Chemical name used: napthaleneacetic acid (NAA).