Primocane-fruiting Raspberries Research Articles

Research Article Canonical correlations among morphological and yield traits in primocane-fruiting raspberries

Raspberry (Rubus idaeus) is an economically important crop, and its cultivation has expanded recently across temperate and subtropical regions of Brazil. There is no brazilian raspberry cultivar so far. Therefore, the indirect selection can be an useful tool to help during the breeding process. We evaluated linear and canonical correlations in primocane-fruiting raspberry cultivars in 2013 and 2014, in a completely randomized experimental design, with eight replications. The genotypes 'Alemazinha', 'Heritage' and 'Fallgold' were evaluated during two harvesting seasons, autumn and spring. Canonical groups were established among morphological (Group 1) and yield (Group 2) traits. In Group 1, plant yield and fruit weight were evaluated; in Group 2 the productive period, plant height, stem diameter, dry mass of pruning and plant leaf area were assessed. The linear and canonical correlations among morphological, phenological, and yield traits varied according to harvesting season. The phenological and morphological traits had greater linear correlation with yield traits in autumn than in spring. Based on our findings, to obtain more productive raspberry genotypes, plant leaf area and dry mass of pruning should be prioritized in the indirect selection.

Cropping on Primocanes and Floricanes Increases Yields of Organic Raspberries in High Tunnels

Red raspberry cultivars that produce fruit on current season canes (primocanes) can produce additional fruit the following year on floricanes. The primocane-fruiting raspberries ‘Himbo Top’, ‘Joan J’, and ‘Polka’ were grown organically in high tunnels and pruned to different floricane densities to determine the effects on fruit yield (primocane, floricane, total) and harvest times. Floricane densities were 0, 2.4, or 4.8 canes per meter of row length in 2015, and 0, 4.9, or 9.8 canes per meter in 2016 and 2017. Total yield (floricane plus primocane) was significantly greater with low floricane density (17 t·ha−1) or high density (19 t·ha−1) compared with no floricanes (12 t·ha−1). Floricane density did not affect primocane yield or harvest times. Primocanes of ‘Polka’ were taller when floricanes were present, but primocanes of other cultivars were unaffected. Results indicate that producing fruit on both primocanes and floricanes (double cropping) can improve sustainable overall yields.

Advancing Primocane-fruiting Raspberry Production in the Intermountain West Using Spring Protection

Winter injury to raspberry floricanes commonly limits productivity in cold climates. Primocane-fruiting raspberries avoid winter injury by fruiting on first year canes, but fruit production in the high-elevation valleys of the Intermountain West is later than needed for local markets, and may be limited by early fall freezes. High tunnels were used for early spring heat to advance primocane growth and the fruiting season of two primocane-fruiting red raspberry cultivars. Tunnels were covered with plastic in March and April. Then, they were covered with shade cloth during fruit ripening. Tunnel-covered plots were compared with field plantings for primocane growth rate, fruiting season, yield, and fruit quality over two seasons. High tunnels increased cane growth rate, with the harvest season advanced by 18 to 26 days depending on season and cultivar, but they did not consistently affect the total season yield or fruit size. Low-cost two-season tunnels used in conjunction with early-season primocane-fruiting raspberries may provide a viable method for small acreage producers in harsh climates to reliably supply high-value seasonal raspberry markets.

Primocane-fruiting Raspberry Production in High Tunnels in a Cold Region of the Upper Midwestern United States

Five primocane raspberry (Rubus idaeus) cultivars were evaluated in a high tunnel and in the field at Grand Rapids, MN, which is located in U.S. Department of Agriculture (USDA) plant hardiness zone 3b. Bare root plants of five cultivars (Autumn Bliss, Autumn Britten, Caroline, Joan J, and Polana) were planted in the high tunnel and in the field, each with a randomized complete block design at 2 × 5.2-ft spacing on 8 May and 14 May 2008, respectively. A propane heater was used periodically for frost protection in the high tunnel. All five cultivars overwintered well and primocanes emerged with minor or no winter damage in the high tunnel in 2009. The high tunnel extended the growing season for ≈4 weeks in both years. Raspberry plants in the high tunnel produced higher yield than those in the field, total 154 lb (6655 lb/acre) from the high tunnel vs. 0.5 lb (43 lb/acre) from the field in 2008 and 379 lb (16,378 lb/acre) vs. 80 lb (3457 lb/acre) in 2009. ‘Caroline’ and ‘Polana’ had higher yields than ‘Autumn Bliss’; ‘Joan J’ and ‘Autumn Britten’ yields were intermediate and not different from ‘Caroline’, ‘Polana’, or ‘Autumn Bliss’ yields. In terms of harvest date, ‘Polana’ was the earliest among the five cultivars tested, followed by ‘Autumn Britten’, ‘Autumn Bliss’, and ‘Joan J’. ‘Caroline’ was the latest. Essential nutrients in leaves for all cultivars both in the field and in the high tunnel were within sufficient ranges. Spider mites (Tetranychidae) and raspberry sawflies (Monophanoides geniculatus) were the major insect problems. In conclusion, primocane-fruiting raspberries can be successfully grown in high tunnels and produce substantially higher yields than in field plantations in northern Minnesota or areas with similar climatic conditions.

Primocane-fruiting Raspberry Production

Primocane-fruiting raspberries (Rubus idaeus L.) have the capacity to fruit in the fall and again the next summer. Because of their low chilling requirement, this type is used to produce a double crop in warmer regions of the world. However, many growers prune canes to the ground after the fall crop, sacrificing the summer crop for a single, large fall crop. This practice is less labor-intensive than the selective cane removal required for double-cropping and crop quality is often higher. Primocane-fruiting raspberries also are easily manipulated to extend the season. Early- and late-fruiting cultivars, cultural manipulations, rowcovers, high tunnels, and greenhouses are all used commercially to extend the season of primocane raspberries year-round. This is beneficial for consumers because high-quality fruit is now available for a much longer period than was possible in the past.

The Effect of V-Trellising on Primocane-Fruiting Raspberries (Rubus idaeusL.)

Abstract Primocane-fruiting (PF) red raspberries (Rubus idaeus L. cvs. Summit and Heritage) at two locations in Southern Ontario were maintained in a hedgerow or trained to a V-trellis to determine the effect of trellising on productivity. Trellising increased yield per cane in ‘Heritage’ at Cambridge by 56% with a concomitant increase in fruit number per cane, but did not significantly affect yield of either ‘Heritage’ or ‘Summit’ at Campbellville. Plots at Campbellville had significantly greater cane densities than plots at Cambridge, and so light penetration into the walls of the V-trellis at Campbellville was likely diminished due to crowding and competition between canes. Response of PF raspberries to V-trellising may be dependent on cane density of the planting.

Scheduling primocane-fruiting raspberries (Rubus idaeus L.) for year-round production in greenhouses by chilling and Summer-pruning of canes

SummaryTwo greenhouse experiments were performed to investigate the effects of Summer-pruning in the first year, and cold-storage, on primocane-fruiting raspberry (Rubus idaeus L.) cultivars. In the first year in the greenhouse, primocanes were Summer-pruned when they were 60 cm tall which delayed fruiting by approx. 1 month, but decreased yields slightly. Plants cold-stored below 7°C for 6 weeks, markedly and consistently out-yielded those that had not been cold-treated. In the second experiment, yields on the floricanes and primocanes were separated and clearly showed that floricane dormancy was broken, so that double-cropping could occur. ‘Heritage’ produced few fruits on its floricanes, which indicated that it requires a longer cold treatment than cvs. ‘Autumn Britten’, ‘Polana’ and ‘Summit’. In this system, 10 canes m–2 appeared to be the optimum number of primocanes needed to produce the highest yields. These experiments confirmed that adventitious buds will eventually break dormancy without a chilling period, as daylength increases. Also, they show that primocane-fruiting raspberries can be manipulated to fruit all-year-round in the greenhouse.

SCHEDULING PRIMOCANE FRUITING RASPBERRIES FOR YEAR-ROUND PRODUCTION IN GREENHOUSES

In Ontario, raspberries have the potential to be grown year-round in greenhouses. Initial research has shown that primocane-fruiting raspberries can fruit for several years without a cold period, although in the winter production ceased. Since primocane raspberries can also fruit on overwintered canes, two experiments, one in 1998 and one in 1999, were set up to schedule fruit production throughout the year. In the first experiment, potted plants of 'Autumn Britten', 'Heritage', 'Polana' and 'Summit' were grown in the greenhouse and in the first year, plants either had their canes cut to 30cm, cut to the surface or left uncut. In December the plants were either left in the greenhouse or subjected to 6 weeks below 7°C. In the second experiment the treatments were the similar except that only 'Autumn Britten', and 'Polana' were used and the cut to the surface treatment omitted. In the first experiment, all the plants cut to the surface died and in the first year, and the other treatments had similar yields. In the second experiment, plants with canes cut to 30 cm yielded less than the uncut plants. In both experiments, the plants cut to 30cm produced about one month later. In the second year, in both experiments the plants that had been chilled, fruited sequentially on their floricanes and primocanes from late March onwards. Those plants that were not chilled fruited on their primocanes from May onwards and had lower annual yields than those that were chilled. These results indicate that primocane -fruiting cultivars can be manipulated to fruit throughout most of the year, so fewer plants are needed compared to production systems which use floricane cultivars.

BREEDING PRIMOCANE-FRUITING RASPBERRIES AT MEDWAY FRUITS -- PROGRESS AND PROSPECTS

Cultivars of primocane-fruiting raspberries have improved considerably in the last 20 years, but their shelf-life and yields are still inferior to those of summer-fruiting kinds. Breeding at Medway Fruits aims to improve these qualities. For shelf-life, the success of cultivars like 'Glen Lyon' and 'Tulameen' suggests that the fruits should combine good skin strength with resistance to compression. For yield, fruit size is emphasised because it is a particularly important yield component in primocane-fruiting cultivars. To attain both objectives we have transferred genes from summer-fruiting to primocane-fruiting cultivars, notably genes for prolonged shelf-life from 'Glen Lyon' and related germplasm, and genes for large fruits from 'Glen Moy'. The cultivars 'Joan Squire', 'Joan J' and 'Joan Irene' have some of the qualities required. 'Joan Squire' can be manipulated to crop from mid-August to mid-December in the UK, while cropping from over-wintered canes provides for early production. However, for 'Joan Squire' and other material the quality of floricane fruit is always inferior to that of primocane fruit.

Supplementary Irrigation and Mulch Benefit the Establishment of `Heritage' Primocane-fruiting Raspberry

Field experiments including supplementary trickle irrigation (IR), IRT-76 plastic film (PF), and straw mulch (STR) treatments were conducted during 1993 and 1994 to determine the influence of root-zone temperature and soil moisture status on carbon assimilation and dry mass distribution, and soil and plant nutrient content, during the establishment of Rubus idaeus L. `Heritage' primocane-fruiting raspberries. The IR, PF, and STR treatments were reapplied after the 1993 establishment year to examine their effects on an established, hedgerow planting. Physical environment, vegetative and reproductive data were collected. PF increased root and shoot mass, total flower number, and total berries harvested. Maximum leaf net photosynthetic (Pn) rates were observed under cool air temperatures and root-zone temperature of 25 °C. Field Pn measurements indicated that there was no seasonal decline in Pn. Mulch treatments however, were not beneficial to the established (i.e., 2-year-old) hedgerow planting. The root system of the 2-year-old planting was largely confined to an area within the foliage wall and also at a greater depth from the mulch treatments. Therefore, beneficial effects of mulch management on the growth and development of raspberries may be limited to the establishment year.

Performance of Advanced Breeding Selections of Primocane-fruiting Raspberries in New Jersey

A major objective of the MD/NJ/VA/WI Cooperative Raspberry Breeding Program is to develop new primocane-fruiting raspberry cultivars that are early, with large fruit size, and good fresh flavor, relative to the `Heritage' standard. Step I seedling selections were made and tissue culture-propagated. The Step III advanced selection trial, planted in 1993, consisted of two advanced selections, JCR-F1 [Geo-1 (Autumn Bliss × Glen Moy) × Heritage–red], and JEF-B1 (Amity × Glen Eagles–golden), with a `Heritage' check. The planting was a RCB (four replications), with 3-m plots, 60-cm plant spacing, on raised beds with black plastic mulch (establishment year), and trickle irrigation. The 1994 season started dry, and mid-summer was warm and wet, inducing an early harvest overall. JCR-F1 was >2 weeks earlier, 40% higher yielding, with 18% larger fruit size than `Heritage'. JCR-F1 fruit was tall conic, cohesive, and had good flavor; plant vigor was very good. JEF-B1 was 10 days earlier than `Heritage', had 40% larger fruit size, but was 25% lower yielding; plant vigor was also good. The flavor was described as banana and apricot. The planting will be fruited for multiple seasons for continued comparison.

Rowcovers Accelerate Fruiting and Increase Productivity in Primocane-fruiting Red Raspberries

Studies were conducted over eight location-years to evaluate the effects of rowcover material, time of application, and time of removal on `Heritage' red raspberry cane growth, flowering, and fruiting. We anticipated that rowcovers would accelerate fruit maturity so that more of the crop could be harvested before the onset of cold temperatures in autumn. In seven of the eight experiments, rowcovers either increased yields or accelerated harvest. With a March application, harvest began 3 weeks earlier, and August yields of covered plants were 42 times higher than those of noncovered plants. Responses were observed with spunbonded polypropylene and polyester covers, but not with polyethylene covers. Rowcovers placed over the row before primocane emergence and removed when canes were ≈50 cm tall resulted in the greatest plant response. The use of polyester or polypropylene rowcovers with primocane-fruiting raspberries appears to be economically feasible in most years in northern climates.

Primocane (autumn)-fruiting raspberries: a review with particular reference to progress in breeding

SummaryThe characteristics of primocane-fruiting (PF) raspberries (developmental cycle, ripening season, yield) and the effects on these of changes in the environment (day-length, length of growing season, temperature, nutrition, growth regulator applications) are described. Economic aspects are discussed in relation to extending the season, reduction in establishment and production costs compared with summer-cropping raspberries, and mechanical harvesting. Progress in breeding new PF varieties in North America and Europe and current and potential future prospects for growing PF raspberries are discussed.