Search Results
Abstract
The intervals, in days, between 10%, 50%, and 90% ripened fruit, as well as crop load, were estimated over 2 years in progenies from a partial diallel cross among 17 blueberry (Vaccinium corymbosum L., V. angustifolium Ait., and V. corymbosum × V. angustifolium hybrids) parents. General combining ability (GCA) mean squares were highly significant for all ripening intervals and for crop load, while specific combining ability mean squares were nonsignificant, indicating a large proportion of additive genetic variance. Narrow-sense heritability estimates were about 0.50 for the three ripening intervals (10–50%, 50–90%, and 10–90%). Several parents had large positive GCA effects, indicating their contribution to a long ripening interval. Most progenies with large crop loads required >15 days between 10% and 90% ripened fruit. Despite the consistently positive relationship between ripening interval length and crop load, variation among families and the potential for within-family segregation suggest the possibility of obtaining genotypes with high yield potential and improved uniform ripening.
The trailing blackberries (Rubus sp. L.), particularly `Marion', are the primary blackberries grown for the processing market and they are largely machine harvested. While `Marion' is well known for its processed fruit quality, particularly flavor, aroma, and perception of low seediness, it has spines (thorns) that can be dislodged when machine harvested and end up in the product. A primary goal of the USDA–ARS blackberry breeding program in Corvallis is the development of cultivars that are comparable to `Marion' in fruit quality but are spineless (thornless). Nine thornless selections were compared with four standard cultivars as individually quick-frozen (IQF) and puree products in a blind evaluation. Each sample was scored panelists from the blackberry industry and research program. IQF samples were scored for appearance, color, seediness, flavor, and overall quality by 21 panelists and purees were scored for color, flavor, aroma, and overall quality by 25 panelists. Both panels used a 9 point hedonic scale (1 = dislike extremely, 5 = neither like nor dislike, 9 = like extremely). With the exception of color, there were significant differences among all genotypes for all traits evaluated in the IQF and pureed products. ORUS 1380-1 was ranked similar to `Marion' and significantly better than `Waldo', in overall quality of the IQF product. In puree form, ORUS 1843-1 and ORUS 1843-3 had the highest ranking in overall quality, but were only both statistically different from ORUS 1489-2. For pureed product flavor, ORUS 1843-1 was the highest rated selection but was not statistically different from `Marion'. While ORUS 1843-1 and ORUS 1843-3 hold great promise, they are from a cross between wild collected Rubus ursinus Cham. & Schlt. and `Waldo' and as a result have some negative characteristics of the native species, particularly small fruit size. The puree quality of NZ 9128R-1, NZ 9351-4 and ORUS 1380-1 was similar to `Marion' and these genotypes offer promise as thornless replacements for `Marion'.
Strawberry (Fragaria ×ananassa Duch.) cultivars used by commercial producers in North America often change rapidly due to several factors including modified cultural practices, processing and marketing practices, the desire for new cultivars with larger and higher quality berries, resistant insect and disease pests, loss of traditional chemical control methods, and private sector breeding programs. Within the past decade, the annual plastic-mulched production system has quickly expanded into eastern North America prompting the need for cold-hardy cultivars adapted to that system. The continuing loss of traditional chemical controls for strawberry insects and diseases, including the impending loss of methyl bromide, has prompted the need for increased insect and disease resistance. In addition, consumer demands for a healthier food product with lower chemical residues has heightened this need. Small fruit experts from across North America provided information on the primary strawberry cultivars used in the recent past, the present, and potential cultivars for the future, as well as on current strawberry acreage in their respective states and provinces.
Abstract
Genetic variance components, narrow-sense heritabilities, and general combining ability (GCA) effects were estimated for plant growth habit traits from a partial diallel cross among 17 blueberry (Vactinium corymbosum L., V. angustifolium Ait., and V. corymbosum x V. angustifolium hybrids) parents. Plant height, plant diameter, and a subjective stature rating were recorded for parent and progeny plants in 1984 after 9 growing seasons at Becker, Minn. General and specific (SCA) combining ability variances were significant for all traits. GCA variance components were larger than SCA components for height and stature rating, and heritabilities (family-mean basis) were 0.68 and 0.64, respectively, indicating the relative importance of additive genetic variance for these traits. Desired stature or height in this population should be recoverable through recurrent phenotypic selection. SCA variance components were much larger than GCA components for plant diameter measures, and heritability was low. Vaccinium angustifolium parents had very negative GCA effects for plant height and stature ratings, while parents with largely V. corymbosum ancestry had positive effects. Coefficients of determination between parental phenotype and GCA effects indicated that progeny performance should be predicted by parental phenotype for stature or height but not for diameter.
Oregon produces most of the processing blackberries in the United States. `Marion' blackberry (Rubus hybrid) is a trailing, thorny plant type with fruit highly prized for its unique flavor and superior processing quality. Blackberries developed in other parts of the United States grow well in Oregon but differ in flavor from `Marion' fruit. `Marion' blackberry plants are thorny and highly susceptible to freeze injury; growers desire a thornless, higher yielding, and more winter tolerant plant with similar fruit flavor and quality. This experiment was done to identify volatiles unique to `Marion' that may be incorporated into new germplasm. Forty-two volatile peaks were identified in blackberries using headspace gas chromatography and known standards. Ethylacetate and trans-2-hexenol were present in very low amounts and nerilidol was present in an unusually high amount in fresh `Marion' homogenates relative to other blackberry cultivars. Nerilidol is a volatile commonly associated with raspberry flavor and may come from the raspberry germplasm in the breeding background of `Marion'. It appears that the flavor of `Marion' fruit results from proportional differences in several volatile compounds rather than the presence of volatiles unique to this cultivar.
Spaniards brought Fragaria chiloensis when they conquered Ecuador the mid-1700s. The `Fluachi' strawberry, which was developed from these plants, became renowned in Ecuador and was eventually produced or on 500 to 800 ha in the town of Huachi Grande near Ambato. This white-fruited, long, wedge-shaped strawberry is still praised for its firmness, flavor, aroma, and shipping quality. The fruit are produced year-round on plants grown on volcanic, sandy soils in a very dry environment at an ≈3000-m elevation near the equator. The USDA germplasm explorers Paopenoe and Darrow documented the production of the `Huachi' in the 1920s and 1950s and brought it to North America for breeding. Selections from seedling populations were determined to be red stele resistant and found their way into several Pacific Northwest cultivars, although the `Huachi' was eventually lost in North America. Recently, we traveled to Ecuador to re-collect `Huachi' and assess the strawberry industry there. Huachi is still grown commercially in Ecuador, although there are now only 4 to 5 ha remaining. Drought in the 1970s, “tired” soils, and the introduction of the more productive and easier to produce California cultivars have supplanted its cultivation. Ecuador now produces ≈350 ha of strawberries using California production systems. This fruit is exported fresh, primarily to the United Sates, or is frozen in a 4 + 1 sugar pack. We brought `Huachi' back for distribution to interested breeders and to set up fertilizer trials on an established field to try to boost its productivity.
Northern highbush blueberry (Vaccinium corymbosum L.) cultivars were evaluated from planting (Oct. 2006) through 2014 in a certified organic research site in Aurora, OR. The treatments included cultivar (Duke, Bluecrop, Reka, Bluejay, Bluegold, Draper, Legacy, Liberty, Ozarkblue, and Aurora), amendment-mulch [“compost + sawdust” (included preplant amendment and a surface mulch of either an agricultural on-farm crop waste compost or yard-debris compost and sawdust), and “weed mat” (no preplant amendments but with a sawdust mulch topped with weed mat)]. Adding on-farm compost as a preplant amendment and as part of the mulching program increased soil pH from 4.9 to 6.9, organic matter content (OM), and calcium (Ca), magnesium (Mg), and potassium (K) levels compared with the weed mat treatment. The reduced plant growth and yield in some cultivars grown in the compost + sawdust treatment was likely due to the higher soil pH. ‘Bluegold’ and ‘Draper’ were among the cultivars with consistently high flower bud set (40% to 57%), whereas others had consistently low values (e.g., 22% to 45% in ‘Bluecrop’). The number of flowers per bud was affected only by cultivar. There was no effect of year or amendment-mulch treatment on percent fruit set which averaged 93% during the study; however, ‘Ozarkblue’ had a significantly lower fruit set (88%) than only ‘Aurora’ (96%). Berry weight was affected by year (plant age), cultivar, and amendment-mulch treatment. ‘Ozarkblue’ produced the largest berries. Type of amendment-mulch had little effect on berry weight, except in ‘Ozarkblue’, ‘Aurora’, and ‘Reka’ where plants grown with weed mat produced larger fruit than those grown with compost + sawdust. On average, ‘Bluejay’, ‘Draper’, and ‘Liberty’ fruit had the highest percent soluble solids (TSS) and ‘Ozarkblue’ the lowest. Fruit harvested from plants grown with weed mat were firmer than when compost + sawdust was used. ‘Draper’ fruit were much firmer than those of the other cultivars in all years of the study. The number of flower buds per plant multiplied by the number of flowers/bud and berry weight (cultivar specific) and average fruit set was a good predictor of yield in young plants. Yield per plant increased from the second through seventh growing seasons as plants matured in all cultivars except for ‘Duke’ which had the greatest yield in 2014. Cumulative yield was highest in ‘Legacy’ and lowest in ‘Bluejay’ and in ‘Draper’, which had relatively low yield when plants were young. Most cultivars had greater yield when grown with weed mat, whereas ‘Bluegold’ and ‘Liberty’ were unaffected by amendment-mulch treatment. Because weeds were managed in all plots, the cultivar response to amendment-mulch was likely a reflection of sensitivity to preplant amendment with on-farm compost and the resulting higher soil pH. It is possible that the cultivars differed in their adaptability to the various fertility regimes caused by the amendment-mulch treatments and fertilizers used in our study.
One- or two-node hardwood cuttings were taken from 9-year-old ‘Triple Crown’ and ‘Siskiyou’ blackberry (Rubus) plants on 5 Nov. 2009, 3 Dec. 2009, and 21 Jan. 2010. The response of cuttings with and without partially excised axillary buds to an application of cytokinin was compared with control cuttings with intact axillary buds and no cytokinin. Differences in root development were evident in the two cultivars tested. The cuttings of ‘Siskiyou’ and ‘Triple Crown’ callused on cut ends, but many of the adventitious roots developed from the base of the axillary buds. Shoots emerged from the bud in ≈90% of ‘Siskiyou’ cuttings stuck in November, December, and January. Rooting occurred in more than 90% of cuttings stuck in November and December but declined in cuttings stuck in January. In ‘Siskiyou’, bud excision had no effect on shoot and root emergence, but cytokinin treatment suppressed rooting in cuttings collected in November and January. Shoot emergence and rooting were poorer in ‘Triple Crown’ cuttings than in ‘Siskiyou’. In ‘Triple Crown’ cuttings, partial excision of buds reduced shoot emergence only in January but had no effect on rooting at three sticking dates. Cytokinin treatment improved shoot emergence in November and December but reduced rooting in January. The enclosed system is a viable method for propagating ‘Siskiyou’ blackberry by non-leafy floricane cuttings.
Twenty blueberry (Vaccinium sp. L.) families were planted in Michigan and Oregon to determine variability among families, locations and the importance of family×location interaction. The families were generated at Michigan State University from crosses among parents with a diverse genetic background. Seedlings were planted in field locations in Corvallis, Ore., and East Lansing, Mich., in 1995 and managed following standard commercial blueberry production practices with no insecticide or fungicide applications. In 1998-2000 the plants were evaluated for survival, bloom date, ripening date, plant growth and the fruit were scored for crop load, color, picking scar, firmness and size. All traits, except fruit color, varied significantly between locations. Plants in Oregon had a 36% greater survival rate and grew to be much larger, 80% taller and 104% wider, than those in Michigan. Families in Oregon flowered earlier in the year than those in Michigan but ripened at a similar time. Between locations, family differences were only evident for survival and fruit color. In Oregon, there were differences among families for all traits whereas in Michigan only survival, ripening date, plant height and width, and picking scar differed significantly. The family × environment interaction was not significant for crop load, fruit color and fruit firmness, so individuals selected on the basis of crop load, fruit color and fruit firmness should perform similarly in either location. There was a significant family × environment interaction for the other traits including survival, bloom date, ripening date, ripening interval, plant height and width, and for picking scar. Therefore, there is a need for individual selection programs at each location. Genotypes well adapted to Michigan may also do well in Oregon, but numerous promising genotypes could be missed for Oregon, if families are first selected in Michigan. The loss of numerous individuals due to winter cold may have reduced levels of variability in Michigan.