Adam Dale

Utilizing wild Fragaria virginiana in strawberry cultivar development: Inheritance of photoperiod sensitivity, fruit size, gender, female fertility and disease resistance

The genetics of photoperiod sensitivity, flowering date, fruit size, gender, female fertility, and disease resistance were investigated in progeny between sets of elite F. virginiana selections and F. × ananassa cultivars and selections planted at sites in Michigan, Minnesota and Ontario. Progeny means varied considerably for all the production traits. Most notable were the large fruit and high fertility observed in crosses with High Falls 22 at all three sites, and Montreal River 10 in Ontario and Michigan. Fragaria virginiana ssp. virginiana parents yielded progeny with much larger fruit than F. virginianassp. glauca parents. General combining ability was significant for all traits at all locations, while specific combining ability was significant for only fruit diameter, ovule set and fruit set in Michigan. Overall, the highest number of day-neutral genotypes were detected in Ontario (mean =44%) compared to Minnesota (31%) and Michigan (26%). In progeny populations of day-neutral F. × ananassa × short-day F. virginiana almost all fit the 1:1 ratio expected if day-neutrality is regulated by a single dominant gene; however, only a few families of short-day F. × ananassa ×day-neutral F. virginianacrosses fit a 1:1 ratio. Likewise, in progeny of day-neutral F. virginiana ×day-neutral F × ananassa crosses, only a few of them fit the 3:1 ratio expected if day-neutrality is regulated by a single dominant gene. These data suggest that it should be relatively easy to useF. virginiana germplasm in strawberry cultivar improvement, and that several different sources of day-neutrality may exist in natural populations.

Designer fruits and vegetables with enriched phytochemicals for human health

High dietary intake of fruits and vegetables rich in phytochemicals, particularly those with antioxidant activity, has been linked to reduced risks of many chronic diseases including cancer and cardiovascular diseases. Nutraceuticals containing such bioactive phytochemicals have been popular and made available in the market. However, excessive supplementation with these extracted and sometimes purified phytochemicals may pose new health concerns. Non-processed fruits and vegetables that are known to be rich in bioactive phytochemicals are therefore advantageous for the intact and balanced phytochemical contents. However, production of phytochemicals in fruits and vegetables is affected by many factors. Genotype is a fundamental factor that affects the biosynthesis of phytochemicals, but farming practices and environmental factors such as geographic location, growing season, soil type and mineral status, plant maturity, postharvest storage and processing, can all significantly affect the concentration of m...

Improved shoot multiplication and development in hybrid hazelnut nodal cultures by ethylenediamine di-2-hydroxy-phenylacetic acid (Fe-EDDHA)

Garrison, W., Dale, A. and Saxena, P. K. 2013. Improved shoot multiplication and development in hybrid hazelnut nodal cultures by ethylenediamine di-2-hydroxy-phenylacetic acid (Fe-EDDHA). Can. J. Plant Sci. 93: 511-521. Micropropagation of hybrid hazelnut cultivars is difficult because of their recalcitrant nature. The current study assessed the effect of different iron sources on in vitro shoot multiplication and subsequent plantlet development from nodal explants of the cultivar Geneva. Two chelated forms of iron, ethylenediamine di-2-hydroxy-phenylacetic acid (Fe-EDDHA) and ethylenediamine tetraacetic acid (Fe-EDTA) were tested to determine the effect on shoot development. Shoots were longer and had a higher number of nodes when cultured on a modified NCGR-COR medium supplemented with 230 µM Fe-EDDHA, whereas shoots failed to grow on a medium with 460 or 690 µM Fe-EDTA. All plantlets grown in the presence of Fe-EDDHA had more chlorophyll, larger leaves, and higher dry weights compared with Fe-EDTA. Electron microscopy of in vitro grown tissues revealed that the form of Fe influenced the number of granal and stromal lamellae per chloroplast, the number of thylakoids per granum, and the overall chloroplast structure. Nodal explants originating from the proximal end of stems developed longer shoots with more nodes than those derived from the distal region. The use of double-phase culture medium produced plants with longer shoots and more nodes, although these exhibited hyperhydricity, showed greater morphological variation, and contained less chlorophyll. These results demonstrate the efficacy of the use of Fe-EDDHA in growth medium for improving micropropagation efficiency of hazelnut.

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

Summary Two 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.

Effects of Mulch Types on Dayneutral Strawberry Production in Three Distinct Environments in Ontario

Six plastic mulches (black, black-on-white, white-on-black, silver-on-black, brown, and green) were used to grow ‘Albion’ and ‘Seascape’ strawberries outside, and in a high tunnel at Cedar Springs in southwestern Ontario, and outside at New Liskeard in northeastern Ontario over 2 years. In the cooler climate of New Liskeard, there was no effect of mulch type on yields in the first year. In the second year, strawberry plants grown on the black and black-on-white mulches produced greater total and marketable yields than those on the white-on-black and silver-on-black mulches. ‘Albion’ had more tarnished plant bug damage than ‘Seascape’ at this location and, in 1 year, the ‘Albion’ grown on white-on-black mulch had significantly greater tarnished plant bug damage. In the warmer climate of Cedar Springs, there were more differences between mulches in the high tunnel than outside and ‘Albion’ responded more to mulch treatments than ‘Seascape’. In the high tunnel the first picking year, the greatest total and marketable yields of ‘Albion’ were from the white-on-black and silver-on-black mulch treatments. In the second year, these mulch treatments produced the fewest berries and other mulches gave superior yields. Outside in Cedar Springs there were no significant differences between the mulch treatments in the first year and few significant differences in the second year.

Multiple Avenues to Gender in Strawberries

ABSTRACT Common strawberry cultivars are hermaphrodites, producing both anthers and pistils in their flowers. However, octoploid Fragaria species are trioecious and different genotypes can be female with pistillate flowers, hermaphrodites, or males with staminate flowers. One female selection, F. virginiana High Falls 22 and three hermaphrodite selections, N8688, RH23, and Montreal River 10 were hybridized with five June-bearing cultivars. Seedlings of each family were planted in Ontario and Michigan. Two F. chiloensis selections Pigeon Point (female) and FRA1267 (hermaphrodite), were hybridized with 14 F. virginiana selections. Seedlings from each family were planted in Ontario and Minnesota. In all progeny, the presence or absence of anthers was recorded and a subjective scale used to estimate the percentage of fruit set (1–10 representing 10% intervals). Also, FRA1267 was crossed with one F. × ananassa selection and the progeny intercrossed and grown in Ontario. In the sib-crosses gender was recorded. In two female parents, the female progeny had on average a higher fruit set than the hermaphrodite progeny. F. virginiana genotypes varied in their fruit set, which suggested that there are a number of alleles involved in the fertility of hermaphrodites. In crosses, FRA1267 produced 80% females when used as a female parent and 100% hermaphrodites when used as a male parent. It is thought that the trait is inherited cytoplasmically or that the F. chiloensis alleles involved are epistatic when F. virginiana or F. × ananassa is used as a male parent.

The performance of dayneutral strawberries differs between environments in Ontario

Abstract: The strawberry production season can be extended in Ontario if plantings are protected from adverse weather conditions. At present, dayneutral cultivars developed in California are used for production, but are not well adapted to Ontario conditions. The objectives of this study were to determine suitable dayneutral cultivars for production throughout Ontario and to investigate how they react to high tunnel environments. Two sets of trials were run. The first set, planted in 2005 and harvested in 2005-2006, compared six dayneutral cultivars of strawberries in four environments. The second set, planted in 2010 and harvested in 2010-2011, compared five dayneutral cultivars grown in four environments. For the summer crops, high tunnels had higher yields in the cooler environment at New Liskeard and low yields in the warmer environment of Cedar Springs, when compared with outside plantings. In the spring, this trend was reversed. ‘Seascape’ and ‘Tribute’ performed consistently in all environments. ‘Albion’ and ‘Monterey’, although medium yielding with lower winter survival, had large fruit size and exceptional fruit quality. ‘Portola’, had large fruits and performed well, so could be of interest to farmers in Ontario. All the European cultivars tested had medium to small berries.

Fragaria virginiana resists tarnished plant bug

An experiment that involved 79 named cultivars and advanced selections of Fragaria × ananassa L., 46 Fragaria virginiana Duch. clones, and 12 F. virginiana backcross selections, and eight Fragaria virginiana × Fragaria chiloensis (L.) Duch. (all Rosaceae) selections, was conducted to detect variation in strawberry genotypes for resistance to tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae). The F. virginiana genotypes were shown to be more resistant than the cultivars and advanced selections in both 2001 and 2002. Within the group of cultivars and advanced selections, several June‐bearing and dayneutral genotypes were more resistant than others. There were fewer plant bugs on F. virginiana than on the cultivars and hybrids. Insect numbers were consistently correlated with percentage of damaged fruits and damage severity, but total numbers of flowers and fruits were only correlated with insect numbers, percentage fruit damage, and damage severity in 1 of the 2 years. Our results suggest that strawberry cultivars, highly resistant to tarnished plant bug, can be bred, if the trait is introgressed from F. virginiana selections.

Highbush blueberry cultivar trial in Ontario, Canada

ABSTRACT A replicated trial of eleven cultivars was planted at Simcoe, Ontario in 1991. Plants were first harvested in 1994. After eight harvest seasons, ‘Bluegold’ was the highest yielding cultivar, averaging 6.8 t/ha, and ‘Toro’ had the largest berries, averaging 1.81 g per berry. ‘Bluetta’ was the earliest cultivar with on average 50% of its yield picked by 16 July and ‘Elliott’ the latest, with on average 50% of its yield picked by 27 August. Overall, ‘Duke’ proved to have the best combination of characteristics of the early cultivars, and ‘Nelson’ was the most impressive late cultivar.