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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Genetic Improvement for Fruits & Vegetables Laboratory » Research » Research Project #424143

Research Project: Strawberry, Raspberry, Blackberry: Crop Improvement through Genomics and Genetics

Location: Genetic Improvement for Fruits & Vegetables Laboratory

2017 Annual Report

4. Accomplishments
1. Strawberries perform better when grown under low tunnels. Strawberries are economically valuable to farmers and are so popular with consumers that they expect to be able to buy strawberries all year long. In much of the U.S., traditional strawberries produce fruit only three to four weeks a year. To produce strawberry fruit for several months, farmers need to use a different kind of repeat-fruiting strawberry variety that fruits nearly all year long, and they need to grow them in a way that helps protect them from mid-summer outdoor conditions. Repeat-fruiting strawberries were grown in fields in two similar, but slightly different ways (in raised beds and in raised beds under low tunnels) that were used to determine how day length, brightness, soil moisture, humidity and temperature affected strawberry yield. Higher temperatures found under low tunnels, especially in early spring and late fall, resulted in a much longer harvest seasons. Strawberry yield increased as light increased, and also with warmer temperatures up to about 28 degrees-Celsius, above which yields dropped due to excessive heat. Further test showed that yields were more strongly associated with soil temperatures than air temperatures. Growers will benefit from finding ways to keep the soil in the raised beds cool and maximizing the amount of light. This information will be useful to strawberry farmers and to scientists studying ways to help farmers increase the length of the strawberry season to match consumer demand.

2. Creating new strawberries with better flavor and that fruit longer each year. Strawberries are very popular with consumers who would like to have them all year long and would like the strawberries they buy in supermarkets to taste better; therefore, breeders need a better understanding of how they can breed new strawberries that fruit all year long and taste sweeter and less tart. The genetics of repeat fruiting, sweetness and tartness were determined by studying how often each of these traits were inherited in the seedlings of a cross pollination between two strawberry plants. Sweetness was inherited independently from tartness so that no extraordinary methods should be needed by breeders to create new strawberries that are sweet and not too tart, and both these traits were controlled by multiple independent genes. In contrast, repeat fruiting in this study was found to be controlled by a single gene that was dominant over once-fruiting so that a breeder can expect that at least half of the seedlings from a cross-pollination with a repeat-fruiting strawberry and a once-fruiting strawberry should be repeat-fruiting. These results provide strawberry breeders with basic expectations from which they can more efficiently create improved strawberries.

Review Publications
Lewers, K.S., Fleisher, D.H., Daughtry, C.S. 2017. Low tunnels as a strawberry breeding tool and season-extending production system. International Journal of Fruit Science. doi: 10.1080/15538362.2017.1305941.

Castro, P., Lewers, K.S. 2016. Identification of quantitative trait loci (QTL) for fruit quality traits and number of weeks of flowering in the cultivated strawberry. Molecular Breeding. 36(10):138-156.

Darwish, O., Shahan, R., Liu, Z., Slovin, J.P., Alkharouf, N. 2015. Re-annotation of the woodland strawberry (Fragaria vesca) genome. Biomed Central (BMC) Genomics. 16:29.

Inostrozablancheteau, C., Aquea, F., Loyola, R., Slovin, J.P. 2013. Molecular characterization of a calmodulin gene, VcCaM1, that is differentially expressed under aluminum stress in highbush blueberry. Plant Biology. 15:1013-1018.

Vieira, P., Lakshman, D.K., Pandey, R., Slovin, J.P., Kamo, K.K. 2017. Symptom development in response to combined infection of in vitro grown Lilium longiflorum with the root lesion nematode Pratylenchus penetrans and soilborne fungi collected from diseased roots of field-grown lilies. Plant Disease. 101:1-8.