Blackberry (Rubus spp.) is a popular fruit due to its delightful taste and notable health benefits. With a growing demand for regional blackberry production, this study aims to provide Virginia blackberry growers with information on the effectiveness of pre-harvest foliar treatments and shade application on yield, white drupelet disorder, post-harvest attributes, and the aroma profile of two blackberry cultivars, Prime-Ark® Traveler and Prime-Ark® Freedom. The field study was repeated in the 2021 and 2022 growing seasons at the Hampton Roads Agricultural Research and Extension Center in Virginia Beach, VA, in a completely randomized design. Grower standard control (GSC), shade cloth with 30% light reduction (SHA), calcium (CAL), and salicylic acid (SAL) foliar applications were randomly assigned to each variety. Fruit yield and physicochemical attributes of the blackberry were collected and analyzed, and aroma-active compounds in blackberries were identified by use of headspace-solid-phase microextraction-gas chromatography-mass spectrometry-olfaction (HS-SPME-GC-MS-O). Shade cloth significantly reduced the white drupelet disorder (WDD) in Prime-Ark® Freedom but it also reduced the total soluble solid content (°Bx) and °Bx/% titratable acidity (a ratio indicates the sweet and sour balance for fruit) for both cultivars. No significant improvement was found in the TSS, TA, firmness and yield of blackberries treated with CAL and SAL. In total, 16 consistent aroma-active compounds were found across treatments for both varieties and growing seasons. Foliar and shade application did not alter the aroma profile of either blackberry cultivar. However, higher volatile contents were found in 2021 than in 2022, possibly due to climate variation. A clear distinction on aroma profiles of the above two cultivars were also observed: PrimeArk® Freedom was higher in compounds possessing "fruity" and "floral" notes, while PrimeArk® Traveler featured more "green" and "fresh" characteristics. Regional berry growers should be more conservative when adopting foliar and shade applications due to potential seasonal variations surpassing the significance of agronomic treatments. / Master of Science in Life Sciences / Blackberry (Rubus spp.) with its inky purple color, juicy bursts of sweet and tart flavor, and various health benefits has become more popular recently. With growing demands for locally produced blackberries with better flavor, this study will provide Virginia blackberry growers with information on the effectiveness of pre-harvest foliar treatments and shade applications on yield, white drupelet disorder, post-harvest attributes, and aroma profile of two blackberry cultivars, Prime-Ark® Traveler and Prime-Ark® Freedom. The field study was repeated for two growing seasons 2021 and 2022 at the Hampton Roads Agricultural Research and Extension Center in Virginia Beach, VA. All blackberry plants received standard fertigation, with plots receiving additional either calcium or salicylic acid foliar spray, or shade cloth (black mesh cloth) application to reduce 30% direct sunlight. Fruit yield and post-harvest attributes such as sugar content, firmness, phenolic content, and aroma of the Virginia-grown blackberries were studied. Shade cloth (light reduction) was effective in mitigating discoloration in Prime-Ark® Freedom, but it also reduced the sugar content and sweet and sour balance for both varieties. Calcium and salicylic acid were not effective in improving the yield and fruit quality of blackberries. Fruit harvested in 2021 had a more intense aroma and taste when compared to the 2022 season, likely due to the excessive heat and drier climate in year 2. The two cultivars have different aroma profiles, with PrimeArk® Freedom being more "fruity" and "floral" and PrimeArk® Traveler featuring more "green" and "fresh" notes. This study suggests that regional berry growers should be more conservative when adopting agronomic practices such as foliar spray and shade applications due to seasonal variations (temperature, rainfall) possibly surpassing the effectiveness of agronomic treatments.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/115941 |
| Date | 28 July 2023 |
| Creators | Xu, Tianyou |
| Contributors | Food Science and Technology, Yin, Yun, Samtani, Jayesh Bharat, Huang, Haibo |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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