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  • Author or Editor: Brian Lawrence x
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Maintaining shelf life and postharvest quality of blackberries (Rubus subgenus Rubus) from harvest to consumer is challenging for growers and packers due to several postharvest issues including fresh weight (FW) loss, red drupelet reversion, and fruit leakiness. The time of day blackberries are harvested, the time from harvest to cold storage, and the time in cold storage are factors that may alter the incidence and severity of these postharvest problems. In this experiment, blackberries from 10 cultivars were picked at two different times (7:00–7:30 am and 10:00–10:30 am), delivered to cold storage either immediately or following a 90-minute delay, and evaluated after 1 or 2 weeks in cold storage for FW loss, red drupelet reversion, and leakiness. The response of blackberry postharvest quality to time of harvest, delay to cold storage, and storage length was cultivar-specific. In summary, time of harvest, delay to cold storage or storage length did not affect cultivars Arapaho and Ouachita. Different harvest times did not affect FW or incidence of reddening, but increased leakiness in ‘Chester’ and ‘Triple Crown’; thus, these two cultivars should be preferably harvested early in the morning. Our recommendation for ‘Chester’, ‘Triple Crown’, ‘Osage’, ‘Prime-Ark® Traveler’, and ‘Von’ is to store the fruit of these cultivars as soon as possible. Limiting cold storage to 1 week maintained postharvest quality for at least one attribute of most cultivars (all but Arapaho and Ouachita) compared with 2 weeks of storage.

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The photosynthetic light response of commercial blackberry cultivars (Rubus L. subgenus Rubus Watson) is largely unexplored, although they are frequently grown in full sun. In this experiment, light response curves of floricane leaves from the cultivars Natchez, Apache, Navaho, and Von were examined throughout the following production stages: before shiny black fruit were present (before harvest, BH), during peak production of fruit (peak harvest, PH), and when most fruit had fallen from plants or any remaining were dull black (after harvest, AH). Each cultivar was evaluated between an irradiance of 2000 and 0 μmol·m–2·s–1. The estimated maximum photosynthetic rate (photosynthetic capacity, P Nmax ) was greater BH than AH across all cultivars, whereas ‘Natchez’ had a greater P Nmax BH and PH compared with the other cultivars. During AH, all cultivars had a similar P Nmax . The BH response curves declined under the highest irradiance measured, whereas the PH and AH response curves remained stable at similarly high irradiance. Of the four cultivars, Apache, Navaho, and Von appeared to be more photosynthetically limited than Natchez under increasing irradiance. Based on the cultivar-specific performance observed, blackberry response to light is a relevant trait that breeding programs should consider for improving cultivar adaptability to local and regional conditions.

Open Access


Microsprinkler irrigation was used to protect young citrus trees during severe advective freeze conditions in Florida during 24–26 Dec. 1983. Three factors (microsprinkler distance from the tree, compass position, and water volume output) influenced the amount of protection or tree damage. Spray jets that delivered 76 liters/hr (9 mm/hr) and were located 0.7 m or less from the north side of the trees protected the lower scaffold branches and trunk of young trees to temperatures below −6°C. Spray jet irrigation, particularly when jets were more than 1 m away on the east side of the trees resulted in more tree damage than no irrigation. This was due to low dew point temperatures and northwest winds which kept continuously-sprayed water away from the tree. Volume of water per tree needs to be moderately high, and spray jets should be located on the upwind (northwest) side of the tree at a distance no greater than 0.7 m from the tree in order to provide optimum freeze protection with microsprinkler irrigation.

Open Access