Blueberry (
Vaccinium corymbosum
L.) production under tunnels has spread in recent years. However, there is little
information on the productive and physiological responses of blueberry grown under high tunnels. The objective of this
research was to evaluate the effect of high tunnel microclimate on the physiological and productive responses of blueberries.
A total of 1296 plants of highbush blueberry ‘O’Neal’ were grown in high tunnels, leaving the same amount of plants under
open fields (control). Environmental temperature (T, °C) and relative humidity (RH, %), diffuse and total photosynthetically
active radiation (PAR
diffuse and PAR
total, μmol m
-2 s
-1), stomatal conductance (
gs, mmol m
-2 s
-1) and maximum photochemical
efficiency of photosystem II (
Fv/Fm) of the leaf were measured. Fruit yield, date of harvest initiation and fruit growth rate
were also determined. The maximum T was on average 10-12 °C higher inside the high tunnel than the control, whereas
the minimum T averaged only 2-5 °C higher. PAR
total decreased an average of 25% under tunnel, while levels of PAR
diffuse
increased more than 150%. The
gs ranged between 42% and 99% higher in the high tunnel compared to the control, and was
positive and statistically related (r
2 = 0.69**) to PAR
diffuse variations. Blueberries under high tunnel recorded an accumulated
yield 44% higher, while harvest started 14 d earlier compared to control. The results suggest that high tunnels in blueberries
increases fruit yield and improves precocity due to higher temperatures during the flowering stage and fruit set. Particular
light conditions under tunnels would favor higher leaf stomatal conductance in this crop.
