Influence of microclimatic conditions under high tunnels on the physiological and productive responses in blueberry 'O'Neal'

Abstract

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 (g s , mmol m -2 s -1) and maximum photochemical efficiency of photosystem II (F v /F m ) 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 g s 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.

Decrease in artificial radiation with netting reduces stress and improves rabbit-eye blueberry ( Vaccinium virgatum Aiton) ‘Ochlockonee’ productivity

“…These results concur with those pointed out by Li et al (2014) in a study conducted under the same conditions. Ten events of T a ≤ 0 ºC were observed in the control ( Figure 1B) during fruit set and fruit development; this would affect fruit yield because of the death of recently set fruit and developing fruit as pointed out by Retamal-Salgado et al (2015). This technique with the characteristics of the present study would be an effective tool to protect the plant against temperatures ≤ 0 ºC.…”

“…The g s measurements were performed on completely illuminated leaves on the same plants, shoots, location, and frequency as those used to calculate chlorophyll fluorescence (Retamal-Salgado et al, 2015).…”

“…Mature leaves exposed to the sun and shoots of the season located in the second third of the offshoot were evaluated; 10 measurements per plant were taken on different leaves because of their natural variability (Cordon et al, 2016). For all the photosystem II maximum quantum yield (F v /F m ) measurements, the evaluated leaves were adapted to darkness for 30 min (Retamal-Salgado et al, 2015), and leaf clips with a movable shutter plate were used for this procedure. The photosystem II (PSII) F v /F m was quantified with these indicators by the following relationship proposed by Kooten and Snel (1990) and Maxwell and Johnson (2000):…”

“…In countries such as the USA, Switzerland, Germany, Italy, and Spain, netting has been necessary to decrease damage generated by extreme climatic conditions (rain, hail, high temperatures, and excessive radiation), as those observed in Chile in recent years (Lobos et al, 2012;2013;Retamal-Salgado et al, 2015). This should affect not only environmental and soil conditions (Bastías et al, 2012b;Cowan et al, 2014), but also in the photosynthetic apparatus (Lobos et al, 2013).…”

Influencia Del Uso De Malla Perla Y Roja en Las Condiciones Micro-Climáticas, Daño Por Sol Y Desarrollo De Color De Frutos en Huertos De Manzanos Cvs. Gala Y Fuji

“…Recientes estudios desarrollados en arándanos cubiertos con túneles de filme de polietileno, demostraron que bajo esta condición de cultivo la mayor proporción de luz difusa fue estrechamente relacionada con un aumento en la conductancia estomática de la hoja (Retamal-SalGaDO et al, 2015). el efecto positivo de la radiación difusa sobre el intercambio gaseoso de la planta puede ser atribuido a que estas condiciones micro-climáticas de luz resultan favorables en la reducción de la temperatura de la hoja promoviendo así la apertura estomática (URBaN et al, 2007).…”