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

Blueberry production under netting has increased in recent years to mitigate the adverse effects of climate change. The objective of the present study was to evaluate the effect of different radiation intensities on rabbit-eye blueberry (Vaccinium virgatum Aiton) 'Ochlockonee' photosynthetic efficiency and productive parameters. Four treatments were established: T1 (control), T2, T3, and T4 at 0%, 30%, 60%, and 90% radiation decrease (RD), respectively, with black shedding netting. The following were recorded for each treatment: environmental conditions, photosystem II (PSII) maximum quantum yield (F-v/F-m), photosystem II effective quantum yield (Phi(PSII)), leaf stomatal conductance (g(s)), quality parameters, and fruit yield. Results showed an increase of 4.6 degrees C in mean minimum temperatures for the different netting treatments, which promote development and fruit set, as well as prevent damage at temperatures near 0 degrees C. The RD treatments increased FPSII between 175% and 325% (P < 0.05) compared to the control. It can be concluded that netting decreased soil temperature between 1 and 3 degrees C and increased minimum temperatures between 1 and 6 degrees C, which promoted plant development and decreased frost damage during flowering and fruit development. Current direct radiation levels over 1000 mu mol m(-2) s(-1) in V. virgatum inhibited productivity in T1. Netting decreased the degree of photoinhibition and increased photosystem II photochemical efficiency throughout the day, and T4 and T3 exhibited the highest efficiency.