Abstract

Double fruit and deep suture are disorders associated with high temperatures affecting cherry production in the current climate change scenario. This research evaluated the following netting design (colors and density) to prevent double fruit and deep suture in cherry: pearl at 2.1 mm warp x gray at 4.0 mm weft spacing (PG); gray at 2.1 mm warp x blue 5.4 mm weft spacing (GB); and crystal at 2.7 mm warp x crystal at 7.3 mm weft spacing (CR). Plots of 2726 m2 of 'Santina,' 'Regina,' and 'Lapins' cherry trees (blocks) were covered using these protective nets compared to non-covered trees as control. From the end of harvest to before leaf fall, air temperature (Tair, degrees C), relative humidity (RH, %), solar radiation (SR, W m-2), bud temperature (Tbud, degrees C), vapor pressure deficit (VPD, kPa), leaf gas exchange, and stem water potential were evaluated. The incidence of double pistils at flowering; double fruit at immature stages and harvest; and deep suture (mild, moderate, and severe damage) were quantified. Both PG and GB nets significantly decreased the incidence of double pistils (p = 0.0007) by 88% and double fruit at immature stages (p = 0.0016) and harvest (p = 0.0001) by 79% and 89% with respect to the control, respectively. The CR netting decreased double fruits with less effectiveness (44%) and only at harvest. Irrespective of netting design, all nets reduced deep suture with the same significance (p = 0.0045) and magnitude (75%), but only in severe damage. The PG and GB nets reduced SR by 22%, while the CR net reduced it by 10%. Tbud was reduced between 1.5 and 2.5 degrees C under PG and GB nets, and between 0.9 and 1.2 degrees C under the CR net. There was a significant relationship between SR and the incidence of double fruit (R2 = 0.62) and severe suture (R2 = 0.53). The magnitude of variation in response to RS was greater for double fruit (beta 1 = 0.02) when compared with deep suture (beta 1 = 0.0047). These results suggest that slight variations in the thread color and density of netting influence double fruit incidence in cherry, which is also affected by changes in SR conditions, with PG and GB nets being the most promising tools for preventing the occurrence of this disorder. Conversely, the incidence of deep suture depends on other environmental factors and is not necessarily regulated by netting design.