Stone Cameron Hugh, Close Dugald C, Bound Sally A, Corkrey Ross
Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS, Australia.
Front Plant Sci. 2022 Oct 18;13:993817. doi: 10.3389/fpls.2022.993817. eCollection 2022.
Protected cropping systems (PCS) de-risk adverse climatic effects in intensive horticultural production but alter the growing environment. The objectives of this study were to investigate the effects of modern, commercial-scale PCS on sweet cherry orchard microclimate, tree water uptake and fruit quality. Sap flow sensors and weather stations were positioned at four locations under a 21 ha PCS at varying elevations (125, 114, 111, 102 m above sea level) and distances from the block boundary (105, 75, 60 or 50 m, referred to hereafter as Locations 1 to 4, respectively). Generalised additive models (GAMs) were used to predict the effect of individual climate parameters (temperature, relative humidity, solar radiation and wind speed) on tree sap flow at each of the four locations. Average and maximum temperatures and average minimum relative humidity (RH) were higher (15.9°C, 26.1°C and 49.0%) at locations with higher elevations and located further from the PCS boundary (locations 1 and 2) in contrast to locations at lower elevations and closer proximity to the PCS boundary (locations 3 and 4) (15.4°C, 24.6°C and 48.1%). Predicted sap flow was strongly correlated (r = 0.92) with time across the four locations under the PCS. GAMS modelling indicated that the hourly water uptake by trees within close proximity to the block boundary (locations 3 and 4) responded with greater intensity to increases in temperature and reductions in relative humidity, taking up on average 0.15 L h (at temperatures >30°C) and 0.08 L h (at RH<50%), respectively, in contrast to trees further under the PCS (locations 1 and 2) where average tree water uptake was 0.08 and 0.04 L h at temperatures >30°C and RH<50%, respectively. Highest average predicted hourly tree sap flow was associated with high wind speeds (0.67 L h) and low relative humidity levels (0.61 L h). Fruit harvested from locations further from the PCS boundary had significantly higher dry matter content (18.2%), total soluble solids (17.8%) and compression firmness (311.3 g mm) in contrast to fruit closer to the PCS boundaries (16.1%, 15.7% and 258.3 g mm). This study provides greater understanding of the effects of PCS on microclimate and consequences for tree water uptake and fruit quality.
保护性栽培系统（PCS）可降低集约化园艺生产中不利气候影响的风险，但会改变生长环境。本研究的目的是调查现代商业规模的PCS对甜樱桃果园小气候、树木水分吸收和果实品质的影响。在一个21公顷的PCS下，在四个不同海拔（海拔125、114、111、102米）和距地块边界不同距离（105、75、60或50米，以下分别称为位置1至4）的地方设置了液流传感器和气象站。使用广义相加模型（GAMs）来预测各个气候参数（温度、相对湿度、太阳辐射和风速）对四个位置处树木液流的影响。与海拔较低且距离PCS边界较近的位置（位置3和4）（15.4°C、24.6°C和48.1%）相比，海拔较高且距离PCS边界较远的位置（位置1和2）的平均温度和最高温度以及平均最低相对湿度（RH）更高（15.9°C、26.1°C和49.0%）。在PCS下的四个位置，预测的液流与时间高度相关（r = 0.92）。GAMS模型表明，靠近地块边界的树木（位置3和4）每小时的水分吸收对温度升高和相对湿度降低的响应强度更大，在温度>30°C时平均每小时吸收0.15升，在相对湿度<50%时平均每小时吸收0.08升，相比之下，PCS内部更深处的树木（位置1和2）在温度>30°C和相对湿度<50%时平均树木水分吸收分别为0.08升/小时和0.04升/小时。预测的每小时树木液流平均值最高与高风速（0.67升/小时）和低相对湿度水平（0.61升/小时）相关。与靠近PCS边界的果实（16.1%、15.7%和258.3克/毫米）相比，从距离PCS边界较远的位置收获的果实干物质含量（18.2%）、总可溶性固形物（17.8%）和抗压硬度（311.3克/毫米）显著更高。本研究更深入地了解了PCS对小气候的影响以及对树木水分吸收和果实品质的影响。
