Plant response to drought is a critical process for the survival and development of resilient cropping systems. However, drought studies are often based on short-term experiments under controlled environments which may not reflect compounding stress factors experiences under field conditions, such as high air and soil temperature, high light irradiance, among others. In composite plants like apple, both rootstock and scion combine to modulate drought response. Nonetheless, the effect that apple rootstock genotypes have on scion response to water limitations have not been extensively studied. The objective of this study was to measure physiological responses of different apple rootstocks to drought under both field and greenhouse conditions. For both experiments, ‘Honeycrisp’ apple was grafted onto G.41, G.890, M.9, and B.9 rootstocks. Two irrigation treatments were established: drought (~ 50% of field capacity (FC) and control (~ 100% FC). Leaf gas exchange, mid-day stem water potential (Ψ_md), quantum yield of PSII (ΦII) and shoot growth were measured bi-weekly. At the end of each experiment, total leaf area and root, stem and leaf carbon isotope composition (δ¹³C) were measured. In the field, ‘Honeycrisp’ that was grafted onto G8.90 and exposed to water limitations had lower stomatal conductance, net CO2 exchange rates, ΦII, and shoot growth. In contrast, B.9 maintained stomatal conductance and shoot growth when water-limited and δ¹³C was the highest among rootstocks. There were no rootstocks differences for trees grown in the greenhouse. These results show how rootstock can affect scion response to water limitations in apple and how field experiments can magnify these responses.

植物对干旱的反应是弹性种植系统生存和发展的关键过程。然而，干旱研究通常基于受控环境下的短期实验，可能无法反映现场条件下的复合胁迫因素，例如高空气和土壤温度、高光辐照度等。在像苹果这样的复合植物中，砧木和接穗结合起来调节干旱反应。尽管如此，苹果砧木基因型对接穗对水分限制的反应的影响尚未得到广泛研究。本研究的目的是测量不同苹果砧木在大田和温室条件下对干旱的生理反应。对于这两个实验，'Honeycrisp' 苹果被嫁接到 G.41、G.890、M.9 和 B.9 砧木上。_md )，每两周测量一次 PSII (ΦII) 的量子产率和枝条生长。在每个实验结束时，测量总叶面积和根、茎和叶碳同位素组成 (δ ¹³ C)。在田间，嫁接到 G8.90 并暴露于水分限制的“Honeycrisp”具有较低的气孔导度、净 CO2 交换率、ΦII 和枝条生长。相比之下，B.9 在水分限制和 δ ¹³ C 在砧木中最高时保持气孔导度和枝条生长。温室中生长的树木没有砧木差异。这些结果表明砧木如何影响接穗对苹果水分限制的反应，以及田间试验如何放大这些反应。