Rootstocks with Different Vigor Influenced Scion–Water Relations and Stress Responses in AmbrosiaTM Apple Trees (Malus Domestica var. Ambrosia)

Abstract

In recent years, awareness has been raised around the benefits of diversifying rootstocks, in order to enhance tree health and sustain apple fruit production under the influence of climate change. However, performances of many rootstocks under stresses remain unclear. This study aimed to set the first step towards a much-needed comprehensive evaluation on water relationships and stress responses of scion–rootstock systems for the popular apple cultivar AmbrosiaTM (Malus domestica var. Ambrosia), because its production and horticultural knowledge had been largely limited to the Malling 9 rootstock (M.9). Five rootstocks were evaluated in a greenhouse water deficit experiment and at the onset of heat stress in a field trial in Summerland, British Columbia, Canada. Multiple stress indicators of leaves and fruits were analyzed to elucidate water use strategies and drought resistance mechanisms. The rootstocks led to differences in scion vigor, and stomatal and photosynthetic characteristics. The largest semi-dwarfing Geneva 202 (G.202) demonstrated more water use and higher stress susceptibility. Large dwarfing Geneva 935 (G.935) and Malling 26 (M.26) showed more stringent stomatal control and reduced water use under stresses, typical of a drought-avoidance strategy. The smallest large dwarfing M.9NIC29® and the small dwarfing Budagovsky 9 (B.9) led to smaller and denser stomata. B.9 demonstrated the most stable water status and drought tolerance. The study suggested that scion stress responses were influenced by rootstock vigor and tree water use strategies. It implied the necessity of vigor-specific irrigation management for alleviating stresses and achieving production goals of different rootstocks.

Variation in scion water relations mediated by two newly released Geneva series rootstocks

“…The midday stem water potential measured in this well irrigated orchard ranged from -0.87 to -0.98 MPa (Table 1). These observations follow similar patterns observed for different rootstocks in apple (Sarita et al, 2013;Xu et al, 2021) has been previously reported for apple rootstocks. Like stem length, stem water potential was the lowest for M.9.…”

“…Rootstocks can also be used to improve water and nutrient uptake (Tworkoski and Fazio, 2015), reduce disorders (Blanco et al; unpublished) contributing to enhanced economic and environmental sustainability. Although dwarfing has been extensively characterized in different apple cultivars, the underlying physiological mechanisms contributing to this dwarfing effect remain unclear (Simon and Chu, 1984;Marguerit et al, 2012;Foster et al, 2017;Xu and Ediger, 2021). Some theories attribute the dwarfing mechanism of rootstocks to changes to the supply of water from the rootstock to the scion (Atkinson, 2003).…”

Changes in Reactive Oxygen Species, Antioxidants and Carbohydrate Metabolism in Relation to Dormancy Transition and Bud Break in Apple (Malus × domestica Borkh) Cultivars

“…Agricultural Research and Extension Center (AREC) in Winchester, VA, the United States (39.11, −78.28) were used. It is worth noting that B.9 and M.9 rootstocks have similar vigor and previous reports showed no significant differences between these rootstocks in stress tolerance [50] and bud break [51]. Three trees from each cultivar were randomly selected, each considered as a biological replicate.…”

Creation and Use of Highly Adaptive Productive and Technological Red Currant Genotypes to Improve the Assortment and Introduction into Different Ecological and Geographical Zones

“…Information about the water status of fruit crops is necessary when planning an irrigation program that will reliably ensure the optimal functioning of physiological indicators. However, at the same time, there is no consensus on a suitable indicator on this issue and the topic remains debatable [ 40 , 41 , 42 , 43 ].…”