Apple rootstock resistance to drought

Abstract

Water for irrigation will likely be less available in apple-growing regions due to climate change and competition with human needs other than agriculture. Apple cultivars and rootstocks may differ in water use necessary for acceptable cropping. In two greenhouse experiments in 2014 and 2015 rootstocks (M.9 and MM.111) and scions ('Gala' and 'Fuji') with known differences in size control and potential resistance to drought were compared under conditions of reduced water availability. After 1 week without irrigation in 2014 the potting soil moisture and leaf water potential (Ψ L) were reduced more in trees on MM.111 than M.9 rootstocks and by 'Gala' than 'Fuji' scions. Abscisic acid (ABA) and associated metabolites dihydrophaseic acid, abscisic acid glucose ester, and phaseic acid generally were greater for both scions on M.9 than MM.111. Concentrations of ABA metabolites were greater in 'Gala' than 'Fuji' suggesting significant metabolic rates in leaves. As noon Ψ L decreased between-1.5 and-2.0 MPa leaf ABA levels increased exponentially to concentrations above 500 ng / g dw and stomatal conductance (g s) decreased to less than 50 mmole H 2 O m-2 s-1. At reduced g s carbon assimilation (A) was low but greater in trees on M.9 than on MM.111. Trees grown on M.9 partitioned less dry weight (dw) to roots than MM.111. However the % dw partitioned to fine roots was greater in M.9 than

Responses of Apple Plants to Drought Stress

“…Decline in stomatal conductance is a defense mechanism to avoid water loss from leaf surface (Mahouachi, 2009). Some experiments have found that more vigorous rootstocks have greater stomatal conductance than dwarfing rootstocks (Atkinson et al, 2000;Tworkoski et al, 2016). In the present study, MM106, more vigorous rootstock, showed higher stomatal conductance compared to M9 and also more decreased in stomatal conductance under drought conditions.…”

“…MM106 provided more salinity-tolerance on the cultivar "Fuji" compared to M9 (Aras and Eşitken, 2019a). Tworkoski et al (2016) studied drought stress on M9 and MM111 apple rootstocks. They found MM111 highly drought tolerant and attributed its higher tolerance to more extensive root system.…”

Differences in Drought Tolerance among Gisela® Cherry Rootstocks Determined Using Automated Weighing Lysimeters

“…Evaluation of physiological adaptability to water stress would enable the selection of rootstocks adapted to the various approaches to precision water stress. Combining physiological adaptability and root vigor may lead to rootstocks with an increased overall drought resistance as Tworkoski et al (2016) suggest in apples. Such optimized orchards could take advantage of the precocity of dwarfing rootstocks like the Gisela Ò series, while customizing the rootstock selection to the irrigation system.…”

“…Interactions between the scion and the rootstock contribute to the overall potential drought resistance of a tree (Adams et al, 2018;Tworkoski et al, 2016). Grafting Gisela Ò rootstocks with common scion would provide a way to further evaluate drought tolerance of whole trees because potential interactions between rootstocks and scions and the contribution of any graft incompatibilities to drought tolerance could then be studied.…”

“…This approach would help determine which rootstocks are best adapted to each precision irrigation strategy, whether it be RDI, PRD, irrigation based on long intervals, or highfrequency drip irrigation. Understanding the physiological mechanisms of drought tolerance (e.g., the ability to fully recover quickly following water stress) would also enable the selection of rootstocks that have both a tolerance of water stress and the potential to explore more soil volume (Tworkoski et al, 2016).…”