Influence of furostanol glycosides treatments on strawberry (Fragaria × ananassa Duch.) growth and photosynthetic characteristics under drought condition

• Glycoside treatments improve leaves and roots growth and development.
• In water stress condition glycoside treatments increase root/shoot ratio.
• It alleviated drought effect: enhances photosynthetic rate and water use efficiency.
• Glycosides application mitigated reduction of ΦPS II and ETR, caused by water stress.
• Treatment induced an enhancement of non-photochemical processes in drought condition.

Water availability is one of the major limiting factors for plant growth and productivity. In recent years, efforts to search for specific and practical approaches to improve the adaptability of plants to this environmental condition have been made. In this study we have examined the influence of two furostanol glycoside application on the capacity for acclimation to drought of two strawberry (Fragaria × ananassa Duch.) cultivars, Real and Magic, grown in greenhouse conditions. Two regimes of irrigation were used: well-watered (80% WHC) and drought stress (50% WHC) for one month. Two furostanol glycoside aqueous solutions (G1 and G2) were applied by foliar spraying during late afternoon at 3 days intervals on 5 mature plants for each variant. Changes in plant growth and photosynthesis (gas exchange and chlorophyll fluorescence measurements) were studied.In drought conditions, glycoside application induced a decrease in leaf size and increase in roots length, resulting in significant increases of root/shoot ratio. The two glycoside treatments alleviated the effect of drought and improved photosynthetic rate (A) and water use efficiency (A/E) in both cultivars. In addition, G1 treatment reduced the severity of drought effect by increasing the stomata responsiveness thus maintaining a higher relative water content (RWC), while G2 treatment led to a lower decrease of stomatal conductance (gs) and transpiration rate (E) and a significant decrease in internal CO2 (Ci) concentration compared to untreated plants subjected to stress. The chlorophyll fluorescence measurements indicate that furostanol glycoside treatments mitigated the reduction of photosystem II efficiency (ΦPS II) and electron transport rate (ETR) caused by water stress, compared to untreated plants. Moreover, under drought stress, treated plants recorded higher values of non-photochemical processes (NPQ) than untreated ones. One can safely assume that glycoside treatments induced an enhancement of non-photochemical processes as well as an alleviation of the drought-induced alteration in PS II by increasing the efficiency of light utilization and dissipation of excitation energy in the PSII antennae.