Crops, Vol. 5, Pages 61: Moroccan Ulva rigida Extracts: A Promising Biostimulant for Improving Growth and Photosynthetic Performance in Salt-Stressed Bean Plants

Crops doi: 10.3390/crops5050061

Authors:
Salma Latique

Soil salinity is a crucial factor that limits agricultural production, negatively impacting the growth and physiological functions of salt-sensitive crops, such as beans. The present study examined the efficiency of Ulva rigida seaweed extracts (URE) as biostimulants to enhance the growth and photosynthetic ability of bean plants (Phaseolus vulgaris L.) under saline conditions (51.33 mM NaCl). Seaweed extracts were obtained by maceration and ultrasonic assistance at two concentrations, 25% and 50% (v/v), and applied as a foliar spray or irrigation. The most significant improvement was observed following foliar sprays of 50% ultrasonic extract (UP-50), with an increase of 96% in CCI compared to salt-stressed controls and by 71% compared to non-stressed controls. Stomatal conductance (SC) was also significantly improved with UP-50, reaching levels that were 146% higher than those of salt-stressed plants and 53% higher than those of non-stressed plants. The OJIP transients under salinity were significantly improved by both ultrasonic-assisted and maceration extracts; especially, 50% maceration extracts (MP-50) restored PSII quantum efficiency (ΦPo) and total performance index (PItotal) of salinity-stressed seedlings to 107% and 255% of non-stressed control and 122% and 314% of salt-stressed control, respectively. Root length and indole acetic acid (IAA) levels in treated plants were also enhanced, particularly in response to higher concentrations of the extract, suggesting improved root growth as well as hormonal homeostasis in the presence of salt stress. According to these findings, U. rigida extracts, specifically those applied at high concentrations as a foliar spray, serve as biostimulants that mitigate the adverse effects of salt stress on beans by preventing chlorophyll degradation and enhancing photosynthesis, root development, and hormonal balance.

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