Optimal exogenous calcium alleviates the damage of Snow-melting agent to Salix matsudana seedlings

Abstract

As the main component of snowmelt agents, NaCl is widely used in northern winters and significantly impacts the expected growth of garden plants in north China. Salix matsudana is also faced with salt stress caused by snowmelt, which seriously affects its development as the main tree species in the northern landscape. However, how exogenous calcium alleviates salt stress in Salix matsudana is not yet clear. In this study, the indicators of growth indices, photosynthetic characteristics and stress resistance were measured by hydroponic assays in combination with three NaCl conditions (0, 50 and 200 mmol·L-1) and five calcium concentrations (0, 2.5, 5, 10 and 20 mmol·L-1). The study’s results indicated that the application of exogenous calcium remarkably promoted the growth of Salix matsudana seedlings under NaCl stress. When the exogenous calcium concentration was 10 mmol·L-1, the plant height and basal diameter of Salix matsudana seedlings increased significantly, and the biomass of all parts reached the maximum (P< 0.05). Exogenous calcium can substantially improve the photosynthesis of Salix matsudana seedlings under salt stress. The photosynthetic parameters, photosynthetic pigment content and photosynthetic product synthesis of Salix matsudana seedlings were significantly increased at an exogenous calcium concentration of 10 mmol·L-1, and the photosynthetic level of Salix matsudana seedlings reached the highest value. The chlorophyll fluorescence parameters (Fv/Fm, Fv/F0) of Salix matsudana seedlings were significantly decreased under different concentrations of NaCl stress. The maximum photochemical efficiency (Fv/Fm) and potential photochemical efficiency (Fv/F0) of Salix matsudana seedlings peaked when the exogenous calcium concentration was 10 mmol·L-1, which was significantly higher than that of the other treatments (P< 0.05). The water use efficiency of Salix matsudana was affected considerably by NaCl stress. The WUE and iWUE peak values of Salix matsudana were significantly higher than those of other calcium concentrations at 10 mmol·L-1 (P< 0.05). Exogenous calcium can increase the activities of CAT, SOD and POD enzymes in Salix matsudana seedlings under different NaCl concentrations. Under NaCl stress, adding exogenous calcium promoted the survival rate and growth of Salix matsudana seedlings. In conclusion, the optimum exogenous calcium concentration for Salix matsudana seedlings was 10 mmol·L-1. High or low concentrations of exogenous calcium did not achieve the best results in alleviating salt stress in Salix matsudana.

Exogenous calcium: Its mechanisms and research advances involved in plant stress tolerance

“…(2021) found that exogenous Ca 2+ promoted the function of K + channels and its uptake through the root plasma membrane, reduced the permeability of the plasma membrane for Na + pumping so to decrease the accumulation of passive Na + inward flow. Li et al. (2022a) indicated that the exogenous Ca 2+ treatment could increase the maximum photochemical efficiency (Fv/Fm) under salt stress in Mongolian pines and 10 mM exogenous Ca 2+ could promote the growth of Salix matsudana Koidz seedlings and increase their stomatal conductance, transpiration rate (Tr) and net photosynthetic rate.…”

“…Ca 2+ plays an important role in plant stomatal regulation as the second messenger in coupled with external signals in plant cells. Appropriate amount of Ca 2+ can make plants adapt to abiotic stresses such as drought and salinity quickly by adjusting their stomatal opening/closing, optimizing their gas exchange, and improving their photosynthetic efficiency ( Li et al., 2012 ; Li et al., 2022a ). These plant adjustments and adaptations by using exogenous Ca 2+ could be achieved through reshape, rearrangement and configuration of stomata during their differentiation and development for more efficient of gas exchange and water utilization ( Zhang et al., 2019a ).…”

“…Guo et al (2021) found that exogenous Ca 2+ promoted the function of K + channels and its uptake through the root plasma membrane, reduced the permeability of the plasma membrane for Na + pumping so to decrease the accumulation of passive Na + inward flow. Li et al (2022a) indicated that the exogenous Ca 2+ treatment could increase the maximum photochemical efficiency (Fv/Fm) under salt stress in Mongolian pines and 10 mM exogenous Ca 2+ could promote the growth of Salix matsudana Koidz seedlings and increase their stomatal conductance, transpiration rate (Tr) and net photosynthetic rate. Li et al (2022c) also showed that exogenous Ca 2+ significantly upregulated genes encoding phospholipase C, inositol-3-phosphate synthase, and phosphatidylserine decarboxylase to stabilize cell membranes, up-regulated the expression of PsbQ, PsbP, and Psb28 subunits on encoded PSII, and protected PSII to increase photosynthetic rate of Pennisetum Giganteum, revealing the connections between the gene regulation and biochemical metablisms.…”

“…Exogenous Ca 2+ have also proven to regulate the ABA content in plants under low temperature along with the hormone levels of gibberellic acid (GA), cytokinin (CTK), and indole-3-acetic acid (IAA) to maintain a balance ( Liu et al., 2017 ). In addition, the degradation of plant chlorophylls, the damage to photosynthetic organs, and the stable performance of plant photosynthesis could be alleviated or prevented by exogenous Ca 2+ , which was demonstrated through using a portable chlorophyll fluorescence pulsometer ( Li et al., 2022a ). According to Gong and Wang (2011) the mode of actions with each exogenous calcium applied to alleviate plant stresses has much in common with the mechanism involving in plant responses to abiotic adversities, which is mainly through regulating ion balance, inducing expression of resistance genes and/or proteins, and increasing the enzyme activity and osmoregulatory substance content.…”

Iris typhifolia Responses to Saline–Alkali Stress: Germination, Antioxidant Activity, Hormones, and Photosynthetic Performance

“…Excessive use of snowmelting agents results in a rise in pH levels and the accumulation of toxic concentrations in plant tissues, which can lead to saline-alkali stress and an increased osmotic pressure [3]. This factor has a negative impact on the seed germination and photosynthetic response of plants [4]. In order to enhance the promotion of saline-alkali tolerance cultivars, it is crucial to investigate the mechanisms of plant germination and physiological response under saline-alkali stress.…”