Morphological and physiological responses and plasticity in Robinia pseudoacacia to the coupling of water, nitrogen and phosphorus

Abstract

Background: Under the background of drought and nitrogen deposition, global climate change is changing the supply of resources and environmental conditions that are crucial to plant growth, and plants respond to climate change by environmentally induced phenotypic changes. Aims: The objective of this study was to assess the differences in the plasticity responses of the morphological, photosynthetic, fluorescence and antioxidant parameters of Robinia pseudoacacia seedlings under water, nitrogen and phosphorus interaction conditions. Methods: We analyzed the above parameters of R. pseudoacacia seedlings using methods of morphological measurements, gas exchanges, fluorescence emission and antioxidant assays under two water levels (75% and 55% of field capacity), four nitrogen levels (no urea; 0.2 g kg−1, 0.4 g kg−1, 0.8 g kg−1), and two phosphorus levels (no superphosphate, 0.6 g kg−1). Results: The results showed that drought stress significantly reduced the morphological parameters, actual photochemical efficiency of photosystem II (ΦPSII), superoxide dismutase (SOD) activity, peroxidase (POD) activity and catalase (CAT) activity of R. pseudoacacia seedlings, and significantly increased nonphotochemical quenching (NPQ) and the malondialdehyde (MDA) content. Excessive application of nitrogen (N) fertilizer inhibited plant growth, and phosphorus (P) deficiency significantly weakened the positive effect of the high nitrogen treatment on morphological parameters under drought stress. The high nitrogen treatment effectively weakened the inhibitory effect of drought and phosphorus deficiency on chlorophyll formation. Proper N and P fertilizers increased the SOD, POD and CAT activities and decreased the MDA content under drought stress. The mean plasticity index of POD and CAT activities in response to water, nitrogen and phosphorus was the highest, which indicated that R. pseudoacacia seedlings can adapt to changes in water and nutrients mainly by adjusting their POD and CAT activities. Conclusions: These results may explain the better survival of R. pseudoacacia under the condition of limited water and nutrient resources, which is helpful for understanding the response mechanism of R. pseudoacacia to changes in environmental factors in the future. The results also provide scientific data and a theoretical basis for vegetation restoration and sustainable development of the regional ecological environment.

Physiological responses of black locust‐rhizobia symbiosis to water stress

“…In this context, plants grown in the shade partition relatively more nitrogen into the thylakoids, despite lower photosynthetic capacity per unit of nitrogen (Evans, 1989). Similar leaf P n as observed in the present study (<10 μmol m −2 s −1 ) were previously reported when Robinia plants were exposed to drought and nutrient deficiency (He et al, 2016; Su et al, 2021). Furthermore, specific relationship within gas exchange parameters of Robinia plants, for example, between P n and G s , C i , and intrinsic water use efficiency (WUEi) under drought stress, needs to be elucidated in future studies.…”

“…Increased ROS production will damage proteins, lipids, carbohydrates and DNA, and finally will result in the interruption of cellular homeostasis and, consequently, in cellular death (Ibrahim et al, 2019). In this context, the effect of drought on ROS generation is indicated by increased contents of malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2 ) (Su et al, 2021). Reduced carbon (C) assimilation and allocation will also impair the synthesis of defense compounds (antioxidants, phenolics) and osmolytes (carbohydrates, amino acids) (Ciais et al, 2005; Leuschner et al, 2001; Liu et al, 2013; Netzer et al, 2016), thereby enhancing the susceptibility to other abiotic and biotic stresses.…”

Nitrogen improves the recovery of maize plants under repeated drought stress

“…In maize seedlings under drought, additional nitrogen caused a higher accumulation of chlorophyll a and b and photosynthetic capacity in the leaves (Song et al, 2019). In agreement with the latter, studies across other species and developmental stages support the relationship between chlorophyll and photosynthetic activity under drought stress (e.g., Ahmad et al, 2014;Su et al, 2021;Tariq et al, 2019). Therefore, although no photosynthetic parameters were determined in this study, higher levels of chlorophyll in plants under repeated WDS may have positively impacted plants' photosynthetic performance, thus contributing to the improvement of the plant recovery after the L-WDS.…”

Plant Growth-Promoting Rhizobacteria Improve Growth and Fruit Quality of Cucumber under Greenhouse Conditions

“…It has been reported that in the cultivation of Capsicum annuum, the number of flavonoids increases when the plant is inoculated with P. putida because it uses quercetin and kaempferol catabolizing them as a carbon source [34], moreover, it has been observed that S. meliloti responds to the synthesis of proteins, mainly the Nod protein, excreting flavonoids [35]. Furthermore, if the antioxidant capacity is in dynamic equilibrium under normal growth conditions, it implies the decrease of enzymatic activity which results in the elimination of reactive oxygen, however, membrane lipid peroxidation is induced [29], and this could explain the increase of antioxidant capacity in the fruit of C. sativus in our results.…”

“…It has been suggested that the modification of the root structure of a cucumber plant is related to the phytohormone indoleacetic acid (IAA) produced by S. meliloti, A. radioresistens, and P. paralactis [11,14,27]. In addition, it has been reported that S. meliloti and A. radioresistens possess the ability to fix nitrogen and solubilize phosphate, resulting in an increase on the number of late-stage roots and root hairs, since these elements are essential for the plant to increase photosynthetic pigments and proteins, which improves photosynthetic activity and rate, having a positive effect on plant development and a greater accumulation of biomass [28,29]. Furthermore, it has been pointed out that IAA is associated with cell division and differentiation, which improves the structure of the root system [30][31][32].…”