Low nitrogen level improves low-light tolerance in tall fescue by regulating carbon and nitrogen metabolism

Long

et al. 2022

IJMS

Self Cite

Paclobutrazol (PBZ) is a plant-growth regulator (PGR) in the triazole family that enhances plant tolerance to environmental stresses. Low-light (LL) intensity is a critical factor adversely affecting the growth of tall fescue (Festuca arundinacea Schreb.). Therefore, in this study, tall fescue seedlings were treated with PBZ under control and LL conditions to investigate the effects of PBZ on enhancing LL stress resistance by regulating the growth, photosynthesis, oxidative defense, and hormone levels. Our results reveal that LL stress reduced the total biomass, chlorophyll (Chl) content, photosynthetic capacity, and photochemical efficiency of photosystem II (PSII) but increased the membrane lipid peroxidation level and reactive oxygen species (ROS) generation. However, the application of PBZ increased the photosynthetic pigment contents, net photosynthetic rate (Pn), maximum quantum yield of PSII photochemistry (Fv/Fm), ribulose-1,5-bisphosphate carboxylase (RuBisCO) activity, and starch content. In addition, PBZ treatment activated the antioxidant enzyme activities, antioxidants contents, ascorbate acid-glutathione (AsA-GSH) cycle, and related gene expression, lessening the ROS burst (H2O2 and O2∙−). However, the gibberellic acid (GA) anabolism was remarkably decreased by PBZ treatment under LL stress, downregulating the transcript levels of kaurene oxidase (KO), kaurenoic acid oxidase (KAO), and GA 20-oxidases (GA20ox). At the same time, PBZ treatment up-regulated 9-cis-epoxycarotenoid dioxygenase (NCED) gene expression, significantly increasing the endogenous abscisic acid (ABA) concentration under LL stress. Thus, our study revealed that PBZ improves the antioxidation and photosynthetic capacity, meanwhile increasing the ABA concentration and decreasing GA concentration, which ultimately enhances the LL stress tolerance in tall fescue.

Section: Discussionmentioning

confidence: 99%

Paclobutrazol Ameliorates Low-Light-Induced Damage by Improving Photosynthesis, Antioxidant Defense System, and Regulating Hormone Levels in Tall Fescue

Long

et al. 2022

IJMS

Self Cite

“…Wen et al . [ 21 ] found that reducing N supply enhanced the citric acid cycle, increased the content of glucose and sucrose, and thus improved the low light tolerance of tall fescue. Dziedek et al .…”

Section: Introductionmentioning

confidence: 99%

Nitrogen–potassium balance improves leaf photosynthetic capacity by regulating leaf nitrogen allocation in apple

Xu,

Zhang,

et al. 2023

Horticulture Research

Nitrogen (N) and potassium (K) are two important mineral nutrients in regulating leaf photosynthesis. However, the influence of N and K interaction on photosynthesis is still not fully understood. Using a hydroponics approach, we studied the effects of different N and K conditions on the physiological characteristics, N allocation and photosynthetic capacity of apple rootstock M9T337. The results showed that high N and low K conditions significantly reduced K content in roots and leaves, resulting in N/K imbalance, and allocated more N in leaves to non-photosynthetic N. Low K conditions increased biochemical limitation (BL), mesophyll limitation (MCL), and stomatal limitation (SL). By setting different N supplies, lowering N levels under low K conditions increased the proportion of water-soluble protein N (Nw) and sodium dodecyl sulfate-soluble proteins (Ns) by balancing N/K and increased the proportion of carboxylation N and electron transfer N. This increased the maximum carboxylation rate and mesophyll conductance, which reduced MCL and BL and alleviated the low K limitation of photosynthesis in apple rootstocks. In general, our results provide new insights into the regulation of photosynthetic capacity by N/K balance, which is conducive to the coordinated supply of N and K nutrients.

J. Plant Nutr. Soil Sci.

“…Therefore, the appropriate modulation of light intensity can enhance the photosynthetic rate and the efficiency of nitrogen assimilation in plants, thereby exerting a subsequent impact on amino acid synthesis and quality (Hu et al., 2021). In the case of Festuca arundinacea , the activities of NR, as well as the levels of ammonia and free amino acids, were profoundly influenced by light intensity (Wen et al., 2022). Specifically, under conditions of a light intensity of 40 µmol m −2 s −1 , these parameters were significantly lower compared to those observed under a light intensity of 200 µmol m −2 s −1 while maintaining the same nitrogen level.…”

Section: Introductionmentioning

confidence: 99%

Enhancing growth, quality, and metabolism of nitrogen of alfalfa (Medicago sativa L.) by high red–blue light intensity

Chen,

Liu,

Liu

2023

BackgroundIn countries characterized by limited per capita arable land and grassland, agricultural development is hindered by insufficient forage productivity. The plant factory with artificial light (PFAL) system has emerged as a highly efficient approach to address this challenge by cultivating forage on finite land resources. In the PFAL framework, the regulation of light intensity plays a critical role in determining both the yield and quality of cultivated plants.AimsThis study seeks to delve into the optimal range of light intensity for achieving high efficiency and quality in the production of alfalfa in the PFAL. Additionally, it seeks to explore the effects of light intensity on nitrogen metabolism, as well as the accumulation and metabolism of amino acid in alfalfa.MethodsTo achieve these objectives, alfalfa was sown and subjected to five treatments involving red and blue LED light in a 4:1 ratio. The light intensities used were 200, 300, 400, 500, and 600 µmol m–2 s−1, respectively. The alfalfa plants were then harvested at intervals of 15, 20, 25, 30, and 35 days. The quality and nitrogen metabolisms of alfalfa during this period were assessed by evaluating the plant's growth performance and determining the optimal cutting time.ConclusionIn summary, high‐light intensity (400–600 µmol m−2 s−1) improved alfalfa yield and quality, while also promoting nitrogen and amino acid metabolism. Photon flux density at 400–500 µmol m−2 s−1 light intensity for a duration of 30 days was identified as the optimal condition for PFAL alfalfa production.