scholarly journals Fractal and Topological Analyses and Antioxidant Defense Systems of Alfalfa (Medicago sativa L.) Root System under Drought and Rehydration Regimes

Agronomy ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 805 ◽  
Author(s):  
Shuo Li ◽  
Liqiang Wan ◽  
Zhongnan Nie ◽  
Xianglin Li
Keyword(s):  
Soil Moisture ◽  
Medicago Sativa ◽  
Antioxidant Defense ◽  
Root Systems ◽  
Water Holding Capacity ◽  
Defense Systems ◽  
Antioxidant Defense Systems ◽  
Medicago Sativa L ◽  
Moisture Conditions ◽  
Water Holding

Alfalfa (Medicago sativa L.) is a nutritious forage plant in dryland regions with strong drought tolerance and broad adaptability. To understand the architectural characters and physiological functions of the root systems in response to different drought stress and rehydration, two experiments were conducted in a glasshouse. Experiment 1 used three alfalfa cultivars and four soil moisture treatments in a split-plot design with four replicates to investigate the response of root systems of different alfalfa cultivars to drought stress and subsequent rehydration. Experiment 2 used one alfalfa cultivar and four soil moisture treatments in a randomized complete block (RCB) design with three replicates to measure reactive oxidant species and antioxidant defense systems of alfalfa root. The soil moisture treatments included (1) 75–80% of the water-holding capacity (CK); (2) 60–65% of the water-holding capacity and subsequent rehydration to 75–80% of the water-holding capacity; (3) 45–50% of the water-holding capacity and subsequent rehydration to 60–65% and 75–80% of the water-holding capacity; and (4) 30–35% of the water-holding capacity and subsequent rehydration to 45–50%, 60–65% and 75–80% of the water-holding capacity. Our results demonstrated that plants had higher root biomasses (mean = 0.77 g), fractal dimensions (1.47), fractal abundances (3.84), and branching ratios (0.39) under severe water deficit and rehydration than under less stressful soil moisture conditions. Plant root systems tended to exhibit herringbone branching (Topological Index = 0.63) when soil moisture was at 60–65% water-holding capacity with the soil being then rehydrated, whereas they tended to have a smaller lateral root length, root surface area, root volume, and branching ratio and larger root diameter under more favorable soil moisture conditions for less stressful soil moisture treatments. Severe water stress and subsequent considerably improved superoxide (O2−) generation rate, the content of hydrogen peroxide (H2O2) and Malondialdehyde (MDA), and non-enzyme antioxidant glutathione (GSH), and reduced the content of ascorbate (AsA) and activity of catalase (CAT), ascorbate peroxidase (APX), and glutathione peroxidase (GPX). It is concluded that Medicago sativa L. cv Zhaodong (ZD) and cv Aohan (AH) exhibited higher drought resistances than cv Golden empress (GE) using topological and fractal analyses. This could be a key contributor to altering optimum soil moisture conditions and screening alfalfa cultivars based on root system architecture and antioxidant defense systems. The molecular functions warrant further investigation which could help explain the observed root phenotypes after drought conditions and rehydration.

scholarly journals Influence of drought on the photosynthetic apparatus activity, senescence rate, and productivity in wheat plants

2020 ◽  
Vol 52 (5) ◽  
pp. 371-387
Author(s):  
O.O. Stasik ◽  
Keyword(s):  
Soil Moisture ◽  
Antioxidant Defense ◽  
Flag Leaf ◽  
Photosynthetic Apparatus ◽  
Co2 Assimilation ◽  
Drought Period ◽  
Defense Systems ◽  
Drought Tolerant ◽  
Grain Productivity ◽  
Antioxidant Defense Systems

Effects of soil drought at flowering stage on the functional state of photosynthetic apparatus and chloroplast enzymatic antioxidant defense systems in flag leaf during reproductive period, and the productivity of winter wheat plants of high-protein Natalka variety and drought-tolerant Podolyanka variety were studied in pot experiment. Until flowering and for the control plants during the entire vegetation, the soil moisture content was maintained at a level of 60—70 % of field capacity (FC). Drought treatment (soil moisture 30 % FC) was applied for 7 days covering flowering—early kernel watery ripe period (BBCH 61—71). After that, watering of plants was resumed to a control level which was maintained until the end of the growing season. The estimation of the chlorophyll and Rubisco content, the chloroplast antioxidant enzymes activity, and the net CO2 assimilation and transpiration rates was carried out on flag leaves. The measurements were taken on the third day of watering cessation (the first day the soil moisture reached 30 % FC, BBCH 61), at the end of the drought period (seventh day at 30 % FC, BBCH 71), and after watering resumed at the medium milk (BBCH 75) and late milk (BBCH 77) stages. The components of plant grain productivity were determined by weighing air-dry material at grain full ripeness. It was revealed, that drought stress during flowering inhibited CO2 assimilation and accelerated induction of senescence processes in wheat plants associated with degradation of photosynthetic apparatus and manifested in quicker ontogenetic drop in chlorophyll and Rubisco contents and loss of leaf photosynthetic activity. This exacerbated the drought impact on the plant organism so that after optimal watering return, the physiological and biochemical parameters were not restored to the values of control plants that were all time under optimal moisture supply. Stress-induced premature senescence reduced the supply of plants with assimilates and ultimately led to a decrease in their grain productivity. Impact of drought on flag leaf photosynthetic activity and especially on senescence induction were much more pronounced in the high-protein wheat variety Natalka with a genetically programmed earlier start of the nitrogen-containing compounds remobilization from leaves than in Podolyanka variety. The drought-tolerant variety Podolyanka keep ability to maintain much higher CO2 assimilation activity during drought period and to preserve photosynthetic apparatus from early induction of senescence due to likely more efficient chloroplast antioxidant defense systems, thereby gaining a better assimilates supply for yield formation.

scholarly journals EFFECTS OF COMPACTION ON SUBSTRATE CO2 IN A SUBIRRIGATION SYSTEM

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 718A-718
Author(s):  
Noreen S. Khoury ◽  
E. Jay Holcomb
Keyword(s):  
Soil Moisture ◽  
Water Holding Capacity ◽  
Rooted Cuttings ◽  
Air Samples ◽  
Dry Soil ◽  
Moisture Conditions ◽  
Gas Tight ◽  
Water Holding

Greenhouse substrates are designed to allow maximum aeration. Substrate water holding capacity can be increased by media compaction. Six inch standard pots, fitted with gas tight openings for removing gas samples, were filled with Metromix 350 and Peatwool at 2 different compaction rates. Half the pots were planted with rooted cuttings of Poinsettia pulcherrima `Glory' and half were left fallow. Air samples were taken at both wet and dry soil moisture conditions at early, mid point and at the end of the cropping cycle. In general, wet substrates had higher CO2 than drier substrates and more compacted substrates had higher CO2 than less compacted. CO2 decreased with time in all treatments. The highest CO2 levels occurred in wet heavily compacted Peatwool with a plant and the lowest occurred in dry Metromix with no plant.

Antioxidant Defense Systems

2021 ◽  
pp. 94-143
Author(s):  
Carmen Cecilia Espíndola Díaz
Keyword(s):  
Antioxidant Defense ◽  
Defense Systems ◽  
Antioxidant Defense Systems

scholarly journals The Role of Oxidative Stress in Cardiac Disease: From Physiological Response to Injury Factor

2020 ◽  
Vol 2020 ◽  
pp. 1-29 ◽  
Author(s):  
Rossella D’Oria ◽  
Rossella Schipani ◽  
Anna Leonardini ◽  
Annalisa Natalicchio ◽  
Sebastio Perrini ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Myocardial Injury ◽  
Antioxidant Defense ◽  
Experimental Studies ◽  
Chemical Species ◽  
Oxygen Species ◽  
Molecular Abnormalities ◽  
Defense Systems ◽  
Antioxidant Defense Systems

Reactive oxygen species (ROS) are highly reactive chemical species containing oxygen, controlled by both enzymatic and nonenzymatic antioxidant defense systems. In the heart, ROS play an important role in cell homeostasis, by modulating cell proliferation, differentiation, and excitation-contraction coupling. Oxidative stress occurs when ROS production exceeds the buffering capacity of the antioxidant defense systems, leading to cellular and molecular abnormalities, ultimately resulting in cardiac dysfunction. In this review, we will discuss the physiological sources of ROS in the heart, the mechanisms of oxidative stress-related myocardial injury, and the implications of experimental studies and clinical trials with antioxidant therapies in cardiovascular diseases.

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