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γ-Aminobutyric acid (GABA) has high physiological activity in plant stress physiology. This study showed that the application of exogenous GABA by root drenching to moderately (MS, 150 mM salt concentration) and severely salt-stressed (SS, 300 mM salt concentration) plants significantly increased endogenous GABA concentration and improved maize seedling growth but decreased glutamate decarboxylase (GAD) activity compared with non-treated ones. Exogenous GABA alleviated damage to membranes, increased in proline and soluble sugar content in leaves, and reduced water loss. After the application of GABA, maize seedling leaves suffered less oxidative damage in terms of superoxide anion (O2·−) and malondialdehyde (MDA) content. GABA-treated MS and SS maize seedlings showed increased enzymatic antioxidant activity compared with that of untreated controls, and GABA-treated MS maize seedlings had a greater increase in enzymatic antioxidant activity than SS maize seedlings. Salt stress severely damaged cell function and inhibited photosynthesis, especially in SS maize seedlings. Exogenous GABA application could reduce the accumulation of harmful substances, help maintain cell morphology, and improve the function of cells during salt stress. These effects could reduce the damage to the photosynthetic system from salt stress and improve photosynthesis and chlorophyll fluorescence parameters. GABA enhanced the salt tolerance of maize seedlings.

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Background: Studies have shown that permissive hypotension for uncontrolled hemorrhagic shock can result in good resuscitation outcome. The ideal target mean arterial pressure (MAP) and the tolerance time for permissive hypotension have not been determined. Methods: To elucidate the ideal target MAP and tolerance time for permissive hypotension with uncontrolled hemorrhagic shock rats, the effects of different target MAPs (40, 50, 60, 70, 80, and 100 mmHg) and 60-, 90-, and 120-min permissive hypotension (50 mmHg) on uncontrolled hemorrhagic shock were observed. Results: Rats in normotensive groups (80 and 100 mmHg) had increased blood loss (101%, 126% of total blood volume), decreased hematocrit, decreased vital organ (liver and kidney) and mitochondrial function, and decreased animal survival rate (1 of 10). Rats in the 50-and 60-mmHg target MAP groups had decreased blood loss (52% and 69%, respectively), good hematocrit and vital organ and mitochondrial function, stable hemodynamics, and increased animal survival (8 of 10 and 6 of 10, respectively). Rats in the 40-mmHg target MAP group, although having decreased blood loss (39%), appeared to have very inferior organ function and animal survival (2 of 10). Animal survival (1 of 10) and vital

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DCPTA (2-diethylaminoethyl-3, 4-dichlorophenylether) and CCC (2-chloroethyltrimethyl- ammonium chloride) have a great effect on maize growth, but applying DCPTA individually can promote the increase of plant height, resulting in the rise of lodging percent. Plant height and lodging percent decrease in CCC-treated plants, but the accumulation of biomass reduce, resulting in yield decrease. Based on the former experiments, the performance of a mixture which contained 40 mg DCPTA and 20 mg CCC as active ingredients per liter of solution, called PCH was tested with applying 40mg/L DCPTA and 20mg/L CCC individually. Grain yield, yield components, internode characters, leaf area per plant, plant height and lodging percent as well as chlorophyll content, chlorophyll fluorescence, enzymatic antioxidants, membranous peroxide and organic osmolyte were analyzed in two years (2011 and 2012), using maize hybrid, Zhengdan 958 (ZD 958) at density of 6.75 plants m-2. CCC, DCPTA and PCH were sprayed on the whole plant leaves at 7 expanded leaves stage and water was used as control. Compared to control, PCH significantly increased grain yield (by 9.53% and 6.68%) from 2011 to 2012. CCC significantly decreased kernel number per ear (by 6.78% and 5.69%) and thousand kernel weight (TKW) (by 8.57% and 6.55%) from 2011 to 2012. Kernel number per ear and TKW increased in DCPTA-treated and PCH-treated plants, but showed no significant difference between them. In CCC-treated and PCH-treated plants, internode length and plant height decreased, internode diameter increased, resulting in the significant decline of lodging percent. With DCPTA application, internode diameter increased, but internode length and plant height increased at the same time, resulting in the augment of lodging percent. Bending strength and puncture strength were increased by applying different plant growth regulators (PGRs). In PCH-treated plants, bending strength and puncture strength were greater than other treatments. Compared to control, the bending strength of 3rd internode was increased by 14.47% in PCH-treated plants in 2011, increased by 18.40% in 2012, and the difference was significant. Puncture strength of 1st, 3rd and 5th internode was increased by 37.25%, 29.17% and 26.09% in 2011 and 34.04%, 25% and 23.68% in 2012, compared to control. Leaf area and dry weight per plant reduced significantly in CCC-treated plants, increased in DCPTA-treated and PCH-treated plants from 2011 to 2012. Chlorophyll content and chlorophyll fluorescence improved with CCC and DCPTA application. Due to the additive effect of DCPTA and CCC, PCH showed the significant effect on chlorophyll content and chlorophyll fluorescence. Compared to control, total enzyme activity (SOD, POD, CAT, APX and GR) and soluble protein content increased, malonaldehyde (MDA) and hydrogen peroxide (H2O2) content reduced in PCH-treated plants. The transportation of soluble sugar from leaf to kernel improved significantly at the late silking stage. The research provided the way for the further use of DCPT...

Previous reports have indicated that 2-(3,4-dichlorophenoxy)triethylamine (DCPTA) can promote the growth and photosynthetic capacity of plants. However, only a small number of these studies have focused on crops, and few reports have focused on whether DCPTA affects stress tolerance. In this study, maize (Zea mays L.) seedlings were pretreated with or without DCPTA and then exposed to drought stress in a controlled growth room for 7 days, and the growth and photosynthesis indexes of the seedlings were investigated. The DCPTA treatment partly counteracted the observed decreases in biomass, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), effective photochemical efficiency of photosystem II (ΦPSII), maximum photochemical efficiency of PSII (Fv/Fm), non-photochemical quenching (NPQ), and photosynthetic pigment content and increased the minimal fluorescence (Fo) induced by drought stress. The DCPTA treatment also alleviated the damage induced by drought stress in the photosynthetic apparatus. In addition, DCPTA pretreatment simultaneously increased the root size (e.g., the length, surface area, and volume) and root hydraulic conductivity, which promoted the maintenance of higher relative leaf water contents (RLWCs) under stress conditions. These results indicate that exogenous DCPTA ameliorates simulated drought conditions by improving the growth and photosynthetic capacity of maize seedlings.