[Effects and Mechanisms of Polystyrene Microplastics on Extracellular Antibiotic Resistance Genes in Wastewater].

Microplastics (MPs) and antibiotic resistance genes (ARGs) are typical co-existing emerging pollutants in wastewater treatment plants. MPs have been shown to alter the distribution pattern of ARGs in sludge, but their effects on free extracellular ARGs (feARGs) in wastewater remain unclear. In this study, we used fluorescence quantitative PCR to investigate the dynamics of feARGs (including tetC, tetO, sul1, and sul2) in wastewater and their transition mechanisms after 60 d of exposure to typical MPs (polystyrene, PS). The results showed that the absolute abundance of tetracycline feARGs decreased by 28.4 %-76.0 % and 35.2 %-96.2 %, respectively, under nm-level and mm-level PS exposure and changed by -55.4 %-122.4 % under µm-level PS exposure. The abundance of sul1 showed a trend of nm-level > µm-level > mm-level upon PS exposure, and the changes in sul1 abundance was greater with ρ(PS)=50 mg·L-1 exposure. The relative abundance of sul2 was reduced by 25.4 %-42.6 % and 46.1 %-90.3 % after µm-level and mm-level PS exposure, respectively, and increased by 1.9-3.9 times after nm-level PS exposure, and the sul2 showed a higher reduction at ρ (PS)=50 mg·L-1 exposure than that at ρ (PS)=0.5 mg·L-1. The Pearson correlation analysis showed that the relative abundance of feARGs during PS exposure was positively correlated with cell membrane permeability and typical mobile genetic elements (intI1) abundance and negatively correlated with reactive oxygen species level. Our findings elucidated the effects and corresponding mechanisms of PS on the growth and mobility of feARGs in wastewater, providing a scientific basis for the control of the combined MPs and ARGs pollution in wastewater.

Effects of microbial agents and corn protein ferment on physiological characteristics in leaves and yield of tomato.

Premature senescence in greenhouse tomato is a significant challenge under long-season cultivation, due to suboptimal nutrient management during growth periods. We investigated the effects of microbial agents (T1), corn protein ferment (T2), and their combined application (T3) on photosynthetic characteristics and antioxidant enzyme activities in 'Saint Laurent 3689' tomato leaves, normal management served as the control (CK). We explored the physiological mechanism of delaying leaf senescence. Results showed that applying microbial agents or corn protein ferment individually led to improvements in leaf photosynthetic characteristics and antioxidant enzyme activities. The combined application yielded superior outcomes. Eighty days post the combined application of microbial agents and corn protein ferment (T3), chlorophyll (a+b) content, net photosynthetic rate, and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in leaves increased by 16.4%, 30.9%, 23.4%, 33.0% and 40.3%, respectively, compared with the CK. Furthermore, plant height and stem diameter increased by 8.2% and 7.0%, while the total yield exhibited a significant increase of 9.9% compared with the CK 210 days post-treatment. In conclusion, the combined application of microbial agents and corn protein ferment has promising potential in enhancing chlorophyll content, net photosynthetic rate, and the activities of SOD, POD and CAT in tomato leaves. This approach effectively delayed leaf senescence, thereby promoting tomato growth and remarkably increasing the yield.

Effects of drip irrigation frequency on the yield and nutrient utilization efficiency of tomato under long-season cultivation in solar greenhouse.

To improve the utilization efficiency of nutrients and water and determine the best drip irrigation frequency for long-season tomato cultivation in solar greenhouses, we cultivated tomato grafted seedlings in soil using an integrated water and fertilizer technology: drip irrigation under mulch. Seedlings drip-irrigated with balanced fertilizer (containing 20% N, 20% P2O5, and 20% K2O) and high-K fertilizer (containing 17% N, 8% P2O5, and 30% K2O) once every 12 days were set as control (CK) and that with water once every 12 days as CK1, while other seedling groups, drip-irrigated with a nutrient solution of Yamazaki (1978) formula for tomato, were set as treatments (T1-T4). There were four drip-irrigation frequencies, i.e., once every 2 days (T1), 4 days (T2), 6 days (T3), or 12 days (T4), who received the same total amounts of fertilizer and water over the 12 experimental days. The results showed that, with the decreases of drip irrigation frequency, tomato yield, the accumulation of N, P and K in plant dry matter, the fertilizer partial productivity, and the nutrient utilization rate first increased and then decreased, peaking at the T2 treatment. Compared with CK, under the T2 treatment, plant dry matter accumulation and the accumulation of N, P and K increased by 4.9%, 8.0%, 8.0%, 16.8%, the partial productivity of fertilizer and the utilization efficiency of water increased by 142.8% and 12.2%, the use efficiency of N, P and K was better than CK by 241.4%, 466.6% and 235.9%, respectively, and the tomato yield increased by 12.2%. Under the experimental conditions, drip irrigation with the Yamazaki nutrient solution at a frequency of 4 days could increase the tomato yield, as well as the use efficiency of nutrients and water. Under long-season cultivation, these trends would result in considerable saving of water and fertilizer. Overall, our findings provided a basis for improving the scientific management of water and fertilizers under long-season tomato cultivation in protected facilities.

Optimization of constructed wetlands on purifying black-odorous water and their potential purification mechanism.

Black-odorous water has become a common and widespread problem in recent decades. In this study, nine constructed wetlands (CWs) with different flow types, filters, plants, and hydraulic loadings were designed according to an orthogonal array (L9 (34), and were used for the purification of black-odorous water in summer and winter. The results showed that CWs are regarded as effective to purify black-odorous water in both seasons. Microbial degradation is the major removal pathway of pollutants in CWs during summer, while the joint effect of biodegradation and adsorption is the main treatment route during winter. Flow type and hydraulic loading appear to be the most important factors impacting the purification performance of CWs, by changing the redox condition of systems and retention time of contaminants, respectively. 'Vertical flow-zeolite filter-high loading' is proposed as the best parameter selection for CWs on the purification of black-odorous water: among them, CWs with vertical flow have better oxygen transport capacity that is conductive to aerobic processes of pollutants, zeolite substrates may adsorb more nitrogen via ion exchange, higher hydraulic loadings can extend the contact time between contaminants and filters, and regulate the water temperature for microbial activity.

Longitudinal pattern of resource utilization by aquatic consumers along a disturbed subtropical urban river: Estimating the relative contribution of resources with stable isotope analysis.

The utilization of food resources by aquatic consumers reflects the structure and functioning of river food webs. In lotic water systems, where food availability and predator-prey relationships vary with gradient changes in physical conditions, understanding diet assimilation by local communities is important for ecosystem conservation. In the subtropical Liuxi River, southern China, the relative contribution of basal resources to the diet assimilation of functional feeding groups (FFGs) was determined by stable carbon (13C) and nitrogen (15N) isotope analyses. The output of Bayesian mixing models showed that diatom-dominated periphyton (epilithic biofilm), aquatic C3 plants (submerged hydrophytes), and suspended particulate organic matter (SPOM) associated with terrestrial C3 plants contributed the most to the diet assimilation of FFGs in the upper, middle, and lower reaches, respectively. The relative contribution of consumer diet assimilation was weighted by the biomass (wet weight, g/m2) of each FFG to reflect resource utilization at the assemblage level. From the upper to the lower reaches, the spatial variation in the diet assimilation of fish and invertebrate assemblages could be summarized as a longitudinal decrease in periphyton (from 57%-76% to <3%) and an increase in SPOM (from <7% to 51%-68%) with a notable midstream increase in aquatic C3 plants (23%-48%). These results indicate that instream consumers in the Liuxi River rely more on autochthonous production (e.g., periphyton and submerged hydrophytes) than on terrestrially derived allochthonous matter (e.g., terrestrial plants). The pattern of resource utilization by consumers in the mid-upper Liuxi River is consistent with findings from other open subtropical and neotropical rivers and provides evidence for the riverine productivity model. Our study indicates that protecting inherent producers in rivers (e.g., periphyton and submerged hydrophytes) and restoring their associated habitats (e.g., riffles with cobble substrate) are conducive to aquatic ecosystem management.

Impacts of environmental factors on the food web structure, energy flows, and system attributes along a subtropical urban river in southern China.

Tropical and subtropical rivers are being subjected to multiple stressors from human disturbance (e.g., water pollution and habitat degradation). Understanding the relationship between environmental conditions and the river ecosystem is important for improving river management. We built 14 Ecopath models composed of 28 functional groups (trophic levels [TLs] of 1.0-3.8) along a subtropical urban river to explore the influence of environmental changes on system attributes. From headwaters to downstream, the model outputs showed that the transfer efficiency (TE), energy flow parameters, and ecosystem theory indices exhibited significant (P < 0.05) differences across a longitudinal gradient of disturbance, indicating heterogeneous attributes of local river segments. The high TE values of TLs I, II, and III separated the upper, middle, and lower reaches, respectively, which could be attributed to the shift in dominant consumption flows from upstream 'periphyton - aquatic insects - insectivorous fish' to midstream 'detritus - shrimp - crustaceavorous fish' and to downstream 'phytoplankton - filter-feeding invertebrates/fish'. Structural equation modelling was used to test the causal relationships among environmental variables and demonstrated that abiotic factors directly influenced biomass composition and indirectly influenced trophic networks. Water quality, including dissolved oxygen and flow velocity; habitat characteristics, such as riffles, cobble-gravel substrate, and seasonal floodplain; and biological indicators, including the relative contributions (%) of decapods, insectivorous fish, and insect scrapers to biomass composition, had significant (P < 0.05) positive impacts on system maturity (evaluated by omnivory, connectance, and cycling indices). In the future, it will be possible to evaluate the health of river ecosystems by monitoring representative environmental factors, which could be a cost-effective approach to system-level improvement.

Therapeutic potential of curcumin in diabetic retinopathy (Review).

Diabetic retinopathy (DR) is a type of retinal microangiopathy caused by diabetes mellitus. It has become the leading cause of blindness among working individuals worldwide. DR is becoming increasingly common among younger diabetic patients and there is a need for lifelong treatment. The pathogenic mechanisms of DR are influenced by a number of factors, such as hyperglycemia, hyperlipidemia, inflammatory response and oxidative stress, among others. Currently, the treatment methods for DR mainly include retinal photocoagulation, vitrectomy, or anti­vascular endothelial growth factor (VEGF) therapy. However, these methods have some disadvantages and limitations. Therefore, it is a matter of great interest and urgency to discover drugs that can target the pathogenesis of DR. Since ancient times, traditional Chinese medicine practitioners have accumulated extensive experiences in the use of Chinese herbal medicine for the prevention and treatment of diseases. In the theory of traditional Chinese medicine, curcumin has the effects of promoting blood circulation and relieving pain. A number of studies have also demonstrated that curcumin has multiple biological activities, including exerting anti­apoptotic, anti­inflammatory, antioxidant and antitumor properties. In recent years, studies have also confirmed that curcumin can prevent a variety of diabetic complications, including diabetic nephropathy (DN). However, the preventive and curative effects of curcumin on DR and its mechanisms of action have not yet been fully elucidated. The present review aimed to explore the therapeutic potential of curcumin in diabetes mellitus and DR.

[Effects of combined red, blue and white LED light on the quality of eggplant seedlings and fruit peels.] / LEDçº¢ã€è“ã€ç™½ç»„åˆå ‰å¯¹èŒ„å­å¹¼è‹—è´¨é‡å’Œæžœçš®å“è´¨çš„å½±å“.

The effects of red/blue=3/1 [R/B=3/1(9/3), as control, CK1], white light (W, as control, CK2), and combined light of red, blue and white [R/B/W=3/1/1 (9/3/3), T1; R/B/W=9/3/8, T2; R/B/W=3/1/6 (9/3/18), T3; R/B/W=3/1/16 (9/3/48), T4] on the growth, root development, quality and yield of eggplants were examined to provide theoretical and technical support for intensive and high-efficient light supplement and eggplant seedlings cultivation, using LED to accurately regulate light environment and 'Gailiangdalong' eggplant, based on the previous findings of the benefits of R/B=3/1 to the cultivation of eggplant seedlings. The results showed that R/B/W=9/3/8 treatment significantly increased plant height, stem diameter, seedling index, shoot dry weight, root dry weight, root development, anthocyanins and flavonoids content in eggplant peels and early yield. Root/shoot, total phenolic content in eggplant peels and soluble sugar content in pulps under R/B/W=3/1/1 treatment were significantly higher than those of other treatments. Total leaf area and free amino acid content in pulps were higher under R/B/W=3/1/6 treatment. The soluble protein content in pulps was higher under R/B/W=3/1/16 treatment. In summary, combined LED light of red, blue and white could improve the quality of eggplant seedlings and the yield and quality of eggplant fruits, with R/B/W=9/3/8 treatment being the best one in our study.

Application of high expansion degradable cotton in nasal bleeding model of dog.

BACKGROUND: The discomfort and complications have always been problems for nasal packing materials. This study provided a new nasal packing material called high expansion degradable cotton (HEDC). METHODS: Nasal endoscopic surgery was used to establish a dog model of nasal bleeding, and wound surfaces were filled with Merocel, Nasopore and HEDC, respectively. Intraoperative and postoperative bleeding of 24 h was calculated. We evaluate the absorbability score, adhesion score, infection sore and nasal mucosal epithelium in postoperative 3, 7, 14 and 28 days. HE staining and electron microscopy were used to evaluate the recovery of nasal mucosa. RESULTS: There was no significant difference in nasal bleeding between HEDC, Merocel and Nasopore. Nasal endoscopic examination revealed HEDC absorbability of score, adhesion score, infection score were significantly lower than Merocel and Nasopore. The epithelialization time of HEDC was significantly shorter than that of Merocel and Nasopore. HE staining showed that HEDC and Nasopore could significantly reduce scar hyperplasia on the wound surface. The results of electron microscopy suggested that HEDC could protect the edge cilia of the wound. CONCLUSION: HEDC could be used as new choice for hemostasis after nasal endoscopic surgery, which could reduce nasal epithelialization time, and protect wound edge cilia.

[Optimizing fertilization scheme of N, P2O5 and K2O concentration for eggplant under soilless culture.] / èŒ„å­æ— åœŸæ ½åŸ¹æ°®ç£·é’¾æµ“åº¦ä¼˜åŒ–æ–½è‚¥æ–¹æ¡ˆ.

To get optimal nitrogen (N), phosphorus (P2O5) and potassium (K2O) concentrations range for high quality and yield of eggplant with vermiculite as cultivation substrate, three factors and quadratic saturation D-optimal regression (310) were used to establish a ternary quadratic mathematical model with N, P2O5 and K2O concentrations as independent variables and eggplant yield and quality as objective functions. The results showed that yield and quality of eggplants were significantly influenced by N, P2O5 and K2O concentrations. The yield was most influenced by K2O concentration, and followed by N and then P2O5. The quality was also most influenced by K2O concentration, and followed by P2O5 and then N. There were significant interactive effects of N+P2O5, N+K2O and P2O5+K2O on yield, and significant interaction of N+K2O on eggplant quality. Under lower concentrations, the yield and quality of eggplants enhanced with the increasing N, P2O5 and K2O concentrations. When the nutrient concentrations exceeded a threshold, both yield and quality decreased. According to computer simulations, the yield could reach to 3600 g·plant-1 when the fertilization schemes were N 16.0-20.0 mmol·L-1, P2O5 2.2-2.6 mmol·L-1 and K2O 9.9-12.9 mmol·L-1; the fertilization scheme needed to obtain a comprehensive quality score of higher than 90 were N 18.0-21.1 mmol·L-1, P2O5 1.9-2.6 mmol·L-1 and K2O 10.6-13.3 mmol·L-1. In summary, fertilization scheme of high yield (43.2 kg·plot-1) and high quality(comprehensive score of higher than 90) of eggplants were N 18.0-20.0 mmol·L-1, P2O5 2.2-2.6 mmol·L-1, K2O 10.6-12.9 mmol·L-1, with an appropriate N, P2O5 and K2O proportion of 1:0.13:0.62.

[Effects of exogenous 2,4-epibrassinolide on the growth and redox balance of cucumber seedlings under NaHCO3 stress]. / å¤–æºè¡¨æ²¹èœç´ å† é ¯å¯¹NaHCO3胁迫下黄瓜幼苗生长及氧化还原平衡的影响.

The effects of 0.2 µmol·L-1 exogenous 2,4-epibrassinolide (EBR) on the growth and reactive oxygen species metabolism of cucumber seedlings ('Jinyan 4' cucumber) under salt-alkaline stress (30 mmol·L-1 NaHCO3) were examined by hydroponics method. The results showed that NaHCO3 stress significantly induced production of O2-· and accumulation of H2O2 in leaves and roots, resulting in the increases of MDA content and electrolyte leakage. Under NaHCO3 stress, activities of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, dehydroascorbatereductase, monodehydrodroascorbate reductase, and glutathione reductase as well as contents of ascorbic acid and glutathione were firstly increased and then decreased with progress of stress time. Exogenous EBR application significantly increased the activities of antioxidant enzymes and contents of antioxidants as well as the ratio of AsA/DHA (dehydroascorbic acid) and GSH/GSSG (L-glutathione oxidized) in leaves and roots of cucumber under NaHCO3 stress. Such changes improved the redox hemostasis in plants, reduced the level of reactive oxygen species, and alleviated the membrane lipid peroxidation. Together, they increased the alkaline tolerance of cucumber seedlings.

[Effects of iron deficiency and NO3- stress on tomato seedlings growth and iron absorption under suboptimal temperature]. / äºšé€‚æ¸©æ¡ä»¶ä¸‹ç¼ºé“å’Œç¡é ¸ç›èƒè¿«å¯¹ç•ªèŒ„å¹¼è‹—ç”Ÿé•¿åŠé“å¸æ”¶çš„å½±å“.

The effects of iron deficiency and NO3- stress on the growth and the iron absorption cha-racteristic of tomato seedlings were investigated under suboptimal temperature (18 ℃/12 ℃ (day/night)). The results indicated that the growth was significantly inhibited under suboptimal temperature compared with appropriate temperature treatment; the plant heights, leaf areas and dry matter accumulations were markedly decreased. The effects of iron deficiency under suboptimal temperature on the growth of tomato seedlings were larger than that of under appropriate temperature treatments. Under suboptimal temperature, the plant heights of tomato seedlings in iron deficiency and/or NO3- stress treatments were not significantly different from no stress treatment, but leaf areas and leaf chlorophyll content of tomato seedlings were decreased obviously. The leaf electrolytic leakage, root activity and Fe3+ reductase activity of tomato seedlings were markedly increased under suboptimal temperature, but chlorophyll content, total root length, root surface area, root tip number and root volume were obviously reduced. The iron contents in roots, stems and leaves of tomato seedlings were also remarkably decreased. The NO3- stress and the combined stress of iron deficiency and NO3- stress under suboptimal temperature aggravated the reduction of dry matter, leaf electrolytic leakage and the inhibition of iron ion absorption in tomato seedlings. The iron ion absorption showed the antagonistic impact on the absorption of potassium and calcium ion, but showed different effects among different organs. The iron deficiency symptom of tomato seedlings was aggravated by reducing the concentration of iron ion in the nutrient solution.

[Effects of sodium nitroprusside on growth and physiological characteristics of tomato seedlings under iron deficiency and NO3- stress]. / ç¡æ™®é’ å¯¹ç¼ºé“å’Œç¡é ¸ç›èƒè¿«ä¸‹ç•ªèŒ„å¹¼è‹—ç”Ÿé•¿åŠç”Ÿç†ç‰¹æ€§çš„å½±å“.

The solution culture method was used to study the effects of sodium nitroprusside (SNP) on plant growth, nutrient uptake and antioxidant enzyme activities of tomato seedlings under iron deficiency and NO3- stress. The results indicated that after 7 d of treatment, iron deficiency inhibited the tomato seedling growth, decreased chlorophyll (a and b) and carotenoid contents, and led to obvious chlorosis; iron deficiency also reduced the activity of SOD, POD and CAT, resulting in significant accumulation of MDA contents and higher electrolytic leakage; proline and soluble sugar contents were not significantly changed; contents of N, P, K, Ca, Mg and Fe in both leaves and roots of tomato seedlings were decreased under iron deficiency in varying degrees. The combined stress of NO3- stress and iron deficiency promoted the inhibition of plant growth, decreased chlorophyll (a and b), carotenoid contents and the activities of SOD, POD and CAT; electrolytic leakage MDA, proline and soluble sugar contents of N, P, Mg, Fe in both leaves and roots of tomato seedlings were much lower, but the contents of K and Ca were significantly increased. Compared to the treatment without SNP, adding 0.1 mmol·L-1 SNP could alleviate the growth inhibition of stressed tomato seedlings. Adding 0.1 mmol·L-1 SF (sodium ferrocyanide) also showed alleviating or promoting effect on some above indexes including the activity of SOD, POD and CAT to some degree, but the other physiological indexes were not significantly changed because iron was contained in SF.

[Effects of calcium and ABA on photosynthesis and related enzymes activities in cucumber seedlings under drought stress]. / é’™ä¸Žè„±è½é ¸å¯¹å¹²æ—±èƒè¿«ä¸‹é»„ç“œå¹¼è‹—å ‰åˆåŠç›¸å ³é ¶æ´»æ€§çš„å½±å“.

To investigate the effect of calcium and ABA on photosynthesis and the activities of antioxidant enzymes in cucumber seedlings under drought stress, the cucumber was used as the expe-riment materials, normal nutrient solution culture was considered as the control, and PEG-6000 application in the nutrient solution simulated the drought stress. There were five different treatments which were spraying water, ABA, CaCl2+ABA, LaCl3(calcium channel inhibitor)+ABA and EGTA (calcium ion chelating agent)+ABA under drought stress. The results showed that drought stress inhibited the growth of cucumber seedlings, and reduced the activities of antioxidant enzymes, nitrate reductase, net photosynthetic rate and fluorescence parameters of the cucumber seedlings leaves. The application of ABA reduced the inhibition of activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), photosynthesis (Pn, gs) and the fluorescence parameters (Fv'/Fm', qP and ETR), and decreased the damage of drought stress on plant. Spraying CaCl2+ABAsignificantly promoted the positive effect of ABA, while EGTA+ABA and LaCl3 +ABA didn't show the promoting effect.

[Effect of exogenous melatonin on physiological and biochemical characteristics of cucumber radicles under p-hydroxybenzoic acid.] / å¯¹ç¾ŸåŸºè‹¯ç”²é ¸èƒè¿«ä¸‹è¤ªé»‘ç´ å¯¹é»„ç“œèƒšæ ¹ç”Ÿç†ç”ŸåŒ–ç‰¹æ€§çš„å½±å“.

'Jinyan No. 4'cucumber was used as experimental material. The growth of cucumber radicles treated with different concentrations of p-hydroxybenzoic acid (0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5 and 20 mmol·L-1) was investigated firstly, and 10 mmol·L-1 p-hydroxybenzoic acid was chosen for the further experiment. To investigate if melatonin alleviate p-hydroxybenzoic acid stress on cucumber radical elongation, 0, 1, 10, 25, 50, 75 and 100 µmol·L-1 melatonin were used to pretreat cucumber seeds for 24 h before 10 mmol·L-1 p-hydroxybenzoic acid treatment. The results suggested that exogenous melatonin could alleviate the radicle growth inhibition induced by p-hydroxybenzoic acid, and 75 µmol·L-1 melatonin showed the best effect. The growth of cucumber radical was significantly inhibited with an increase in p-hydroxybenzoic acid concentration, which was accompanied with lower activity of amylase. The melatonin pretreatment could significantly increase the activities of amylase and antioxidant enzymes in cucumber seeds resulting in lower accumulation of O2-·, H2O2 and MDA. Exogenous melatonin effectively reduced the PHBA stress on cucumber germination, which might be due to its function in decreasing oxidative stress and promoting starch catabolism.

[Effects of purified humic acid on growth and nutrient absorption of cucumber (Cucumis sativus)seedlings under low nitrogen stress.] / çº¯åŒ–è æ¤é ¸å¯¹ä½Žæ°®èƒè¿«ä¸‹é»„ç“œå¹¼è‹—ç”Ÿé•¿åŠå »åˆ†å¸æ”¶çš„å½±å“.

Taking 'Xintaimici' and 'Jinyou 1' as experimental cucumber cultivars, this paper studied the effects of watering purified humic acid (PHA) at different levels (0, 50, 100, 150, 200 mg·L-1) on growth and nutrient absorption of cucumber seedlings under low nitrogen stress (1 mmol·L-1 NO3-) in sand culture pots. The results showed that, under low N condition, PHA could significantly increase the total root length, root surface area, root tip number and root volume of cucumber seedlings, and promote plant height, stem diameter and leaf area. Proline and soluble sugar contents in cucumber leaves were significantly increased by PHA. The absorption of N, P, K, Ca, Mg, Fe in cucumber seedlings was promoted. According to the response of the two cucumber cultivars to PHA under low N stress, some traits of two cultivars showed different sensitivity to PHA level. The comprehensive analysis of the above results inferred that the PHA level from 100 mg·L-1 to 150 mg·L-1 could significantly enhance the growth and nutrient absorption of cucumber seedlings.

[Effects of NO3- stress on photosynthetic characteristics and nitrogen metabolism of strawber- ry seedlings].

In order to explore the effects of NO3- stress on photosynthetic characteristics and nitrogen metabolism, strawberry seedlings were grown in sand culture condition under different concentrations of NO3- (64, 112 and 160 mmol · L(-1)) with the control of 16 mmol NO3- · L(-1). The results indicated that at the 8th day after treatment, with the increased NO3- concentration, the strawberry leaf net photosynthetic rate (Pn), stomatal conductance (g(s)), PS II actual photochemical efficiency (ΦPS II), PS II maximum photochemical efficiency (Fv/Fm), and photochemical quenching coefficient (q(P)) significantly decreased, and decreased by 67.7%, 68.4%, 35.7%, 23.2% and 26.9%, respectively, when NO3- concentration reached 160 mmol · L(-1) compared with the control. The non-photochemical quenching coefficient (q(N)) increased by 4.4%, 10.9% and 75.8% respectively in the treatments of 64, 112 and 160 mmol NO3- · L(-1) compared with the control. The intercellular CO2 concentration (Ci) decreased under low NO3- concentration stress and then increased under high NO3- concentration stress, while the stomatal limitation (Ls) was vice versa. With the increased NO3- concentration, the nitrate nitrogen, ammonia nitrogen, total nitrogen and Kjeldahl nitrogen contents in the strawberry leaves and roots increased, but the protein nitrogen content decreased. The activities of nitrate reductase (NR) , glutamine sybthetase (GS), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) increased at low NO3- concentration and then decreased at high NO3 concentration. Consequently, the net photosynthetic rate of strawberry seedling leaves decreased, the PS II electron transfer was blocked, the nitrogen accumulated with the increasing NO3- concentration, and the nitrogen metabolism enzyme activity decreased at high NO3- concentrations. When the NO3- concentration reached 64 mmol · L(-1) or higher in the nutrient solution, the growth of strawberry seedlings were inhibited significantly.

[Eupolyphaga frass and its extracts protected tomato from Meloidogyne incognita infestation].

The control effects of Eupolyphaga (Eupolyphaga sinensis Walker) frass and its extracts on Meloidogyne incognita were studied through laboratory assays and pot experiments, and the organic volatile compounds and oligochitosan contents in the frass were analyzed. The results indicated that the nematode immobility and mortality was significantly increased with increasing the extract concentration and treatment time. Compared with the control, egg hatching was significantly inhibited when the extract concentration was beyond 20%. Pot experiment indicated that root galling of tomato seedlings was reduced and the relative control effect was significantly improved with the increasing frass application. Meanwhile, plant height, stem diameter and leaf number of tomato increased with the increasing dosage of eupolyphaga frass. The ingredients analysis showed that the content of oligochitosan was about 4.35% and there were 9 categories and 110 kinds of volatile compounds in the frass.

[Effects of NO3- stress on cucumber seedling growth and magnesium absorbing under suboptimal temperature].

The effects of NO3- stress on the growth and the magnesium absorption of cucumber seedlings were investigated after 1 and 14 d of suboptimal temperature [18 °C/12 °C (day/night)] treatment. The results indicated that the growth, net photosynthetic rate, transpiration rate, Fv/Fm and ΦPSII of cucumber seedlings were significantly inhibited by NO3- stress under suboptimal temperature. The magnesium content of cucumber seedlings was also significantly decreased compared with control treatment, especially in the IV treatment (suboptimal temperature +140 mmol · L(-1) NO3- + 1 mmol · L(-1) Mg2+), and the antagonistic impact of magnesium ion absorption on the absorption of potassium and calcium ion was observed. The magnesium deficiency symptom of cucumber seedlings could be partly alleviated by increasing the concentration of magnesium ion in the nutrient solution.

[Effects of LED qualities on quality and antioxidation capacity of eggplant fruits].

The effects of red light, blue light, red+blue light and white light (control) generated by LED on the quality and antioxidation capacity of fruit and yield of ' Brita' eggplants were stu died. The results showed that under blue LED, the soluble protein, free amino acids contents o eggplant pulps and the anthocyanin content of eggplant peels were significantly higher by 15.1%, 27.2% and 73.6% than control respectively, but flavonoid and phenolic contents of pulps and the yield were significantly lower than those of the other treatments. Under red LED, the eggplant peels flavonoid was remarkably increased, but vitamin C (Vc) and soluble protein contents were consi derably decreased. Under red+blue LED, the soluble sugar of pulps and phenolic, red pigment yellow pigment contents, total antioxidation capacity (TAG) of peels and the yield were significantly higher than those of the other treatments, in which, the TAC of peels and the yield increased by 43.5% and 43.4% compared with control, respectively. Vc, flavonoid and phenolic contents and TAC of eggplant pulps were the highest under white LED. There was significant positive correlation between the phenol content of peels and Vc content of pulps with TAC. Under the protected cultivation condition, an appropriate amount of blue or red LED could improve the quality of eggplant fruit, and red+blue LED was more beneficial to promote the quality of eggplant peels and the yield.