[Effects of Trichoderma on nitrogen absorption and use efficiency in Lycium chinense roots under saline stress]. / æœ¨éœ‰å¯¹ç›æ¸é€†å¢ƒä¸‹æž¸æžæ ¹ç³»æ°®ç´ å¸æ”¶å’Œæ°®ç´ åˆ©ç”¨æ•ˆçŽ‡çš„å½±å“.

To clarify the mechanisms underlying the improvement of Trichoderma on Chinese wolfberry (Lycium chinense) growth under saline stress, we analyzed the effects of application of organic fertilizer, Trichoderma agent and fertilizer on nitrogen uptake, assimilation, accumulation and use efficiency in Chinese wolfberry, based on a pot experiment with coastal saline soil. The organic fertilizer was the sterilization substance of Trichoderma fertilizer without viable Trichoderma, without any difference in the content of nutrients (such as nitrogen, phosphorus and potassium) between them. The results showed that the application of organic fertilizer, Trichoderma agent and ferti-lizer significantly increased NO3- and NH4+ influx rate in meristematic zone and NO3- influx rate in maturation zone of roots. The magnitude of such enhancement was greater in the application with Trichoderma fertilizer than organic fertilizer. Compared with the control, the application of Trichoderma agent and fertilizer significantly increased root, stem and leaf biomass and nitrogen content as well as plant nitrogen accumulation, strengthened root and leaf nitrate reductase, nitrite reductase and glutamine synthetase activities, and elevated nitrogen uptake efficiency, photosynthetic rate, stable carbon isotope abundance and photosynthetic nitrogen use efficiency. For all those variables, the beneficial effect was obviously stronger in the application with Trichoderma fertilizer than organic fertilizer. Therefore, Trichoderma facilitated nitrogen uptake, assimilation and accumulation in Chinese wolfberry under saline stress, improved photosynthetic carbon fixation ability and nitrogen use efficiency, and ultimately promoted plant growth.

[Effects of elevated ozone concentrations on reactive oxygen metabolism and related gene expression in Ginkgo biloba leaves]. / å¤§æ°”è‡­æ°§æµ“åº¦å‡é«˜å¯¹é“¶æå¶ç‰‡æ´»æ€§æ°§ä»£è°¢åŠç›¸å ³åŸºå› è¡¨è¾¾çš„å½±å“.

By using the open top chambers (OTCs) fumigation method, this paper investigated the changes of foliar injury, level of reactive oxygen species (ROS), activities and gene expression of antioxidant enzymes in Ginkgo biloba leaves under different ozone (ambient ozone≈40, 80, 160, 200 nmol·mol-1) concentrations, in order to study the effects of elevated ozone (O3) concentrations on reactive metabolism. The results showed that the obvious foliar injuries were observed in 160 and 200 nmol·mol-1 O3 treatments, while no visible injury was observed in 80 nmol·mol-1 O3 and ambient O3 treatments. After 20 d, a significant increase in O2-· generation rate was observed in G. biloba leaves exposed to 160, 200 nmol·mol-1 O3, compared with ambient ozone and 80 nmol·mol-1 O3, and there were no significant differences between ambient O3 and 80 nmol·mol-1 treatments. After 40 d, H2O2 content of G. biloba leaves in 160 and 200 nmol·mol-1 O3 was significantly higher than that in 80 nmol·mol-1 and ambient ozone, respectively. The activities of catalase (CAT) in 160 and 200 nmol·mol-1 treatments were also significantly higher than that in 80 nmol·mol-1 and ambient O3 treatments. The ascorbate peroxidase (APX) activity of leaves for each elevated O3 treatment was lower than that of ambient ozone. The level of CAT and APX expression increased progressively after 40 d O3 treatment. The expression intensity of GbD was conspicuously strengthened along with the increase of ozone concentration and fumigation time. Le-vel of reactive oxygen increased, activities of antioxidant enzyme decreased, level of gene expression down-regulated, and foliar visible injury was observed in leaves of G. biloba in elevated ozone stress.

[Effects of elevated Cd, Zn and their combined effects on antioxidant system of tobacco]. / é«˜æµ“åº¦é•‰ã€é”ŒåŠå ¶å¤åˆä½œç”¨å¯¹çƒŸè‰æŠ—æ°§åŒ–ç³»ç»Ÿçš„å½±å“.

A solution culture was conducted to study the effects of elevated Cd and/or Zn ions (0.1 mmol·L-1 Cd2+, 0.15 mmol·L-1 Zn2+, 0.1 mmol·L-1 Cd2++0.15 mmol·L-1Zn2+) on seed germination rate and reactive oxygen species (ROS) level, antioxidants contents, antioxidant enzyme activities and product of membrane lipid peroxidation in tobacco seedling leaves. The results showed that compared to control, the seed germination rate decreased under elevated level of Cd2+or Zn2+, the superoxide radical (O2-· ) generation rate and hydrogen peroxide (H2O2) content in tobacco seedlings increased, the activities of catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR), and glutathione reductase (GR) increased, content of glutathione (GSH) and GSH/GSSG (oxidized glutathione) ratio decreased, and malondialdehyde (MDA) content increased. Compared to elevation of the level of only Cd2+ or Zn2+, the seed germination rate under elevation of both Cd2+ and Zn2+ levels was enhanced significantly; O2-· generation rate, contents of H2O2 and MDA decreased; CAT, APX and MDAR activities increased in the last stage of Cd2+ and Zn2+ exposure. Heavy metal Cd2+ or Zn2+ could induce the physiological injury to tobacco seedlings, and the toxic effects increased with prolonged stress time. The combined treatment of Cd and Zn could alleviate the toxicity of single stress on tobacco seedlings.

[Effects of elevated ozone on Pinus armandii growth: a simulation study with open-top chamber].

By using open-top chamber (OTC) and the techniques of dendrochronology, this paper studied the growth of Pinus armandii under elevated ozone, and explored the evolution dynamics and adaptation mechanisms of typical forest ecosystems to ozone enrichment. Elevated ozone inhibited the stem growth of P. armandii significantly, with the annual growth of the stem length and diameter reduced by 35.0% and 12.9%, respectively. The annual growth of tree-ring width and the annual ring cells number decreased by 11.5% and 54.1%, respectively, but no significant change was observed in the diameter of tracheid. At regional scale, the fluctuation of ozone concentration showed significant correlation with the variation of local vegetation growth (NDVI).

[Effects of elevated O3 concentration on anti-oxidative enzyme activities in Pinus tabulaeformis].

An open-top chamber experiment was conducted to study the effects of high concentration O3 (80 nmol x mol(-1)) on the superoxide anion radical (O2*-) generation rate, hydrogen peroxide (H2O2) content, activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR), and ascorbic acid content in Pinus tabulaeformis leaves. Under high concentration O3 exposure, the superoxide anion radical generation rate and H2O2 and malondialdehyde (MDA) contents increased, while the ascorbic acid content and the activities of SOD, APX, DHAR, MDHAR, and GR increased in early growth season but decreased then to a level lower than the control, which illustrated that the antioxidant system of P. tabulaeformis did respond in an acclimation way in the early growth season, but could not bear the damage of long-term elevated O3 exposure.