[Photosynthetic gas exchange and water utilization of flag leaf of spring wheat with bunch sowing and field plastic mulching below soil on semi-arid rain-fed area.] / åŠå¹²æ—±åŒºè†œä¸Šè¦†åœŸç©´æ’­å¯¹æ˜¥å°éº¦æ——å¶å ‰åˆä½œç”¨å’Œæ°´åˆ†åˆ©ç”¨çš„å½±å“.

Based on the field experiment which was conducted in Dingxi County of Gansu Province, and involved in the three treatments: (1) plastic mulching on entire land with soil coverage and bunching (PMS), (2) plastic mulching on entire land and bunching (PM), and (3) direct bunching without mulching (CK). The parameters of SPAD values, chlorophyll fluorescence parameters, photosynthetic gas exchange parameters, as well as leaf area index (LAI), yield, evapotranspiration, and water use efficiency in flag leaves of spring wheat were recorded and analyzed from 2012 to 2013 continuously. The results showed that SPAD values of wheat flag leaves increased in PMS by 10.0%-21.5% and 3.2%-21.6% compared to PM and CK in post-flowering stage, respectively. The maximum photochemical efficiency (Fv/Fm) , actual photochemical efficiency (ΦPS2) of photosystem 2 (PS2), and photochemical quenching coefficient (qP) of PMS were higher than those of PM and CK, the maximum increment values were 6.1%, 9.6% and 30.9% as compared with PM, and significant differences were observed in filling stage (P＜0.05). The values of qN in PMS were lowest among the three treatments, and it decreased significantly by 23.8% and 15.4% in heading stage in 2012 and 2013 respectively, as compared with PM. The stoma conductance (gs) of wheat flag leaves in PMS was higher than that of PM and CK, with significant difference being observed in filling stage, and it increased by 17.1% and 21.1% in 2012 and 2013 respectively, as compared with PM. The transpiration rate (Tr), net photosynthetic rate (Pn), and leaf instantaneous water use efficiency (WUEi) except heading stage in 2013 of PMS increased by 5.4%-16.7%, 11.2%-23.7%, and 5.6%-7.2%, respectively, as compared with PM, and significant difference of WUEi was observed in flowering stage in 2012. The leaf area index (LAI) of PMS was higher than that of PM and CK, especially, it differed significantly in seasonal drought of 2013. Consequently, the PMS increased the SPAD values in flag leaves of spring wheat, and the capacity of flag leaves for photo energy assimilation and photosynthetic gas exchange were enhanced, caused more photosynthetic energy flowing into photochemical process, as well as decreased the heat dissipation, resulted in the increment of Pn and WUEi. Based on the higher Pn and LAI, the yield and WUE of PMS increased.

[Preparation of Mo-TiO2/activated carbon and degradation of L-acid under visible light].

The photocatalyst of Mo(6+) doped TiO2 was prepared by a sol-gel method and immobilized to granular activated carbon by coating. The photodegradation of 1-naphthol-5-sulphonic acid (L-acid), and the effects of the loading numbers of the photocatalyst on activated carbon and the light sources on the removal efficiency of L-acid and TOC of solution were investigated. The experimental results show that the Mo(6+) doping can help TiO2 to extend the active scope to the visible-light region. The doped TiO2 supported on activated carbon is anatase with the average particle diameter 17.8 nm. It has been found that the activity of catalyst is reduced with its loading number, and the Mo(6+) doping does not affect the catalyst activity in the ultraviolet region and adsorption of L-acid. The removal efficiency of L-acid and TOC of solution is 57% and 53% respectively when 0.4 g doped photocatalyst is applied in 100 mg x L(-1) L-acid solution illuminated by visible light for 4 hours, while it is 13% and 10% respectively in the case of the undoped photocatalyst. The catalyst can be reused for 4 times to keep the degradation efficiency hardly changed.