[Simulation of the responses of spring wheat yield to the rates and depths of nitrogen application in dryland based on APSIM model]. / 基于APSIM模型的旱地春小麦产量对施氮量和施氮深度的响应模拟.

Nitrogen limitation is an important factor for the improvement of crop water production potential in rain-fed areas of the Loess Plateau. The reasonable deep application of nitrogen fertilizer is a promising method to increase yield of rain-fed crop. Based on APSIM model, this study simulated spring wheat yield under different nitrogen application rates and depths, by using meteorological observation data from 1990 to 2020 in the semiarid areas of central Gansu Province, aiming to provide theoretical reference for optimizing wheat fertilization strategy. The results showed that the determination coefficient of simulated spring wheat yield, biomass and soil water content in 0-200 cm soil profile was greater than 0.80, the normalized root mean square error was less than 0.2, and the model validity index was greater than 0.5. These results indicated that the model had good fitting and adaptability in the test area. Across all the levels within the experimental design, increasing nitrogen application rates could significantly increase the yield of spring wheat in different precipitation years, and increasing nitrogen application depth could significantly increase spring wheat yield in wet and normal years, but had no effect in dry years. The rate and depth of nitrogen application had significant interaction effects on spring wheat yield in wet and normal years, but not in dry years. According to the binary quadratic regression fitting equation, when the potential maximum yield reached 2749 kg·hm-2 in wet year, nitrogen application depth was 22.7 cm, and nitrogen application rate was 245 kg·hm-2. When the maximum potential yield reached 2596 kg·hm-2 in normal year, nitrogen application depth was 20.6 cm, and nitrogen application rate was 235 kg·hm-2. Integrating the effects of nitrogen application rate and depth on yield, biomass and agronomic efficiency of nitrogen fertilizer, and farmer's fertilizer application habits, the recommended nitrogen application depth was 20-23 cm, and nitrogen application amount was 120-150 kg·hm-2, which could further improve water productivity and nitrogen use efficiency of spring wheat in arid areas of central Gansu Province.

[Effects of vertical rotary subsoiling with combined organic and inorganic fertilization on water use efficiency and yield of forage maize in a semi-arid area.] / åŠå¹²æ—±åŒºç«‹å¼æ·±æ—‹è€•å’Œæœ‰æœºæ— æœºè‚¥é æ–½å¯¹é¥²ç”¨çŽ‰ç±³æ°´åˆ†åˆ©ç”¨æ•ˆçŽ‡å’Œäº§é‡çš„å½±å“.

Both reasonable soil tillage and fertilization management play critical roles in improving the yield and water use efficiency (WUE) of forage maize in the semi-arid area of Loess Plateau. A field experiment was conducted at Dingxi experimental station of Gansu Academy of Agricultural Sciences between 2017 and 2019. We explored the effects of tillage method and fertilization type on yields and WUE of forage maize, as well as the economic benefits. There were four treatments in the experiment, including traditional rotary tillage + organic-inorganic fertilization (TOF), deep rotary tillage + organic-inorganic fertilization (DOF), and vertical rotary subsoiling + organic-inorganic fertilization (VROF), and the traditional rotary tillage + inorganic fertilization as the control (TF). Our results showed that, compared with DOF, TOF, TF, and VROF all decreased soil water storage in 0-300 cm soil layer at flowering stage, ranging from 16.9 mm to 79.9 mm, but they all increased soil water consumption by 9.7-22.4 mm during vegetative growing stages, 11.0-19.8 mm during reproductive stage in the dry years. Due to significant improvement in water absorption, VROF increased dry matter weight at maturity by 3.9%-13.4% compared to other treatments. Similarly, plant height, ear length, grain number per ear, 100-grain weight, and double ear rate under VROF were significantly increased, while bald head length was decreased significantly, when compared with other treatments. As a result, over the three experimental seasons, VROF increased the grain and biological yield by 4.3%-51.5% and 4.3%-25.7% compared to other treatments, respectively. Accordingly, WUE calculated by grain and biomass yields were increased by 2.7%-36.9% and 3.6%-13.5% under VROF, compared to other treatments. VROF increased the unit gross total output value and the net income by 5.1%-32.9% and 6.9%-80.5% respectively, compared to other treatments. These results demonstrated that VROF is a drought-resistant and yield-increasing farming technology for sustainable forage maize production in the semi-arid area of the Loess Plateau, Northwest China.

[Effects of micro-ridge-furrow with plastic mulching and bunching seeding on soil hydrothermal environment and its response to photosynthesis and grain yield of spring wheat]. / å ¨è†œå¾®åž„æ²Ÿç©´æ’­å¯¹æ˜¥å°éº¦åœŸå£¤æ°´çƒ­çŽ¯å¢ƒçš„å½±å“åŠå ¶å ‰åˆå’Œäº§é‡æ•ˆåº”.

The relieving of drought and cold restriction on spring wheat development is one of the key factors increasing wheat yield in arid areas of central Gansu Province. A field experiment with spring wheat (Longchun No. 35) was carried out in central Gansu Province from 2016 to 2018. There were three treatments: 1) micro-ridge-furrow with whole field plastic mulching and bunching seeding (PRF), 2) whole field soil plastic mulching and bunching seeding (PMS), 3) bunching seeding without mulching (CK). We measured soil temperature in 0-25 cm profile, soil water content in 0-300 cm profile, leaf SPAD, photosynthetic rate, transpiration rate, aboveground biomass in different growth stages, and grain yield to understand the effect of PRF on soil hydrothermal environment, spring wheat yield and water use efficiency (WUE) from the aspect of soil hydrothermal, canopy development and grain yield. The results showed that mean soil temperature in 0-25 cm profile of PRF and PMS increased by 2.8 ℃ and 2.5 ℃ at the seedling stage, decreased by 1.4 ℃ and 0.9 ℃ from filling to maturity stage, respectively. Soil water storage in 0-300 cm profile of PRF and PMS increased by 59.7 mm and 41.8 mm from sowing to seedling stage. Water consumption of PRF and PMS increased by 46.1 mm and 39.8 mm from seedling to filling stage. PRF increased average soil temperature in 0-25 cm profile by 0.3 ℃ at seedling stage, but decreased by 0.5 ℃ from filling to maturity stage, and increased soil water storage in 0-300 cm profile by 18.0 mm from sowing to seedling stage. PMF increased water consumption by 13.0 mm from booting to maturing stage, as compared with PMS. Based on the optimizated soil hydrothermal conditions, leaf SPAD value, aboveground biomass, net photosynthetic rate, and transpiration rate of PRF increased, as compared with PMS and CK. The PRF increased grain yield by 9.1% and 36.5%, WUE by 5.9% and 30.8% compared to PMS and CK, respectively. Consequently, PRF increased soil temperature at wheat seedling stage, reduced it from filling to maturing stage, improved wheat water consumption from sowing to filling stage, increased leaf SPAD value and aboveground biomass, promoted photosynthetic function in leaf from seedling to filling stage, and consequently led to increased yield and water utilization. Such effects were more significant in dry year (2016 and 2017).

[Effects of organic fertilizer application on flag leaf C/N ratio, photosynthetic characteristics and yield of spring wheat with full plastic film mulching]. / å ¨è†œè¦†åœŸä¸‹æ–½æœ‰æœºè‚¥å¯¹æ˜¥å°éº¦æ——å¶ç¢³æ°®æ¯”ã€å ‰åˆç‰¹æ€§å’Œäº§é‡çš„å½±å“.

A field experiment was conducted in the rain-fed semi-arid region of central Gansu in 2016 and 2017, with the treatments 1) hill-drop flat planting with full plastic film mulching (PMS), 2) hill-drop flat planting with full plastic film mulching plus organic fertilizers (PMO), and 3) hill-drop flat planting without soil mulching (CK). We investigated the relations among soil moisture, photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr), C/N ratio, and total nitrogen of flag leaf from the heading stage to the seed-filling stage in different treatments to probe into their effects on the yield and yield components of spring wheat variety 'Longchun 27'. The results showed that organic fertilizer application could increase soil moisture at the middle and late growth stages of spring wheat. PMO increased soil water storage in 0-300 cm depth from the heading stage to the seed filling stage by 4.6% and 8.5%, decreased population canopy temperature by 0.1-1.3 ℃ and 1.4-4.9 ℃, increased net photosynthetic rate of flag leaf by 9.3% and 29.7%, stomatal conductance by 30.9% and 103.8%, transpiration rate by 5.1% and 55.0%, total nitrogen content by 6.6% and 18.9%, and decreased C/N ratio by 6.4% and 22.8%, respectively. Compared with PMS and CK, PMO significantly improved grain number per spike and 1000-grain weight, and increased grain yield by 9.1% and 53.7%, respectively. From the heading stage to filling stage, the Pn and gs of flag leaf had negative correlation with C/N, while C/N was negatively correlated with grain yield. Consequently, PMO could improve soil water storage and promote photosynthesis of flag leaf, reduce the intensity of physiological drought stress and the limitations of nitrogen absorption and assimilation in flag leaf from the heading stage to the seed-filling stage, and increase grain number and grain weight and consequently the yield of spring wheat in semi-arid region.

[Effects of annual whole-film mulching on freezing-thawing characteristics, moisture, and temperature distribution of maize soil in semi-arid area]. / åŠå¹²æ—±åŒºå‘¨å¹´å ¨è†œè¦†ç›–å¯¹çŽ‰ç±³ç”°åœŸå£¤å†»èžç‰¹æ€§å’Œæ°´çƒ­åˆ†å¸ƒçš„å½±å“.

Based on a 3-year field experiment (2015-2017) with two treatments, annual whole-film mulching (PM) and uncovered (CK), we analyzed the relationship between soil temperature, moisture, and soil hydrothermal movement in semi-arid area. The results showed that freezing-thawing processes under both PM and CK were one-way freezing and two-way melting. Compared with CK, the freezing period in PM treatment was lagged, freezing rate was slowed down, freezing depth was 20 cm shallower, but melting rate was faster, and melting period was shortened by 6-7 days. In freezing period, soil temperature gradients of PM and CK were positive, with heat being transmitted toward top soil layer, and the conduction strength in PM treatment was greater than CK. During the melting period, soil temperature gradient of PM was also positive, with heat being transmitted toward upper soil layer, and that of CK was conversed. Soil water in PM treatment transported to upper soil layer during freezing-thawing period, but it appeared a "down-up-down" movement mode under CK in freezing period, "up-down" in thawing period. There was positively correlation between temperature and moisture gradient in the freezing period under both PM and CK treatments, with closer correlation in PM than CK. During melting period, soil temperature and moisture gradient was positively correlated in PM treatment with soil heat and moisture moved upward synchronously, while that in CK was negatively correlated with soil heat and moisture simultaneously moved to the lower layer soil. Driven by soil temperature and moisture gradient, soil temperature in 0-10 cm, 10-20 cm and 20-30 cm layers increased by 1.13-1.34 ℃, 0.96-1.24 ℃ and 0.89-1.32 ℃, while average soil water content increased by 3.4%-5.6%, 1.4%-2.2% and 6.7%-7.8%, respectively in PM treatment before sowing. Our results indicated that PM could provide water and heat protection for re-greening of winter crop and sowing, emergence and seedling of spring-sown crops in semi-arid areas.

[Effects of optimal nitrogen fertilizer management on water and fertilizer utilization efficiency and yield under double-ridge-furrow sowing with the whole plastic film mulching in maize in a semi-arid area]. / åŠå¹²æ—±åŒºæ°®è‚¥è¿ç­¹å¯¹å ¨è†œåŒåž„æ²Ÿæ’­çŽ‰ç±³æ°´è‚¥åˆ©ç”¨å’Œäº§é‡çš„å½±å“.

Improper fertilization style is one of the main reasons for low water and fertilizer use efficiency of double-ridge-furrow sowing with the whole plastic film mulching in maize production in the semi-arid area. Understanding the effects of reduction, postponing, and organic fertilizer substitution of nitrogen fertilizer on water and fertilizer use efficiency and yield of maize can provide theore-tical basis for effective management of water and fertilizer in maize production. Based on a 4-year field experiment with three treatments: all fertilizers as base fertilizer under double-ridge-furrow sowing with the whole plastic film mulching (CK), nitrogen fertilizer reduced by 15% and topdres-sing in tasseling stage (RN), 30% of the chemical fertilizer replaced by organic fertilizer and topdressing in tasseling stage (RNM), we measured water consumption characteristics, growth and development, water and fertilizer utilization efficiency of maize. The results showed that fertilization pattern significantly affected water and fertilizer utilization efficiency and yield of maize, which was dependent on annual rainfall. In dry and normal rainfall year, water consumption in pre-flowering stage of RN was decreased by 16.1%-18.8% and that in post-flowering stage was increased by 18.0%-22.2%, while water consumption in pre-flowering and post-flowering stages of RNM did not differ from that in CK. In wet year, water consumption in pre-flowering stage of RN and RNM was decreased by 16.7% and 6.3%, while that in post-flowering stage was increased by 11.4% and 29.7%, respectively. Compared with CK, RN significantly increased the relative content of chlorophyll (SPAD) of maize leaves after topdressing, the biomass in post-flowering stage was increased by 15.6%-44.9%, the ear length, the number and weight of grains per spike and the 100-grain weight were increased significantly, yield was increased by 9.8%-17.0%, and water use efficiency (WUE) was increased by 6.3%-21.4%, with the partial productivities of fertilizer (PEPT), N (PEPTN), P (PEPTP) and K (PEPTK) were all increased significantly. In conclusion, RN could improve water consumption and the SPAD value in post-flowering stage of maize in different precipitation years, increase post-flowering biomass, and optimize the ear character, obviously improve yield, water and fertilizer use efficiency. It was a effective fertilizer management mode with high-efficiency utilization of water and fertilizer under double-ridge-furrow sowing with the whole plastic film mulching in maize in the semi-arid area.

Regulation of mulch conditions on photosynthesis and water utilization of spring wheat in northwest semi-arid area of China.

A field experiment was conducted from 2015 to 2016 in the northwestern Loess Plateau, China, to analyze the relationships among flag-leaf photosynthetic characteristics, water-consumption characteristics, and yield components of spring wheat (Triticum aestivum 'Longchun 35'). There were three treatments: whole-field plastic mulching (PMS), sand mulching (SM), and uncovered (CK). The results showed that soil-water storage levels at 0-300 cm of soil profile before wheat filling under PMS and SM treatments were greater than that in CK by 47.8 and 31.6 mm, respectively, while that under PMS was lower than CK by 15.6 mm at the filling stage. Water consumption under PMS and SM increased in the flagging-heading and flowering-filling stages compared with the CK. Leaf area indices under PMS and SM were increased by 59.0%-73.7% and 40.1%-52.7%, respectively, and leaf SPAD values were increased by 3.5%-28.4% and 2.9%-23.9%, respectively, compared with CK. The net photosynthetic rate of PMS was increased by 23.5%, 33.0% and 17.7% at the flagging, heading, and flowering stages. The corresponding stoma-tal conductance rate was increased by 32.6%, 76.4% and 66.9%, respectively. Net photosynthetic and stomatal conductance rates at the filling stage were decreased by 26.2% and 16.4%, respectively. At the heading, flowering, and filling stages, stomatal limitation values in PMS were decreased by 14.6%, 23.9% and 22.3%, respectively, and by 25.7%, 29.8% and 17.4%, respectively in SM. The instantaneous water-use efficiency of spring wheat in PMS was increased by 57.8% at the flagging stage and decreased by 11.2% at the flowering stage. At the heading and flowering stages, the apparent quantum efficiency was increased by 22.6% and 18.7% in PMS, and by 26.8% and 14.3% in SM, respectively. Plant height and yield component indices in PMS and SM were significantly greater than that in CK, with the enhancement being greater than that in dry years. Grain yield was increased by 36.2% and 8.7% and water-use efficiency increased by 9.4% and 3.4% in PMS and SM, respectively. PMS and SM treatments increased soil water storage before the pre-filling stage of wheat, aggravated water consumption during the flagging-shooting and flowering-filling stages, resulting in greater SPAD values and leaf area indices, which promoted the photosynthetic functions of flag leaves, facilitated sink formation and photosynthetic assimilate transportation, resulting in increased grain yields and water use efficiency of spring wheat. The effects of PMS treatment were more remarkable than those of SM in terms of increasing spring wheat's yield potential in wet years and adaptability in dry years.

Effects of vertically rotary sub-soiling tillage on water utilization and yield of potato in semi-arid area of northwest China.

To examine the effects of vertically rotary sub-soiling tillage (VRT) on stage water consumption, individual and population development, yield, water use efficiency, and economic profit of potato is helpful to find the optimized tillage method which could increase crop drought-resistant, yield, and resource use efficiency. With randomized block design, the field experiment involved in three treatments, 1) vertically rotary sub-soiling tillage for 40 cm depth (VRT), 2) deep loosing tillage for 40 cm (DLT), and 3) rotary tillage for 15 cm (TT). The soil water storage in 0-200 cm soil profile in different growth stages of potato, foliar SPAD value, leaf area index (LAI), plant dry matter content, tuber yield were recorded, and stage water consumption, water use efficiency (WUE), tuber commodity rate, tuber commodity yield, and profit were calculated, to investigate the effects of VRT on production efficiency and economic profit. The results showed that VRT increased water consumption in flowering and tuber expanding stage by 46.7, 35.7 mm in 2016 and 27.2, 47.3 mm in 2017, as compared with DLT and TT. Based on the increased stage water consumption, foliar SPAD value, dry matter content, and LAI increased significantly, suggesting the VRT promoted individual and population development. The higher individual and population biomass resulted in significant increase in tuber yield which increased by 156.8%, 47.8% in 2016 and 24.8%, 41.0% in 2017 respectively, as compared with DLT and TT. Accordingly, WUE increased by 92.3%, 19.2% and 18.9%, 26.6%. The tuber commodity yield and profit significantly increased in VRT treatment, as well as the profit which reached to 12631.9, 11019.1 yuan·hm-2 in 2016 and 29498.3, 18245.5 yuan·hm-2 in 2017, respectively. VRT promoted potato water consumption in flowering and tuber expanding stages, resulted in significant increases of foliar SPAD value, plant dry matter, and LAI, with positive consequences on the tuber yield, WUE, as well as the tuber commodity yield and economic profit. These indicated that the VRT was helpful to increase potato drought resistance, yield and profit, and thus would be the appropriate tillage method on semi-arid northwest Loess Plateau.

[Effects of fertilizer application on water consumption characteristics and yield of potato cultured under ridge-furrow and whole filed plastic mulching in rain-fed area.] / æ–½è‚¥å¯¹æ—±åœ°å ¨è†œè¦†ç›–åž„æ²Ÿç§æ¤é©¬é“ƒè–¯è€—æ°´ç‰¹å¾åŠäº§é‡çš„å½±å“.

Chemical fertilizer reduction and organic manure substitution are the useful methods to increase potato water-and nutrient use efficiency, which is cultured under ridge-furrow and whole soil surface mulched by plastic film in semiarid rain-fed area. A 4-year field experiment was carried out from 2011 to 2014 with three treatments: 1) traditional chemical fertilizer application (F), 2) chemical nitrogen fertilizer reduced by 25% and dressing at flowering stage (DF), and 3) chemical nitrogen fertilizer reduced by 50% and organic manure substitution (OF). The soil moisture and potato yield were investigated, and seasonal water consumption, water use efficiency (WUE) were calculated to study the regulations of different nutrient management methods on potato water use process, as well as its effects on potato tuber yield and WUE. The results showed that soil water storage in potato flowering stage was the highest under DF treatment, but there were no significant difference among these three treatments. The depth of soil water depletion in DF and OF showed an increasing trend at post-flowering stage. Potato water consumption decreased significantly at pre-flowering stage, but increased by 36.2%, 23.2%, 24.8% and 19.0% respectively at post-flowering stage in 2011-2014 under DF treatment, as compared with those under F treatment. OF treatment increased potato water consumption by 20.7% and 16.3% than that under F treatment at post-flowering stage from 2011 to 2012, respectively, but exerted no significant effect at pre-flowering stage. Compared with F, DF increased potato tuber yield averagely by 2595.1 kg·hm-2 from 2012 to 2014 and significantly increased the WUE by 14.4% and 6.3% in 2013 and 2014, respectively; OF significantly increased potato tuber yield averagely by 2945 kg·hm-2 tuber yield in 4 experimental years and WUE was significantly higher than that under F from 2012 to 2014. It was indicated that both DF and OF could regulate water consumption between pre-flowering and post-flowering stages, and increase potato tuber yield and WUE. OF showed more significant effects than DF on the increment of tuber yield and WUE.

[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.

[Effects of nitrogen application and elevated atmospheric CO2 on electron transport and energy partitioning in flag leaf photosynthesis of wheat].

Wheat (Triticum aestivum) plants were pot-cultured in open top chambers at the nitrogen application rate of 0 and 200 mg x kg(-1) soil and the atmospheric CO2 concentration of 400 and 760 micromol x mol(-1). Through the determination of flag leaf nitrogen and chlorophyll contents, photosynthetic rate (Pn)-intercellar CO2 concentration (Ci) response curve, and chlorophyll fluorescence parameters at heading stage, the photosynthetic electron transport rate and others were calculated, aimed to investigate the effects of nitrogen application and elevated atmospheric CO2 concentration on the photosynthetic energy partitioning in wheat flag leaves. Elevated atmospheric CO2 concentration decreased the leaf nitrogen and chlorophyll contents, compared with the ambient one, and the chlorophyll a/b ratio increased at the nitrogen application rate of 200 mg x kg(-1). With the application of nitrogen, no evident variations were observed in the maximal photochemical efficiency (Fv/Fm), maximal quantum yield under irradiance (Fv'/Fm') of PS II reaction center, photochemical fluorescence quenching coefficient (q(p)), and actual PS II efficiency under irradiance (phi(PS II) at elevated atmospheric CO2 concentration, and the total photosynthetic electron transport rate (J(F)) of PS II reaction center had no evident increase, though the non-photochemical fluorescence quenching coefficient (NPQ) decreased significantly. With no nitrogen application, the Fv'/Fm', psi(PS II), and NPQ at elevated atmospheric CO2 concentration decreased significantly, and the J(F) had a significant decrease though the Fv/Fm and q(p) did not vary remarkably. Nitrogen application increased the J(F) and photochemical electron transport rate (Jc); while elevated atmospheric CO2 concentration decreased the photorespiration electron transport rate (J0), Rubisco oxidation rate (V0), ratio of photorespiration to photochemical electron transport rate (J0/Jc) , and Rubisco oxidation/carboxylation rate (Vo/Vc), but increased the photochemical electron transport rate (Jc) and Rubisco carboxylation rate (Vc). It was concluded that elevated atmospheric CO2 concentration decreased the leaf nitrogen and chlorophyll contents, while nitrogen application increased the photosynthetic electron transport rate of PS II reaction center significantly, and promoted the photosynthetic electron flow towards photochemistry, making more photosynthetic electron take part in Rubisco carboxylation and leading to the significant increase of Pn.

[Effects of whole field-surface plastic mulching and planting in furrow on soil temperature, soil moisture, and corn yield in arid area of Gansu Province, Northwest China].

Taking spring corn (Zea mays) cultivar Shendan 16 as test material, a field experiment was conducted to study the effects of the treatments whole-field surface plastic mulching and planting in furrow (PMF), whole-field surface sand mulching and flat planting (SM), and uncovered and flat planting (CK) on the soil temperature, soil moisture, and corn yield on the dry land of arid area (annual average precipitation 415 mm) in middle Gansu Province. Comparing with CK, treatments PMF and SM increased the average temperature in 0-25 cm soil layer before tasselling stage, with the highest increment in treatment PMF. As for the soil water consumption, its depth in the three treatments increased with increasing years of planting. In the first year of planting, the soil water consumption was the most in 20-120 cm soil layer; whereas in the second year, the consumption was the most in 120-200 cm soil layer, with the soil water loss being the highest in treatment PMF. Treatment PMF had the highest grain number, grain weight per spike, and 100-grain weight, followed by treatment SM, and CK. In 2009 and 2010, the average grain number, average grain weight per spike, and average 100-grain weight in treatment PMF were increased by 13.5% and 114.2%, 29.8% and 321.1%, and 14.4% and 95.4% respectively, as compared to treatments SM and CK, and the grain yield and water use efficiency in treatments PMF and SM were increased by 333.1% and 240.2%, and 290.6% and 227.6%, respectively, as compared to CK. After two years continuous cropping of corn, the soil water loss in 120-200 cm soil layer in treatment PMF was up to 72 mm, being significantly higher than that in treatments SM (45 mm) and CK (40 mm). It was suggested that PMF could increase the soil temperature at seedling-tasselling stage, promote the corn growth in its early growth period, improve the soil water use by corn, and consequently, increase the grain number per spike and 100-grain weight, manifesting a good effect in improving corn yield and water use efficiency. However, PMF also induced more soil water consumption in 100-200 cm soil layer, which was not beneficial to the water balance through years.

[Effects of nitrogen fertilization on wheat leaf photosynthesis under elevated atmospheric CO2 concentration].

In this paper, the effects of nitrogen (N) fertilization on the wheat leaf photosynthesis under long-term elevated atmospheric CO2 concentration (760 micromol x mol(-1)) was studied, based on the measurements of photosynthetic gas exchange parameters and light intensity-photosynthetic rate response curves at jointing stage. Under the long-term elevated atmospheric CO2 concentration, applying sufficient N could increase the wheat leaf photosynthetic rate (Pn), transpiration rate (Tr), and instantaneous water use efficiency (WUEi). Comparing with those under ambient atmospheric CO2 concentration, the Po and WUEi under the elevated atmospheric CO2 concentration increased, while the stomatal conductance (Gs) and intercellular CO2 concentration (Ci) decreased. With the increase of light flux intensity, the Pn and WUEi under the elevated atmospheric CO2 concentration were higher those under ambient atmospheric CO2 concentration, Gs was in adverse, while Ci and Tr had less change. At high fertilization rate of N, the Gs was linearly positively correlated with Pn, Tr, and WUEi, and the Gs and Ci had no correlation with each other under the elevated atmospheric CO2 concentration but negatively correlated under ambient atmospheric CO2 concentration. At low fertilization rate of N, the Gs had no correlations with Pn and WUEi but linearly positively correlated with Ci and Tr. It was suggested that under the elevated atmospheric CO2 concentration, the wheat leaf Pn at low N fertilization rate was limited by non-stomatal factor.