[Impacts of arbuscular mycorrhizal fungi (AMF)on growth, N bio-fixation, and phosphorus uptake of legume crop.] / ä¸›æžèŒæ ¹çœŸèŒå¯¹è±†ç§‘ä½œç‰©ç”Ÿé•¿å’Œç”Ÿç‰©å›ºæ°®åŠç£·ç´ å¸æ”¶çš„å½±å“.

To explore the effects of arbuscular mycorrhizal fungi (AMF) on the growth of legume crop, pot and field experiments with soybean were conducted. Treatments of inoculation (+AMF) and non-inoculation with AMF (-AMF) were set up for the pot experiment, and AMF mycelium non-limited and limited for the field experiment. Results of the pot experiment showed that inoculation with AMF significantly increased soybean aboveground biomass (16.5%) and root nodules number (131.4%), above-ground plant phosphorus and nitrogen concentrations and uptakes. In the field trial, the above-ground and root biomasses and root nodules number under AMF mycelium non-limited were significantly increased by 123.6%, 61.5%, and 212.5% compared with those under the limited condition, respectively. Plant phosphorus uptake, nitrogen concentration and uptake, and soil available nitrogen and phosphorus concentrations were significantly higher under AMF mycelium non-limited than the limited both in both shoot and root. Our findings provide theoretical reference for further understanding the relationship between legume crop and AMF, as well as the efficient utilization of phosphorus fertilizer.

[Effects of increased planting density with reduced nitrogen fertilizer application on rice yield, N use efficiency and greenhouse gas emission in Northeast China].

The traditional rice growing practice has to change to save resource and protect environment, and it' s necessary to develop new technology in rice cultivation. Therefore, a two-year field experiment of Japonica rice (Liaoxing 1) was conducted in Northeast China in 2012 and 2013 to investigate the integrated effects of dense planting with less basal nitrogen (N) and unchanged top-dressing N (IR) on rice yield, N use efficiency (NUE) and greenhouse gas emissions. Compared with traditional practice (CK), we increased the rice seedling density by 33.3% and reduced the basal N rate by 20%. The results showed that the average N agronomy efficiency and partial factor productivity were improved by 49.6% (P<0.05) and 20.4% (P<0.05), respectively, while the area and yield-scaled greenhouse gas emissions were reduced by 9.9% and 12.7% (P<0.05), respectively. Although IR cropping mode decreased panicle number and biomass production, it significantly enhanced rice seed setting rate and harvest index, resulting in an unchanged or even highei yield. NH4+-N and NO3(-)-N concentrations in rice rhizosphere soil were reduced, resulting in an increment of N recovery efficiency. Generally, proper dense planting with less basal N applicatior could be a good approach for the trade-off between rice yield, NUE and greenhouse gas emission.

[Effects of shading and plant density on ear development and plant productivity of spring maize in Northeast China]. / é®é˜´å’Œç§æ¤å¯†åº¦å¯¹ä¸œåŒ—æ˜¥çŽ‰ç±³ç©—éƒ¨å‘è‚²å’Œæ¤æ ªç”Ÿäº§åŠ›çš„å½±å“.

It is important to investigate the effects of shading on maize ear characteristics and yield, which can provide references to variety breeding and agronomic technique improvement for coping with climate change and dense planting. An experiment was carried out with two varieties (compact type hybrid ZD909, flat type hybrid ND4) and two planting densities (45000 and 90000 plants·hm-2) at Gongzhuling City, Jilin Province. Two treatments were conducted for each variety and planting density, including shading (with a shading degree of 65% from small bell mouth stage to mature stage) and no shading treatment (CK). The results showed that shading affected maize ear development significantly. Shading delayed maize anthesis and silking stages, especially prolonging the length of anthesis-silking interval by 3-15 days compared with the CK. Moreover, shading decreased dry matter accumulation of spring maize significantly, leading to more than 50% (50.8%-87.0%) of reduction in grain yield. The negative effects of shading on ear characteristics and yield of spring maize with dense planting was greater than that with sparse planting. The variety with a dense plant type achieved fewer effects on ear characteristics and grain yield than the variety with a sparse plant type under shading and dense planting. The variety with a dense plant type had strong adaptability to ecological environment change and the consistency in density-tolerance and shade-tolerance.

[Carbon footprints of major staple grain crops production in three provinces of Northeast China during 2004-2013.] / 2004­2013年东北三省主要粮食作物生产碳足迹.

Northeast China is one of the most important farming regions in China, due to its great contribution to national food security. Crop production is a main source of carbon emission. To assess the differences in carbon footprints of major grain crop production will benefit the achievement of low carbon agriculture. Therefore, this study calculated the regional carbon foot prints of rice (Oryza sativa), maize (Zea mays) and soybean (Glycine max) production in Northeast China du-ring 2004-2013 using the provincial statistical data, including crop yield, sown area and production inputs. The results showed that the highest area-scale carbon footprint was found in rice production, with the average value of (2463±56) kg CE·hm-2, while the second was found in maize production during 2004-2013. The sharpest rise occurred in maize production, from 1164 kg CE·hm-2 in 2004 to 1768 kg CE·hm-2 in 2013, with the average rate of 67 kg CE·hm-2·a-1. The application of chemical fertilizer contributed to the carbon footprint largely, accounting for 45%, 90% and 83% for rice, maize and soybean, respectively. Moreover, the contribution of electricity for irrigation in rice production ranged from 29% to 42%, which was larger than that in maize and soybean production. The carbon footprints were significantly different among the three provinces of Northeast China. The highest yield-scaled carbon footprints for three crops were found in Jilin Province, while the lowest area-scaled carbon footprints found in Heilongjiang Province. Given to the large transfer of rural labor from agricultural to non-agricultural sections and the development of mechanization, diesel and other mechanical inputs would increase rapidly in the future. Therefore, improving ferti-lizer utilization, mechanical and irrigation efficiencies in crop production would be the main approaches to promoting low-carbon agriculture in Northeast China.

[Effects of tillage patterns on photosynthetic and chlorophyll fluorescence characteristics of maize in rainfed area of Northeast China].

In 2010-2011, a field experiment was conducted in Northeast China to evaluate the effects of different tillage patterns on the temperature and moisture in topsoil layer and the leaf photosynthesis and chlorophyll fluorescence of maize. The effects of tillage patterns on the soil temperature and moisture mainly manifested at sowing-jointing stage. In treatments flat planting with ridging at early jointing stage (PL) and flat planting without ridging (PP), the soil moisture content at the depth of 0-40 cm was significantly higher than that in treatment ridge planting (LL), with the increment being 5.6% and 5.2%, 4.6% and 7.3%, and 3.9% and 4.8% at emergency, seedling, and jointing stages, respectively. The minimum temperature at the soil depth 5 cm at seedling stage in PL and PP was 1.4 and 1.3 degrees C higher than that in LL, respectively. Due to the improvement of soil water and thermal conditions, the leaf photosynthetic rate (Pn) and transpiration rate (Tr) at jointing stage in PL and PP were significantly higher than those in LL, whereas the PS II potential activity (Fv/Fo) and PS II maximal photochemical efficiency (Fv/Fm) had no significant differences among the treatments, indicating that the stomatal factors such as stomata conductivity and stomata limitation were the main factors inducing the photosynthesis differences among the treatments. Furthermore, the Pn and Tr at grain filling stage in LL and PL were higher than those in PP, mainly due to the high water-logging risk in PP in strong rainfall season. Consequently, treatment PL could promote maize photosynthesis through improving soil water and thermal conditions, and further, increase maize grain yield.

[CH4 emission features of leading super-rice varieties and their relationships with the varieties growth characteristics in Yangtze Delta of China].

A pot experiment was conducted to study the CH4 emission features of fourteen leading super-rice varieties (six Japonica rice varieties and eight Indica hybrid rice varieties) and their relationships with the varieties growth characteristics in Yangtze Delta. Two distinct peaks of CH4 emission were detected during the entire growth period of the varieties, one peak occurred at full-tillering stage, and the other appeared at booting stage. The average total CH4 emission of Japonica rice varieties was 37.6% higher than that of the Indica hybrid rice varieties (P<0.01), and the differences in the CH4 emission between rice types occurred at the post-anthesis phase. For all the varieties, there was a significant positive correlation between the total CH4 emission and the maximum leaf area, but the correlations between the CH4 emission and the other growth characteristics varied with variety type. The total CH4 emission of Japonica rice varieties had a significant positive correlation with plant height, while the correlations between the total CH4 emission of Indica hybrid rice varieties and their plant height were not significant. The total CH4 emission of Indica hybrid rice varieties had significant negative correlations with the total aboveground biomass, grain yield, and harvest index, but the correlations were not significant for Japonica rice varieties. The lower CH4 emission of Indica hybrid rice varieties was likely due to their significantly higher root biomass, as compared with Japonica rice varieties.

[Effects of asymmetric warming on the growth characteristics and yield components of winter wheat under free air temperature increased].

In 2007-2009, a field warming experiment was performed in Nanjing of Jiangsu Province, China to investigate the effects of asymmetric warming (all-day warming, AW; daytime warming from 6:00 to 18:00, DW; and nighttime warming from 18:00 to 6:00, NW) on the growth and development of winter wheat under free air temperature increase (FATI). Asymmetric warming increased the effective tillers and decreased the ineffective tillers. In CK plot, the ineffective tillers were 2.6, 1.7 and 3.5 times of those in AW, DW and NW plots, while the effective tillers were decreased by 13.7%, 3.2%, and 0.5%, respectively. Asymmetric warming also increased the plant height, flag leaf area, and the total green leaf area and green leaf ratio at flowing stage. In treatments AW, DW, and NW, the plant height was increased by 5.6%, 4.5%, and 1.3%, flag leaf area increased by 45.7%, 39.4% and 26.1%, total green leaf area increased by 25.1%, 29.8%, and 17.3%, and green leaf ratio increased by 37.7%, 43.3%, and 38.7%, respectively, compared with CK. As for the yield components, the spikelet number per panicle and the filled grain number per panicle in treatments AW, DW and NW were increased by 4.1%, 5.7%, and 1.7%, and by 2.2%, 5.3%, and 2.6%, respectively. Though the grain/leaf ratio in treatments AW, DW, and NW was decreased by 15.3%, 8.5%, and 11.3%, the thousand-grain mass in the treatments was increased by 6.9%, 6.2% and 11.8%, and thus, the yield per unit was increased by 27.0%, 40.1%, and 18.3%, respectively, compared to the CK. Our results suggested that under anticipated warming, the winter wheat productivity in eastern China would be further enhanced.

Comparison between conventional indirect competitive enzyme-linked immunosorbent assay (icELISA) and simplified icELISA for small molecules.

A simplified indirect competitive enzyme-linked immunosorbent assay (icELISA) for small molecules was established by modifying the procedure of conventional icELISA. The key change was that the analyte, antibody, and enzyme-labeled second antibody in the simplified icELISA were added in one step, whereas in conventional icELISA these reagents were added in two separate steps. Three small chemicals, namely zeatin riboside, glycyrrhetinic acid, and chlorimuron-ethyl, were used to verify the new assay format and compare the results obtained from conventional icELISA and simplified icELISA. The results indicated that, under optimized conditions, the new assay offered several advantages over the conventional icELISA, which are simpler, less time consuming and higher sensitive although it requires more amount of reagents. The assay sensitivity (IC50) was improved for 1.2-1.4-fold. Four licorice roots samples were analyzed by conventional icELISA and simplified icELISA, as well as liquid chromatography (LC). There was no significant difference among the content obtained from the three methods for each sample. The correlation between data obtained from conventional icELISA and simplified icELISA analyses was 0.9888. The results suggest that the simplified icELISA be useful for high throughput screening of small molecules.