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2015 Vol. 14 No. 12 Previous Issue    Next Issue

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Special Focus: Best Soil Management from Long-Term Field Experiments for Sustainable Agriculture
Crop Genetics · Breeding · Germplasm Resources
Plant Protection
Animal Science · Veterinary Science
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Special Focus: Best Soil Management from Long-Term Field Experiments for Sustainable Agriculture

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Best soil managements from long-term field experiments for sustainable agriculture XU Ming-gang, TANG Hua-jun, YANG Xue-yun, ZHOU Shi-wei 2015, 14(12): 2401-2404.  DOI: 10.1016/S2095-3119(15)61235-7 Abstract ( )   PDF in ScienceDirect

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Soil aggregation and aggregate associated organic carbon and total nitrogen under long-term contrasting soil management regimes in loess soil XIE Jun-yu, XU Ming-gang, Qiangjiu Ciren, YANG Yang, ZHANG Shu-lan, SUN Ben-hua, YANG Xue-yun 2015, 14(12): 2405-2416.  DOI: 10.1016/S2095-3119(15)61205-9 Abstract ( )   PDF in ScienceDirect   This study investigated the effects of three contrasting soil management regimes and different nutrient treatments on the distribution of water-stable aggregates (>2, 1–2, 0.5–1, 0.25–0.5, and <0.25 mm) and associated soil organic carbon (SOC) and total nitrogen (TN) content in loess soil. A 21-yr long-term experiment was performed, in which soil management regimes include cropland abandonment (Abandonment), bare fallow (Fallow) and wheat-fallow cropping (Cropping). Under Cropping, the following nutrient treatments were employed: control (CK, no nutrient input), nitrogen only (N), nitrogen and potassium (NK), phosphorus and potassium (PK), NP, NPK, and manure (M) plus NPK (MNPK). Results demonstrated that Abandonment significantly increased the content of soil macro-aggregates (>0.25 mm) and mean weight diameter (MWD) at 0–10 and 10–20 cm soil horizons compared with Cropping, whereas Fallow yielded lower values of above two parameters. Abandonment increased SOC and TN contents in all aggregate sizes by 17–62% and 6–60%, respectively, at 0–10 cm soil layer compared with Cropping. Conversely, Fallow decreased SOC and TN contents in all aggregates by 7–27% and 7–25%, respectively. Nevertheless, the three soil management regimes presented similar SOC contents in all aggregates at 10–20 cm soil horizon. Only Cropping showed higher TN content in >0.5 mm aggregates than the two other regimes. Consequently, Abandonment enhanced the partitioning proportions of SOC and TN in >1 mm macro-aggregates, and Fallow promoted these proportions in micro-aggregates compared with Cropping. Under Cropping, long-term fertilization did not affect the distribution of aggregates and MWD values compared with those under CK, except for NPK treatment. Fertilizer treatments enhanced SOC and TN contents in aggregates at all tested soil depths. However, fertilization did not affect the partitioning proportions of SOC and TN contents in all aggregates compared with CK. Comprehensive results showed that different soil management regimes generated varied patterns of SOC and TN sequestration in loess soil. Abandonment enhanced soil aggregation and sequestered high amounts of SOC and TN in macro-aggregates. Long-term amendment of organic manure integrated with NPK maintained soil aggregate stability and improved SOC and TN sequestration in all aggregates in loess soil subjected to dryland farming.

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Soil carbon sequestration under long-term rice-based cropping systems of purple soil in Southwest China FAN Hong-zhu, CHEN Qing-rui, QIN Yu-sheng, CHEN Kun, TU Shi-hua, XU Ming-gang, ZHANG Wen-ju 2015, 14(12): 2417-2425.  DOI: 10.1016/S2095-3119(15)61225-4 Abstract ( )   PDF in ScienceDirect   Carbon sequestration in agricultural soils is a complex process controlled by farming practices, climate and some other environment factors. Since purple soils are unique in China and used as the main cropland in Sichuan Basin of China, it is of great importance to study and understand the impacts of different fertilizer amendments on soil organic carbon (SOC) changes with time. A research was carried out to investigate the relationship between soil carbon sequestration and organic carbon input as affected by different fertilizer treatments at two long-term rice-based cropping system experiments set up in early 1980s. Each experiment consisted of six identical treatments, including (1) no fertilizer (CK), (2) nitrogen and phosphorus fertilizers (NP), (3) nitrogen, phosphorus and potassium fertilizers (NPK), (4) fresh pig manure (M), (5) nitrogen and phosphorus fertilizers plus manure (MNP), and (6) nitrogen, phosphorus and potassium fertilizers plus manure (MNPK). The results showed that annual harvestable carbon biomass was the highest in the treatment of MNPK, followed by MNP and NPK, then M and NP, and the lowest in CK. Most of fertilizer treatments resulted in a significant gain in SOC ranging from 6.48 to 29.13% compared with the CK, and raised soil carbon sequestration rate to 0.10–0.53 t ha–1 yr−1. Especially, addition of manure on the basis of mineral fertilizers was very conducive to SOC maintenance in this soil. SOC content and soil carbon sequestration rate under balanced fertilizer treatments (NPK and MNPK) in the calcareous purple soil (Suining) were higher than that in the acid purple soil (Leshan). But carbon conversion rate at Leshan was 11.00%, almost 1.5 times of that (7.80%) at Suining. Significant linear correlations between soil carbon sequestration and carbon input were observed at both sites, signifying that the purple soil was not carbon-saturated and still had considerable potential to sequestrate more carbon.

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Determination of optimum nitrogen application rates in Zhejiang Province, China, based on rice yields and ecological security LI Yan, CHEN Yi, WU Chun-yan, TANG Xu, JI Xiao-jiang 2015, 14(12): 2426-2433.  DOI: 10.1016/S2095-3119(15)61168-6 Abstract ( )   PDF in ScienceDirect   Excessive nitrogen (N) fertilization in intensive agricultural areas such as the plain region of South China has resulted in low nitrogen use efficiency and serious environmental problems. To determine the optimum N application rate, grain yield, apparent nitrogen recovery efficiency (ANRE), apparent N loss, and ammonium (NH3) volatilization under different N application rates in the three years from 2012 to 2014 were studied. The results showed that the relationship between grain yields and N application rate in the three years were well fitted by quadratic equations. When N application rate reached 197 kg ha–1 in 2012, 199 kg ha–1 in 2013 and 196 kg ha–1 in 2014, the plateau of the grain yields appeared. With the increase of N application rate, the ANRE for rice decreased which could be expressed with sigmoidal equation; when N application rate was 305 kg ha–1 in 2012, 275 kg ha–1 in 2013 and 312 kg ha–1 in 2014, the curves of ANRE appeared turing points. Besides, the relationship between soil Nresidual and N application rate was fitted by the quadratic equation and the maximums of soil Nresidual were reached in the three years with the N application rate of 206, 244 and 170 kg ha–1, respectively. Statistical analysis indicated that NH3 volatilization and apparent N loss in three years all increased with the increasing N application rate. When the amount of NH3 volatilization increased to 11.6 kg N ha–1 in 2012, 40.5 kg N ha–1 in 2013 and 57.0 kg N ha–1 in 2014, the apparent N loss in the three years had obvious increase. To determine the optimum N application rate, the average N application on the plateau of the grain yield was considered as the lower limit while the average N application rate at the turning points of ANRE, the residual N in soil and apparent N loss was taken as the upper limit. According to the results in three years, the optimum N application rate for rice in Zhejiang was 197–255 kg ha–1.

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Simulation of water and nitrogen dynamics as affected by drip fertigation strategies ZHANG Jian-jun, LI Jiu-sheng, ZHAO Bing-qiang, LI Yan-ting 2015, 14(12): 2434-2445.  DOI: 10.1016/S2095-3119(15)61231-X Abstract ( )   PDF in ScienceDirect   The aim of drip fertigation is synchronising the application of water and nutrients with crop requirements, and maintaining the proper concentration and distribution of nutrient and water in the soil. The wetting patterns and nutrient distributions under drip fertigation have been proved to be closely related to the fertigation strategies. In order to find out the critical factors that affect the nutrient distribution under different drip fertigaiton strategies, a computer simulation model HYDRUS2D/3D was used to simulate the water and nitrate distribution for various fertigation strategies from a surface point source. Simulation results were compared with the observed ones from our previous studies. A 15° wedge-shaped plexiglass container was used in our experiment to represent one-twenty-fourth of the complete cylinder. The height of container is 40 cm, and the radius is 41 cm. The ammonium nitrate solution was added through a no. 7 needle connected to a Mariotte tube with a flexible hose. The soil water content, nitrate and ammonium concentrations were measured. The comparison of simulated and observed data demonstrated that the model performed reliably. The numerical analysis for various fertigation strategies from a surface point source showed that: (1) The total amount of irrigation water, the concentration of the fertilizer solution and the amount of pure water used to flush the pipeline after fertilizer solution application are the three critical factors influencing the distribution of water and fertilizer nitrogen in the soil. (2) The fresh water irrigation duration prior to fertigation has no obvious effect on nitrate distribution. The longer flushing time period after fertigation resulted in nitrate accumulation closer to the wetting front. From the point of avoiding the possibility of nitrate loss from the root zone, we recommended that the flushing time period should be as shorter as possible. (3) For a given amount of fertilizer, higher concentration of the fertilizer applied solution reduces the potential of nitrate leaching in drip irrigation system. While, lower concentration of the fertilizer solution resulted in an uniform distribution of nitrate band closer to the wetted front.

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Soil phosphorus dynamic, balance and critical P values in longterm fertilization experiment in Taihu Lake region, China SHI Lin-lin, SHEN Ming-xing, LU Chang-yin, WANG Hai-hou, ZHOU Xin-wei, JIN Mei-juan, WU Tong-dong 2015, 14(12): 2446-2455.  DOI: 10.1016/S2095-3119(15)61183-2 Abstract ( )   PDF in ScienceDirect   Phosphorus (P) is an important macronutrient for plant but can also cause potential environmental risk. In this paper, we studied the long-term fertilizer experiment (started 1980) to assess the soil P dynamic, balance, critical P value and the crop yield response in Taihu Lake region, China. To avoid the effect of nitrogen (N) and potassium (K), only the following treatments were chosen for subsequent discussion, including: C0 (control treatment without any fertilizer or organic manure), CNK treatment (mineral N and K only), CNPK (balanced fertilization with mineral N, P and K), MNK (integrated organic manure and mineral N and K), and MNPK (organic manure plus balanced fertilization). The results revealed that the response of wheat yield was more sensitive than rice, and no significant differences of crop yield had been detected among MNK, CNPK and MNPK until 2013. Dynamic and balance of soil total P (TP) and Olsen-P showed soil TP pool was enlarged significantly over consistent fertilization. However, the diminishing marginal utility of soil Olsen-P was also found, indicating that high-level P application in the present condition could not increase soil Olsen-P contents anymore. Linear-linear and Mitscherlich models were used to estimate the critical value of Olsen-P for crops. The average critical P value for rice and wheat was 3.40 and 4.08 mg kg–1, respectively. The smaller critical P value than in uplands indicated a stronger ability of P supply for crops in this paddy soil. We concluded that no more mineral P should be applied in rice-wheat system in Taihu Lake region if soil Olsen-P is higher than the critical P value. The agricultural technique and management referring to activate the plant-available P pool are also considerable, such as integrated use of low-P organic manure with mineral N and K.

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Review grain yield and nitrogen use efficiency in rice production regions in China CHE Sheng-guo, ZHAO Bing-qiang, LI Yan-ting, YUAN Liang, LI Wei, LIN Zhi-an, HU Shu-wen, SHEN Bing 2015, 14(12): 2456-2466.  DOI: 10.1016/S2095-3119(15)61228-X Abstract ( )   PDF in ScienceDirect   As one of the staple food crops, rice (Oryza sativa L.) is widely cultivated across China, which plays a critical role in guaranteeing national food security. Most previous studies on grain yield or/and nitrogen use efficiency (NUE) of rice in China often involved site-specific field experiments, or small regions with insufficient data, which limited the representation for the current rice production regions. In this study, a database covering a wide range of climate conditions, soil types and field managements across China, was developed to estimate rice grain yield and NUE in various rice production regions in China and to evaluate the relationships between N rates and grain yield, NUE. According to the database for rice, the values of grain yield, plant N accumulation, N harvest index (HIN), indigenous N supply (INS), internal N efficiency (IEN), reciprocal internal N efficiency (RIEN), agronomic N use efficiency (AEN), partial N factor productivity (PEPN), physiological N efficiency (PEN), and recover efficiency of applied N (REN) averaged 7.69 t ha–1, 152 kg ha–1, 0.64 kg kg–1, 94.1 kg kg–1, 53.9 kg kg–1, 1.98 kg kg–1, 12.6 kg kg–1, 48.6 kg kg–1, 33.8 kg kg–1, and 39.3%, respectively. However, the corresponding values all varied tremendously with large variation. Rice planting regions and N rates had significant influence on grain yield, N uptake and NUE values. Considering all observations, N rates of 200 to 250 kg ha–1 commonly achieved higher rice grain yield compared to less than 200 kg N ha–1 and more than 250 kg N ha–1 at most rice planting regions. At N rates of 200 to 250 kg ha–1, significant positive linear relationships were observed between rice grain yield and AEN, PEN, REN, IEN, and PFPN, and 46.49, 24.64, 7.94, 17.84, and 88.24% of the variation in AEN, PEN, REN, IEN, and PFPN could be explained by grain yield, respectively. In conclusion, in a reasonable range of N application, an increase in grain yield can be achieved accompanying by an acceptable NUE.

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Effects of long-term full straw return on yield and potassium response in wheat-maize rotation BAI You-lu, WANG Lei, LU Yan-li, YANG Li-ping, ZHOU Li-ping, NI Lu, CHENG Ming-fang 2015, 14(12): 2467-2476.  DOI: 10.1016/S2095-3119(15)61216-3 Abstract ( )   PDF in ScienceDirect   The effect of long-term straw return on crop yield, soil potassium (K) content, soil organic matter, and crop response to K from both straw and chemical K fertilizer (K2SO4) were investigated in a fixed site field experiment for winter wheat-summer maize rotation in 6 years for 12 seasons. The field experiment was located in northern part of North China Plain with a sandy soil in relatively low yield potential. Two factors, straw return and chemical K fertilizer, were studied with two levels in each factor. Field split design was employed, with two straw treatments, full straw return of previous crop (St) and no straw return, in main plots, and two chemical K fertilizer treatments, 0 and 60 kg K2O ha–1, as sub-plots. The results showed that straw return significantly increased yields of winter wheat and summer maize by 16.5 and 13.2% in average, respectively, and the positive effect of straw return to crop yield showed more effective in lower yield season. Straw return significantly increased K absorption by the crops, with significant increase in straw part. In treatment with straw return, the K content in crop straw increased by 15.9 and 21.8% in wheat and maize, respectively, compared with no straw return treatment. But, straw return had little effect on K content in grain of the crops. Straw return had significant influences on total K uptake by wheat and maize plants, with an increase of 32.7 and 30.9%, respectively. There was a significant correlation between crop yield and K uptake by the plant. To produce 100 kg grain, the wheat and maize plants absorbed 3.26 and 2.24 kg K2O, respectively. The contents of soil available K and soil organic matter were significantly affected by the straw return with an increase of 6.07 and 23.0%, respectively, compared to no straw return treatment. K2SO4 application in rate of 60 kg K2O ha–1 showed no significant effect on wheat and maize yield, K content in crop straw, total K uptake by the crops, soil available K content, and soil organic matter. The apparent K utilization rate (percentage of applied K absorbed by the crop in the season) showed difference for wheat and maize with different K sources. In wheat season, the K utilization rate from K2SO4 was higher than that from straw, while in maize season, the K utilization rate from straw was higher than that from chemical fertilizer. In the whole wheat-maize rotation system, the K absorption efficiency by the two crops from straw was higher than that from K2SO4.

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Long-term organic and inorganic fertilizations enhanced basic soil productivity in a fluvo-aquic soil ZHA Yan, WU Xue-ping, GONG Fu-fei, XU Ming-gang, ZHANG Hui-min, CHEN Li-ming, HUANG Shao-min, CAI Dian-xiong 2015, 14(12): 2477-2489.  DOI: 10.1016/S2095-3119(15)61191-1 Abstract ( )   PDF in ScienceDirect   The improvement of soil productivity depends on a rational input of water and nutrients, optimal field management, and the increase of basic soil productivity (BSP). In this study, BSP is defined as the productive capacity of a farmland soil with its own physical and chemical properties for a specific crop season under local field management. Based on 19-yr data of the long-term agronomic experiments (1989–2008) on a fluvo-aquic soil in Zhengzhou, Henan Province, China, the decision support system for agrotechnology transfer (DSSAT ver. 4.0) crop growth model was used to simulate yields by BSP of winter wheat (Triticum aestivium L.) and summer maize (Zea mays L.) to examine the relationship between BSP and soil organic carbon (SOC) under long-term fertilization. Five treatments were included: (1) no fertilization (control), (2) nitrogen, phosphorus and potassium fertilizers (NPK), (3) NPK plus manure (NPKM), (4) 1.5 times of NPKM (1.5NPKM), and (5) NPK plus straw (NPKS). After 19 yr of treatments, the SOC stock increased 16.7, 44.2, 69.9, and 25.2% under the NPK, NPKM, 1.5NPKM, and NPKS, respectively, compared to the initial value. Among various nutrient factors affecting contribution percentage of BSP to winter wheat and summer maize, SOC was a major affecting factor for BSP in the fluvo-aquic soil. There were significant positive correlations between SOC stock and yields by BSP of winter wheat and summer maize (P<0.01), and yields by BSP of winter wheat and summer maize increased 154 and 132 kg ha–1 when SOC stock increased 1 t C ha–1. Thus, increased SOC accumulation is a crucial way for increasing BSP in fluvo-aquic soil. The manure or straw combined application with chemical fertilizers significantly enhanced BSP compared to the application of chemical fertilizers alone.

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Integrated application of February Orchid (Orychophragmus violaceus) as green manure with chemical fertilizer for improving grain yield and reducing nitrogen losses in spring maize system in northern China BAI Jin-shun, CAO Wei-dong, XIONG Jing, ZENG Nao-hua, GAO Song-juan, Shimizu Katsuyoshi 2015, 14(12): 2490-2499.  DOI: 10.1016/S2095-3119(15)61212-6 Abstract ( )   PDF in ScienceDirect   The development of more efficient management systems is crucial to achieving high grain yields with high nitrogen use efficiency (NUE). February Orchid-spring maize rotation system is a newly established planting system with the benefits of ground cover and potential wind erosion in northern China. A field experiment was conducted to evaluate the effects of integrated application of February Orchid as green manure with reduction of chemical fertilizers (INTEGRATED) on spring maize yield, N uptake, ammonium volatilization, and soil residual mineral N in northern China. Compared to farmers’ traditional fertilization (CON), integrated application of February Orchid as green manure with 30% reduction of nitrogen fertilizers (INTEGRATED) increased maize grain yield and biomass by 9.9 and 10.2%, respectively. The 0–100 cm soil residual Nmin at harvest was decreased by 58.5% and thus nitrogen use efficiency was increased significantly by 26.7%. The nitrogen balance calculation further demonstrated that the INTEGRATED approach performed better than CON with lower apparent nitrogen loss (decreased by 48.9%) which evidenced by the ammonium volatilization of top-dressing fertilizer was decreased by 31.1%, the Nmin movement to the deeper soil layers was reduced, and the apparent nitrogen leaching loss nearly equal to 0 under the INTEGRATED treatment. Therefore, in northern China, integrated application of green manure and chemical fertilizers is an efficient management approach for improving maize yields and NUE simultaneously.

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Microbial community structure and functional metabolic diversity are associated with organic carbon availability in an agricultural soil LI Juan, LI Yan-ting, YANG Xiang-dong, ZHANG Jian-jun, LIN Zhi-an, ZHAO Bing-qiang 2015, 14(12): 2500-2511.  DOI: 10.1016/S2095-3119(15)61229-1 Abstract ( )   PDF in ScienceDirect   Exploration of soil environmental characteristics governing soil microbial community structure and activity may improve our understanding of biogeochemical processes and soil quality. The impact of soil environmental characteristics especially organic carbon availability after 15-yr different organic and inorganic fertilizer inputs on soil bacterial community structure and functional metabolic diversity of soil microbial communities were evaluated in a 15-yr fertilizer experiment in Changping County, Beijing, China. The experiment was a wheat-maize rotation system which was established in 1991 including four different fertilizer treatments. These treatments included: a non-amended control (CK), a commonly used application rate of inorganic fertilizer treatment (NPK); a commonly used application rate of inorganic fertilizer with swine manure incorporated treatment (NPKM), and a commonly used application rate of inorganic fertilizer with maize straw incorporated treatment (NPKS). Denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA gene was used to determine the bacterial community structure and single carbon source utilization profiles were determined to characterize the microbial community functional metabolic diversity of different fertilizer treatments using Biolog Eco plates. The results indicated that long-term fertilized treatments significantly increased soil bacterial community structure compared to CK. The use of inorganic fertilizer with organic amendments incorporated for long term (NPKM, NPKS) significantly promoted soil bacterial structure than the application of inorganic fertilizer only (NPK), and NPKM treatment was the most important driver for increases in the soil microbial community richness (S) and structural diversity (H). Overall utilization of carbon sources by soil microbial communities (average well color development, AWCD) and microbial substrate utilization diversity and evenness indices (H’ and E) indicated that long-term inorganic fertilizer with organic amendments incorporated (NPKM, NPKS) could significantly stimulate soil microbial metabolic activity and functional diversity relative to CK, while no differences of them were found between NPKS and NPK treatments. Principal component analysis (PCA) based on carbon source utilization profiles also showed significant separation of soil microbial community under long-term fertilization regimes and NPKM treatment was significantly separated from the other three treatments primarily according to the higher microbial utilization of carbohydrates, carboxylic acids, polymers, phenolic compounds, and amino acid, while higher utilization of amines/amides differed soil microbial community in NPKS treatment from those in the other three treatments. Redundancy analysis (RDA) indicated that soil organic carbon (SOC) availability, especially soil microbial biomass carbon (Cmic) and Cmic/SOC ratio are the key factors of soil environmental characteristics contributing to the increase of both soil microbial community structure and functional metabolic diversity in the long-term fertilization trial. Our results showed that long-term inorganic fertilizer and swine manure application could significantly improve soil bacterial community structure and soil microbial metabolic activity through the increases in SOC availability, which could provide insights into the sustainable management of China’s soil resource.

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Long-term rice-rice-green manure rotation changing the microbial communities in typical red paddy soil in South China GAO Song-juan, ZHANG Ren-gang, CAO Wei-dong, FAN Yuan-yuan, GAO Ju-sheng, HUANG Jing, BAI Jin-shun, ZENG Nao-hua, CHANG Dan-na, Shimizu Katsu-yoshi, Kristian Thorup-Kristensen 2015, 14(12): 2512-2520.  DOI: 10.1016/S2095-3119(15)61230-8 Abstract ( )   PDF in ScienceDirect   On the basis of a long-term (30 years) field experiment that involved four rotation systems, rice-rice-winter fallow (RRF), rice-rice-ryegrass (RRG), rice-rice-rape (RRP), and rice-rice-milk vetch (RRV), this study described the effects of green manure on the microbial communities in the red paddy soils using 454 pyrosequencing for the 16S rRNA gene. The Chao1 richness and non-parametric Shannon’s index increased in all soil samples that received green manure treatments. The communities’ structures with the green manure applications were significantly dissimilar from that under the winter fallow. Using Metastats tests, many genera in the RRG, RRP and RRV soils were significantly different from those in the RRF soil, including a number of genera that functioned in the nitrogen and sulfur cycles. Analyses of the genera with these functions revealed the shifts in microbial ecosystem functions after long-term green manuring. Changes in the microbial communities increased the ammonium supply and decreased the soil acidification in green-manure-amended soils. Together, these data suggested powerful effects of green manure on both the microbial communities and the biogeochemical cycle driven by the shifts in bacterial functional groups.

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Hyper-spectral characteristics and classification of farmland soil in northeast of China LU Yan-li, BAI You-lu, YANG Li-ping, WANG Lei, WANG Yi-lun, NI Lu, ZHOU Li-ping 2015, 14(12): 2521-2528.  DOI: 10.1016/S2095-3119(15)61232-1 Abstract ( )   PDF in ScienceDirect   The physical and chemical heterogeneities of soils make the soil spectral different and complicated, and it is valuable to increase the accuracy of prediction models for soil organic matter (SOM) based on pre-classification. This experiment was conducted under a controllable environment, and different soil samples from northeast of China were measured using ASD2500 hyperspectral instrument. The results showed that there are different reflectances in different soil types. There are statistically significant correlation between SOM and reflectence at 0.05 and 0.01 levels in 550–850 nm, and all soil types get significant at 0.01 level in 650–750 nm. The results indicated that soil types of the northeast can be divided into three categories: The first category shows relatively flat and low reflectance in the entire band; the second shows that the spectral reflectance curve raises fastest in 460–610 nm band, the sharp increase in the slope, but uneven slope changes; the third category slowly uplifts in the visible band, and its slope in the visible band is obviously higher than the first category. Except for the classification by curve shapes of reflectance, principal component analysis is one more effective method to classify soil types. The first principal component includes 62.13–97.19% of spectral information and it mainly relates to the information in 560–600, 630–690 and 690–760 nm. The second mainly represents spectral information in 1 640–1 740, 2 050–2 120 and 2 200–2 300 nm. The samples with high OM are often in the left, and the others with low OM are in the right of the scatter plot (the first principal component is the horizontal axis and the second is the longitudinal axis). Soil types in northeast of China can be classified effectively by those two principles; it is also a valuable reference to other soil in other areas.

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An asymmetric membrane of polyimide 6FDA-BDAF and its pervaporation desulfurization for n-heptane/thiophene mixtures YANG Xiang-dong, YE Hong, LI Yan-ting, LI Juan, LI Ji-ding, ZHAO Bing-qiang, LIN Yang-zheng 2015, 14(12): 2529-2537.  DOI: 10.1016/S2095-3119(15)61213-8 Abstract ( )   PDF in ScienceDirect   Polyimide (PI) is a type of important membrane material. A soluble polymer was synthesized from 4,4´-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 2,2-bis[4-(4-aminophenoxy) phenyl] hexafluoropropane (BDAF) by the two-step polymerization method. The polymer was proved to be polyimide 6FDA-BDAF by the Fourier transform infrared (FT-IR), the 1H-NMR and 19F-NMR spectra. An asymmetric membrane was prepared with the synthesized polyimide 6FDA-BDAF, it was porous in the 50 μm height bulk and dense in a 3–5 μm height surface. The membrane was used to separate n-heptane/ thiophene mixtures by pervaporation with sulfur (S) contents from 50 to 900 μg g–1. The total flux was enlarged from 7.96 to 37.61 kg m–2 h–1 with temperature increasing from 50 to 90°C. The membrane’s enrichments factor for thiophene were about 3.13 and dependent on the experimental conditions. The experimental results demonstrated that polyimide 6FDA-BDAF would be a potential membrane material for desulfurization and controlled release of the S-containing fertilizer.

Crop Genetics · Breeding · Germplasm Resources

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Development and application of marker-assisted reverse breeding using hybrid maize germplasm GUAN Yi-Xin, WANG Bao-hua, FENG Yan, LI Ping 2015, 14(12): 2538-2546.  DOI: 10.1016/S2095-3119(14)61004-2 Abstract ( )   PDF in ScienceDirect   Humankind has been through different periods of agricultural improvement aiming at enhancing our food supply and the performance of food crops. In recent years, whole genome sequencing and deep understanding of genetic and epigenetic mechanisms have facilitated new plant breeding approaches to meet the challenge of growing population, dwindling resources, and changing climate. Here we proposed a simple and fast molecular breeding method, marker-assisted reverse breeding (MARB), which will revert any maize hybrid into inbred lines with any level of required similarity to its original parent lines. Since all the pericarp DNA of a hybrid is from the maternal parent, whereas one half of the embryo DNA is from the maternal parent and the other half from the paternal parent, so we firstly extract DNA from seed embryo and pericarp of a selected elite hybrid separately and then we derived the genotypes of the two parents with high-density single nucleotide polymorphism (SNP) chips. The following marker-assisted selection was performed based on an Illumina low-density SNP chip designed with 192 SNPs polymorphic between the two parental genotypes, which were uniformly distributed on 10 maize chromosomes. This method has the advantages of fast speed, fixed heterotic mode, and quick recovery of beneficial parental genotypes compared to traditional pedigree breeding using elite hybrids. Meanwhile, MARB has the advantage of not requiring sophisticated transformation and double haploid (DH) technologies over RNA interference (RNAi)-mediated reverse breeding. In addition, MARB can also be used with feed corn harvested from big farms, which is often similar to F2 populations, and the relevant transgenes in the population can be eliminated by marker-assisted selection. As a result, the whole global commercial maize hybrids can be utilized as germplasm for breeding with MARB technology. Starting with an F2 population derived from an elite hybrid, our experiment indicates that with three cycles of marker-assisted selection, selected lines could recover over 80% of the parental genotypes and associated beneficial genes in a fixed heterotic mode. The success application of MARB in maize suggests that this technology is applicable to any hybrid crop to breed new inbreds with improved hybrid performance but the same heterotic mode. As chip technology becomes cheap, it would be expected that polymorphism screening and following marker-assisted selection could be done with one all-purpose high density chip.Several issues associated with MARB were discussed, including its rationale, efficiency and advantages, along with food/ feed and environmental safety issues and applications of MARB in variety protection and marker-assisted plant breeding.

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QTL consistency for agronomic traits across three generations and potential applications in popcorn DONG Yong-bin, ZHANG Zhong-wei, SHI Qing-ling, WANG Qi-lei, ZHOU Qiang, DENG Fei, MA Zhi-yan, QIAO Da-he, LI Yu-ling 2015, 14(12): 2547-2557.  DOI: 10.1016/S2095-3119(15)61060-7 Abstract ( )   PDF in ScienceDirect   Favorable agronomic traits are important to improve productivity of popcorn. In this study, a recombinant inbred line (RIL) population consisting of 258 lines was evaluated to identify quantitative trait loci (QTLs) for nine agronomic traits (plant height, ear height, top height (plant height subtracted ear height), top height/plant height, number of leaves above the top ear, leaf area, stalk diameter, number of tassel branches and the length of tassel) under three environments. Meta-analysis was conducted then to integrate QTLs identified across three generations (RIL, F2:3 and BC2F2) developed from the same crosses. In total, 179 QTLs and 36 meta-QTLs (mQTL) were identified. The percentage of phenotypic variation (R2) explained by any single QTL varied from 3.86 to 28.4%, and 24 QTLs with contributions over 15%. Nine common QTLs located in the same or similar chromosome regions were detected across three generations. Five meta-QTLs were identified including QTLs in three independent studies. Seven important mQTLs were composed of 11–26 QTLs for 4–7 traits, respectively. Only 11 mQTLs were commonly identified in the same or similar chromosome regions across agronomic traits, popping characteristics (popping fold, popping volume and popping rate) and grain yield components (ear weight per plant, grain weight per plant, 100-grain weight, ear length, kernel number per row, ear diameter, row number per ear and kernel ratio) by meta-QTL analysis. In conclusion, we identified a list of QTLs, some of which with much higher contributions to agronomic traits should be valuable for further study in improving both popping characteristics and grain yield components in popcorn.

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Comparative proteomics analysis of pomegranate seeds on fruit maturation period (Punica granatum L.) CAO Shang-yin, NIU Juan, CAO Da, LI Hao-xian, XUE Hui, CHEN Li-na, ZHANG Fu-hong, ZHAO Di-guang 2015, 14(12): 2558-2564.  DOI: 10.1016/S2095-3119(15)61029-2 Abstract ( )   PDF in ScienceDirect   Seeds play a central role in the life cycle of plants. Seed hardness in pomegranates is of economic relevance, yet scarcely studied and poorly understood in China. In this study, we compared the proteomic differences between Zhongnonghong (soft-seeded) and Sanbai (hard-seeded) pomegranates. A total of 892 protein spots from both varieties were detected on two-dimensional electrophoresis gels (2-DE); 76 spots showed greater than a 1.5-fold or less than a 0.66-fold difference (P<0.05) in Zhongnonghong compared to Sanbai, of which 24 exhibited greater than a 2-fold change. Compared with Sanbai, Zhongnonghong possessed 14 up-regulated, and 10 down-regulated proteins. We identified and annotated 5 of these by using MALDI-TOF-TOF MS: pyruvate dehydrogenase (PDH) E1-β family protein (spot 4 609); alanine aminotransferase 2-like (ALT2L); mitochondrial glycine decarboxylase complex P-protein (spot 5 803); phosphofructokinase B (PfkB)-type family of carbohydrate kinase (spot 8 411); and putative dnaK-type molecular chaperone heat shock cognate protein 70 (Hsc70) (spot 9 006). Of these, 3 proteins (spots 4 609, 5 608, 5 803) were hypothesized to play a role in the formation of seed hardness. The other two proteins (spots 8 411, 9 006) were theorized to play a role in protecting the seeds from adverse stress during periods of fruit maturation. This study sets the foundation for further research on molecular mechanisms related to pomegranate seed hardness.

Plant Protection

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Transgenic Arabidopsis thaliana expressing a wheat oxalate oxidase exhibits hydrogen peroxide related defense response WEI Fang, HU Jie, YANG Yan, HAO Zhi-da, WU Rui-hua, TIAN Bao-ming, CAO Gang-qiang, ZANG Xin 2015, 14(12): 2565-2573.  DOI: 10.1016/S2095-3119(15)61040-1 Abstract ( )   PDF in ScienceDirect   Oxalic acid (OA) is considered as an important pathogenetic factor of some destructive diseases caused by some fungal pathogens such as Sclerotinia sclerotiorum. Oxalate degradation is important for plant health, and plants that contain oxalate oxidase (OXO) enzymes could breakdown oxalate into CO2 and H2O2, which subsequently evokes defense responses. However, some species, such as Arabidopsis thaliana, have no oxalate oxidase activity identified to date. The present study aims to develop transgenic Arabidopsis expressing a wheat oxalate oxidase, to test for the response to OA exposure and fungal infection by S. sclerotiorum. The results showed that the transgenic Arabidopsis lines that expressed the wheat OXO exhibited enhanced resistance to OA exposure and S. sclerotiorum infection in the tolerance assays. In the same manner, it could convert OA to CO2 and H2O2 to a higher extent than the wild-type. Intensive osmotic adjustments were also detected in the transgenic Arabidopsis lines. The higher level of produced H2O2 subsequently induced an elevated activity of antioxidant enzymes including superoxide dismutase (SOD) and peroxidase (POD) in the transgenic Arabidopsis plants. The present study indicated that the expression of a gene encoding wheat OXO could induce intensive osmotic adjustments and hydrogen peroxide related defense response, and subsequently increased tolerance to S. sclerotiorum in transgenic A. thaliana.

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Differential effects of insecticides on mitochondrial membrane fluidity and ATPase activity between the wolf spider and the rice stem borer LI Hai-ping, CHANG Jing, FENG Tao, GAO Xi-wu 2015, 14(12): 2574-2580.  DOI: 10.1016/S2095-3119(15)61074-7 Abstract ( )   PDF in ScienceDirect   Differential effects of methamidophos and three pyrethroids on ATPase activity and membrane fluidity of mitochondria were investigated between the wolf spider (Pirata subpiraticus (Boes. et Str.)) and the rice stem borer (Chilo suppressalis (Walker)). Based on a comparison of LD50 values, the toxicities of the tested insecticides were higher to the wolf spider than to the rice stem borer. Cyhalothrin at 1×10–4 mmol L–1 caused inhibition of the mitochondrial Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities, and it’s inhibitions on Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities were significantly higher in the wolf spider (44 and 28%) than in the rice stem borer (19 and 11%). Methamidophos at 1×10–4 mmol L–1 decreased Ca2+-Mg2+-ATPase activity by 16 and 27% in the wolf spider and the rice stem borer, respectively, but no significant effect on the specific activity of Na+-K+-ATPase was observed. The DPH (1,6-diphenyl-1,3,5-hexatriene) fluorescence polarization values of mitochondrial membranes were not significantly affected by methamidophos in either species. However, cyhalothrin and alpha-cypermethrin induced the values of DPH polarization of mitochondrial membrane increasing with the concentration of cyhalothrin and alpha-cypermethrin from 20 to 100 μmol L–1 in the rice stem borer and the wolf spider. Effect of ethofenprox on fluidity of the wolf spider and the rice stem borer was contrary. These results suggest that both inhibition of membrane ATPase and changes of membrane fluidity could be appended to the action mechanisms of pyrethroid insecticides.

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Effects of imidacloprid and thiamethoxam as seed treatments on the early seedling characteristics and aphid-resistance of oilseed rape HUANG Liang, ZHAO Chun-lin, HUANG Fang, BAI Run-e, Lü Yao-bin, YAN Feng-ming, HAO Zhong-ping 2015, 14(12): 2581-2589.  DOI: 10.1016/S2095-3119(15)61140-6 Abstract ( )   PDF in ScienceDirect   Seed treatments with the neonicotinoid insecticides imidacloprid and thiamethoxam were evaluated to determine whether the chemicals at effective concentrations for aphid control would influence the germination and early growth of oilseed rape, Brassica napus. Treatment with imidacloprid or thiamethoxam did not affect the cumulative germination rate, but significantly inhibited establishment potential by suppressing root system development in the cotyledon stage. However, these alterations in seedling development in the thiamethoxam-treated seeds appeared not to be detrimental as leaves developed; in contrast, for the seedlings with imidacloprid as seed treatment agent, a significantly decreased shoot/root ratio was still evident at the late two-leaf stage. After two leaves developed, chlorophyll content per leaf in the thiamethoxam treatment was significantly higher than that of the control, while chlorophyll content per leaf in the imidacloprid treatment remained close to that in the control. Most other parameters, i.e., height, leaf area, weight of stem, leaf or root, and other growth indexes, between the treatments and the control showed no significant difference. Additionally, it was found that storage time of the treated seeds had a significant effect on cumulative germination rate. Treatment 30 d before planting significantly reduced germination relative to that of the control. All of the plants treated with neonicotinoids were shown to have significant anti-aphid characteristics that persisted until the end of the trial.

Animal Science · Veterinary Science

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Genome-wide association study for rib eye muscle area in a Large White×Minzhu F2 pig resource population GUO Yun-yan, ZHANG Long-chao, WANG Li-xian, LIU Wen-zhong 2015, 14(12): 2590-2597.  DOI: 10.1016/S2095-3119(14)60981-3 Abstract ( )   PDF in ScienceDirect   Rib eye muscle area (REMA) is an economically important trait and one of the main selection criteria for breeding in the swine industry. In the genome-wide association study (GWAS), the Illumina PorcineSNP60 BeadChip containing 62 163 single nucleotide polymorphisms (SNPs) was used to genotype 557 pigs from a porcine Large White×Minzhu intercross population. The REMA (at the 5th–6th, 10th–11th and the last ribs) was measured after slaughtered at the age of (240±7) d for each animal. Association tests between REMA trait and SNPs were performed via the Genome-Wide Rapid Association using the Mixed Model and Regression-Genomic Control (GRAMMAR-GC) approach. From the Ensembl porcine database, SNP annotation was implemented using Sus scrofa Build 10.2. Thirty-three SNPs on SSC12 and 3 SNPs on SSC2 showed significant association with REMA at the last rib at the chromosome-wide significance level. None of the SNPs of REMA at the 5th–6th rib and only a few numbers of the SNPs of REMA at the 10th–11th ribs were found in this study. The Haploview V3.31 program and the Haplo.Stats R package were used to detect and visualize haplotype blocks and to analyze the association of the detected haplotype blocks with REMA at the last rib. A linkage analysis revealed that 4 haplotype blocks contained 4, 4, 2, and 4 SNPs, respectively. Annotations from pig reference genome suggested 2 genes (NOS2, NLK) in block 1 (266 kb), one gene (TMIGD1) in block 2 (348 kb), and one gene (MAP2K4) in block 3 (453 kb). A functional analysis indicated that MYH3 and MYH13 genes are the potential genes controlling REMA at the last rib. We screened several candidate intervals and genes based on the SNPs location and the gene function, and inferred that NOS2 and NLK genes maybe the main genes of REMA at the last ribs.

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Effect of graded levels of fiber from alfalfa meal on apparent and standardized ileal digestibility of amino acids of growing pigs CHEN Liang, GAO Li-xiang, LIU Li, DING Ze-ming, ZHANG Hong-fu 2015, 14(12): 2598-2604.  DOI: 10.1016/S2095-3119(14)60924-2 Abstract ( )   PDF in ScienceDirect   Two experiments were conducted to determine the effects of fiber level from alfalfa meal and sampling time on the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of amino acids (AA) in growing pigs. A total of 24 ileal-cannulated pigs (Duroc×(Large White×Landrace) with body weight (21.4±1.5) kg) were randomly allotted to 4 treatments. The pigs were provided a corn-soybean meal diet or a diet containing 5, 10 or 20% of alfalfa meal during two 10-d experimental periods. The AID of AA was measured. Six ileal-cannulated pigs were fed a protein-free diet in order to estimate the endogenous protein losses and SID of AA. Ileal AA digestibility was not affected by inclusion of 5 or 10% alfalfa meal in the diet (P>0.05). The AID of His, Lys, Met, Phe, Thr, Val, Ala, Asp, Cys, Gly, Pro, Ser and Tyr reduced by 2.0–6.8% with the addition level of alfalfa meal (linear, P<0.05). The SID of His, Lys, Ser, Thr and Tyr decreased by 2.2–4.3% as the level of alfalfa meal in the diet increased (linear, P<0.05). The AID and SID of AA were not affected by the sampling time (P>0.05). A multiple linear regression analysis, taking into account both the soluble and insoluble fiber content in the diets, explained more than 36% of variation in SID of Ser and Thr (P<0.05). In conclusion, the corn-soybean meal diet containing 10% of alfalfa meal did not affect ileal AA digestion. The AID and SID of AA were similar between two sampling times. Increasing the concentration of total dietary fiber from 12.3 to 21.4% by adding graded levels of alfalfa meal (0–20%) to a corn-soybean meal control diet induced a linear reduction in AID and SID of most AA. Soluble and insoluble fibers from alfalfa meal have differential roles in the AA digestion, which may help explain the variation observed in the SID of partial AA. These findings would provide important information for dietary fiber level and composition related to AA digestion.

Animal Science · Veterinary Science

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Energy requirements of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation LOU Can, SI Bing-wen, DENG Kai-dong, MA Tao, JIANG Cheng-gang, TU Yan, ZHANG Nai-feng, JI Shou-kun, CHEN Dan-dan, DIAO Qi-yu 2015, 14(12): 2605-2617.  DOI: 10.1016/S2095-3119(14)60963-1 Abstract ( )   PDF in ScienceDirect   This experiment was conducted to investigate the energy requirement of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation. Fifteen ewes after parturition were randomly assigned to three treatments: ad libitum (100%) feed intake and 80 or 60% ad libitum intake, and another nine non-pregnant ewes were assigned to a blank control group. Digestibility trials were performed in the non-pregnant ewes and in the lactating ewes on the 20th, 50th, and 80th d of lactation. In parallel with the digestibility trial, a respirometry experiment was conducted to determine the methane and carbon dioxide production with an open-circuit respirometry system that was equipped with respiratory chambers. The net energy (NE) and metabolizable energy (ME) requirements for maintenance and growth were calculated using the carbon and nitrogen balance method. The results revealed that the carbon (C) and nitrogen (N) excretions and energy losses at faeces and urine, as well as the output of methane and CO2, increased significantly with decreasing feed intake (P<0.01). The apparent digestibilities of C in the stages of non-pregnancy and early, middle and late lactation were 55.8–58.3%, 62.5–73.8%, 64.8– 71.3%, and 61.7–65.0%, respectively, and the apparent digestibilities of N were 45.2–51.3%, 73.7–82.7%, 72.8–80.5%, and 73.6–76.5%, respectively. The corresponding energy apparent digestibilities were 52.0–56.3%, 60.7–76.6%, 61.0–68.8%, and 61.4–67.7%, respectively. The ME/DE (digestible energy) values were 79.5–85.9%, 79.4–83.5%, 81.0%–85.3% and 78.6–82.9%, respectively. The maintenance requirements of NE, ME, and the efficiencies of ME utilisation for maintenance during the stages of non-pregnancy and early, middle and late lactation were 215.5, 253.1, 247.7, and 244.7 kJ kg–1 BW0.75 d, and 372.4, 327.1, 320.9, and 362.0 kJ kg–1 BW0.75 d, and 0.58, 0.77, 0.77, and 0.68, respectively. The ME requirement for the growth of non-pregnant ewes was 31.3 MJ kg–1 BW gain.

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Analysis of the function of D279N mutation of VP2 of infectious bursal disease virus QI Xiao-le, LU Zhen, WANG Nian, CHEN Yu-ming, ZHANG Li-zhou, GAO Li, LI Kai, REN Xian-gang, WANG Yong-qiang, GAO Hong-lei, GAO Yu-long, Nicolas Eterradossi, WANG Xiao-mei 2015, 14(12): 2618-2625.  DOI: 10.1016/S2095-3119(14)60933-3 Abstract ( )   PDF in ScienceDirect   Infectious bursal disease virus (IBDV) is responsible for the highly contagious infectious bursal disease of chickens. Further understanding the gene-function is necessary to design the tailored vaccine. The amino acid residue 279, located on strand PF of VP2, is one of the three residues that have been reported to be involved in cell-tropism but with some inconsistency. In this study, to further clarify the amino acids involved in the cell tropism of IBDV, a series of mutations about residue 279 were introduced into the VP2 of vvIBDV Gx strain. With the reverse genetic system, we found single mutation of D279N, double mutations of D279N/A284T or Q253H/D279N were not enough to adapt IBDV to chicken embryo fibroblast (CEF) cell. To evaluate whether residue 279 could influence the replication and virulence of IBDV, the virus rGxHT-279 with three mutations (Q253H/D279N/A284T) was rescued and evaluated. Results showed that the mutation of residue 279 in VP2 had no efficient effects on both the replication efficiency in vitro and the virulence to SPF chickens of IBDV. In summary, the results demonstrated that residue 279 of VP2 did not contribute efficiently to cell tropism, replication efficiency, and virulence of IBDV at least in some strains. These findings provided further information for understanding the gene function of IBDV.