Wheat-growing Season Research Articles

Assessment of short- and long-term memory in trends of major climatic variables over Iran: 1966–2015

In arid and semi-arid regions, water scarcity is the crucial issue for crop production. Identifying the spatial and temporal trends in aridity, especially during the crop-growing season, is important for farmers to manage their agricultural practices. This will become especially relevant when considering climate change projections. To reliably determine the actual trends, the influence of short- and long-term memory should be removed from the trend analysis. The objective of this study is to investigate the effect of short- and long-term memory on estimates of trends in two aridity indicators—the inverted De Martonne (ϕIDM) and Budyko (ϕB) indices. The analysis is done using precipitation and temperature data over Iran for a 50-year period (1966–2015) at three temporal scales: annual, wheat-growing season (October–June), and maize-growing season (May–November). For this purpose, the original and the modified Mann–Kendall tests (i.e., modified by three methods of trend free pre-whitening (TFPT), effective sample size (ESS), and long-term persistence (LTP)) are used to investigate the temporal trends in aridity indices, precipitation, and temperature by taking into account the effect of short- and long-term memory. Precipitation and temperature data were provided by the Islamic Republic of Iran Meteorological Organization (IRIMO). The temporal trend analysis showed that aridity increased from 1966 to 2015 at the annual and wheat-growing season scales, which is due to a decreasing trend in precipitation and an increasing trend in mean temperature at these two timescales. The trend in aridity indices was decreasing in the maize-growing season, since precipitation has an increasing trend for most parts of Iran in that season. The increasing trend in aridity indices is significant in Western Iran, which can be related to the significantly more negative trend in precipitation in the West. This increasing trend in aridity could result in an increasing crop water requirement and a significant reduction in the crop production and water use efficiency. Furthermore, the modified Mann–Kendall tests indicated that unlike temperature series, precipitation, ϕIDM, and ϕB series are not affected by short- and long-term memory. Our results can help decision makers and water resource managers to adopt appropriate policy strategies for sustainable development in the field of irrigated agriculture and water resources management.

Effects of controlled-release fertilizer on nitrous oxide and nitric oxide emissions during wheat-growing season: field and pot experiments

Outdoor pot and field experiments were conducted to study the effect of controlled-release fertilizer (CRF) on nitrous oxide (N2O) and nitric oxide (NO) emissions and wheat yields during the 2011–2013. Three treatments, namely conventional N fertilizer (CF; urea and compound fertilizer, 300 kg N ha−1), CRF (210 kg N ha−1, which is 70% of the N applied in the CF treatment), and check (CK, 0 N), were applied in three replicates. The soil temperature, soil moisture, N uptake by wheat, wheat yield, and variations in NO3–N, NH4–N, N2O, and NO emissions were measured. Results showed that the average total N2O and NO emissions in the CRF treatment in the pot and field experiments decreased by 26.5 and 19.4%, respectively. The average N2O and NO emission factors decreased by 32.1 and 24.8%, respectively, compared with the CF treatment. However, the CRF wheat yields were insignificantly lower than those from the CF treatment. Results indicated that CRF could improve the efficiency of fertilizer N use, reduce labor cost, and increase economic benefit without sacrificing the yield.

Regional Differences of Winter Wheat Phenophase and Grain Yields Response to Global Warming in the Huang-Huai-Hai Plain in China Since 1980s

The Huang-Huai-Hai (3H) Plain is one of the most important winter wheat production areas in China. In this paper, the relationship between climate factors, growth duration and yield of winter wheat from 1980 to 2013 in the 3H Plain was examined to reveal the responses of winter wheat growth duration and yield to global warming. The results showed that daily average, maximum and minimum air temperatures during the winter wheat growing season increased by 0.43, 0.35 and 0.54 °C every 10 years, respectively, on average across the whole region in the past 30 years, although temperatures varied with different spatial distributions. Historical changes in winter wheat phenology have been observed across the 3H Plain since 1990s in that the vegetative growth period of winter wheat shortened by 4.6 days, the reproductive growth period increased by 1.8 days and the whole growth period was shortened by 2.9 days per 10-year period. The changes in the growth period were significantly negatively correlated with minimum temperature increases. The 1 °C minimum temperature increase shortened the vegetative growth period of winter wheat by 4.5 days. Accounting for agricultural technical improvement and other non-climatic factors, an average temperature increase of 1 °C enhanced winter wheat yield by 2.1% in the northern plain and decreased yield by 4.0% in the southern plain. We found an average temperature during the winter wheat growth season of 8.6 °C as the yield variation threshold, and the yield would decrease above this threshold in this region.

Flux footprint of winter wheat farmland ecosystem in the North China Plain

The flux data of winter wheat farmland ecosystem observed by eddy covariance system in the North China Plain from 2013 to 2014 were used to combine with the footprint model FSAM. The temporal and spatial distributions of footprint of winter wheat farmland ecosystem in the North China Plain were analyzed. The differences of footprint distribution in different atmospheric stratification and growing seasons were contrastively studied. The results indicated that in the predominant wind direction, the source areas of stable atmospheric stratification were larger than unstable atmospheric stratification during the growing season of winter wheat. When the wind direction was between 0°-90°, the source area of stable atmospheric stratification was about 17.8 m longer than unstable atmospheric stratification in initial growing season. The source area of stable atmospheric stratification was about 11 m longer than unstable atmospheric stratification in late growing season. The location of the maximum flux footprint in initial growing season was 15 m (stable atmospheric stratification) and 12.4 m (unstable atmospheric stratification) further away from the observing tower than late growing season, respectively. Meanwhile, the location of the maximum flux footprint in stable atmospheric stratification was 5 m (initial growing season) and 2.4 m (late growing season) further away from the observing tower than unstable atmospheric stratification, respectively. When the wind direction was non-dominant between 90°-180°, the location of the maximum flux footprint in diffe-rent growing seasons and atmospheric stratification were 67.8 and 53.4, 47.0 and 30.8 m away from the observing tower, respectively. When the wind direction was between 270°-360°, the location of the maximum flux footprint in different growing seasons and atmospheric stratification were 58.8 and 42.0, 41.1 and 33.1 m away from the observing tower, respectively. The flux information was mainly from the northeast, southwest and southeast, which accounted for 35.4%, 32.5% and 19.4% of the whole gro-wing season scale, respectively. The major changes of flux footprint in the whole gro-wing season of winter wheat were observed from 16.0 to 173.8 m in the northeast and from 14.7 to 209 m in the southwest. The flux information was all from the farmland ecosystem. The characteristics of diurnal variations of flux footprint in two typical dates were obvious. The source area changed with atmospheric stratification and wind direction. The flux information was all from farmland ecosystem at night, while little flux information was from residential area and orchard at daytime. The quantitative results of this study could provide basis for the research of flux footprint in farmland ecosystem.

Spatial and temporal distribution of pesticides and PCBs in the atmosphere using XAD-resin based passive samplers: A case study in the Quequén Grande River watershed, Argentina

XAD-resin based passive air samplers were deployed at 10 sites in the Quequén Grande River watershed in Argentina during three periods to evaluate the spatial and temporal variations of pesticides and PCBs in the atmosphere. Endosulfan and chlorpyrifos were the most prevalent pesticide because of their continued usage in Argentina, while DDTs, HCHs, chlordanes, dieldrin and heptachlors registered lower levels, reflecting their use in the past. Atmospheric endosulfan levels were 1–2 orders of magnitude higher during the application period (application: 800–12,000 pg/m3, pre- and post-application: <2–350 pg/m3), suggesting that its use in the area continued even after a ban came into effect. The remaining organochlorine pesticides also reached higher concentrations during this period, which is more likely attributable to temperature controlled air-surface exchange than current applications. The highest concentrations of chlorpyrifos were recorded during the application period, in particular at agricultural sites, where its use is wide-spread on soybean fields. The fungicide chlorothalonil was found predominantly at urban sites and in proximity to Quequén harbor, suggesting that its use might be domestic and as a biocide in antifouling paints. A different temporal pattern was observed for the herbicide trifluralin, suggesting its use in the early stages of the wheat-growing season during winter. Limited spatial variations in PCBs levels indicate a diffuse contamination source in the study area, while their relatively high correlation with temperature suggests re-volatilization from local sources. Relative enrichment of lighter PCBs congeners could be attributed to re-evaporation from secondary sources as well as atmospheric transport from urban sites.

Characteristics of Biochar-mediated N2O Emissions from Soils of Different Surface Conditions

It was aimed to investigate the response to biochar addition on N2O gas production and emission in different surface conditions. To study the dynamic changes of soil N2O release, soil nitrate(NO3--N) and ammonium(NH4+-N), a field trials experiment was conducted from 2014 to 2015 in wheat and corn season, which contained three treatments[the blank control group (CK), biochar applied at 5 t·(hm2·a)-1(BC5) and 45 t·(hm2·a)-1(BC45), respectively] under crop cultivation(+) and non-cultivation(-) condition. The results indicated that:1 During the season of wheat growth, the soil N2O emissions of CK+, BC5+, BC45+ were 21.70-88.91, 21.42-130.09, 64.44-179.58 μg·(m2·h)-1 respectively, and that of BC45+ possessed a higher value than those of the other treatments(P<0.05). Compared with wheat winter period, the soil N2O emissions of the three treatments decreased evidently in wheat peak stage(returning green and jointing stage, booting and heading stage) (P<0.05), and the amplification of BC45+ reduced by 18.43% and 14.62% in comparison with CK+ and BC5+ in wheat booting and heading stages. In the early stage of maize growth, the soil N2O emissions of BC45+ were significantly increased compared with CK+ and BC5+(P<0.05). However, there were no significant differences among treatments of maize heading stage and mature stage. It showed that the biochar-mediated promotion effect of soil N2O emissions was effectively inhibited by crop growth and the increase of surface mulch. Besides, the result of soil N2O release in the same treatment had also confirmed this conclusion in bare land. 2 Under the conditions of wheat cultivation and homochronous non-cultivation, the soil NO3--N and NH4+-N contents of BC5+ and BC45+ treatments were raised with respect to CK+, but the values dropped significantly in wheat peak stage, especially for BC45+ treatment, with 96.44% and 69.40% decrease respectively. The soil inorganic nitrogen content of maize growth season had a similar trend in wheat season. Parallel to this result of the apparently falling soil NO3--N and NH4+-N concentrations, the soil N2O emissions of BC45+ also declined remarkably in peak stage. The decline in respiratory substrate caused by the increase of nitrogen uptake by crop growth, may be one of the reasons for the decrease of N2O emission. 3 In wheat growth season, the soil pH values of the biochar treatments were improved from 4.62 to 5.18. In maize season, the soil pH values ranged from 4.42 to 5.02. When the soil pH value was relatively low, the soil N2O emission was high, and vice versa. The soil N2O emission was partly influenced by the soil pH value.

Identification of Candidate Genes and Biosynthesis Pathways Related to Fertility Conversion by Wheat KTM3315A Transcriptome Profiling.

The Aegilops kotschyi thermo-sensitive cytoplasmic male sterility (K-TCMS) system may facilitate hybrid wheat (Triticum aestivum L.) seed multiplication and production. The K-TCMS line is completely male sterile during the normal wheat-growing season, whereas its fertility can be restored in a high-temperature environment. To elucidate the molecular mechanisms responsible for male sterility/fertility conversion and candidate genes involved with pollen development in K-TCMS, we employed RNA-seq to sequence the transcriptomes of anthers from K-TCMS line KTM3315A during development under sterile and fertile conditions. We identified 16840 differentially expressed genes (DEGs) in different stages including15157 known genes (15135 nuclear genes and 22 plasmagenes) and 1683 novel genes. Bioinformatics analysis identified possible metabolic pathways involved with fertility based on KEGG pathway enrichment of the DEGs expressed in fertile and sterile plants. We found that most of the genes encoding key enzyme in the phenylpropanoid biosynthesis and jasmonate biosynthesis pathways were significant upregulated in uninucleate, binuclate or trinucleate stage, which both interact with MYB transcription factors, and that link between all play essential roles in fertility conversion. The relevant DEGs were verified by quantitative RT-PCR. Thus, we suggested that phenylpropanoid biosynthesis and jasmonate biosynthesis pathways were involved in fertility conversion of K-TCMS wheat. This will provide a new perspective and an effective foundation for the research of molecular mechanisms of fertility conversion of CMS wheat. Fertility conversion mechanism in thermo-sensitive cytoplasmic male sterile/fertile wheat involves the phenylpropanoid biosynthesis pathway, jasmonate biosynthesis pathway, and MYB transcription factors.

Droughts in India from 1981 to 2013 and Implications to Wheat Production

Understanding drought from multiple perspectives is critical due to its complex interactions with crop production, especially in India. However, most studies only provide singular view of drought and lack the integration with specific crop phenology. In this study, four time series of monthly meteorological, hydrological, soil moisture, and vegetation droughts from 1981 to 2013 were reconstructed for the first time. The wheat growth season (from October to April) was particularly analyzed. In this study, not only the most severe and widespread droughts were identified, but their spatial-temporal distributions were also analyzed alone and concurrently. The relationship and evolutionary process among these four types of droughts were also quantified. The role that the Green Revolution played in drought evolution was also studied. Additionally, the trends of drought duration, frequency, extent, and severity were obtained. Finally, the relationship between crop yield anomalies and all four kinds of drought during the wheat growing season was established. These results provide the knowledge of the most influential drought type, conjunction, spatial-temporal distributions and variations for wheat production in India. This study demonstrates a novel approach to study drought from multiple views and integrate it with crop growth, thus providing valuable guidance for local drought mitigation.

Multi-temporal monitoring of wheat growth by using images from satellite and unmanned aerial vehicle

Recently near-ground remote sensing using unmanned aerial vehicles (UAV) witnessed wide applications in obtaining field information. In this research, four Rapideye satellite images and eight RGB images acquired from UAV were used from early June to the end of July, 2015 covering two experimental winter wheat fields, in order to monitor wheat canopy growth status and analyze the correlation among satellite images based normalized difference vegetation index (NDVI) with UAV’s RGB images based visible-band difference vegetation index (VDVI) and ground variables of the sampled grain protein contents. Firstly, through image interpretation of UAV’s multi-temporal RGB images with fine spatial resolution, the wheat canopy color changes could be intuitively and clearly monitored. Subsequently, by monitoring the changes of satellite images based NDVI as well as VDVI values and UAV’s RGB images based VDVI values, the conclusions were made that these three vegetation indices demonstrated the same and synchronized trend of increasing at the early stage of wheat growth season, reaching up to peak values at the same timing, and starting to decrease since then. The results of the correlation analysis between NDVI of satellite images and sampled grain protein contents show that NDVI has good predicative capability for mapping grain protein content before ripening growth stage around June7, 2015, while the reliability of using satellite image based NDVI to predict grain protein contents becomes worse as ripening stage approaches. The regression analysis between UAV’s RGB image based VDVI and satellite image based VDVI as well as NDVI showed good coefficients of determination. It is concluded that it is feasible and practical to temporally complement satellite remote sensing by using UAV’s RGB images based vegetation indices to monitor wheat growth status and to map within-field spatial variations of grain protein contents for small scale farmlands. Keywords: satellite remote sensing, UAV remote sensing, wheat growth monitoring, wheat lodging; wheat protein content, multi-temporal images, NDVI DOI: 10.25165/j.ijabe.20171005.3180 Citation: Du M M, Noguchi N, Itoh A, Shibuya Y. Multi-temporal monitoring of wheat growth by using images from satellite and unmanned aerial vehicle. Int J Agric & Biol Eng, 2017; 10(5): 1–13.

Different Response Patterns of Soil Respiration to a Nitrogen Addition Gradient in Four Types of Land-Use on an Alluvial Island in China

It has been well documented that nitrogen (N) additions significantly affect soil respiration (R s) and its components [that is, autotrophic (R a) and heterotrophic respiration (R h)] in terrestrial ecosystems. These N-induced effects largely result from changes in plant growth, soil properties (for example, pH), and/ or microbial community. However, how R s and its components respond to N addition gradients from low to high fertilizer application rates and what the differences are in diverse land-use types remain unclear. In our study, a field experiment was conducted to examine response patterns of R s to a N addition gradient at four levels (0, 15, 30, and 45 g N m−2 y−1) in four types of land-use (paddy rice–wheat and maize–wheat croplands, an abandoned field grassland, and a Metasequoia plantation) from December 2012 to September 2014 in eastern China. Our results showed that N addition significantly stimulated R s in all four land-use types and R h in croplands (paddy rice–wheat and maize–wheat). R s increased linearly with N addition rates in croplands and the plantation, whereas in grassland, it exhibited a parabolic response to N addition rates with the highest values at the moderate N level in spite of the homogeneous matrix for all four land-use types. This suggested higher response thresholds of R s to the N addition gradient in croplands and the plantation. During the wheat-growing season in the two croplands, R h also displayed linear increases with rising N addition rates. Interestingly, N addition significantly decreased the apparent temperature sensitivity of R s and increased basal R s. The different response patterns of R s to the N addition gradient in diverse land-use types with a similar soil matrix indicate that vegetation type is very important in regulating terrestrial C cycle feedback to climate change under N deposition.

Phosphorus fertilization to the wheat-growing season only in a rice–wheat rotation in the Taihu Lake region of China

Crop production in the Taihu Lake Region (TLR) of China has been greatly improved by increasing phosphorus (P) fertilizer input. However, overuse has led to accumulation of P and increased the risk of environmental pollution. In this study, we investigated the effects of four P fertilization regimes in paddy soils at two field stations (CS1 and CS2) during four years of a rice-wheat cropping system. The fertilization regimes were as follows: P fertilization only during the wheat-growing season (PW), P fertilization only during the rice-growing season (PR), P fertilization during both the rice- and wheat-growing seasons (PR+W, current farming practice), and no P fertilization during either season (Pzero, control). The PW treatment did not reduce crop yield in either CS1 or CS2 compared to the PR+W. Moreover, soil Olsen-P concentrations during each rice-wheat rotation were maintained, and a positive increase in phosphate utilization efficiency by 1.2–3.6% (p>0.05) was observed over the four rice-wheat rotations. In contrast, the PR treatment reduced the straw and grain yield of wheat by 8.74–43.2 and 19.4–47.7%, respectively, as did the Pzero treatment by 7.21–60.0 and 19.6–84.1%, respectively (p<0.05). During the rice season, the PW treatment showed no significant differences in P fractionation and microorganism communities compared to the PR and PR+W treatments. The results suggest that the PW fertilization regime is suitable for rice–wheat rotation systems in agro-ecosystems such as the Taihu Lake Region of China.

Use of slow-release plant infochemicals to control aphids: a first investigation in a Belgian wheat field.

Using infochemicals to develop a push–pull strategy in pest control is a potential way to promote sustainable crop production. Infochemicals from plant essential oils were mixed with paraffin oil for slow release in field experiments on wheat to control the population density of cereal aphids and to enhance their natural enemies. (Z)-3-Hexenol (Z3H) attracted Metopolophum dirhodum and Sitobion avenae, the predominant species on wheat in Belgium, and may be a useful infochemical for aphid control by attracting aphids away from field plots. Release of (E)-β-farnesene (EBF) or a garlic extract (GE) led to a significant decrease in the abundance of wheat aphids. The main natural enemies of cereal aphids found were lacewings (47.8%), hoverflies (39.4%), and ladybirds (12.8%). Ladybird abundance varied little before the end of the wheat-growing season. Our results suggest that these chemicals can form the basis of a “push–pull” strategy for aphid biological control, with GE and EBF acting as a pest- and beneficial-pulling stimulus and Z3H for aphid pulling.

A data fusion and spatial data analysis approach for the estimation of wheat grain nitrogen uptake from satellite data

ABSTRACTThe selection of the optimal band combination for the estimation of specific crop variables is a key aspect in order to obtain reliable estimation of in-field variability from multi- and hyperspectral remote-sensing data. The selection of the bands is strongly influenced by the phenological stage of the crop at the acquisition time. In this work, the influence of the growing stage on the combination of spectral bands related to grain nitrogen (N) uptake in wheat was evaluated using multispectral (Satellite Pour l’Observation de la Terre – SPOT) and hyperspectral (Compact High Resolution Imaging Spectrometer – CHRIS-PROBA) satellite images at different growth stages over two wheat growth seasons in central Italy. In order to identify the more appropriate covariates (spectral bands) for each phenological stage, stepwise regression with backward selection was combined with stepwise variance inflation factors (VIFs) analysis and linear mixed effect model (LMEM). The results obtained in this study suggest that the spectral region most related to N uptake varies over the growing season of the wheat crop. For SPOT data, near-infrared (NIR) region was selected at all the phenological stages in both growing seasons, except for the latest stage, with low chlorophyll content due to the onset of senescence, in which the red band was selected. At stem elongation, the shortwave infrared (SWIR) band of SPOT data was also selected. At this stage, the best N estimation accuracy was obtained using an LMEM (root mean square error, RMSE = 0.012 t ha−1). The inclusion of a spatial component in the estimation model by means of LMEMs provided a more accurate estimation than ordinary least square (OLS) models at all growth stages. The test carried out with CHRIS-PROBA data at the fourth stage confirmed the importance of NIR and in particular of the red-edge region for N uptake prediction. A novel methodology is proposed, which involves two crucial aspects in the context of the use of remote-sensing data in precision agriculture: i) the standardization of the spatial resolution for in-field and satellite data by a geostatistical data technique (data fusion); and ii) the selection of the most appropriate spectral bands for each phenological stage, taking into account both correlation with the target variable and collinearity.

A Newly Practice to Mitigate N2O Emission from Winter Wheat Soil by Intercropping Isatis indigotica

&lt;p&gt;Greenhouse gas (GHG) emitted from agricultural field was received considerable attention worldwide, depending on differed land use and cropping system. An innovative strategy to mitigate agricultural N&lt;sub&gt;2&lt;/sub&gt;O by intercropping traditional Chinese medicinal herb &lt;em&gt;Isatis indigotica&lt;/em&gt; in winter wheat field was assessed. By exogenously applying root exudates of &lt;em&gt;I. indigotica&lt;/em&gt; in a lab incubation study, we testify and quantify whether N&lt;sub&gt;2&lt;/sub&gt;O emission was inhibited.&lt;/p&gt;&lt;p&gt;Results demonstrated great reduction of N&lt;sub&gt;2&lt;/sub&gt;O emission from winter field soil intercropping &lt;em&gt;I. indigotica&lt;/em&gt; (NPKWR-N+P+K+wheat+&lt;em&gt;I. indigotica&lt;/em&gt;) compared to CK (NPKW-N+P+K+wheat but no &lt;em&gt;I. Indigotica&lt;/em&gt;) was found. N&lt;sub&gt;2&lt;/sub&gt;O emission in treatment of NPKWR was decreased by 32% than that in CK during the whole winter wheat growth season, among which the best decreasing N&lt;sub&gt;2&lt;/sub&gt;O emission was obtained in the stage of grain filling of winter wheat, N&lt;sub&gt;2&lt;/sub&gt;O emitting from NPKWR was reduced by 60% than that in CK. The N&lt;sub&gt;2&lt;/sub&gt;O emission intensity per kg of harvested wheat grain treated with &lt;em&gt;I. indigotica&lt;/em&gt; was declined to 0.15 g N&lt;sub&gt;2&lt;/sub&gt;O/kg grain from 0.24 g N&lt;sub&gt;2&lt;/sub&gt;O/kg grain in CK.&lt;/p&gt;&lt;p&gt;qPCR (quantitative fluorescent polymerase chain reaction) analysis indicated nitrifying microbial population in wheat soil was severely suppressed by &lt;em&gt;I. indigotica&lt;/em&gt;. The number of qPCR gene copy in both soil intercropping &lt;em&gt;I. indigotica&lt;/em&gt; and exogenously applying root exudates of &lt;em&gt;I. indigotica&lt;/em&gt; was lower than in CK. Such trend of decreased microbial population number was in agreement with that of N&lt;sub&gt;2&lt;/sub&gt;O emission from winter wheat field. This suggested that intercropping &lt;em&gt;I. indigotica&lt;/em&gt; was a practical and simple technique to reduce N&lt;sub&gt;2&lt;/sub&gt;O emission from winter wheat field which was an effective strategy for mitigating and adapting global change worldwide in agriculture.&lt;/p&gt;

Approaches to the development of durum wheat cultivars (Triticum durum Desf.) with a wide variability of the growth season

Differentiation in the duration of the growth season is an inherent and, in many respects, decisive factor of the task-oriented formation of the cultivar pool in the region. This is because one cannot develop a universal cultivar that would be equally effective in utilization of environmental resources and equally responsive to precipitation at different stages of plant growth, to temperature backgrounds, and to the hot wind pattern. That is why the aim of the research was to find ways to extend the range of parameters of the durum wheat growth season in the Middle Volga region. Experiments were conducted to study the effects of Vrn genes (1, 2) on the structure and duration of the growth season. The chief parameters of the integral production processes were determined with regard to the early ripening. The formation of the yield components and the parameters of the growth season were tested in Harman’s system of principal components in the context of cultivar adaptability. The experiments showed the following results. (1) The diversity of durum wheat in early ripening in the Middle Volga region was determined by the predominance of genetic systems other than the system of Vrn genes. (2) Mid-ripening and mid–late genotypes had higher productivity potentials compared to early-ripening ones. In the climatic conditions of the Middle Volga region, it was due to the production of a large foliage surface and photosynthetic potential. (3) The duration of the emergence–heading time span was greatly influenced by the interaction of the cultivar–air temperature. Opposing responses were recorded in cultivars of different ecological and geographic origins, and this should be taken into account in breeding programs. (4) The strongest correlation of the yield components and duration of the growth season was observed in groups of nonadapted genotypes. (5) The variation limits of the durum wheat growth season in the Middle Volga region can be extended mainly due to the late-ripening components of cultivar pools.

Changes in the Russian Wheat Aphid (Hemiptera: Aphididae) Biotype Complex in South Africa.

Russian wheat aphid Diuraphis noxia (Kurdjumov) has spread from its native area in central Asia to all the major wheat-producing countries in the world to become an international wheat pest. Because the Russian wheat aphid is a serious threat to the wheat industry in South Africa, it is important to investigate the key factors involved in the distribution of Russian wheat aphid biotypes and in the changes of the Russian wheat aphid biotype complex in South Africa. There are currently four known Russian wheat aphid biotypes occurring in South Africa. Russian wheat aphid samples were collected from 2011 to 2014 during the wheat-growing season in spring and summer and these samples were screened to determine the biotype status. RWASA1 occurred predominantly in the Western Cape, while RWASA2 and RWASA3 occurred predominantly in the Eastern Free State. Following the first record of RWASA4 in 2011, this biotype was restricted to the Eastern Free State. The surveys suggest that the Russian wheat aphid bioype complex was more diverse in the Eastern Free State than in the other wheat production areas. There was also a shift in Russian wheat aphid biotype composition over time. The Russian wheat aphid biotype complex is dynamic, influenced by environmental factors such as host plants, altitude, and climate, and it can change and diversify over time causing fluctuation in populations over sites and years. This dynamic nature of the Russian wheat aphid will continue to challenge the development of Russian wheat aphid-resistant wheat cultivars in South Africa, and the continued monitoring of the biotypic and genetic structure, to determine genetic relatedness and variation in different biotypes, of Russian wheat aphid populations is important for protecting wheat.

施肥对麦田土壤可溶性有机氮的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 施肥对麦田土壤可溶性有机氮的影响 DOI: 10.5846/stxb201412122482 作者: 作者单位: 青岛农业大学资源与环境学院,青岛农业大学资源与环境学院,西北农林科技大学资源环境学院,西北农林科技大学资源环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（31372137，31401947） Effect of fertilization on extractable organic nitrogen in wheat monoculture cropping systems Author: Affiliation: Qingdao Agriculture University,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:利用长期定位试验，研究施肥和小麦生长对土壤可溶性有机氮（EON）的影响。长期不同施肥土壤包括不施肥（No-F）、施用化肥（NPK）和有机肥与化肥配施（MNPK）3种。EON含量范围为7.5-29.3 kg/hm2，No-F、NPK和MNPK土壤中EON分别占可溶性总氮的40%、56%和56%。长期有机肥与化肥配施显著提高0-15 cm土层EON含量，但对30 cm以下土层EON含量无影响。在小麦开花期，可溶性有机氮的含量及其相对含量显著高于拔节期和收获期。虽然施用氮肥对当季EON含量无显著影响，但同位素示踪微区试验表明，土壤耕层（0-15 cm）中仍有0.4%-2.8%的可溶性有机氮来源于当季施入的肥料氮。可见，化学氮肥向可溶性有机氮的转化缓慢，但农田土壤中可溶性有机氮含量与矿质态氮含量相当，发生淋溶损失的风险大。 Abstract:Soil extractable organic nitrogen (SON) is an important nutrient pool involved in N transformations, and the content and conversion of SON are affected by fertilization practices. However, many gaps remain in our understanding of SON, especially in agricultural soil. The effects of long-term (1990-2009) fertilization on SON at elongation, flowering, and harvest stages in wheat were evaluated in a loess soil (Eum-Orthic Anthrosol) in northwestern China. The treatments included no fertilization (No-F), application of inorganic NPK fertilizer (NPK), and combined application of inorganic NPK and manure (MNPK). Using 15N tracer techniques, 15N-labeled urea (165 kg N/hm2) was applied to microplots within each treatment to investigate the effect of short-term addition of N on content of SON during the wheat-growing season in wheat monoculture cropping systems. The SON content was 7.5-29.3 kg/hm2 and accounted for 40%, 56%, and 56% of total extractable N in No-F, NPK, and MNPK, respectively. Compared with No-F, application of inorganic NPK fertilizer increased SON content significantly (55% on average) in the 0-15 cm soil layer. Soil extractable organic N content in the MNPK treatment was significantly higher (by 32%-35%) than that in the NPK treatment in the 0-15 cm layer. Long-term fertilization had no effect on SON content below 30 cm. SON was highest at flowering and was significantly higher during flowering than at the elongation stage in NPK and MNPK (by 48% and 82%, respectively). In relation to No-F, fertilization treatments increased the SON significantly in the 0-100 cm soil profile, SON was 43.1, 51.6, 55.2 kg/hm2 in No-F, NPK, and MNPK, respectively. Addition of N had no significant effect on SON content in the 0-15 cm soil layer during the same growing season; however, 0.4%-2.8% of SON was derived from the 15N-labeled fertilizer applied before seeding, representing 0.03%-0.24% of the fertilizer, and short-term addition of N increased SON in the 0-100 cm soil profile by 35%, 30%, and 14% in No-F, NPK, and MNPK, respectively. We conclude that the conversion of inorganic N to extractable organic N was slow. However, long-term fertilization increased SON content in the topsoil, and SON is a significant nitrogen pool in agriculture soils. 参考文献 相似文献 引证文献

Optimizing Fertilizer Nitrogen for Winter Wheat Production in Yangtze River Region in China

Excessive nitrogen (N) application has been considered as one of the reasons for restricting yield increases in rice-wheat rotation system in the Yangtze River area. From 2007 to 2009, field experiments were conducted to evaluate the effects of optimized N management on grain yield, nitrogen use efficiency (NUE) and N surplus of winter wheat in Jianghan Plain (Hubei province, China). Results indicated that grain yield and crop N uptake of treatments with reducing fertilizer N (N135(2) for the first year and N120(3) for the second season) did not significantly reduce yield compared to farmers’ practice (FP). Under the same amount of N application, three-time splitting improved grain yield and enhanced NUE as compared with two-time splitting. The optimized N treatment of N135(2) and N120(3) was observed with higher NUE parameters, i.e. recovery efficiency (REN), agronomic efficiency (AEN) and partial factor productivity (PFPN). Positive correlation between SPAD value and leaf N concentration provided the effective tool to evaluate N status during the growth season. The optimized N rate and top dressing frequency could reduce the residual N retained in the 0–20 cm soil layer after harvest, which could reduce the possibility of soil N loss to the environment. This paper provides insights into N management strategy based on farmers’ practices, which could be regarded as a guideline to improve agricultural management for wheat growth season.

Effects of experimental warming and nitrogen addition on soil respiration and CH4 fluxes from crop rotations of winter wheat–soybean/fallow

Soil respiration and CH4 emissions play a significant role in the global carbon balance. However, in situ studies in agricultural soils on responses of soil respiration and CH4 fluxes to climate warming are still sparse, especially from long-term studies with year-round heating. A warming experiment was conducted at Luancheng research station in the North China Plain from 2008 to 2013. Two levels of temperature (T: increase on average 1.5°C at 5cm soil depth by infrared heaters, C: ambient temperature) were combined with two levels of nitrogen (N) treatments (N1: with 315kgNha−1 y−1, N0: no nitrogen input) in the farmland.Soil was found to be a sink for CH4 with no marked seasonal variations. In the wheat-growing season, warming and N input both decreased cumulative CH4 uptake, probably because warming-induced soil drying in N1 treatment reduced (or limited) methanotroph activity by affecting soil NH4 concentration. Across years, CH4 emissions were negatively correlated with soil temperature in N1 treatment.Soil respiration showed clear seasonal fluctuations, with the largest emissions during summer and smallest in winter. Warming and nitrogen fertilization had no significant effects on total cumulative soil CO2 fluxes. Soil respiration was positively correlated with microbial biomass C, and microbial biomass C was not affected significantly by warming or nitrogen addition. The lack of significant effects of warming on soil respiration may have resulted from: (1) warming-induced soil drying offsetting the effects of soil temperature; or (2) adaption of soil respiration to increased temperature.

不同有机类肥料对小麦和水稻根际土壤线虫的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 不同有机类肥料对小麦和水稻根际土壤线虫的影响 DOI: 10.5846/stxb201402160264 作者: 作者单位: 1南京农业大学资源与环境科学学院; 2 江苏省有机固体废弃物资源化协同创新中心,1南京农业大学资源与环境科学学院,3江苏省金坛市土壤肥料技术指导站,1南京农业大学资源与环境科学学院,1南京农业大学资源与环境科学学院,1南京农业大学资源与环境科学学院,1南京农业大学资源与环境科学学院,1南京农业大学资源与环境科学学院; 2 江苏省有机固体废弃物资源化协同创新中心 作者简介: 通讯作者: 中图分类号: 基金项目: 农业部行业公益性项目-利用有机(类)肥料调控我国土壤微生物区系关键技术研究(201103004) Effects of different organic fertilizers on soil nematodes in the rhizosphere of rice and wheat cropland Author: Affiliation: 1 College of Resources and Environmental Sciences, Nanjing Agricultural University; 2 Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization,1 College of Resources and Environmental Sciences, Nanjing Agricultural University,3 Soil and Fertilizer Technical guidance Station of Jintan City,1 College of Resources and Environmental Sciences, Nanjing Agricultural University,1 College of Resources and Environmental Sciences, Nanjing Agricultural University,1 College of Resources and Environmental Sciences, Nanjing Agricultural University,1 College of Resources and Environmental Sciences, Nanjing Agricultural University,1 College of Resources and Environmental Sciences, Nanjing Agricultural University; 2 Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:国内外对土壤线虫的研究绝大部分都是基于旱地的非根际土壤,对水田土壤,尤其是水旱轮作下根际土壤线虫对有机肥的响应研究非常地有限。因此,探讨在稻麦轮作体系中以猪粪堆肥和秸秆为原料的不同有机类肥料,对水稻和小麦根际土壤线虫的影响。田间试验处理为:CK(不施肥)、F(100%化肥)、PF(猪粪堆肥+50%化肥)、SF(秸秆全量还田+100%化肥)、PSF(猪粪堆肥+秸秆全量还田+50%化肥)、PMF(猪粪商品有机无机复合肥)。结果表明:小麦根际主要线虫优势属为头叶属(Cephalobus)、拟丽突属(Acrobeloides)和丝尾垫刃属(Filenchus);水稻根际则为杆咽属(Rhabdolaimus)、潜根属(Hirschmanniella)和丝尾垫刃属(Filenchus)。小麦根际土壤线虫总数显著高于水稻根际;SF和PSF对两季土壤线虫总数的提高显著高于PF和PMF,F对线虫总数没有显著影响。线虫营养类群表现为小麦根际食真菌线虫相对丰度显著高于水稻根际,植食性线虫和杂食/捕食性线虫丰度显著低于水稻根际。有机肥对稻季线虫群落的影响远大于麦季,秸秆配施有机肥显著提高麦季瓦斯乐斯卡指数(WI);施肥均显著提高稻季的多样性指数(H'),降低优势度指数(λ)。土壤线虫对肥料的响应取决于作物及肥料的质量和养分含量;在稻麦轮作系统下,同时添加秸秆和猪粪对提高土壤线虫数量和食微线虫丰度更有益。 Abstract:With rapid global nutrient enrichment, the responses of soil biota to nutrient addition have gained much attention. There are numerous studies addressing the responses of soil nematodes and microorganisms to chemical or organic fertilization. Moreover, existing studies of nematode communities mostly focused on uplands as well as on bulk soil. As yet, the responses of soil nematodes in the rhizosphere to both chemical and organic fertilization remain unclear. This is of special significance for the widespread rice-wheat rotation agro-ecosystem in China, where chemical fertilization is commonly used and organic fertilization is promoted, e.g. straw return. The aim of our study was to assess the effects of both chemical and organic fertilization on soil nematodes in the rhizosphere of rice-wheat rotation agro-ecosystems in eastern China. We applied fertilization treatments (CK: no fertilizer, F: 100% chemical fertilizer, PF: pig manure compost + 50% chemical fertilizer, SF: straw return + 100% chemical fertilizer, PSF: pig manure + straw return + 50% chemical fertilizer, PMF: commercial fertilizer of pig manure mixed with chemical fertilizer) in a factorial experimental design to rice- and wheat- cropland in Jintan, Jiangsu Province. We measured soil nematode abundance and diversity, as well as soil nutrients and soil environmental parameters in the rice and wheat rhizospheres. Two-way analysis of variance (ANOVA) was performed after testing variable normality and homogeneity of variance. Duncan tests were used for post-hoc comparisons. Cephalobus, Acrobeloides and Filenchus were the dominant genera in the wheat-growing season;while Rhabdolaimus, Hirschmanniella and Filenchus dominated in the rice-growing season. Total nematode abundance was significantly higher in the wheat-growing season than rice-growing season;SF and PSF increased the total abundance of nematodes compared to PF and PMF;there was no significant difference between CK and F. For nematode trophic groups, the relative abundance of fungivores was significantly higher in the wheat-growing season than the rice-growing season, while plant-parasites and omnivores/predators tended to be more abundant in the rice-growing season. In terms of individual abundance and diversity, the effects of organic fertilization on the soil nematode community were more pronounced in the rice-growing season than in the wheat-growing season. For example, the straw addition tended to increase the Wasilewska index (WI), while both 100% chemical fertilizer and all the combined organic fertilizer treatments increased the Shannon-weaver index (H') but deceased the Dominance index (λ). This suggests that the responses of soil nematodes to fertilization depend not only on crop type, but also on fertilizer quality and nutrient content. For example, combined addition of straw and pig manure was most advantageous for improving both nematode abundance and the relative abundance of microbivores in our study system. 参考文献 相似文献 引证文献