The effect of plastic mulch on the fate of urea-N in rain-fed maize production in a semiarid environment as assessed by 15N-labeling

A better understanding of the fate of fertilizer nitrogen (N) is critical to design appropriate N management strategies in plastic-mulched croplands. We evaluated the effects of plastic mulch on urea-N recovery by crops and loss from soil in furrow-ridge plots, with and without maize (Zea mays L.) cropping, in a semi-arid rain-fed site in China. We applied the same rate of urea-N (281 kg ha⁻¹) to all treatments during the preparation of the furrow-ridges in 2011 and 2012 but ¹⁵N-labeled the urea in 2011 only. We used transparent film to cover all soil surfaces in the mulched treatments and seeded maize in furrows in treatments with crop. In 2011, plastic mulch increased the total N uptake in the aboveground biomass of maize by 53%, whereas it decreased the in-season labeled-N uptake by 19%, compared to non-mulched treatment. At harvest in 2011, in mulched treatments the total labeled-N remaining in the 0−170 cm soil layer was 25% greater whereas unaccounted labeled-N was 69% less, than in non-mulched treatments, regardless of whether maize was cropped. In 2012 the effect of mulch on total maize N uptake was comparable to that in 2011, but the residual soil labeled-N uptake by maize was 63% higher in mulched compared to non-mulched treatment. At harvest in 2012, plastic mulch increased total labeled-N remaining in the 0−170 cm depth in cropped soils and unaccounted labeled-N in non-cropped soils, compared with no mulch. Our results indicate that plastic mulch profoundly changes the fate of urea-N in maize production in cold and dry croplands.     

Effect of irrigation and nitrogen fertilization on the production of biogas from maize and sorghum in a water limited environment

The expansion of biogas production from anaerobic digestion in the Po Valley (Northern Italy) has stimulated the cultivation of dedicated biomass crops, and maize in particular. A mid-term experiment was carried out from 2006 to 2010 on a silt loamy soil in Northern Italy to compare water use and energy efficiency of maize and sorghum cultivation under rain fed and well-watered treatments and at two rates of nitrogen fertilization. The present work hypothesis were: (i) biomass sorghum, for its efficient use of water and nitrogen, could be a valuable alternative to maize for biogas production; (ii) reduction of irrigation level and (iii) application of low nitrogen fertilizer rate increase the efficiency of bioenergy production. Water treatments, a rain fed control (I0) and two irrigation levels (I1 and I2; only one in 2006 and 2009), were compared in a split–split plot design with four replicates. Two fertilizer rates were also tested: low (N1, 60 kg ha⁻¹ of nitrogen; 0 kg ha⁻¹ of nitrogen in 2010) and high (N2, 120 kg ha⁻¹ of nitrogen; 100 kg ha⁻¹ of nitrogen in 2010). Across treatments, sorghum produced more aboveground biomass than maize, respectively 21.6 Mg ha⁻¹ and 16.8 Mg ha⁻¹ (p < 0.01). In both species, biomass yield was lower in I0 than in I1 and I2 (p < 0.01), while I1 and I2 did differ significantly. Nitrogen level never affected biomass yield. Water use efficiency was generally higher in sorghum (52 kg ha⁻¹ mm⁻¹) than in maize (38 kg ha⁻¹ mm⁻¹); the significant interaction between crop and irrigation revealed that water use efficiency did not differ across water levels in sorghum, whereas it significantly increased from I0 and I1 to I2 in maize (p < 0.01). The potential methane production was similar in maize and sorghum, while it was significantly lower in I0 (16505 MJ ha⁻¹) than in I1 and I2 (21700 MJ ha⁻¹). The only significant effect of nitrogen fertilization was found in the calculation of energy efficiency (ratio of energy output and input) that was higher in N1 than in N2 (p < 0.01). These results support the hypothesis that (i) sorghum should be cultivated rather than maize to increase energy efficiency, (ii) irrigation level should replace up to 36% of ETr and (iii) nitrogen fertilizer rate should be minimized to maximize the efficiency in biomass production for anaerobic digestion in the Po Valley.     

浅谈玉米制种基地村生产技术指导与管理措施

稳定的良种生产基地是完善和提高良繁技术,保证种子质量和数量,满足生产要求,推进种子产业化的重要基础;也是玉米制种育、繁、推一体化的关键和保证.     

Cover crops and interrow tillage for weed control in short season maize (Zea mays)

Weed competition can cause substantial maize (Zea mays L.) yield reductions. Interseeding maize with cover crops or a combination of interrow cultivation and interseeded cover crops are possible alternative methods of weed control. This study was conducted to examine the potential of interrow cultivation plus cover crops to reduce weed density in maize without reducing the grain yield. Field experiments were conducted in 1993 and 1994 at two sites in Québec to determine the effects of planting 12 cover crops with maize on weed control. Fall rye (Secale cereal L.), hairy vetch (Vicia villosa Roth), a mixture of red clover (Trifolium pratense L.) and ryegrass (Lolium multiflorum Lam), a mixture of white clover (Trifolium repens L.) and ryegrass, subterranean clover (Trifolium subterraneum L.), yellow sweet clover (Meliotus officinalis Lam), black medic (Medicago lupulina L.), Persian clover (Trifolium resupinatum L.), strawberry clover (Trifolium fragiferum L.), crimson clover (Trifolium incarnatum L.), alfalfa (Medicago sativa L.), and berseem clover (Trifolium alexandrinum L.) were seeded at two planting dates, 10 and 20 days after maize emergence. Interrow cultivation was carried out weekly until forage seeding, with a final cultivation being conducted just prior to cover crop seeding. Cover crop planting date did not affect maize yields or the ability of interrow tillage plus cover crops to suppress the development of weed populations. Maize yield was less affected by the interseeded cover crops under conditions of adequate rainfall. Corn planted in fields heavily infested with weeds resulted in substantial yield reductions even when rainfall was adequate. Except for 1993 at l'Assomption interrow tillage plus cover crop treatments had consistently lower weed biomass when compared to the weedy control. Most of the weed control was due to the interrow cultivation performed prior to seeding of the cover crops. The lowest weed density occurred in the herbicide treated plots. The ability of interrow tillage plus cover crops to suppress the development of weeds was affected by the level of weed infestation, the growing conditions and location. The cover crops provide additional weed control but the interrrow tillage or some herbicide application may still be necessary.     

Genotype x environment interaction for root traits in maize,as analysed with factorial regression models

Summary The efficiency of genotopic and climatic characteristics in accounting for the interaction between genotypes and environments has been assessed in a three-year trial involving a set of genotypes presenting a range of root morphology characteristics (number and size). Climatic information on rainfall and temperature was recorded during the experiments, together with extra data on the growth and development of the genotypes. Their effects have been tested in factorial regression models.Climatic covariates were very powerful in accounting for the genotype by year interaction as well as the year main effect alone. For the number of adventitious roots on internode 7, the main effect of year could be described as a linear function of the average temperature and precipitation that occurred during the period of root initiation and growth. For internode 6, no clear conclusion was possible. For the root traits studied, 74 to 98% of the interaction could be explained by one climatic covariate. The regression coefficients can be considered as measures of genotypic stability.The genotypic covariates describing aerial development performed rather poorly, compared with environmental ones, even though the physiological and functional relationships between root and shoot are well known. Neither genotype main effect nor genotype by year interaction could be described sufficiently by factorial regression. Still, the genotypic covariates performing best clearly differed between root counts and size. Also the best genotypic covariates differed for main effect and interaction.     

关于玉米生产需求及发展方向的几点思考

1我国玉米生产的技术发展特点 在我国玉米生产发展过程中,杂种优势的利用,是玉米生产技术上一项最出色的成就,同时带动了高产栽培技术的迅速发展.我国玉米生产的进步经历了三个明显的历史阶段.     

张掖国家级玉米制种基地生产经营模式探讨

甘肃省张掖市作为全国最大的杂交玉米制种基地,多年来凭借独特的自然资源优势和人力资源优势,每年为全国供应着45%以上的优质玉米杂交种。但随着现代种业不断发展,一家一户小生产和种植用工密集型的种子生产经营模式已成为阻碍玉米制种跨越发展的瓶颈。从开展土地规模化流转、促进生产经营模式创新角度出发,分析了玉米制种规模化生产经营的现状和规模化土地流转中存在的问题,并提出了破解难题的对策建议,以期为张掖国家级玉米制种基地建设提供参考。     

制种玉米种子机械化收获的实践与思考

玉米机械化收获是传统农业向现代农业转变的必然选择。在对玉米机械收获发展的必要性及存在问题进行分析与总结的基础上,从农机与农艺配套、机械优化升级、改变果穗收获方式、农业机械制造创新、区域布局错期收获等方面提出玉米机械化收获的对策。     

The effect of spikelet position on the success frequencies of wheat haploid production using the maize cross system

Barbela is an old Portuguese landrace of wheat that is highly genetically heterogeneous. Different Barbela populations when subjected to aluminium stress show variable levels of tolerance. In order to study the inheritance of this character, doubled haploid (DH) lines were developed. These DH were obtained by intergeneric crosses of 14 different lines of Barbela with maize. During this process the efficiency of the technique was evaluated and suggestions for its improvement were obtained. Several parameters were studied in the crosses: % of crossability, % of embryos per florets pollinated and % of embryos per seed set. The different genotypes of Barbela showed significant variation for the parameters analysed. When the reciprocal crosses were analysed, no differences were found, indicating that cytoplasm differences do not influence the parameters of DH production. However, different spikelet positions (lower, middle and upper) gave highly significant differences in all parameters analysed. Highest success frequencies were obtained for pollinated spikelets in the middle of the spike. This can indicate that concentrating on the middle part of the spike can increase the frequency of DHs obtained using inter generic crosses of wheat with maize. This revised version was published online in August 2006 with corrections to the Cover Date.     

玉米杂交种南种北制应注意的问题

南方选育的玉米杂交种,一般其中有一个自交系感光感温性强所需积温较多;北方玉米制种,生长期温差大,灌溉条件好,不但制种产量高,且稳产.南方制种易遇高温干旱,灌溉条件差,导致产量低,且不稳产.随着南方丘陵山区发展畜牧业的需要,玉米种植面积逐年扩大,所需玉米种数量不断增加,南方小面积制种不能满足需要,很多种子公司进行南种北制来满足农民的需求.郧西县种子公司从 2003年起开始在北方制种. 2003年在适宜玉米生长、灌溉条件好的蒙陕边境制种 167hm2、 4个品种,平均 667m2产 405kg,最高达 550kg; 2004年在宁蒙边境制种 100hm2、 3个品种,平均 667m2产 410kg,最高达 600kg.通过两年的异地制种,积累了几点经验和教训.     

制种玉米发芽率低的原因及预防措施

发芽率是玉米种子质量检验的4项重要指标之一，也是种子公司大量调人前非常关心的内容之一。发芽率高表示有生活力的种子多，播种后出苗数多。农四师65团近年来种植玉米制种面积较大，但是由于发芽率低，造成种子等级低，种子价格就低，给玉米制种户造成了一定的经济损失。     

有机培肥与轮耕方式对夏玉米田土壤碳氮和产量的影响

探明不同轮耕和有机培肥方式对夏玉米田土壤碳氮及其酶活性的影响,对提升农田土壤肥力及促进玉米高产具有重要意义。设秸秆(P)与牛粪(F)两种有机培肥方式和小麦季旋耕-玉米季深松(RS)、小麦季深松-玉米季免耕(SN)、小麦季翻耕-玉米季免耕(CN) 3种轮耕方式,共6个处理,于2015—2016和2016—2017玉米收获期采样测定,研究了不同有机培肥和轮耕方式对土壤碳氮及其酶活性和作物产量的影响。结果表明,轮耕方式、有机肥及其交互效应对土壤肥力有显著影响。在0～10 cm和10～20 cm土层,与轮耕方式CN相比, RS和SN能够显著提高土壤有机碳、全氮含量和脲酶、蔗糖酶活性。在轮耕方式RS中,与施用牛粪相比,秸秆还田显著提高了10～20 cm、20～30 cm和30～40 cm土层的有机碳含量,增加了10～20 cm土层的全氮含量和蔗糖酶活性。在轮耕方式SN中,与秸秆还田相比,施用牛粪显著提高了0～10 cm和10～20 cm土层的有机碳、全氮含量和蔗糖酶活性,增加了各土层脲酶活性。与秸秆还田+翻耕-免耕(PCN)相比,秸秆还田+旋耕-深松(PRS)和施用牛粪+深松-免耕(FSN)能显著提高土壤肥力。在0～10 cm和10～20 cm土层,各处理中以FSN增加土壤有机碳、全氮含量和蔗糖酶、脲酶活性最为明显。轮耕方式、有机肥及其交互效应对产量有显著影响。轮耕方式RS和SN的产量较CN分别显著提高了1.89%～10.49%、5.44%～11.99%。在轮耕方式RS中,产量表现为秸秆还田较施用牛粪显著提高了2.91%～3.11%;而在轮耕方式SN中,则表现为秸秆还田较施用牛粪显著降低了5.02%～9.07%。两年玉米产量均表现为FSNPRSFRSPSNFCNPCN。综上所述,在6种处理中,处理FSN在提高土壤肥力和产量方面最为显著,可以作为试验及周边地区适宜的轮耕培肥方式。     

Regional Business Cycles and the Emergence of Sheltered Economies in the Southern Periphery of Europe

ABSTRACT Recent research has highlighted that in the last few years, the evolution of regional disparities in many European states has become pro‐cyclical. This represents a change with respect to the predominantly anti‐cyclical pattern of the 1960s and 1970s. This paper addresses the question of whether and when this change has taken place in the southern periphery of Europe, before analysing the factors that may have played a role in such a change. The analysis relies on a regional database that includes the evolution of the GDP per capita of NUTS II regions in five European countries (France, Greece, Italy, Portugal, and Spain) between 1980 and 2000. The results of the analysis support the hypothesis of a change towards a pro‐cyclical evolution of regional disparities in the cases of Italy, Portugal, and Spain, but not in those of Greece and France. A relationship between these pro‐cyclical patterns and the emergence of less dynamic sheltered economies is also detected in peripheral regions. This lack of dynamism is related to the fact that numerous peripheral areas in southern Europe have become increasingly dependent on factors such as transfers or public investment and employment, and therefore are less exposed to changes in market conditions.     

On-farm evaluation of integrated weed management tools for maize production in three different agro-environments in Europe: Agronomic efficacy,herbicide use reduction,and economic sustainability

The development and implementation of integrated weed management (IWM) strategies that provide good weed control while reducing dependence on herbicides, and preferably without having side effects on the overall system economic performance, is still a challenge that has to be met. In 2011 and 2012, nine on-farm experiments (i.e., real field conditions on commercial farms, with natural weed flora) were conducted in three important European maize producing regions-countries, which represent the range of climatic and edaphic conditions in Europe, to evaluate the efficacy of different locally selected IWM tools for direct weed control in maize vs. the conventional approach (CON) followed by the farms. The IWM tools tested were: (1) early post-emergence herbicide band application combined with hoeing followed by a second hoeing in Southern Germany, (2) early post-emergence herbicide broadcast application when indicated by a predictive model of weed emergence after performing one scouting in the field to supply data for the model, followed by hoeing in Northern Italy, and (3) tine harrowing at 2–3rd leaf stage of maize and low dose of post-emergence herbicide in Slovenia. Results showed that the IWM tools tested in the different countries: (1) provided sufficient weed control without any significant differences in yields, (2) greatly reduced maize reliance on herbicides, and (3) IWM implementation was economically sustainable as no significant differences in gross margin were observed in any country compared to CON.     

2005年河南省气象因素对玉米生产影响分析

玉米属C4植物，玉米植株产量的90％以上是靠光合作用制造的有机物，光合作用是植物获得能量和赖以生存的基础，光合同化能力的高低直接影响到玉米的产量。因此玉米生长发育和产量形成常常受气候变化的影响。河南省作为一个农业大省，地理位置承北启南，地域辽阔，常年玉米种植面积240万hm^2，占河南省秋粮生产60％以上，如何根据气象因素等气候特点搞好玉米生产是值得我们探讨的一个问题。     

The effect of the opaque-2 gene on yield in maize

Summary It is difficult to use opaque-2 hybrids mainly because of their present low yield as compared with that of normal hybrids.Our studies were based on an experimental design allowing the comparison between 10 normal hybrids and their opaque-2 counterparts.The differences between normal and opaque-2 hybrids indicate that the opaque-2 (o ₂) gene chiefly affects kernel characters, and slightly some other characters.The observed phenotypical variability is mainly related with genetical causes. This means that the selection for suitable hybrid combinations may lessen the opaque-2 negative effects, which should be possible without modifying the protein quality of the opaque-2 maize.     

山东省优质专用玉米生产现状及产业化发展策略

山东省是全国玉米主产区之一,多年来种植面积和总产量均居全国前列。在我国加入WTO之后,随着科技经济全球化进程的加快,山东省的玉米生产和流通将面临着巨大的挑战和机遇。优质专用玉米是指具有优良品质和专门用途的玉米,如优质蛋白玉米、高油玉米、高赖氨酸玉米、高淀粉玉米、鲜食玉米、青贮玉米等。当前,在农业产业结构调整过程中,大力发展优质专用玉米,把传统的产量型、数量型玉米生产转变为质量型、效益型产业是玉米生产发展的必然趋势。发展优质专用玉米生产,加快优质专用玉米的产业化进程,提高玉米生产的整体效益,增加农民收入,是维…     

Landscape Position and Precipitation Effects on Spatial Variability of Wheat Yield and Grain Protein in Southern Italy

Wheat yield and protein content are spatially variable because of inherent spatial variability of factors affecting the yield at field scale. In Mediterranean environments, yield variability is often caused by the irregular weather pattern, particularly rainfall and by position on the landscape. The objective of this study was to determine the effects of landscape position and rainfall on spatial variability of wheat yield and protein in a rolling terrain field of Southern Italy, and to propose stable management areas through simulation modelling and georesistivity imaging in rolling landscape. The study was carried out in Southern Italy, during 2 years of wheat monoculture; extensive soil properties and in-season plant measurements were measured. This study showed that soil water content was the main factor affecting spatial variation of yield for both years. The interactions between rainfall, topography and soil attributes increase the chances to observe yield variability among years. The principal component analysis demonstrated that for both years, soil water content explained most of the variability. The crop simulation model provided excellent results when compared with measured data with root mean square error of 0.2 t ha⁻¹. The simulated cumulative probability function showed that the model was able to confirm the yield temporal stability of three different zones.     

Application of the CSM-CERES-Maize model for planting date evaluation and yield forecasting for maize grown off-season in a subtropical environment

In recent years, maize has become one of the main alternative crops for the Autumn–Winter growing season (off-season) in several regions of Brazil. Water deficits, sub-optimum temperatures and low solar radiation levels are some of the more common problems that are experienced during this growing season. However, the impact of variable weather conditions on crop production can be analyzed with crop simulation models. The objectives of this study were to evaluate the Cropping System Model (CSM)-CERES-Maize for its ability to simulate growth, development, grain yield for four different maturity maize hybrids grown off-season in a subtropical region of Brazil, to study the impact of different planting dates on maize performance under rainfed and irrigated conditions, and for yield forecasting for the most common off-season production system. The CSM-CERES-Maize model was evaluated with experimental data collected during three field experiments conducted in Piracicaba, SP, Brazil. The experiments were completely randomized with three replications for the 2001 experiment and four replications for the 2002 experiments. For the yield forecasting application, daily weather data for 2002 were used until the forecast date, complemented with 25 years of historical daily weather data for the remainder of the growing season. Six planting dates were simulated, starting on February 1 and repeated every 15 days until April 15. The evaluation of the CSM-CERES-Maize showed that the model was able to simulate phenology and grain yield for the four hybrids accurately, with normalized RMSE (expressed in percentage) less than 15%. The planting date analysis showed that a delayed planting date from February 1 to April 15 caused a decrease in average yield of 55% for the rainfed and 21% for the irrigated conditions for all hybrids. The yield forecasting analysis demonstrated that an accurate yield forecast could be provided at approximately 45 days prior to the harvest date for all four maize hybrids. These results are promising for farmers and decision makers, as they could have access to accurate yield forecasts prior to final harvest. However, to be able to make practical decisions for stock management of maize grains, it is necessary to develop this methodology for different locations. Future model evaluations might also be needed due to the release of new cultivars by breeders.     

登海9号玉米优质高产制种技术

登海9号系由山东省莱州市农科院用DH65232自交系为母本，8723自交系为父本杂交育成的紧凑型玉米单交种，2000年通过国家农作物品种审定委员会审定。该品种属中晚熟，适宜东北、河北、内蒙东南部等春玉米区和黄淮海夏玉米区种植。