Dense planting with less basal nitrogen fertilization might benefit rice cropping for high yield with less environmental impacts     

《European Journal of Agronomy》2016

Dense planting and less basal nitrogen (N) fertilization have been recommended to further increase rice (Oryza sativa L.) grain yield and N use efficiency (NUE), respectively. The objective of this study was to evaluate the integrative impacts of dense planting with reduced basal N application (DR) on rice yield, NUE and greenhouse gas (GHG) emissions. Field experiments with one conventional sparse planting (CK) and four treatments of dense planting (increased seedlings per hill) with less basal N application were conducted in northeast China from 2012 to 2013. In addition, a two-factor experiment was conducted to isolate the effect of planting density and basal N rate on CH₄ emission in 2013. Our results show that an increase in planting density by about 50% with a correspondingly reduction in basal N rate by about 30% (DR1 and DR2) enhanced NUE by 14.3–50.6% and rice grain yield by 0.5–7.4% over CK. Meanwhile, DR1 and DR2 reduced GWP by 6.4–12.6% and yield-scaled GWP by 7.0–17.0% over CK. According to the two-factor experiment, soil CH₄ production and oxidation and CH₄ emission were not affected by planting density. However, reduced basal N rate decreased CH₄ emission due to it significantly reduced soil CH₄ production with a smaller reduction in soil CH₄ oxidation. The above results indicate that moderate dense planting with less basal N application might be an environment friendly mode for rice cropping for high yield and NUE with less GHG emissions.  相似文献   

淮安区水稻测土配方施肥配方校正与示范对比试验报告     

成军 《北方水稻》2015,(1):35-36,59

为验证肥料配方的准确性,发挥配方肥料施用的最大效益。通过田间校验,示范对比测土配方施肥的增产效果,进一步验证并完善淮安区的肥料配方,优化测土配方施肥技术参数。  相似文献   

Physiological Response of Multiple Contrasting Rice (Oryza sativa L.) Cultivars to Suboptimal Temperatures          下载免费PDF全文

M. M. Rachoski  A. Vidal  O. A. Ruiz  A. B. Menéndez  A. A. Rodríguez 《Journal of Agronomy and Crop Science》2015,201(2):117-127

The physiological response of multiple rice cultivars, eighteen initially and eight cultivars later on, to suboptimal temperatures (ST) conditions was investigated in laboratory and outdoor experimental conditions. Treatment with ST decreased growth in different extents according to the cultivar and affected the PSII performance, determined by chlorophyll fluorescence fast‐transient test, and stomatal conductance, regardless the experimental condition. Two groups of cultivars could be distinguished on the base of their growth and physiological parameters. The group of cultivars presenting higher growths displayed optimal JIP values, and higher instantaneous water use efficiency (WUE_i), due to a lower Gs under ST, unlike cultivars showing lower growth values, which presented worse JIP values and could not adjust their Gs and hence their WUE_i. In this work, we detected at least two cultivars with superior tolerance to ST than the cold tolerant referent Koshihikari. These cultivars could be used as parents or tolerance donors in breeding for new crop varieties. On other hand, positive and significant correlations between data obtained from laboratory and outdoor experiments suggest that laboratory measurements of most of the above mentioned parameters would be useful to predict the response of rice cultivars to ST outdoor.  相似文献   

不同叶龄蘖、穗氮肥组合对粳稻产量及氮素利用的影响   总被引：4，自引：0，他引：4  

WANG Yan  YI Jun  GAO Ji-Ping  ZHANG Li-Na  YANG Ji-Fen  ZHAO Yan-Ze  XIN Wei  ZHEN Xiao-Xi  ZHANG Wen-Zhong 《作物学报》2020,46(1):102-116

以主茎叶片数不同的粳稻品种吉粳88 (14片)、沈农265 (15片)和沈农1401 (16片)为试材,采用大田筒栽方式,在总施氮量225kghm–2及轻简施肥(基肥、蘖肥、穗肥)模式基础上,设置基蘖肥∶穗肥6∶4和8∶2两种施肥比例,并分设不同源、库叶龄期施氮组合即不同叶龄蘖、穗肥精确施氮组合。分析了不同源库期氮肥运筹模式对水稻农艺性状、产量及氮素利用特性的影响。结果表明:(1)在有效穗数、分化颖花数、产量和氮素利用率方面,吉粳88、沈农265、沈农1401不同氮肥运筹下最佳蘖、穗肥叶龄组合均为6∶4显著高于8∶2。(2)不同氮肥运筹下,吉粳88在8叶(叶龄指数57.1%)、沈农265在9叶(叶龄指数60.0%)、沈农1401在10叶(叶龄指数62.5%)时,即叶龄指数在60%左右时,施用蘖肥效果最佳,最终穗数最多,对保蘖起主要作用;吉粳88在11叶(叶龄指数78.6%)、沈农265在12叶(叶龄指数80.0%)、沈农1401在13叶(叶龄指数81.3%)时,即叶龄指数在80%左右时,施用穗肥效果最佳,最终穗粒数最多,对促花起主要作用。(3)吉粳88-6∶4 (8, 11),沈农265-6∶4 (9, 12),沈农1401-6∶4 (10, 13) 3组处理,在产量、氮素积累量、氮素吸收利用率、农学利用率及偏生产力等方面,显著高于同品种不同叶龄蘖、穗氮肥组合中的其他处理。因此,适当延迟蘖肥施用叶龄期(叶龄指数60%左右)、提前穗肥施用叶龄期(叶龄指数80%左右)同时增加穗肥施用比例,既可以显著提高氮素积累量、氮素吸收利用率、农学利用率及偏生产力,又能显著促进成穗率的提高和颖花数的分化,达到保蘖促花的双重作用,实现优源、扩库、充实的目标,从而获得高产。  相似文献   

水产类上市公司经营绩效评价及影响因素分析——基于DEA-Tobit模型     

高升  王颖 《安徽农业科学》2015,(24):332-334

2012年以来水产类上市公司经营面临困局.该研究根据11家水产类上市公司2012～2014年的面板数据,首先运用DEA模型进行生产效率的评价,研究发现水产类上市公司的技术效率、纯技术效率和规模效率3年平均值都较高,但2014年整体绩效有走低的趋势;然后运用Tobit模型,分析经营绩效的影响因素,发现公司总资产周转率和高等教育人员比例与技术效率正相关,而研发人员比例与技术效率不相关.最后,从资产整合、加强营销、重视人才和发展休闲渔业等方面提出了提高水产类上市公司经营绩效的对策建议.  相似文献   

Therapeutic Erythrocytapheresis Is Effective in Treating High Altitude Polycythemia on the Qinghai-Tibet Plateau     

《The Forestry Chronicle》2020,31(4):426-430

  相似文献   

关于PA-250感应电机效率提高的研究     

喻佩佩 《湖南农机》2014,(8)

随着社会经济的飞速发展,对于节能环保的要求越来越高,传统的G/M代码已经成为现代先进制造技术的瓶颈。而基于STEP标准的STEP-NC将为现代CNC的高速和高精度加工提供条件。  相似文献   

Selecting the hologenome to breed for an improved feed efficiency in pigs—A novel selection index     

Ramona Weishaar  Robin Wellmann  Amelia Camarinha-Silva  Markus Rodehutscord  Jörn Bennewitz 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2020,137(1):14-22

Most traits in animal breeding, including feed efficiency traits in pigs, are affected by many genes with small effect and have a moderately high heritability between 0.1 and 0.5, which enables efficient selection. Since the microbiota composition in the gastrointestinal tract is also partly heritable and was shown to have a substantial effect on feed efficiency, the host genes affect the phenotype not only directly by altering metabolic pathways, but also indirectly by changing the microbiota composition. The effect of the microbiota composition on the breeding value of an animal is the conditional expectation of its breeding value, given the vector with microbiota frequencies, that is The breeding value of an animal can therefore be decomposed into a heritable contribution that arises from an altered microbiota composition and a heritable contribution that arises from altered metabolic pathways within the animal, so Instead of selecting for breeding value , an index comprising the two components and with appropriate weights, that is , can be used. The present study shows how this breeding strategy can be applied in pig genomic selection breeding scheme for two feed efficiency traits and daily gain.  相似文献   

Time‐lapse monitoring of soil water content using electromagnetic conductivity imaging          下载免费PDF全文

J. Huang  E. Scudiero  W. Clary  D. L. Corwin  J. Triantafilis 《Soil Use and Management》2017,33(2):191-204

The volumetric soil water content (θ) is fundamental to agriculture because its spatiotemporal variation in soil affects the growth of plants. Unfortunately, the universally accepted thermogravimetric method for estimating volumetric soil water content is very labour intensive and time‐consuming for use in field‐scale monitoring. Electromagnetic (EM) induction instruments have proven to be useful in mapping the spatiotemporal variation of θ. However, depth‐specific variation in θ, which is important for irrigation management, has been little explored. The objective of this study was to develop a relationship between θ and estimates of true electrical conductivity (σ) and to use this relationship to develop time‐lapse images of soil θ beneath a centre‐pivot irrigated alfalfa (Medicago sativa L.) crop in San Jacinto, California, USA. We first measured the bulk apparent electrical conductivity (EC_a – mS/m) using a DUALEM‐421 over a period of 12 days after an irrigation event (i.e. days 1, 2, 3, 4, 6, 8 and 12). We used EM4Soil to generate EM conductivity images (EMCIs). We used a physical model to estimate θ from σ, accounting for soil tortuosity and pore water salinity, with a cross‐validation RMSE of 0.04 cm³/cm³. Testing the scenario where no soil information is available, we used a three‐parameter exponential model to relate θ to σ and then to map θ along the transect on different days. The results allowed us to monitor the spatiotemporal variations of θ across the surveyed area, over the 12‐day period. In this regard, we were able to map the soil close to field capacity (0.27 cm³/cm³) and approaching permanent wilting point (0.03 cm³/cm³). The time‐lapse θ monitoring approach, developed using EMCI, has implications for soil and water use and management and will potentially allow farmers and consultants to identify inefficiencies in water application rates and use. It can also be used as a research tool to potentially assist precision irrigation practices and to test the efficacy of different methods of irrigation in terms of water delivery and efficiency in water use in near real time.  相似文献   

Soil physical changes and maize growth in a structurally fragile tropical soil due to mulching and duration between irrigation intervals          下载免费PDF全文

E. G. Moura  V. R. A. Macedo  V. G. L. Sena  L. S. Campos  A. C. F. Aguiar 《Soil Use and Management》2017,33(4):631-638

Under tropical meteorological conditions, the volume of soil explored by plant roots is crucial for crop growth as it allows increased water and nutrient use efficiency. We hypothesized that, under different irrigation intervals, leguminous mulch can extend the duration between irrigation events but maintain crop performance, because decreased evaporative fluxes also reduce constraints to root exploration imposed by mechanical stress. We evaluated the combined effects of leguminous mulch and irrigation intervals on soil physical properties to determine whether the growth and productivity of maize were modified in a structurally fragile tropical soil. The experiment involved the following treatments: 4‐day irrigation intervals with soil mulched (4C) or bare (4S), 6‐day irrigation intervals with soil mulched (6C) or bare (6S), 8‐day irrigation intervals with soil mulched (8C) or bare (8S) and 10‐day irrigation intervals with soil mulched (10C) or bare (10S). Mulch decreased soil penetration resistance and increased to 4 days the favourable time for root development in drying soil. Relative to bare soil, mulch with a 6‐day irrigation interval almost doubled nitrogen uptake post‐tasselling, which decreased nitrogen remobilization and increased the crop growth rate during this stage. These conditions had a positive effect on the transpiration rate and stomatal conductance as well as on the growth and yield of maize. A 6‐day irrigation interval with mulch compared to 4 days with bare soil resulted in similar conditions for root development, but greater uptake of nitrogen (102.73–78.70 kg/ha) and better yield (6.2–5.3 t/ha), which means greater efficiency in nitrogen and water use.  相似文献