Environmental and genotypic effects on bulb development in onion – a review

Environmental and genetic factors influence growth and bulb development of onions by affecting their physiology. Photoperiod plays critical a role in bulb development and determines the suitability of a cultivar for a particular region. Long days and high temperatures promote onion bulbing. Bulbing is regulated more by temperature than photoperiod, as determined by growing degree days. Far-red light promotes bulbing most effectively. High-temperature storage of sets (above 20–25°C) results in increased total bulb yields, while very high temperature (25.5–31°C) or temperature below 0°C depresses yield. Plant density has an impact on bulb size: the higher the plant density the smaller the bulb size. Onion is more sensitive to water stress during bulb formation and enlargement than during the vegetative stage. Nitrogen improves bulb development, but too much nitrogen promotes excessive vegetative growth and delays maturity. Growth hormones (gibberellins and ethrel) promote the growth and development of bulbs. Flowering and bulb formation in onion is regulated by different (Flowering Locus T) FT genes. Two antagonistic FT-like genes regulate bulb formation. AcFT1 promotes bulb formation, while AcFT4 prevents AcFT1 up-regulation and inhibits bulbing. There is a need to link our research with the genetics and physiology of onions, to enhance bulb yield.     

水稻均衡营养肥对杂交稻生长发育的影响及养分吸收特性

研究了水稻均衡营养肥对杂交稻生长发育的影响及养分吸收特性,以为精准施肥及秸秆还田养分循环利用提供必要的科学参数。结果表明,水稻均衡营养肥处理的株高、总粒数、实粒数、结实率、穗质量和产量均高于常规施肥处理,稻谷中的总钾、S~(6+)和Fe~(2+)含量均高于常规施肥处理,但总磷、Ca~(2+)和Mg~(2+)的含量低于常规施肥处理,总氮含量则基本相同;常规施肥处理的秸秆中总氮、总钾、Mg~(2+)和S~(6+)含量均高于水稻均衡营养肥处理,总磷、Ca~(2+)和Fe~(2+)含量基本相同。均衡营养肥处理氮、磷、钾利用率分别为67.8%、60.0%和95.5%,农民常规施肥处理分别为32.3%、86.0%和100%。可见,水稻均衡营养肥能均衡的为杂交稻生长提供必需的养分,大幅度提高肥料利用率。     

不同氮效率小麦品种临界氮浓度模型与营养诊断研究

为探讨不同氮效率小麦品种临界氮浓度模型的差异和开展小麦氮素营养诊断研究,基于两年大田试验,以不同氮效率小麦品种周麦27(高氮高效)、豫麦49-198(低氮高效)和矮抗58(低氮低效)为研究对象,系统分析了不同氮效率小麦品种地上部生物量、地上部氮含量和氮素营养指数的变化规律。结果表明,不同氮效率小麦品种地上部生物量和地上部氮含量均随施氮量的增加而增加,临界氮浓度(N_C)与地上部最大干物质(DM)均呈幂函数关系(N_C=aDM~(-b)),且氮高效型品种模型的两个参数(a和b)值均大于氮低效型品种。经检验,模型的标准化均方根误差分别为13.87%(周麦27)、7.7%(豫麦49-198)和13.02%(矮抗58),通过临界氮浓度模型所建立的氮素营养指数推荐的麦田施肥量均在120~225kg·hm~(-2)范围,其中周麦27和豫麦49-198的推荐施肥量分别为225和120kg·hm~(-2),矮抗58的推荐施肥量介于二者之间。     

Analysis of the variations in dry matter yield and resource use efficiency of maize under different rates of nitrogen,phosphorous and water supply

Abstract

Increasing resources use efficiency in intensive cultivation systems of maize (Zea mays L.) can play an important role in increasing the production and sustainability of agricultural systems. The objectives of the present study were to evaluate DM yield and the efficiency of inputs uses under different levels of water, nitrogen (N) and phosphorus (P) in maize. Therefore, three levels of irrigation including 80 (ETc₈₀), 100 (ETc₁₀₀) and 120% (ETc₁₂₀) of crop evapotranspiration were considered as the main plots, and the factorial combination of three levels of zero (N₀), 200 (N₂₀₀) and 400 (N₄₀₀) kg N ha^?1 with three levels of zero (P₀), 100(P₁₀₀) and 200 (P₂₀₀) kg P ha^?1 was considered as the sub plots. The results showed that increasing the consumption of water and P was led to the reduction of N and P utilization efficiency, while RUE increased. WUE was also increased in response to application of N and P, but decreased when ET_C increased. DM yield under ETc₈₀ treatment reduced by 11 and 12%, respectively, compared to ETc₁₀₀ and ETc₁₂₀ which was due to reduction of cumulative absorbed radiation (R_abs(cum)) and RUE. Under these conditions, changes of stomatal conductance (gs) had little effect on DM yield. It was also found that N limitation caused 11 and 20% reduction in DM yield compared to N₂₀₀ and N₄₀₀, respectively. This yield reduction was mainly the result of decrease in RUE. By decreasing R_abs(cum), P deficiency also reduced DM yield by 5 and 9%, respectively, relative to P₁₀₀ and P₂₀₀ treatments.     

硫素的营养诊断及对土壤、环境的影响

本文对硫素的营养诊断及硫肥对土壤、环境的影响作了系统的综述。内容主要包括硫肥的种类和性质、作物硫素营养诊断方法、硫肥的营养作用、土壤中硫的形态和作用以及硫肥对大气、水体的危害,并提出了施用硫肥时应注意的问题。     

不同龄期及不同长势核桃的养分特征

通过对核桃苗期、幼龄期、始果期的植株叶片和果实营养元素N、P、K和微量元素Fe、Zn含量的分析测试,结果表明,核桃1年生苗木叶片中N、P、K、Zn含量高于幼龄期和始果期植株;核桃各龄期在年生长过程中,叶片中的N、P、K、Fe、Zn养分含量总体呈下降趋势,但N素含量在第2次生长期7月较年生长初期低,比其它生长时期高,在年生长中N、P、K养分含量的比例存在差异,N、K素营养相对含量经历“低-高-低”的过程,N素营养相对含量表现尤其明显;核桃幼龄期、始果期植株长势的差异主要体现在同一时间叶片及果实中N含量的差异。     

山核桃溃疡病与营养元素的关系

调查并分析了安徽省宁国市不同种植区山核桃溃疡病与土壤因子、树皮中营养元素等之间的关系,结果表明:山核桃林分中土壤条件与溃疡病的发生与发展的关系十分密切,其感病指数与土壤密度,树皮中P、Fe的含量呈正相关关系;与土层深度,土壤中N、P、K元素的含量和土壤中有机质的含量及树皮中N、K、M g的含量等呈负相关关系。     

不同栽培密度对棉花植株养分特征及产量的影响

田间小区试验研究了不同栽培密度对棉花植株养分特征及产量的影响。结果表明:密度为18.0×104株/hm2(A3处理)皮棉产量最高,为3247.4 kg/hm2;吐絮期铃中氮、磷、钾含量以18.0×104株/hm2(A3)、22.5×104株/hm2(A4)处理积累量较高,与产量一致;不同密度处理单株氮、磷、钾含量随密度的增大而减小;群体变化趋势则不同,虽然最高值仍都出现在8月15日,但在盛铃~吐絮期却以A3处理各元素的含量最高。说明后期养分积累对产量的形成具有重要的作用,尤其是植株群体和生殖器官的养分积累量。     

基于Web of Science文献计量学分析的全球老年食品研究进展

为深入了解国内外老年食品的研究现状和研究热点,该研究基于Web of Science核心合集(SCI-E)数据库,采用文献计量学理论和可视化分析技术,对1990～2020年全球老年食品研究文献进行分析,以为中国老年食品的研究和开发提供参考。全球有64个国家/地区、852个研究机构,236种期刊开展了老年食品研究,跨区域合作、多学科交叉融合频繁,美国、日本、法国、加拿大、中国等国家均表现出较大的研究体量和较强的合作关系,美国、荷兰老年食品研究的总体质量较高,优势研究机构大多位于欧美等发达国家,研究领域主要集中于营养学、食品科学技术、老年医学等,重点关注膳食补充、健康状况和相关风险。研究前沿有粮食不安全(food insecurity)、健康状况(health status)、生活质量(quality of life)、康复(rehabilitation)、超重(overweight)、有效性(validity)、吞咽困难(dysphagia)、滋味(taste)等。中国老年食品以糊粉类为主,分类混乱、结构单一、科技含量低,与美国、日本、荷兰等国相比还有较大的差距。中国作为世界上人口最多的国家,在人口老龄化加速发展的关键时期,老年食品的研发显得尤为迫切和重要。因此,未来老年食品研究应以老年医学和营养学理论为基础,重点开发营养强化食品和功能性食品,加强食品的感官修饰研究力度,以满足老年人营养和健康的多元化需求,积极应对全球人口老龄化问题。     

降雨前后库滨带表层土壤养分研究

在官厅水库库滨地区对降雨前后库滨带表层土壤养分进行试验研究。结果表明,降雨前农田土壤总磷的含量最高,其次为湿生草本带,乔灌草带和挺水植物带则相对较低;土壤表层总氮的含量乔灌草带最高。降雨前后库滨带各区土壤表层的氮和磷大部分以颗粒态存在,库滨带各区表层颗粒直径<0.002 mm的土壤颗粒是颗粒态磷的主要载体,直径为0.02￣0.05 mm的土壤颗粒是颗粒态氮的主要载体。农田和乔灌草带表层土体截流了来水中的总磷,而挺水植物带则表现为总磷的释放,农田、乔灌草带和湿生草本带对总氮有去除作用,而以乔灌草带的去除效果最明显。