Compatibility of root growth and tuber production of potato cultivars with dynamic and static water‐saving irrigation managements

The important root characteristics of root length density (RLD) and root mass density (RMD) generally differ among irrigation managements and potato cultivars. The objective of this study was to investigate the RLD and RMD variations and their functional relationships with gross potato tuber yield for two commercial potato cultivars, Agria and Sante, under different irrigation strategies. Full irrigation and water‐saving irrigation strategies, deficit and partial root drying irrigations, were applied statically (S) and dynamically (D) based on daily crop evapotranspiration. Results showed that SPRD had significantly greater RLD (3.64 cm/cm³) and RMD (132.7 μg/cm³) than other irrigation treatments. Between the potato cultivars, Agria had significantly larger values of RLD (3.50 cm/cm³) and RMD (138.7 μg/cm³) than Sante. The functional relationship between the root growth characteristics and tuber yield showed that under water‐saving irrigations, Agria increased root mass at the expense of gross tuber yield but Sante increased root mass to maintain larger gross tuber yields. However, Agria produced more roots and gross tuber yield than Sante, and it is concluded that Agria is a more drought‐tolerant potato cultivar, which is recommended for tuber production in regions where water might be scarce. It was shown that larger root production in potatoes was associated with improved tolerance to water stress.     

全球植物科学领域发展态势分析

基于农业科技创新的发展需求,为农业科技资源的有效配置提供支撑,从文献计量角度对全球植物科学领域研究现状及态势进行分析。利用定性、定量相结合的方法构建检索策略,基于Web of Science数据库及文献计量分析工具,对文献发表量、文献主要贡献国家、机构、期刊及发文量较高的作者H指数进行统计分析。结果表明,1995—2018年植物科学领域的文章发表量整体上呈现稳定增长趋势,学科呈现蓬勃发展的整体势头。美国和中国是文献主要贡献国家,文献量和总被引频次显著高于其他国家,但美国及欧洲国家的篇均被引数量高于中国。从全球来看,中国科研机构在发文数量占有绝对优势,而德国马克思普朗克的文章篇均被引数量高,达到10以上。对2016—2018年的高被引文献(Top10)进行内容分析,并通过高频词共现主题聚类可视化分析。从论文影响力及主题词规模2个维度表征领域内研究方向。结果表明,“植物应对生物及非生物胁迫”、“基因编辑技术”、“基因组学分析”、“植物生殖发育调控”是近年来植物科学的高关注度研究方向,主题内容与前期的需求调研相符,初步预测这些研究方向将对农业创新发展起到重要推动作用。     

Atypical thymoma in a horse: Diagnostic approach and application of an alternative histological classification system

Thymoma is a rare condition in horses. This case of a 24-year-old Warmblood gelding that was presented with oedema and signs of vascular congestion of the left forelimb caused by a thoracic mass is described. The diagnostic work-up included blood chemistry, cytology of pleural effusion, ultrasonography, radiography and the visualisation and collection of a tissue sample by thoracoscopy. Finally, post-mortem findings and histopathology revealed thymic epithelial neoplasia with histomorphologic features previously unreported in horses. The unique mixture of spindle-shaped and epithelioid tumour cells in combination with clear features of malignancy suggested the application of the Moran and Suster histological classification system for thymomas in humans (Moran and Suster, 2008, Curr. Treat. Options Oncol., 9, 288), which has not been reported in an equine case before and fits well to the present case.     

基于电动汽车生态系统的中国电动汽车发展

电动汽车的推广依赖于整个电动汽车生态系统,只有整个健康的生态系统才能有效促进电动汽车的发展。电动汽车生态系统包括政府的推动、电动汽车用户的意愿、充电运营公司的运营方式、供电公司的运营方式和电动汽车动力电池的回收等,其中各个环节相互影响。从电动汽车的各个生态环节的目前研究现状及对电动汽车发展的影响进行研究,得出电动汽车发展需要注意的几个问题。     

Do cover crops change the lability of phosphorus in a clayey subtropical soil under different phosphate fertilizers?

Plants have developed different mechanisms to absorb and solubilize phosphorus (P) in the soil, especially in environments with low P availability. This study evaluated the effects of different winter cover crops on soil P availability in a clayey subtropical (Hapludox) soil receiving soluble P fertilizer and a rock phosphate applied to the summer crop, under no‐tillage. The experiment was carried out over 3 yrs (2009–2011) with five different cover crop species: common vetch, fodder radish, ryegrass, black oat, white clover and fallow as control. The soil was sampled after the third year of cover crop cultivation and analysed for inorganic and organic P forms according to the well‐established Hedley fractionation procedure. Phosphate fertilizers promoted accumulation of both labile and nonlabile P pools in soil in the near surface layer, especially under rock phosphate. Fertilizer applications were not able to change P fractions in deeper layers, emphasizing that the Brazilian clayey soils are a sink of P from fertilizer and its mobility is almost nil. Although the cover crops recycled a great amount of P in tissue, in a short‐term evaluation (3 yrs) they only changed the content of moderately labile P in soil, indicating that long‐term studies are needed for more conclusive results.     

Phenological and physiological evaluation of first and second cropping periods of sorghum and maize crops

Environmental conditions influence phenology and physiological processes of plants. It is common for maize and sorghum to be sown at two different periods: the first cropping (spring/summer) and the second cropping (autumn/winter). The phenological cycle of these crops varies greatly according to the planting season, and it is necessary to characterize the growth and development to facilitate the selection of the species best adapted to the environment. The aim of this study was to characterize phenological phases and physiological parameters in sorghum and maize plants as a function of environmental conditions from the first cropping and second cropping periods. Two parallel experiments were conducted with both crops. The phenological characterization was based on growth analyses (plant height, leaf area and photoassimilate partitioning) and gas exchange evaluations (net assimilation rate, stomatal conductance, transpiration and water-use efficiency). It was found that the vegetative stage (VS) for sorghum and maize plants was 7 and 21 days, respectively, longer when cultivated during the second cropping. In the first cropping, the plants were taller than in the second cropping, regardless of the crop. The stomatal conductance of sorghum plants fluctuated in the second cropping during the development period, while maize plants showed decreasing linear behaviour. Water-use efficiency in sorghum plants was higher during the second cropping compared with the first cropping. In maize plants, in the second cropping, the water-use efficiency showed a slight variation in relation to the first cropping. It was concluded that the environmental conditions as degree-days, temperature, photoperiod and pluvial precipitation influence the phenology and physiology of both crops during the first and the second cropping periods, specifically cycle duration, plant height, leaf area, net assimilation rate, stomatal conductance and water-use efficiency, indicating that both crops respond differentially to environmental changes during the growing season.     

The effect of feeding a novel multistrain yeast fraction on European seabass (Dicentrachus labrax) intestinal health and growth performance

Fish were fed a single‐strain yeast fraction (SsYF; 2 g/kg) or a multistrain yeast fraction (MsYF; 0.8 g/kg) for 10 weeks. The results demonstrated significant (p ≤ 0.03) elevations in weight gain, specific growth rate, protein efficiency ratio, and feed conversion ratio in fish fed the yeast fraction‐supplemented diets. In the distal intestine, a significant elevation in microvilli density was observed after 5 and 10 weeks of dietary supplementation with MsYF and SsYF, respectively, compared to control fed fish (p < 0.001). A significant elevation (p = 0.02) in the perimeter ratio was observed in fish fed diets supplemented with the yeast fractions. After 10 weeks of feeding on the experimental diets, Rt‐qPCR demonstrated a significant downregulation (p < 0.05) in the stress response genes, heat‐shock protein 70 (hsp70) and proliferating cell nuclear antigen (pcna), in fish fed diets supplemented with the yeast fractions. Significant (p < 0.05) elevations in interleukin 1‐beta (il1β) and interleukin‐10 (il10) gene expression were observed in fish fed diets supplemented with the MsYF compared to the other dietary groups. These findings suggest that feeding an MsYF specifically at a lower incorporation rate < 1 g/kg, compared to a commercial SsYF at 2 g/kg, is effective in improving the intestinal health status and growth performance of European seabass.     

软枣猕猴桃叶片愈伤组织诱导技术的研究

[目的]由于软枣猕猴桃在初代培养中外植体诱导率极低且快繁效果差,因此进行其组织培养技术体系的研究,以期解决其人工种植的难题.[方法]本研究以软枣猕猴桃展叶为外植体,通过采用不同消毒试剂及消毒处理时间,筛选出最佳的灭菌程序;将不同培养基与不同浓度的KT、2,4-D组合,筛选出最佳的初代培养基配方.[结果]选用展叶为外植体,75％CH3CH2OH处理30 s后以10％NaClO处理20 min,0.1％HgCl2处理15 min后无菌水冲洗3～4次,接至pH=5.8的MS+1 mg·L-1 KT+0.5 mg·L-12,4-D+3％白糖+0.55％琼脂培养基上,置于光照2500 lx、8 h·d-1,26℃下培养8 d后有少部分愈伤组织出现,60 d后平均单芽愈伤组织达0.8 g以上,平均单个愈伤组织长度0.7～1.4 cm,属中块愈伤组织.[结论]以本实验得出的愈伤组织培养方法进行培养,可有效提高诱导率,达到快繁的目的.     

11个葡萄品种在乐山地区的花芽分化规律

研究了11个葡萄品种3年生树在四川乐山地区避雨栽培条件下的花芽分化表现。结果表明,结果母枝的花芽分化率,魏可、维多利亚、黑芭拉多、金手指、金优2号和巨玫瑰6个品种的都高于50%,较易形成花芽;户太8号、巨峰、夏黑的在43%~48%;美人指和红指较难形成花芽。结果母枝不同节位的花芽分化率,多数品种在第3节位≥50%;结果枝上花穗着生节位在第3.8~4.9节,其中双花率以巨玫瑰、巨峰和户太8号较高,分别为83.45%、73.61%和73.06%。以结果母枝的花芽分化率≥50%节位作为冬剪的最低节位,则金优2号、户太8号、巨玫瑰、金手指、维多利亚5个品种在第3~4节,黑芭拉多和巨峰2个品种在第2~3节,魏可在1~2节。夏黑表现花芽分化率较低,为43.33%,可能与夏黑不耐弱光有关,设施栽培时应加强透光性。