长期施肥条件下菜田—蔬菜生态系统变化的研究( Ⅳ) 蔬菜生态系统的变化

 以2002 年设施番茄栽培为代表计算其N、P、K投入量与携出量之间的表观平衡状态, 其结果基本上和14.5 年后的土壤实测值与设施栽培本底值之间纵向比较的增长关系一致, 前者只能说明系统养分变化的趋势, 后者才是实际的养分盈亏状态, 养分盈亏主要取决于有机肥的施用与养分元素的供给。5个代表性处理模拟了蔬菜施肥的不同现状, 从土壤肥力及产量等方面的变化真实反映出各自的系统变化及发展趋势, 在本试验条件下以ANK施肥下的系统最优。对有机肥施用、化学肥料的配施以及测土施肥等问题进行了探讨。     

Visualization of the effect of a surfactant on the uptake of xenobiotics into plant foliage by confocal laser scanning microscopy

A radiolabelling method is generally used to determine the foliar uptake of xenobiotics. This technique cannot provide any information on the localization of chemicals inside leaf tissues. The influence of an alcohol ethoxylate surfactant on the uptake of three fluorescent dyes, difluorofluorescein (hydrophilic), rhodamine B (moderately lipophilic) and a naphthalimide dye (lipophilic), into the leaves of three contrasting species, bean (Vicia faba), wheat (Triticum aestivum) and cabbage (Brassica oleracea), at 16 h after treatment was measured using a conventional wash‐off method and also visualized in vivo by confocal laser scanning microscopy (CLSM). Whereas the lipophilic dyes showed greater intrinsic uptake than the hydrophilic one, the enhancing effect of the surfactant on uptake was more pronounced for the latter. CLSM revealed that the presence of the surfactant increased the transport of difluorofluorescein into the epidermal cells of bean and wheat leaves, but not cabbage leaves. Rhodamine B showed greatest transcuticular diffusion in all three species, but most of the dye moved into the vacuole of the epidermal cells. The naphthalimide dye was strongly retained by the wax–cuticle layer of all species, even in the presence of the surfactant. CLSM has proven to be an attractive tool for studying xenobiotic diffusion. The results obtained using fluorescent dyes are believed to be applicable to the foliar uptake of herbicides.     

Absorption, translocation and allocation of glyphosate in resistant and susceptible Chilean biotypes of Lolium multiflorum

Glyphosate [N-(phosphonomethyl) glycine] is currently the most important non-selective, wide-spectrum herbicide used worldwide. Introduced in 1974, glyphosate was initially a non-crop herbicide and plantation crop herbicide, although it is now widely used in no-till crop production and, more recently, for weed control in herbicide-resistant transgenic crops, such as maize, soybean and cotton ( Baylis 2000 ; Caseley & Copping 2000 ). Despite its widespread and long-term use, no case of evolved resistance to glyphosate was documented until 1996 ( Pratley et al . 1996 ). Since then, a few other cases have been reported. To date, evolved resistance to glyphosate has been identified and documented in Lollium rigidum in Australia ( Powles et al . 1998 ; Pratley et al . 1999 ), Eleusine indica in Malaysia ( Lee & Ngim 2000 ), and L. rigidum in South Africa and California (USA), and Conyzia canadensis in Delawere (USA) ( Van Gessel 2001 ). Also, accessions of L. rigidum from South Africa and California have been reported to resist glyphosate ( Heap 2001 ). In Chile, the first case of glyphosate-resistance in Lolium multiflorum was reported in 1999 and documented in 2003 ( Pérez & Kogan 2003 ). This case was the result of an intensive selection pressure caused by the continuous applications of glyphosate in fruit orchards over 8–10 years. The present study is a first approach to elucidating the mechanism involved in the resistance of one biotype of L. multiflorum selected in Chilean orchards.     

豆科与禾本科牧草间作的生长互作效应及对氮、磷养分吸收的影响

为了解牧草间作对作物生长和养分吸收的影响,以及为不同牧草优化配置、豆科和禾本科牧草间作提高结氮量提供理论依据,本试验采用随机区组试验设计,研究了间作对柱花草、扭黄茅和孔颖草的生物量和氮磷吸收的影响。结果表明,由于柱花草生物固氮,对扭黄茅和孔颖草养分吸收和生长有促进作用,与柱花草间作后的扭黄茅和孔颖草与禾本科牧草单作模式相比,能获得高的养分吸收量和产量。与各自单作对比,间作体系中的禾本科牧草生物量高于单作0.06%和26.78%;与柱花草单作对比,两个间作体系中的柱花草生物量低于单作9.70%和12.83%。扭黄茅与柱花草间作后,对氮磷的吸收量高于单作扭黄茅24.26%和35.18%,对氮磷的吸收量高于单作孔颖草40.64%和47.50%。相对于单作而言,柱花草分别与扭黄茅和孔颖草间作,对氮吸收量分别降低8.31%和28.94%,磷吸收量分别降低3.56%和20.58%。而且两种间作模式当量比均大于1,具有间作优势;柱花草/扭黄茅间作系统生产力、种间竞争能力高于柱花草/孔颖草,具有产量优势。在株行距为50 cm种植密度下,间作体系中禾本科牧草生长旺盛,柱花草的生长受到抑制,在与两个禾本科牧草间作中为弱竞争作物。结果表明,在合理的种植密度下,适合的牧草配置能够充分利用各种资源,促进种间有益作用,提高单位面积牧草产量和禾本科牧草氮磷的吸收,有利于改善牧草品质。     

Meta‐analysis of the energy and protein requirements of hair sheep raised in the tropical region of Brazil

The objective of this study was to estimate, through mathematical models, energy and protein requirements for maintenance and gain of hair sheep raised in the tropical region of Brazil. To determine the equation parameters, a meta‐analysis of seven independent experiments of nutrient requirements was performed, comprising a total of 243 experimental units (animals), which were conducted under tropical conditions, using hair sheep in growing and finishing phases and endowed of the following quantitative data for each animal: body weight (BW ), empty body weight (EBW ), average daily gain (ADG ), empty body gain (EBG ), heat production (HP ), metabolizable energy intake (MEI ), retained energy (RE ), metabolizable protein intake (MPI ) and body protein content. The regression equations generated were as follows: for Net Energy for maintenance, (NE _m): ; for Net Energy for gain, (NE _g): ; for Metabolizable Protein for maintenance,(MP _m): MPI _(g/day) = 24.8470 (±7.3646) + 560.28 (±99.6582) × EBG _(kg/day); for Net Protein for gain, (NP _g): . The NE _m requirement was 0.246 MJ EBW^?0.75 day^?1. The metabolizable energy for maintenance requirement was 0.391 MJ EBW^?0.75 day^?1. Considering an ADG of 100 g, the NE _g requirement ranged from 0.496 to 1.701 MJ/day for animals with BW ranging from 10 to 40 kg respectively. The efficiencies of use of the metabolizable energy for maintenance and gain were 0.63 and 0.36 respectively. The MP _m requirement was 3.097 g EBW^?0.75 day^?1. Considering an ADG of 100 g, the NP _g requirement ranged from 12.4 to 10.5 g/day for animals with BW ranging from 10 to 40 kg respectively. The total metabolizable energy and protein requirements were lower than those reported by the NRC and AFRC systems. Thus, our results support the hypothesis that nutrient requirements of hair sheep raised in tropical regions differ from wool sheep raised in temperate regions. Therefore, the use of the equations designed in this study is recommended.     

The effects of late gestation nutrient restriction of dams on beef heifer intake,metabolites and hormones during an ad libitum feeding trial

This study's objective was to determine if nutrient restriction during late gestation affected beef heifer feed intake, body weight (BW) gain and endocrine regulation during a 10‐week feeding trial. During the last 100 days of gestation, control (CON) dams were fed to increase body condition score (BCS). Whereas, nutrient‐restricted dams (NR) and NR dams protein supplemented 3 days/week (NRS) were fed to decrease BCS by 1.2. After parturition, all cow‐calf pairs were moved to a common pasture and fed in excess of requirements until weaning. At 15 months of age, heifers were randomly sorted into two pens and adjusted to a commercial total mixed ration over a 2‐week period. Blood samples and BW were taken at the initiation of feeding and on a biweekly basis for the duration of the feeding trial. Feed intake was monitored for 10 weeks using a GrowSafe System. After 10 weeks, an intravenous glucose tolerance test (IVGTT) was performed on 21 randomly subsampled heifers. During the feeding trial, NR heifers consumed more feed than CON and NRS heifers. Heifers from NR dams tended to increase BW compared to NRS and CON heifers when adjusted for initial BW. Heifers from NR and NRS dams had a greater increase in BCS compared to heifers from CON dams. Plasma glucose and insulin concentrations during the feeding trial increased in NR heifers compared to the other groups beginning at 2 and 4 weeks respectively. Plasma leptin concentrations were increased in the NR and NRS heifers compared to the CON heifers beginning at week 4 of feeding. During the IVGTT at the conclusion of the feeding challenge, plasma glucose and insulin were increased in NR heifers compared to other treatment groups. These results show that nutrient restriction during late gestation alters appetite and endocrine regulation in heifer offspring.     

滴灌水肥一体化下施氮量对小麦氮素吸收及土壤硝态氮含量的影响

为探明华北地区山前平原水肥一体化条件下小麦合理的氮肥运筹。于2013-2015年2个小麦生长季,设置4个滴灌施氮量(N0-不施氮、N1-120 kg/hm~2、N2-240 kg/hm~2、N3-360 kg/hm~2)处理,研究滴灌水肥一体化下施氮量对小麦氮素吸收积累和土壤硝态氮含量的影响。结果表明:施氮量N1、N2和N3处理的小麦干质量及产量较处理N0显著增加,N1、N2和N3处理间无显著差异;施氮量对小麦茎秆的氮含量影响较大,但对籽粒氮含量的影响差异不显著;处理N3的小麦总吸氮量分别显著高于处理N0、N1和N2,但处理N1和N2之间无显著差异;氮肥收获指数以N2处理最高,氮肥当季回收利用率、氮肥农学效率、氮肥生产效率和氮肥利用效率均表现出随施氮量增加而降低的趋势;施氮量超过240 kg/hm~2,土壤硝态氮含量增加,且随种植年限的延长更加明显。采用一元二次方程拟合,获得小麦最高产量的施氮量为238.46~250.78 kg/hm~2,经济施氮量为174.28~207.18 kg/hm~2。综合考虑经济效益和生态效益,该条件下小麦滴灌经济施氮量以174~207 kg/hm~2为宜。     

Increasing selenium supply during the close-up dry period improves nutrient metabolism and attenuates inflammatory response after calving in dairy cows

The objective of this study was to investigate whether feeding selenium (Se)-replete cows a Se-yeast supplement in late pregnancy affects nutrient metabolism and inflammatory response during the periparturient period. Twenty cows were randomly assigned to two groups with 10 cows each. Cows in one group received Se-yeast at 0.3 mg Se/kg DM during the last 4 weeks before calving in addition to fed a TMR containing supplemented sodium selenite at 0.3 mg Se/kg DM (Se-yeast), while cows in another group were only fed a TMR containing supplemented sodium selenite at 0.3 mg Se/kg DM (Control). Blood samples were collected and analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), glucose, insulin, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, serum amyloid A (SAA), haptoglobin (Hp), and albumin. In control cows, plasma NEFA, IL-1β, IL-6, SAA, and Hp levels increased after calving, but glucose, insulin, and albumin levels decreased after parturition. Se-yeast supplemental cows had lower postpartum concentrations of NEFA, TNF-α, IL-1β, IL-6, SAA, and Hp, and higher postpartum levels of glucose, insulin, and albumin compared with control cows. The results indicate that feeding Se-replete cows a Se-yeast supplement in late pregnancy improves nutrient metabolism and attenuates the inflammatory response after calving.     

新型尿素对冬小麦产量及氮素吸收利用的影响

为明确新型尿素在冬小麦的应用效果，采用田间试验，研究了普通尿素（Urea）、控失尿素（LC Urea）、海藻酸尿素（H Urea）、聚能网尿素（N Urea）、含锰尿素（Mn Urea）、控失尿素一次施肥（LC Urea 1）、普通尿素+等量锰（Urea+Mn）和不施肥（CK）对冬小麦产量、叶片SPAD、叶片光合生理特性和氮素吸收利用的影响。结果表明，LC Urea和H Urea处理较Urea处理的小麦拔节期叶片SPAD分别显著提高1500%和1300%，灌浆期净光合速率分别显著增加3304%和2076%，气孔导度分别显著提高2609%和2174%，氮素积累量分别显著增加1439%和1236%，氮肥利用率分别提高4575%和3902%。N Urea和Mn Urea处理与Urea处理的产量无显著差异，LC Urea和H Urea处理较Urea处理显著增产1449%和1333%。控失尿素和海藻酸尿素能够有效提高穗数，改善冬小麦光合生理特性，促进氮素吸收利用，提高冬小麦产量和氮肥利用率，可在豫北潮土区推广应用。     

灌草立体配置对退化草地土壤水分和养分的影响

【目的】比较灌草立体配置模式下3种不同生境的土壤水分、养分和植物根系相关参数的差异，探究灌草立体配置30年对退化草地土壤水分和养分以及植物根系的影响，为黄土高原水土保持和生态恢复提供理论依据。【方法】以位于黄土高原云雾山国家草原自然保护区种植30年的人工柠条和野山桃搭配灌丛带样地为研究对象，采集灌丛带内部、灌丛带边缘和灌丛带外部不同土层的土样和植物根系，比较3种位置下土壤水分、养分含量和植物根系特征的差异，并分析了根长与土壤水分和养分含量的相关性。【结果】在0～80 cm土层，灌丛带内部的土壤含水量明显高于灌丛带边缘和灌丛带外部。在0～80 cm土层，随着土层深度增加，灌丛带3个位置土壤全氮、碱解氮和有机碳含量均呈下降趋势，而全磷含量变化不明显；在同一土层，灌丛带内部的全氮、碱解氮和有机碳含量均明显高于灌丛带边缘和灌丛带外部。在灌丛带内部、灌丛带边缘和灌丛带外部3个位置，植物根系生物量呈减小的趋势。从垂直分布来看，灌丛带内部、灌丛带边缘和灌丛带外部0～15 cm土层的植物根系生物量分别占0～40 cm土层植物根系生物量的90.86%，90.79%，92.91%，说明植物根系生物量主要集中分布于0～15 cm土层。3个取样位置中，灌丛带内部植物根长、根表面积和根体积均最大。相关性分析表明，灌丛带植物根长与0～20 cm土层的土壤含水量，0～40 cm土层土壤有机碳和全氮、0～80 cm土层碱解氮均呈显著或极显著正相关。【结论】在黄土高原退化草地上进行灌草立体配置可以促进植物根系生长，提高土壤水分和养分含量，有利于退化草地的恢复。