桓仁水库初级生产力和限制性营养盐研究

2018年4月10日、6月11日、8月14日在桓仁水库的上游(江南九队)、中游(砬砬岗子)和下游(泗河大地)3个站位用500 mL具塞磨口瓶盛装采水器采集的水库水样,进行限制性营养盐原位试验,同时测定水中溶解氧和初级生产力,并检测分析水体理化指标,以查明辽宁桓仁水库氮磷分布、营养盐限制和初级生产力状况,保护桓仁水库生态系统的结构和功能完整性。试验结果显示,营养盐加富试验中,0.5 mg/mL氮+0.3 mg/mL磷的添加组可显著提高水体中的溶解氧水平(P<0.05);上游和中游氮磷比为2∶1、下游氮磷比为4∶1可显著提高水体中的溶解氧水平(P<0.05);初级生产力随季节变化特征明显,原始P/R系数均小于试验组。根据试验结果分析得知,桓仁水库营养盐限制因素受季节变化的影响显著,具有氮、磷双限制等特征;根据初级生产力判断桓仁水库为自养代谢型水体。     

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.     

施肥浓度对摇臂式喷头喷灌施肥均匀性的影响

为了研究施肥浓度对喷灌施肥均匀性的影响规律,选用摇臂式喷头10PY₂H,测量其喷灌施肥时肥液体积、施肥浓度、施肥量3种参数的径向分布.试验中,氯化钾溶液质量浓度(即母液浓度)分别为0,20,35,50,65,80 g/L.采用叠加法计算组合喷洒时3种施肥参数的均匀度CU、分布均匀度DU和统计均匀度U_s.分析表明施肥浓度对摇臂式喷头的灌水施肥影响呈现非线性特点.增加母液浓度对肥液体积分布和施肥浓度分布均匀性的影响相对较小,但对施肥量分布均匀性的影响十分显著.组合喷灌加剧了不同测点的数值差异.随着母液浓度增大,施肥量径向分布变化增大,当母液质量浓度增大到80 g/L时,施肥量主要集中在20%~60%射程处,导致施肥均匀性急剧下降;当母液质量浓度小于等于35 g/L时,远端90%~100%射程处的施肥浓度相对更高,与前人得出的滴灌施肥系统施肥浓度沿管道方向递减的规律相反.3个评价指标中,均匀度CU数值最高,分布均匀度DU总体数值最低、变化最大,且以DU变化最为明显,这说明了DU能反映低值区的施肥情况.喷灌施肥等值线图表明肥液与施肥量的分布规律相似,但施肥浓度的分布情况则相反,这可能与射程远端施肥浓度更大有关.     

优化施肥下长江流域冬小麦产量及肥料增产效应

【目的】针对长江流域冬小麦不合理施肥带来的肥料利用率低的现状,探讨冬小麦产量分布特征及施用氮、磷和钾肥料的增产效应,为长江流域冬小麦肥料减施增效和优化养分管理措施提供依据。【方法】本文数据来源于国际植物营养研究所（IPNI）于2000—2018年在我国长江流域开展的田间试验,以及在中国知网（CNKI）数据库通过检索字段或字段组合（冬小麦、冬小麦+产量及冬小麦产量+肥料利用率等）得到的此期间关于长江流域冬小麦田间试验的论文,共1 732个田间试验。试验处理包括：优化施肥处理,农民习惯施肥,以及在优化施肥和农民习惯施肥基础上的不施氮肥、不施磷肥和不施钾肥处理,以探究长江流域各省（市）（四川、云南、贵州、重庆、湖北、安徽、江苏、浙江和上海）冬小麦在优化施肥下的可获得产量、产量反应、相对产量、农学效率和偏生产力特征。【结果】我国长江流域冬小麦优化施肥处理下的平均产量为6.6 t·hm^-2,其中安徽省平均产量水平最高,为7.3 t·hm^-2,重庆市最低,为3.6 t·hm^-2。施用氮、磷和钾肥的平均产量反应分别为2.3、0.9和0.6 t·hm^-2,但变异范围较大。氮、磷和钾肥平均相对产量分别为0.6、0.8和0.9,氮是小麦产量的主要限制因子。优化施肥处理的氮、磷和钾肥的平均农学效率分别为12.6、11.6和7.7 kg·kg^-1,平均偏生产力分别为34.0、78.9和73.4 kg·kg^-1。与农民习惯施肥措施相比,优化施肥处理平均增产0.5 t·hm^-2,增幅为8.8%;氮、磷、钾肥的农学效率分别提高了41.1%、121.1%和84.6%;偏生产力分别提高了42.4%、23.5%和25.4%。【结论】优化施肥有效提高了长江流域冬小麦的产量和养分利用率,但各省（市）间存在一定差异且省（市）内变异较大。四川、云南、湖北和江苏省的部分地区具有较低的产量反应,说明具有较高的土壤养分供应,应因地制宜地制定养分优化管理方案。分析长江流域优化养分管理措施下的小麦产量反应和肥料利用率等参数,可以确定氮为小麦产量的第一限制因子。     

不同海拔的大别山山核桃林地土壤性质和叶片营养元素分析

为了比较不同海拔大别山山核桃林地土壤性质和叶片营养元素的差异及相关性,为大别山山核桃林地科学施肥和养分管理提供参考,采用酸度计法、重铬酸钾容量法、半微量凯氏定氮法、碱解扩散法、盐酸氟化铵浸提-分光光度法和醋酸铵-火焰光度计法分别测定了不同海拔大别山山核桃林地0 ~ 30 cm土层pH、有机质、速效氮、速效磷、速效钾,采用原子吸收分光光度法测定了土壤和叶片的氮、磷、钾、钙、镁、锌含量,并进行显著性分析和相关性分析。结果表明：（1）不同海拔大别山山核桃林地土壤速效磷、全氮、全磷、全钾、钙、镁和锌含量存在显著性差异（P < 0.05）,大别山山核桃叶片钾、钙和镁含量存在显著性差异（P < 0.05）。（2）不同海拔大别山山核桃林地土壤pH随着海拔升高而降低,而有机质和氮含量随着海拔升高而升高;叶片钾含量随海拔升高而升高,钙和镁含量则是随着海拔升高而降低,其余营养元素受海拔影响较小。（3）大别山山核桃叶片营养元素之间、土壤营养元素之间、以及叶片与土壤之间存在一定相关性,其中土壤间相关性达到显著水平的有2对,叶片间相关性达到显著水平的有4对,土壤和叶片间相关性达到显著水平的有2对（P < 0.05）。大别山山核桃林地土壤平均pH值为5.18,偏酸性;有机质含量均值为5.07%;速效氮、速效磷含量较高,速效钾较匮乏;微量元素平均含量依次为Mg>Ca>Zn。建议增施生石灰进行土壤改良,减少氮肥施用,增施磷钾肥,尤其是钾肥,将化学肥料和有机肥料混合增施,保持土壤养分平衡。     

3种冷季型草坪草混播配方优化组合筛选试验

在河西走廊中部地区气候条件下,通过对草地早熟禾Poa pratensis、高羊茅Festuca arundinacea、多年生黑麦草Lolium perenne3种冷季型草坪草18种混播配方进行了成坪品质的观察测定,筛选出了适应当地气候条件的优化组合配方10个。     

Nutrient addition and disturbance effects on the community composition and assembly in a desert steppe北大核心CSCD

The effects of short-term nutrient additions (NPKμ, 10 g·m- 2) and disturbances on the species diversity, functional traits, soil properties, and community assembly mechanisms of the herbaceous community in the Urat desert steppe were examined. A mixed linear model, principal component analysis, and null model methods were utilized and both disturbance and interaction treatments were found to significantly reduce species richness and β diversity. Short-term nutrient additions significantly reduced soil pH but increased soil electrical conductivity. Six functional traits of the dominant species (i.e. Stipa glareosa, Peganum harmala, Salsola collina, Corispermum mongolicum) and six community-weighted mean significant changes under the disturbance and nutrient addition treatments were identified. The disturbance and nutrient additions promoted the transformation of the dominant species in the community from conservative strategies to acquisitive strategies. The results of the two null models revealed that community assembly under the control tended to be a stochastic process, while the disturbance and interaction treatments tended to be deterministic processes, and that of the nutrient addition treatments tended to be weaker deterministic processes. Plant communities in the desert steppe responded and adapted to the nutrient additions and disturbances through changes in the dominant species and their crucial functional traits. © 2023 Chinese Academy of Sciences. All rights reserved.     

Effect of Mediterranean saltbush (Atriplex halimus) ensilaging with two developed enzyme cocktails on feed intake,nutrient digestibility and ruminal fermentation in sheep

The aim of this study was to assess the effects of feeding Atriplex halimus (AH) silage treated with two developed enzyme cocktails to sheep on feed intake, nutrient digestibility and ruminal fermentation. The AH silage was treated without or with 2 L of ZAD1^® or ZAD2^®/1000 kg with 5% molasses and ensiled for 30 days. Barley grain (300 g/head/day) was fed as an energy supplement once daily at 10.00 hours and AH silage with or without enzyme treatment was offered ad libitum to animals twice daily at 09.00 and 16.00 hours. Sheep were fed on four experimental forage diets comprised of AH silage and barley (D1), AH silage treated with ZAD1^® and barley (D2), AH silage treated with ZAD2^® and barley (D3) and AH silage treated with a combination of ZAD1^® and ZAD2^® (1:1) and barley (D4). Ensiling AH with enzymes reduced its contents of neutral detergent fiber and acid detergent fiber. The dry matter intake of AH of D2, D3 and D4 decreased (P < 0.001) as compared to D1. However, enzyme‐treated diets had greater total digestible nutrients intake (P < 0.001) as compared to D1. The nutrients digestibility for D2, D3 and D4 were higher than those for D1 (P < 0.001), and were higher for D3 as compared to both D2 and D4. Sheep fed on D3 had highest (P < 0.001) ruminal total volatile fatty acids concentration, ammonia nitrogen concentration and microbial protein yield. It could be concluded that AH silage treated with ZAD1^® or ZAD2^® improved digestibility and rumen fermentation in sheep.     

断母乳日龄对犊牛营养物质消化和血清生化指标的影响

本试验旨在研究不同断母乳日龄对犊牛营养物质消化和血清生化指标影响。试验选用新生红安格斯与西门塔尔杂交肉犊牛60头,根据日龄和体重随机分成5个处理,每个处理12头犊牛,公母各占1/2,试验组分别在28、42、56和70日龄进行断母乳(分别为28A、42B、56C、70D组),随后人工哺乳代乳品至90日龄;对照组( CK组)随母哺乳至150日龄。试验时间为出生至150日龄,期间测定体重(0、70、90、150日龄)和血清生化指标(70、90、150日龄)的变化。每个处理选取6头犊牛分别在断奶前(85~90日龄)和断奶后(145~150日龄)进行2期消化代谢试验。每期6 d,其中2 d预试期,4 d正试期。结果显示：1)试验全期体重各组间无显著差异(P>0.05)。2)断奶前各组犊牛营养物质消化率差异不显著(P>0.05),断奶后28A、42B组犊牛干物质消化率显著高于56C、70D组( P<0.05),有机物消化率显著高于70D组( P<0.05),其中42B组消化率略高。3)150日龄试验结束时,28A和42B组血清葡萄糖、总蛋白、甘油三酯、尿素氮、胆固醇、结合珠蛋白、白细胞介素-2、胰岛素样生长因子-1、免疫球蛋白M含量与CK组相比差异不显著( P>0.05),血清免疫球蛋白G、免疫球蛋白A含量分别显著低于、高于CK组( P<0.05),其中42B组略高。由此可见,红安格斯与西门塔尔杂交肉犊牛的断母乳时间以42日龄较为适宜。