饲粮中添加叶酸对乐平母猪繁殖性能的影响

本研究选用本地猪种乐平花猪以探讨饲粮中添加叶酸对繁殖母猪的作用效应。２７头经产母猪根据年龄、胎次与系祖来源随机分为３个处理组，即在妊娠和哺乳期基础日粮中分别添加叶酸０（作为对照）、２ｍｇ／ｋｇ和６ｍｇ／ｋｇ。结果表明：添加叶酸提高了总窝产仔数、窝产活仔数及４０日龄育成数（Ｐ＜０．１或Ｐ＜０．０５），尤其是添加叶酸６ｍｇ／ｋｇ组的总窝产仔数和窝产活仔数分别提高了１．８９头和１．３４头；３个处理组的仔猪平均初生体重没有明显差异（Ｐ＞０．２５），但是初生窝重及４０日龄断奶窝重随着补充叶酸的增加而明显地增加（Ｐ＜０．１或Ｐ＜０．０１）。虽然各处理组的母猪在繁殖周期各阶段的体重没有变化（Ｐ＞０．２５）。，但添加叶酸组母猪的孕期增重及哺乳期掉膘却趋向于增加，且母猪妊娠期的增重愈多，其哺乳期掉膘亦愈多。本研究结果证明，在母猪妊娠和哺乳期基础饲粮中添加适宜剂量的叶酸，通过增加其窝产活仔数可以进一步发挥乐平母猪较高的生产性能     

华南典型人工林的土壤物理性质及其水源涵养功能

对杉木、马尾松、湿地松、尾叶桉和马占相思林的土壤物理性质、凋落物持水量以及土壤贮水性能进行了研究。5种林分土壤的毛管孔隙度、非毛管孔隙度和总孔隙度均为上层大于下层,而土壤容重为上层小于下层。总体来看,5种林分中杉木和马占相思林土壤疏松、孔隙度大;尾叶桉林土壤紧实、孔隙度小,马尾松林和湿地松的土壤孔隙度中等。凋落物最大持水量呈现杉木林(18thm-2)>马占相思林(15thm-2)>尾叶桉林(14thm-2)>马尾松林(11thm-2)>湿地松林(10thm-2)。土壤是森林涵养水源的主体,其最大持水量占林地最大持水量的99%以上,顺序为杉木林地和马占相思林(2064和2061thm-2)>湿地松林(2041thm-2)>马尾松林(2032thm-2)>尾叶桉林(1941thm-2)。林地最大持水量的顺序为杉木林地(2082thm-2)>马占相思林地(2076thm-2)>湿地松林地(2051thm-2)>马尾松林地(2043thm-2)>尾叶桉林地(1955thm-2)。     

木荷凋落物分解及对土壤作用规律的研究

在福建省永春碧卿林场开展的木荷凋落物分解及土壤淋溶试验表明 :木荷人工林凋落物量和养分积累量下坡 >中坡 >上坡 ,养分积累量Ca >N >K >Mg >Fe >P >Zn >Cu ;凋落物分解的失重率Ws与时间t之间存在Ws =34 45 2Lnt -3 0 741(R =0 98)的对数关系 ;木荷凋落物可通过增加土壤有机质 ,提高土壤和下渗液的盐基量 ,提高土壤pH值 ,降低土壤水解性总酸度等途径来缓解土壤的酸化作用     

Carbon storage capacity of high altitude Quercus semecarpifolia,forests of Central Himalayan region

Abstract

Quercus semecarpifolia, Smith. (brown oak) forests dominate the high altitudes of central Himalaya between 2400 and 2750 m and the timber line areas. The species is viviparous with short seed viability and coincides its germination with monsoon rains in July–August. These forests have large reserves of carbon in their biomass (above and below ground parts) and soil. We monitored the carbon stock and carbon sequestration rates of this oak on two sites subjected to varying level of disturbance between 2004 and 2009. These forests had carbon ranging between 210.26 and 258.02 t ha^?1 in their biomass in 2009 and mean carbon sequestration rates between 3.7 and 4.8 t ha^?1 yr^?1. The litter production in both the sites ranged from 5.63 to 7.25 t ha^?1 yr^?1. The leaf litter decomposition of species took more than 720 days for approximately 90% decomposition. Even at 1 m soil depth soil organic carbon was close to 1.0%.     

低温季节西南亚高山森林土壤多酚氧化酶动态研究

以亚高山针叶林均质化土壤为研究对象,采用裸露地表、凋落物覆盖、积雪覆盖、凋落物和积雪同时覆盖4个不同覆盖处理的原位培养实验,对各处理在低温季节(11月～5月)土壤表层(0~10cm)和下层(10～20 cm)多酚氧化酶(PPO)活性动态进行了分析,结果表明:(1)在低温季节,所有处理表层PPO活性在12~2月出现波动,差异不显著;下层土壤PPO活性逐渐升高,到低温季节结束前后活性达到最高,但是不同处理的升高幅度不同;(2)积雪和凋落物覆盖变化引起不同处理和不同深度土壤PPO活性动态的差异性响应。不论是表层还是下层土壤,在整个低温季节积雪对PPO活性的影响达到极显著水平,但凋落物覆盖能缓冲积雪对PPO活性的效应。(3)降雪时空格局变化对亚高山土壤PPO的影响主要体现在没有凋落物覆等盖层的裸露土壤,在有凋落物等覆盖情况下,全球变化可能导致的积雪减少甚至消失对土壤PPO活性的影响不大。     

应用森林土壤化学性质和枯落物持水性对不同改造模式效果的评价——以大兴安岭阔叶混交低质林为例

对大兴安岭阔叶混交低质林进行了块状改造(6个样地)和带状改造(4个样地);运用主成分分析法分析不同改造模式对森林土壤化学性质(有机质、pH值、全氮、全钾、全磷、水解氮、速效钾、速效磷)和枯落物(蓄积量、最大持水量)的影响。结果表明:块状改造的效果,由优到劣依次为G_3(15 m×15 m)、G_1(5 m×5 m)、CK(对照)、G_4(20 m×20 m)、G_6(30 m×30 m)、G_2(10 m×10 m)、G_5(25 m×25 m);带状改造效果,由优到劣依次为S_3(14 m)、S_2(10 m)、S_1(6 m)、S_4(18 m)、CK(对照)。当块状改造面积为225 m^2、带状改造带宽为14 m时,改造效果最佳,并且随着改造强度的逐步加大,改造效果呈现先上升后下降的趋势。     

内蒙古白绒山羊母羊产羔效应的遗传分析

[目的]探讨内蒙古白绒山羊产羔数的遗传规律。[方法]对2000-2007年出生的22 721只内蒙古阿尔巴斯白绒山羊羔羊的初生重及3 044只母本羊产羔数进行统计分析。[结果]最小二乘方差分析表明,性别、胎次和出生类型对羔羊初生重有显著影响;约束性最大似然法分析表明,胎次、群体和母体效应对产羔数有显著影响。羔羊初生重遗传力单羔为0.16,双羔为0.40,全部为0.17。[结论]该研究为下一步建立内蒙古白绒山羊高繁殖性能品系奠定了一定的基础。     

长白山4种森林凋落物分解过程中养分动态变化

于2003年5月至2004年9月,在长白山自然保护区北坡垂直植被带的4种林分(阔叶红松林、红松云冷杉林、岳桦云冷杉林和岳桦林)内,利用凋落物原位减少法对凋落物分解过程中的养分动态变化进行了研究.结果表明:4种森林凋落物分解过程中C质量分数变化幅度不大,N和P质量分数都是先上升后下降;K质量分数呈逐渐降低的趋势;阔叶红松林、红松云冷杉林、岳桦云冷杉林和岳桦林凋落物的养分年释放总量依次为1380.80、1145.46、418.74和599.91kg·hm-2·a-1.     

Recovering decomposing plant residues from the particulate soil organic matter fraction: size versus density separation

 A detailed size separation of particulate organic matter (POM) from soils amended with straw from Hordeum vulgare or Vicia sativa revealed that the loss of C during the first 56 days of incubation mainly occurred from particles >2,000 μm, without a concomitant reduction in the size of these large particles. Preliminary studies of POM from non-amended soil had shown that the stable heavy (>1.4 g cm^–3) POM fraction was mainly (>80%) composed of particles <400 μm, whereas the light fraction was dominated by larger particles (>80%). Therefore we decided to compare the POM <1.4 g cm³ with POM >400 μm. There was a very close relationship between POM>400 μm and POM <1.4 g cm^–3 with regard to amounts of C and N, as well as the appearance of these fractions under the microscope. Similarly there was a close relationship between changes in the C content of the POM fractions and the CO₂ respired, and this was also the case when comparing changes in POM-N with net N mineralization. This indicated that the biological activity during decomposition was actually localized in the POM. Due to the lighter workload and lower expenditure for reagents in connection with size separation of POM, we recommend the size separation procedure in connection with studies of residue decomposition in arable systems. Received: 23 May 2000     

Morphological analysis of viral communities in the floodwater of a Japanese paddy field

Capsid size distributions of viral communities in the floodwater of a Japanese paddy field under a long-term fertilizer trial were surveyed during the rice cultivation period by using transmission electron microscopy. The capsid size distributions were monophasic, and the median values fell within the range of 50-70 nm. The quartile intervals were narrow from either 40-50 nm or 50-60 nm to either 60-70 nm or 70-80 nm for most samples. There was no clear seasonal variation in the capsid size distribution of viral communities. The difference in size distributions among different fertilizer plots was also not found. Viral communities in the floodwater were predominated by isometric icosahedral forms. Viruses with octahedral capsids and elongated ones were rare and sporadic in the floodwater.