免耕与翻耕直播对土壤特性及水稻生长的影响

通过对土壤的容重,氧化还原电位,土温,通气孔隙,剖面结构和水稻根系,伤流液,灌浆速度,分蘖状况,经济性状等项目的测定,试验研究免耕与翻耕直播技术,明确了免耕 对于翻耕直播不但能促进水稻生长,还能改善土壤结构,保护土壤,是一项更轻型化的栽培技术。     

免耕与翻耕直播对土壤特性及水稻生长的影响

通过对土壤的容重、氧化还原电位、土温、通气孔隙、剖面结构和水稻根系、伤流液、灌浆速度、分蘖状况、经济性状等项目的测定,试验研究免耕与翻耕直播技术,明确了免耕直播相对于翻耕直播不但能促进水稻生长,还能改善土壤结构、保护土壤,是一项更轻型化的栽培技术.     

土壤特性对保水剂吸水性能的影响

该文测试了保水剂与砂壤土、壤砂土、砂黏壤土1和砂黏壤土2四种土壤混合后的吸水倍率,研究了土壤特性对保水剂吸水性能的影响,混合时土壤为风干土,保水剂与土壤的混合比例为0.5%。结果表明：与对照相比,保水剂与土壤混合后明显降低了吸水倍率,且随着吸水时间加长,降低幅度增大。吸水10 min后,吸水倍率下降14.4%～58.0%,70 min后,下降41.8%～90.2%。研究认为：吸水初期,吸水倍率主要受土壤孔隙特性的影响,随着吸水时间的加长,土壤溶液中离子增多,对保水剂吸水倍率产生了影响。土壤溶液中离子量与黏粒含量有关,黏粒含量高,土壤溶液中离子量大,反之则小,保水剂在黏粒含量高的土壤中的吸水倍率较在黏粒含量低的土壤中低。与土壤混合还改变了保水剂的吸水规律,对照中,吸水倍率随着吸水时间加长而加大,达到最大后趋于稳定;而在土壤中,短时间内吸水倍率达到最大,随着吸水时间加长,吸水倍率逐渐下降。     

土壤特性对保水剂持水性能的影响

为研究土壤特性对保水剂持水性能的影响,测试了4种保水剂分别与砂壤土、壤砂土、砂粘壤土1和砂粘壤土2共4种土壤混合后的保水率,混合时土壤为风干土,保水剂与土壤混合的质量百分比为0.5%。结果表明:与单纯保水剂或者保水剂与砂子混合相比,保水剂与土壤混合后可明显降低保水剂的释水速度,提高保水剂的持水能力。土壤特性对保水剂释水速度有明显影响,土壤粘粒含量高,保水剂的释水速度慢,反之,则快。土壤粘粒含量高,土壤含水量高,保水剂表面水势梯度变低,使释水速度变慢;粘粒含量低,水势梯度变大,保水剂释水速率加快。经过7 h的恒温蒸发后,4种保水剂在粘粒含量较高的砂粘壤土(粘粒含量25%)中的保水率比在粘粒含量低的壤砂土(12.5%)中的保水率高43.7%~71.3%,且具有明显的差异。     

晋南旱垣土壤质地和茬口对小麦产量及水分利用效率的影响

在山西临汾、襄汾采用大区对比法研究了土壤质地和茬口对小麦产量及水分利用效率的影响。结果表明：小麦产量轻壤土质夏季复播作物茬口低于夏季休闲茬口,而中壤土质夏季复播作物茬口高于夏季休闲茬口;小麦播前贮水量轻壤土质夏季复播作物茬口低于夏季休闲茬口,而中壤土质夏季复播作物茬口高于夏季休闲茬口;轻壤土质全生育期0～100 cm,0～200 cm,100～200 cm的耗水量均以休闲茬口〉大豆茬口〉绿豆茬口,中壤土质拔节期贮水量、拔节至成熟阶段0～100 cm,0～200 cm,100～200 cm的耗水量均以花生茬口〉谷子茬口〉休闲茬口;水分利用效率中壤土质明显高于轻壤土质,各茬口间的极差中壤土质大于轻壤土质。该项研究为以旱地小麦为主要作物的轮作制度选择土壤质地和夏季复播（春播）作物茬口提供了理论依据。     

科尔沁沙地农牧交错带土地利用方式对土壤特性的影响

以彰武县北部为样区,研究了科尔沁沙地农牧交错带不同土地利用方式对于土壤特性的影响。研究结果表明：草甸碱土草地开垦为早作农田后,土壤次生盐渍化加重;草甸草地开垦成为水田,则有利于对土壤次生盐渍化的防止和抑制;固沙林地或草地开垦成为农田,在一定的程度和范围会导致土壤养分含量特别是速效养分N含量显著降低,土壤颗粒的粗化（沙化）,且这种趋势随着开垦年限的增加而加重。     

再生水滴灌对黄瓜地土壤特性的影响

再生水滴灌是解决水资源短缺的有效途径之一。采用大田试验方法,以地下水滴灌为对照,分析研究了滴灌条件下不同再生水水质对黄瓜根际土壤特性的影响。结果表明:在土壤理化性状方面,再生水滴灌情况下,黄瓜地土壤pH与对照相比无显著差异;再生水滴灌处理土壤EC值高于地下水滴灌;在土壤养分方面,与对照相比,碱解氮、有效磷、速效钾含量差异不显著;再生水浓度越大,对土壤呼吸的增强效应越明显。     

施用启动肥对土壤特性、玉米生长及产量的影响

研究了滴灌条件下施用启动肥对石灰性土壤特性和玉米产量的影响.供试玉米品种为新玉109号,在全生育期等磷量下,设置了启动肥不同用量[0 kg·hm-2(CF,对照)、45 kg·hm-2(SF3.0)、90 kg·hm-2(SF6.0)、135 kg·hm-2(SF9.0)]的田间试验,研究启动肥施用量对土壤特性、玉米产...     

浓缩沼液配方肥对小白菜生长及土壤特性的影响

利用盆栽试验种植小白菜,比较研究施用浓缩沼液配方肥、腐植酸和氨基酸水溶肥及"奥捷"水溶性肥对蔬菜生长和土壤理化性质的影响。结果表明:与腐植酸、氨基酸水溶肥和"奥捷"水溶肥相比,施用浓缩沼液配方肥可显著提高小白菜产量及还原型Vc、可溶性糖等的含量,抑制硝酸盐积累,提高土壤过氧化氢酶、脲酶活性和土壤养分含量:浓缩沼液配方肥配施氧基酸叶面肥模式对小白菜生长和土壤理化件质的改善效果最显著。     

三峡库区坡耕地植物篱对土壤特性的影响研究

植物篱在减少坡耕地径流、控制土壤侵蚀和降低非点源污染方面具有重要的作用。采用中国科学院万州典型区生态环境监测重点站监测的三峡库区坡耕地皇竹草植物篱小区和对照小区连续6年的监测资料,研究了坡耕地皇竹草植物篱对土壤特性的影响,结果表明植物篱能有效地改善坡耕地土壤结构、提高土壤养分含量。植物篱的实施有利于三峡库区坡耕地的可持续利用。     

模拟氮沉降对一年生香椿幼苗生长和光合特性的影响

为研究氮沉降对一年生香椿(Toonasinensis)幼苗夏季生长以及光合特性的影响,通过在夏季模拟氮沉降控制试验,以尿素为氮源供体,设置0kg(N)×hm~(-2)×a~(-1)(CK)、20kg(N)×hm~(-2)×a~(-1)、40kg(N)×hm~(-2)×a~(-1)、80kg(N)×hm~(-2)×a~(-1)、120 kg(N)×hm~(-2)×a~(-1)、180 kg(N)×hm~(-2)×a~(-1)不同氮添加水平以模拟氮沉降,对香椿幼苗地径、苗高、生物量及其分配和光合作用等进行研究。结果表明:1)不同氮添加量均促进了香椿幼苗地径、苗高和生物量的增加,地径、苗高和生物量均以氮添加水平180kg(N)×hm~(-2)×a~(-1)下最高,分别较CK高42.5%、64.4%和304.9%,且生物量向根、叶分配较多; 2)香椿幼苗叶片相对叶绿素含量(SPAD)随氮添加水平的增加而增加,在180 kg(N)×hm~(-2)×a~(-1)下最高,较CK增加73.9%;3)香椿幼苗表观量子效率(AQY)、最大净光合速率(Pnmax)、光饱和点(LSP)、光补偿点(LCP)以及暗呼吸速率(Rd)随氮添加水平的增加均呈现先升高后降低的趋势,其中LCP以80 kg(N)×hm~(-2)×a~(-1)下最高, AQY、Pnmax、LSP和Rd均以120kg(N)×hm~(-2)×a~(-1)下最高。结果表明,适量氮沉降能够促进香椿幼苗生长和光合能力的提高,但更高水平的氮沉降可能对香椿幼苗产生一定抑制作用。     

苜蓿生物覆盖对幼龄茶园生理生态特征的影响

试验研究了不同带型苜蓿生物覆盖对幼龄茶园生态系统的生理生态效应,结果表明：在盛夏季节,随苜蓿种植比例的增加,系统郁闭度提高,茶园光照强度、气温、土壤温度渐次降低,而湿度增加;苜蓿种植比例的增加,可明显改善盛夏季节茶树叶片的“午休”现象,茶树的净光合速率（Pn）提高,2：1带型、2：3带型和2：5带型的Pn分别比纯茶树处理（BS1）增加29．17％、57．29％和80．73％。幼龄茶树与苜蓿间作可改善茶园生态环境,有利于幼龄茶树生长,但带型差异对幼龄茶树生长速率、新稍数量影响规律性不强;幼龄茶园苜蓿生物覆盖可以获得可观的优质牧草,不同带型与纯紫花苜蓿（BS2）之间以及2：1带型、2：3带型、2：5带型之间的苜蓿干草、鲜草产量差异均达到极显著水平。2：5带型的间作模式效果最好,在改善幼龄茶园生态环境的同时,可收获可观的优质紫花苜蓿。构建茶树、苜蓿人工复合生态系统,不仅能够为幼龄茶树生长创造良好的生态环境,而且可为南方丘陵山区畜牧业发展提供优质饲料。     

Effects of soil compaction and arbuscular mycorrhiza on corn (Zea mays L.) nutrient uptake

Soil compaction is of great importance, due to its adverse effects on plant growth and the environment. Mechanical methods to control soil compaction may not be economically and environmentally friendly. Hence, we designed experiments to test the hypothesis that use of plant symbiotic fungi, arbuscular mycorrhiza (AM) may alleviate the stressful effects of soil compaction on corn (Zea mays L.) growth through enhancing nutrient uptake. AM continuously interact with other soil microorganisms and its original diversity may also be important in determining the ability of the fungi to cope with the stresses. Hence, the objectives were: (1) to determine the effects of soil compaction on corn nutrient uptake in unsterilized (S1) and sterilized (S2) soils, and (2) to determine if inoculation of corn with different species of AM with different origins can enhance corn nutrient uptake in a compacted soil. Using 2 kg weights, soils (from the field topsoil) of 10 kg pots were compacted at three and four levels (C1, C2, C3 and C4) (C1 = non-compacted control) in the first and second experiment, respectively. Corn (cv. 704) seeds were planted in each pot and were inoculated with different AM treatments including control (M1), Iranian Glomus mosseae (M2), Iranian G. etunicatum (M3), and Canadian G. mosseae, received from GINCO (Glomales In Vitro Collection), Canada (M4). Corn leaf nutrient uptake of N, P, K, Fe, Mn, Zn and Cu were determined. Higher levels of compaction reduced corn nutrient uptake, however different species of AM and soil sterilization significantly increased it. The highest increase in nutrient uptake was related to P (60%) and Fe (58%) due to treatment M4S2C3. Although it seems that M3 and M4 may be the most effective species on corn nutrient uptake in a compacted soil, M2 increased nutrient uptake under conditions (C3 and C4 in unsterilized soil) where the other species did not. Through increasing nutrient uptake AM can alleviate the stressful effects of soil compaction on corn growth.     

紫云英还田量对烟田土壤微生物及酶的影响

为在翻耕条件下合理施用紫云英,保障农业的可持续性发展,定位试验研究了15000kg·hm-2、22500kg·hm-2、30000kg·hm-2紫云英还田和22500kg·hm-2紫云英还田减施化肥(施肥时扣除紫云英中氮、磷、钾)及紫云英不还田5个处理对烟田土壤微生物数量、微生物活度、酶的影响。结果表明:烟草生育期内,不同处理好气性细菌数量呈前期均迅速上升、中期均稍有上升,但后期各有升降的趋势;烟草生长早期,紫云英还田减施化肥能增加好气性细菌数量。放线菌数量烟草生育前期略有下降,中期有所回升,后期又缓慢下降;烟草生长早期,紫云英还田能增加放线菌数量;整个烟草生育期,紫云英还田减施化肥可减少放线菌数量。真菌呈现烟草生育前中期迅速上升,后期缓慢下降的趋势;相对较少的紫云英还田量对土壤真菌数量增长的刺激作用较为明显。微生物活度呈烟草生育前期下降、中期趋于平稳、后期迅速升高达到最高点的趋势;烟草成熟期,紫云英还田的微生物活度明显高于不还田处理,增加紫云英还田量,微生物活度增加,但紫云英还田减施化肥会降低微生物活度。土壤纤维素酶活性以烟草旺长期为界点,表现出前期增加、后期下降的特点;烟草生长后期,紫云英还田土壤的纤维素酶活性高于对照土壤。土壤脲酶活性呈先快速下降,再缓慢上升,最后再快速上升趋势。土壤蛋白酶活性呈烟草生育前期下降,后期缓慢上升的特点;土壤蛋白酶活性与紫云英施用量呈正相关。过氧化氢酶活性在烟草各生育期的变化不大。土壤生物学评价发现,22500kg·hm-2紫云英翻耕还田栽培烟草较佳。     

水分胁迫对茶树叶片叶绿素荧光特性的影响

以"铁观音"和"福鼎大白茶"两个茶树品种为试验材料,研究水分胁迫对茶树叶片叶绿素荧光特性的影响.结果表明:水分胁迫下,茶树叶片的基础荧光(Fo)显著升高,最大荧光(Fm)、可变荧光(Fv)、PSⅡ原初光能转化效率(Fv/Fm)、PSⅡ的潜在活性(Fv/Fo)显著下降,表明水分胁迫使茶树叶片PSⅡ反应中心受到伤害;水分胁迫还可降低茶树的光化学反应速率(Prate),缩短荧光上升时间(T1/2),抑制PSⅡ反应中心电子的传递(ETR降低),导致天线色素热耗散速率(Drate)、非光化学猝灭(qN)和光合功能相对限制值(LPFD)升高,光化学猝灭(qP)和PSⅡ实际光化学效率(Yield)显著下降.比较水分胁迫下"铁观音"和"福鼎大白茶"叶片叶绿素荧光变化发现,"铁观音"PSⅡ反应中心的胁迫耐性较强,叶片光化学效率较高.     

Growth of Lumbricus terrestris and Aporrectodea caliginosa in an acid forest soil, and their effects on enchytraeid populations and soil properties

A laboratory experiment was carried out to test the hypothesis that the earthworms Lumbricus terrestris and Aporrectodea caliginosa are able to maintain their populations and reproduce in the acid forest soil of a deciduous forest where no lumbricids were found in the field. The experiment was conducted in 45-l containers in which layers of mineral subsoil, humus and organic topsoil collected from the site were established. Both species survived and at least L. terrestris reproduced during the 60 weeks’ incubation. Burrows and middens of L. terrestris were recorded and quantities of litter were consumed. The presence of lumbricids increased the organic matter content of humus, reduced the acidity of the topsoil and humus layers, and suppressed the population of the enchytraeid Cognettia sphagnetorum. A dense population of Enchytraeus albidus was found in L. terrestris middens. It is concluded that edaphic factors do not explain the absence of earthworms, but isolation from cultural landscapes and lack of opportunity to colonize the site from the surroundings is the decisive factor.     

转 AtPAP15基因大豆种植对根际土壤养分及酶活性的影响

以转入AtPAP15基因的两个磷养分高效转基因大豆株系AP15-1、AP15-3及其各自受体YC03-3、YC04-5为材料,在大田连续种植两季,通过在苗期、盛花期和成熟期采集根际土,对其进行pH和全磷、速效磷、有机磷、全氮、碱解氮、全钾、速效钾、及钼等八种微量元素含量的测定,并分析了盛花期AP15-1与其受体YC03-3根际土中酸性磷酸酶、过氧化氢酶、蔗糖酶和脲酶的活性变化,从而了解上述磷高效转基因大豆的种植是否会对根际土中主要养分和酶活性产生影响.研究结果显示:秋春两季根际土中除全钾和微量元素含量外,其他养分含量在个别时期,转基因大豆AP15-1或AP15-3与其受体之间,均存在显著性的差异,但这些显著性差异大部分出现在苗期,成熟期仅有机磷含量在AP15-1与其受体YC03-3、速效钾含量在AP15-3与其受体YC04-5之间呈显著差异,并且这些差异在两季中均未重复出现.根际土中四种土壤酶活性测定结果显示:同季转基因大豆与其受体之间差异不显著.总体结果表明,上述转AtPAP15基因磷高效大豆种植对根际土中磷、氮、钾等养分和四种土壤酶活性均未产生显著的影响.     

紫茎泽兰和黄顶菊入侵对土壤微生物群落结构和旱稻生长的影响

为比较入侵植物与本地植物对土壤微生态影响的差异, 探索外来植物入侵的土壤微生物学机制, 本研究通过同质园试验, 比较分析了2种入侵菊科植物(紫茎泽兰、黄顶菊)和2种本地植物(马唐、猪毛菜)对土壤肥力和微生物群落的影响, 并通过盆栽反馈试验验证入侵植物改变后的土壤微生物对本地植物旱稻生长的反馈作用。同质园试验结果表明: 2种入侵植物和2种本地植物分别对土壤微生态产生了不同的影响, 尤其是紫茎泽兰显著提高了土壤有效氮、有效磷和有效钾含量,紫茎泽兰根际土壤中有效氮含量为39.80 mg·kg^-1,有效磷含量为48.52 mg·kg^-1。磷脂脂肪酸指纹图谱结果表明, 2种入侵植物与2种本地植物相比, 较显著增加了土壤中放线菌数量, 而紫茎泽兰比其他3种植物显著增加了细菌和真菌数量。盆栽结果表明: 黄顶菊生长过的土壤灭菌后比灭菌前旱稻株高增加113%, 紫茎泽兰也使旱稻的株高增加17%。由以上结果可知, 紫茎泽兰和黄顶菊可能通过改变入侵地土壤的微环境, 形成利于其自身生长扩散的微生态环境从而实现其成功入侵。     

Cd、Pb和Zn在土壤 紫茎泽兰 泽兰实蝇系统中的生物富集效应研究

泽兰实蝇(Procecidochares utilis Stone)是目前入侵杂草紫茎泽兰(Eupatorium adenophorum Spreng)的一种重要天敌, 但在重金属污染的矿区泽兰实蝇对紫茎泽兰的植株寄生率明显降低。故利用同心圆采样法在云南兰坪金顶铅锌矿区5 km范围内采集土壤、紫茎泽兰及泽兰实蝇并测定重金属含量, 以研究重金属在土壤 紫茎泽兰茎 泽兰实蝇系统中的生物富集效应, 探讨重金属胁迫影响泽兰实蝇控制效果的机制。结果表明: 土壤 紫茎泽兰茎 泽兰实蝇系统中Pb、Zn和Cd含量随着距矿中心距离的增加而极显著下降, Cd、Pb和Zn在土壤 紫茎泽兰茎系统中的富集系数分别为0.205~0.614、0.058~0.079和0.222~0.398, 平均值分别为0.453、0.067和0.315, 在紫茎泽兰茎 泽兰实蝇系统中的富集系数分别为1.06~7.69、9.68~20.13和1.13~1.56, 平均值分别为2.47、12.83和1.42。Cd和Zn属于强聚集, Pb属于很强聚集的元素。本研究结果证明, Pb、Zn和Cd可以在土壤 紫茎泽兰茎 泽兰实蝇系统逐级传递富集, 并初步阐明了重金属Cd、Pb和Zn在土壤 紫茎泽兰 泽兰实蝇系统中的传递规律。这丰富了重金属污染的生态毒理学效应, 为进一步研究重金属胁迫影响泽兰实蝇控制效果的机制奠定了基础。     

Defoliation effects on Plantago lanceolata resource allocation and soil decomposers in relation to AM symbiosis and fertilization

Plants can mediate interactions between aboveground herbivores and belowground decomposers as both groups depend on plant-provided organic carbon. Most vascular plants also form symbiosis with arbuscular mycorrhizal fungi (AMF), which compete for plant carbon too. Our aim was to reveal how defoliation (trimming of plant leaves twice to 6 cm above the soil surface) and mycorrhizal infection (inoculation of the fungus Glomus claroideum BEG31), in nutrient poor and fertilized conditions, affect plant growth and resource allocation. We also tested how these effects can influence the abundance of microbial-feeding animals and nitrogen availability in the soil. We established a 12-wk microcosm study of Plantago lanceolata plants growing in autoclaved soil, into which we constructed a simplified microfood-web including saprotrophic bacteria and fungi and their nematode feeders. We found that fertilization, defoliation and inoculation of the mycorrhizal fungus all decreased P. lanceolata root growth and that fertilization increased leaf production. Plant inflorescence growth was decreased by defoliation and increased by fertilization and AMF inoculation. These results suggest a negative influence of the treatments on P. lanceolata belowground biomass allocation. Of the soil organisms, AMF root colonization decreased with fertilization and increased with defoliation. Fertilization decreased numbers of bacterial-feeding nematodes, probably because fertilized plants produced less root mass. On the other hand, bacterial feeders were more abundant when associated with defoliated than non-defoliated plants despite defoliated plants having less root mass. The AMF inoculation per se increased the abundance of fungal feeders, but the reduced and increased root AM colonization rates of fertilized and defoliated plants, respectively, were not reflected in the numbers of fungal feeders. We found no evidence of plant-mediated effects of the AM fungus on bacterial feeders, and against our prediction, soil inorganic nitrogen concentrations were not positively associated with the concomitant abundances of microbial-feeding animals. Altogether, our results suggest that (1) while defoliation, fertilization and AMF inoculation all affect plant resource allocation, (2) they do not greatly interact with each other. Moreover, it appears that (3) while changes in plant resource allocation due to fertilization and defoliation can influence numbers of bacterial feeders in the soil, (4) these effects may not significantly alter mineral N concentrations in the soil.