TDZ对尾细桉叶片离体再生的影响

为合理利用生物质炭改良热带地区土壤提供理论依据,通过培养试验,研究不同水分培养条件下添加生物质炭对砖红壤pH及养分含量的影响。结果表明,生物质炭能显著提高土壤pH,增加土壤有机碳及全N、全P和全K的含量;淹水显著提高添加了生物质炭的土壤碱解N含量,但极大地降低了其速效P和速效K含量。说明利用生物质炭改良热带土壤时,要根据改良目的合理进行水分管理。     

有机肥替代对京郊夏播青贮玉米土壤养分动态与平衡的影响

通过田间试验设置4个处理,100%化肥、70%化肥+30%有机肥、40%化肥+60%有机肥和100%有机肥,研究青贮玉米生产中施用有机肥替代化肥对土壤养分动态和平衡的影响。通过测定生育期内表层土壤速效N、P、K养分、土壤微生物量C与N、1 m土体NO_3-含量和青贮玉米N、P、K吸收量发现,在大喇叭口期,有机肥替代化肥处理降低表层土壤无机N的供应水平,提高有效P和速效K的供应水平;在收获期,有机肥替代显著提高土壤微生物量C、N,显著降低81～100 cm土层NO_3-含量和1 m土体NO_3-累积量。有机肥替代提高养分生产力和养分回收量,加剧土壤养分的亏缺。本研究条件下,30%有机肥替代化肥处理土壤N、P、K养分供应水平高,养分回收率高,加剧土壤养分的亏缺,需考虑长期的养分平衡问题。     

福建省长汀县植烟耕地土壤肥力状况

2008-2009年对长汀县烤烟种植地烟前烟后土壤养分测定表明,烤烟耕地土壤整体较酸,全县土壤烟前pH值为4.31,烟后4.42;有机质含量处于中等水平,烟后土壤有机质含量26.33 g·kg-1,比烟前（24.69 g·kg-1）有所增加;植烟后土壤碱解N含量与植烟前差别不大,略有增加,含量处于中等水平;速效P含量较为丰富,植烟前土壤速效P含量为44.18mg·kg-1,植烟后显著增加,达60.25 mg·kg-1;速效K含量植烟前偏低,仅75.17 mg·kg-1,植烟后增加显著,达324.87 mg·kg-1,烟后土壤速效K含量丰富。不同土属pH值差别不大,有机质含量、碱解N、速效P、速效K以黄泥田、灰泥田、紫泥田、潮沙田较高。     

信阳地区农业用地土壤养分状况调查研究

[目的]对信阳不同利用形式农业用地土壤的养分进行分析测试研究.[方法]取耕作层土壤样品,测定土壤质地、pH、全量N、P、K含量和速效N、P、K含量.[结果]大部分土壤为壤质土,土壤pH均低于7.0,土壤呈偏酸性,有机质含量均低于20 g/kg,处于较低的水平.绿化带速效氮、磷、钾的平均含量分别为33.4、18.6、136.9 mg/kg;旱地土壤和稻田土壤速效氮平均含量分别为90.6和104.6 mg/kg,速效磷的平均含量46.5和42.3 mg/kg,速效钾平均含量90.6和104.8 mg/kg;茶园土壤速效氮、磷、钾平均含量分别为169.7、35.8、119.5mg/kg.[结论]可对信阳农业生产、土壤改良、合理施肥提供理论依据和实践指导.     

稻田年内水旱轮作对土壤肥力的影响

经过6年的稻田年内水旱轮作（两旱一水的麦-玉米-稻）和水水连作(麦-稻-稻)定位试验研究,结果表明随着种植年限增加,不论哪一种复种轮作方式均可使土壤有机质、全N、全P含量增加,并可以明显增加土壤速效N、P、K养分,也可使土壤物理性状得到改善,如土壤容重下降,孔隙度、尤其是非毛管孔隙增加,土壤固液相比减低。从两种不同种植方式来看,年内水水连作比年内水旱轮作更有利于土壤有机质和全N、全P含量增加,但年内水旱轮作的土壤速效N、P、K含量则比年内水水连作高。年内水旱轮作更有利于土壤物理性状的改善从而使土壤好气性微生物增加,厌气性微生物减少,土壤还原性物质含量下降。试验结果还表明年内水旱轮作使晚季稻田土壤速效养分明显增加,从而有利于晚稻的生长。     

槟榔间作香露兜对土壤养分和养分吸收的影响

为了研究槟榔间作香露兜对土壤养分和养分吸收的影响,采用盆栽试验的方法,对槟榔单作、槟榔间作香露兜和香露兜单作3种种植模式的土壤理化性质和养分吸收进行比较研究。结果表明：槟榔间作香露兜后,相对于单作槟榔,土壤EC值和碱解氮含量显著降低47.15%和25.74%,土壤速效磷含量显著增加32.32%,其中碱解氮与过氧化氢酶和过氧化物酶极显著负相关,速效磷与总根长、根系总表面积、根体积、根数目、脲酶和酸性磷酸酶显著正相关,速效磷与过氧化氢酶和过氧化物酶极显著正相关;槟榔地上部N浓度以及香露兜地上部P和K浓度分别显著增加41.56%、26.56%和25.69%;而槟榔和香露兜根系以及地上部N、P和K养分含量均高于单作,其中根系槟榔P和K含量和香露兜K含量显著增加;同时,间作后槟榔和香露兜对N的吸收效率均高于单作,香露兜的P和K的吸收效率高于单作并略高于槟榔的吸收效率,其中P和K的吸收效率与总根长、总表面积、根体积、根数目均显著正相关,氮的吸收效率与根系形态无显著相关关系。综上所述,槟榔间作香露兜增加了土壤中速效磷含量,促进了槟榔和香露兜对氮、磷和钾养分的吸收,土壤速效磷含量的增加、养分吸收效率的提高均与根系形态显著正相关。     

间作作物收获后胶园土壤肥力对比研究

通过对比法研究收获幼龄胶园间作作物香蕉和葛藤后土壤肥力的变化。结果显示,除速效N含量上升外,收获香蕉、葛藤后,胶园土壤全K、全P、全N、有机质、速效K和速效P年平均含量相比空白对照均出现下降,尤以速效磷、速效钾下降最为明显。收获香蕉后土壤pH值和含水量变化不明显,而收获葛藤后,土壤含水量和pH值均出现下降。这说明,间作作物香蕉和葛藤被收获后易导致土壤N、P、K等养分流失,土壤肥力明显下降,为防止土壤肥力退化,应做好胶园水土保持、保留地表植被、收获间作作物后及时施加有机肥和氮磷钾等无机肥料。     

福建县级区域耕地土壤养分时空变异研究

运用地理信息系统和地统计学相结合的方法,研究福建沿海县级区域耕地土壤主要养分指标——有机质、碱解氮、速效磷、速效钾的空间变异规律,并按照肥力指标法对耕层土壤进行养分分级。结果表明,空间上,从县级区域耕层土壤分析,不同地块土壤养分含量变化差异大;空间变异结构也存在较大差异,晋江速效养分表现为结构性因素影响,而闽侯表现为结构性因素和随机性因素共同作用;建立了土壤养分空间分布图,分析其空间分布规律;按照肥力等级划分,该区域耕地氮素表现为部分区域缺乏,钾素大部分区域严重亏缺,磷素大部分区域盈余;时间上,以土壤速效磷为例,与20世纪80年代第2次土壤普查资料对照,其含量有所增长,从农田养分平衡角度也证实了该区域大部分耕地土壤累积磷素。     

长泰县耕地土壤养分变化及其对策

为有效提高土地利用率,分析近年来福建省漳州市长泰县耕地土壤养分的变化情况,结果表明：与1982年测定结果相比,2009年本县耕地土壤有机质含量变化小,碱解氮、有效磷、速效钾等成分含量明显提高,土壤pH值趋向微酸性或中性,但仍有58.5%的耕地土壤处于缺钾状态,且部分土壤出现富磷化污染状态和强酸性,为此,根据其变化情况提出在施足有机肥基础上,实行适氮、重钾、轻磷的科学施用原则,按需调整N、P、K的比例,人工现配现施或施用作物专用配方肥等改善土壤养分的对策。     

菠萝蜜高产园土壤养分特征研究

对菠萝蜜高产园0～20、20～40 cm土层的土壤养分状况进行研究。结果表明,菠萝蜜高产园0～20 cm土层大量元素速效养分高于临界值,中量元素低于临界值,微量元素除有效B外均高于临界值,部分试验结果偏低。随土层加深,除有效B含量增加外,其余养分含量均呈下降趋势。利用变异系数反映受外界环境和养分补充程度影响下土壤养分变化快慢的特征。0～20 cm土层全P,20～40 cm土层速效P,各土层全K、速效K、交换性Mg、有效S、微量元素变异系数较大,含量变幅较大。     

濒危物种白花延龄草的生物学特性调查研究

目的为开展白花延龄草驯化栽培研究提供参考。方法对白花延龄草生物学特性进行调查研究,总结白花延龄草生长发育特性。结论白花延龄草种子生理发育不完全,需经长时间完成形态后熟和生理后熟方可萌芽。     

The origin and distribution of the golden nematode and its potential in the U.S.A.

Potato cyst-nematodes,Globodera pallida andG. rostochiensis (golden nematode), and their preferred host, the potato, originated in the Andes of South America. Both were introduced into Europe from the Andean region, the potato about 1570 and the nematode nearly 300 years later. Potato cyst-nematodes are believed to have been introduced into Europe in the 1850’s along with potato collections from the Andes for use in breeding for late blight resistance, but the nematodes went unnoticed until 1881. Since that time the nematodes have spread to virtually everywhere that potatoes are grown, as one or both species have now been reported from 47 countries. It is believed that the golden nematode was introduced into the U.S.A. from Europe on military equipment brought back after the First World War to Long Island, NY, but the nematode was not recognized until some 20 years later. Yield losses in countries with general infestations of potato cyst-nematodes are probably 9% or more; the potential for losses is greatest in countries where average yields are greatest, such as the U.S.A. Good resistance to the pathotype of the nematode that occurs in the U.S.A. is commercially available. If all potatoes grown in the U.S.A. contained this resistance, further spread would be restricted and the golden nematode could perhaps be eliminated from the U.S.A.; but the present supply and diversity of resistant varieties are insufficient for the total potato acreage. Restricting spread of the golden nematode in the U.S.A. minimizes costs borne by growers and government agencies in dealing with the pest. At present, the most promising approach to restricting spread is through management systems developed for keeping nematode densities below the critical level above which spread will occur. If the golden nematode is to be contained, management systems must eventually be applied to all potato acreages. Increased research effort is needed to develop resistant varieties, resistance to a broad range of pathotypes, nematode management systems, and biological control     

Screening the U.S. potato collection for frost hardiness

Potato is one of the most important world vegetables with respect to value of production and nutritional impact. Frost susceptibility reduces or precludes production on millions of hectares worldwide. In contrast to disease and pest problems, cultural or chemical treatments are not likely to be helpful in combating frost, so genetic improvement must be sought. Fortunately, wild relatives of the cultivated potato have been shown to exhibit frost tolerance far superior to that of cultivated species. In this research, over 2,600 accessions representing 101 species in the US potato collection at Sturgeon Bay, Wisconsin were visually screened after natural frosts in a uniform field in 1992. This provided a more comprehensive survey of germplasm accessions, further characterized species’ hardiness and intraspecific variation. The most hardy species wereSolanum acaule, S. albicans, S. commersonii, andS. demissum. An additional previously unreported extremely frost hardy species (Solanum paucissectum) was discovered. This information should expand the insights and germplasm options available to those intent on breeding desirable varieties with high levels of frost hardiness.     

A review of the biology and control of selected weed species in the genus Oxalis: O. stricta L., O. latifolia H.B.K. and O. pes-caprae L.

This review considers the distribution, weed problems, biology and control of Oxalis stricta, O. latifolia and O. pes-caprae. The rhizomatous O. stricta is a persistent seed-producing weed which invades horticultural crops in North America. Chemical control is generally most effective in situations where soil-applied residual herbicides can be used; in turfgrass however, foliage-applied herbicides provide suppression only. O. latifolia is widely distributed in a range of annual and perennial crops growing in temperate and tropical locations. This pernicious perennial weed reproduces exclusively by asexual structures, underground bulbs, stolons and tubers. The complexities of the perennating system have rendered ineffective a wide range of herbicide families as a means of restricting the spread of O. latifolia. Similarly, cultural methods of control have not been successful. O. pes-caprae also grows and perennates from bulbs. This weed is essentially a problem in cereal crops in Southern Australia and Mediterranean fruit orchards. Cultural and chemical control difficulties and inadequacies are similar to those in O. latifolia. Future research strategies involving weed physiology, herbicide action and cultural control including biological control are discussed in relation to obtaining improved control methods for the selected Oxalis species.     

美国转基因玉米的生产概况和发展趋势

美国是世界上最大的玉米生产国, 种植面积、总产和单产均居世界首位。转基因玉米自1996年引入生产以来,使玉米生产上了一个新台阶。当前推广利用的转基因玉米品种基本上是抗虫和抗除草剂两种类型。抗虫是由在玉米体内表达Bacillus Thuringiensis(Bt)毒素结晶蛋白(cry蛋白)基因所致,除草剂的抗性(Herbicide tolerance, HT)是由外源的或改良的EPSPS基因在玉米体内表达来实现。转基因玉米的种植面积每年都稳步上升,转基因玉米的也由单一的Bt或HT转变为多基因多性状的叠加,将抗玉米螟和抗Rootworm结合,使玉米的地上部和地下部都得到了有效的保护,再加之抗除草剂基因的叠加,使得转基因品种在生产上更具竞争力。转基因玉米的抗虫和抗除草剂等优良性状带来了巨大的经济和环境效益, 并被越来越多的大众所接受。转基因玉米在短短10年间的应用和发展,还不能回答转基因作物对人类和环境的长期影响等问题。因此,对转基因作物的管理和利用仍不能掉以轻心,不能因对生物技术的热情而对人类和环境造成无意的不可挽回的破坏。