不同施肥水平下全膜双垄沟播玉米土壤酶活性及氮磷养分含量的动态变化

为进一步完善全膜双垄沟播玉米栽培技术体系,采用大田随机区组试验法,研究了不同施肥水平下全膜双垄沟播玉米土壤酶活性及氮磷养分含量的动态变化情况。结果表明：在玉米生长前期,土壤脲酶、碱性磷酸酶、蔗糖酶活性以及碱解氮、速效磷含量均呈现快速增长趋势。脲酶、蔗糖酶、过氧化氢酶活性和碱解氮含量均在拔节期达到最大值,碱性磷酸酶活性和速效磷含量在抽雄期达到最大值。在玉米生长后期,各种土壤酶活性和氮磷养分含量又呈降低趋势。土壤脲酶活性与氮磷养分含量,土壤碱性磷酸酶活性与速效磷含量均存在显著或极显著正相关关系,土壤蔗糖酶活性与氮磷养分含量也存在显著的正相关关系,而土壤过氧化氢酶活性与氮磷养分含量之间,土壤碱性磷酸酶活性与碱解氮之间无显著相关关系。西北干旱半干旱地区全膜双垄沟播玉米种植密度确定为6．75×104株·hm-2时,最佳施肥量为纯N 210 kg·hm-2、P2O5168 kg·hm-2。     

甜樱桃重茬土壤有效养分及酶活性的变化

为了探讨甜樱桃重茬土壤中有效养分以及酶活性的变化,在樱桃苗圃地分别从尚未栽种过甜樱桃苗、正茬、重茬区域采集土壤样品,测定土壤有效养分含量(NO3--N、NH4+-N、速效K、有效P及有效B等)和4种土壤酶(脲酶、过氧化氢酶、碱性磷酸酶以及蔗糖酶)的活性。结果表明:与樱桃正茬土壤相比,甜樱桃重茬土壤NO3--N、速效K、有效P、有效B、有效Zn、有效Fe、有效Cu、可交换性Mg含量、脲酶以及碱性磷酸酶活性含量显著降低;与正茬土壤相比重茬土壤中随着土层深度的增加,矿质元素含量(除有效Mn、Fe以及可交换性Ca含量外)和4种土壤酶活性显著降低,但可交换性Ca含量上升;樱桃重茬土壤有效养分比例失调,其中Ca/P、Ca/K及Ca/Zn严重失调,其中0~20 cm土层失调比例高达104.93%、140.45%和184.59%,20~40 cm土层失调比例分别为110.03%、178.42%以及144.47%,Zn/Mn和Zn/Mg失调较严重,失调比例高达50%以上。其中相关性分析表明:茬数与有效Mn含量呈线性极显著正相关;脲酶和碱性磷酸酶与速效K、有效P、有效B、有效Zn及有效Cu呈极显著正相关;蔗糖酶与速效K、有效P和有效Cu呈极显著正相关;脲酶、碱性磷酸酶和蔗糖酶与交换性Ca含量呈极显著负相关。总之,重茬土壤的有效养分含量以及土壤酶活性显著降低,养分比例失调。     

蔬菜大棚土壤脲酶、过氧化氢酶活性与土壤养分的关系

以山东省寿光市蔬菜大棚土壤为供试材料,运用相关和通径分析,分析了土壤脲酶、过氧化氢酶活性与土壤养分的关系.结果表明,土壤脲酶、过氧化氢酶活性与其有机质、全氮、碱解氮、全磷、速效磷、速效钾含量之间呈显著或极显著正相关,可以作为土壤肥力指标.土壤全氮、碱解氮、速效磷对脲酶活性的影响主要表现在直接作用上,是影响脲酶活性的主要...     

施用生物炭后土壤生物活性与土壤肥力的关系

分析了生物炭不同用量条件下土生物活性与土壤主要肥力指标之间的关系。相关分析表明,除蔗糖酶活性和微生物量碳外,土壤其它生物活性指标与土壤容重间呈显著负相关。土壤脲酶和过氧化氢酶活性、微生物量氮和三大类微生物与土壤主要肥力指标间呈显著或极显著正相关。除蔗糖酶外,酶活性与三类微生物数量间显著相关,但蔗糖酶、土壤脲酶、碱性磷酸酶、过氧化氢酶的活性间并不完全显著相关。通径分析表明,脲酶和微生物量氮对土壤肥力影响以直接作用为主,而过氧化氢酶则以间接作用为主。主成分分析结果表明,可以用微生物因子、酶活性因子和速效磷因子进行综合描述土壤肥力特征。其中,各处理综合得分在玉米季大于小麦季,且随生物炭用量的增加而增加,表明高用量生物炭对土壤肥力的提高作用明显。     

豫西旱坡地长期保护性耕作土壤酶活性及其与肥力关系

为探讨多年保护性耕作下土壤酶活性及其与土壤肥力的关系,对豫西旱区坡耕地定位试验第7年保护性耕作的土壤酶活性以及土壤养分进行了测定和分析.结果表明:深松覆盖和免耕覆盖能够提高3种酶活性,特别是能明显提高0～10 cm土层土壤酶活性,其中脲酶活性增加最多.脲酶与有机质、全磷、速效磷、速效钾、碱解氮呈显著或极显著相关关系,转...     

黑土区坡耕地土壤酶活性与土壤养分关系研究

对东北黑土区东山沟坡耕地土壤有机质、全氮、碱解氮、速效磷和土壤转化酶、脲酶、碱性磷酸酶活性进行了测定,并对其结果做相关分析,表明土壤酶可以作为评价黑土土壤肥力的指标,有机质仍是黑土土壤养分和酶活性的源和库。黑土区坡耕地土壤表层养分含量和酶活性高于次表层的相应指标,且呈现显著性差异。据此,建议黑土区坡耕地积极探索和推广秸秆还田、免耕等水土保持新措施,提高有机质含量,以遏制土壤表层质量退化。     

高原沟壑区套作苹果幼儿园土壤养分及酶活性研究

对黄土高原沟壑区塬面不同套种作物的幼树苹果园土壤养分和酶活性状况的研究表明：土壤有机质、全Ｎ、水解Ｎ和速效Ｐ含量在套作行和果树行是不均衡的。套种烤烟对土壤速效性养分的消耗最大,地有机质和全Ｎ的积累最小。土壤的过氧化氢酶、蔗糖酶、脲酶以及中性磷酸酶活性在套种小麦的果园中以套作行高于果树行,而套种烤烟则使脲酶和中性磷酸知性有所降低。豆类作物有利于土壤肥力的均衡发展。     

荒漠灌区不同种植年限苜蓿地土壤酶活性的变化研究

在干旱荒漠绿洲区大田试验条件下,研究了不同种植年限(0,3,4,5,7,10 a)苜蓿地土壤脲酶、碱性磷酸酶、蔗糖酶、淀粉酶、纤维素酶及过氧化氢酶活性的季节性动态变化,旨在探讨种植不同年限苜蓿对土壤生物化学性状的影响,为粮草合理轮作周期的制订提供科学依据。结果表明:种植苜蓿与撂荒地相比,土壤酶活性得到不同程度的提高,且各年限间土壤酶活性差异显著。其中土壤脲酶、蔗糖酶及纤维素酶活性均随生长年限增加呈先增高后降低再增加的变化趋势,而淀粉酶、碱性磷酸酶及过氧化氢酶活性均随种植年限增加呈先升高后降低的变化趋势,种植苜蓿5a土壤酶活性增加最明显,0~60 cm土层依次较CK分别增加了80.56%、69.91%、46.75%、533.33%、110.71%、11.81%;土壤6种酶的活性均随着土层深度的增加而减小,在表层0~20 cm土层,土壤酶活性最强。脲酶和淀粉酶活性在夏季最高,蔗糖酶、纤维素酶、过氧化氢酶及碱性磷酸酶活性均在春季达到最高。对6种酶之间的相关性进行分析,研究发现除蔗糖酶外,其余5种酶间呈显著或极显著相关。     

子午岭地区植被演替过程中土壤养分及酶活性特征研究

选择植被自然恢复不同年限的阳坡梁坡地作为研究对象,采用时空互代法研究子午岭地区植被恢复过程中土壤养分和酶活性的变化.结果表明,植被恢复140 a内,不同土层土壤有机质含量、全氮含量、蔗糖酶活性、脲酶活性、碱性磷酸酶活性和过氧化氢酶活性增加,且表土层(0～20 cm)土壤养分含量和酶活性高于下层土壤(20～40 cm).以裸露地为对照,土壤0～20 cm土层,有机质含量、全氮含量、蔗糖酶活性、脲酶活性、碱性磷酸酶活性和过氧化氢酶活性分别增加了23.8%～534.9%、9.3%～300.0%、213.6%～521.5%、40.4%～286.5%、22.7%～232.2%和3.2%～22.4%,土壤速效磷含量呈现波动变化, 过氧化氢酶活性变化幅度比其他三种酶低.土壤有机质含量与全氮、速效磷含量密切相关;土壤蔗糖酶与土壤有机质、全氮均为极显著的相关关系(0.930/0.918);土壤脲酶活性与全氮含量相关系数最高(0.804);土壤碱性磷酸酶活性与有机质、全氮含量都呈极显著相关(0.977/0.984);土壤过氧化氢酶活性与全氮含量极显著相关,相关系数达0.996.     

农田沙漠化演变中土壤质量的生物学特性变化

通过研究处于沙漠化过程中的科尔沁沙地旱作农田土壤酶活性与基础土壤呼吸活性，分析了土壤质量生物学特性的沙漠化演变。结果表明，土壤酶活性与基础土壤呼吸对沙漠过程中环境的变化反应敏感，随着沙漠化程度增加，与土壤物理化学肥力因素有关的过氧化氢酶、脲酶和碱性磷酸酶的活性和土壤呼吸活性随之下降。土壤酶活性和呼吸活性与土壤有机质和养分有极显著的相关，在一定程度上可以用酶活性和呼吸强度表征有机质和养分的状况及其数量的变异，因此，可以作为农田沙漠化演变中土壤质量特征变化的重要辅助指标。     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.     

Brief Guide for Authors

正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad     

The parasitoid complex ofLiriomyza cicerina on chickpea (Cicer arietinum)

Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.     

Plant–herbivore asynchrony necessitates augmentative releases of the exotic beetle,Zygogramma bicolorata,to enhance the biological control of P arthenium hysterophorus

Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F ₃, F ₄ and F ₅, but not in F ₁ and F ₂ that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F ₁ and F ₂ in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.     

Effect of botanical insecticides and bacterial toxins on the gut enzyme of the rice leaffolderCnaphalocrocis medinalis

The effect of botanical insecticides and bacterial toxins on gut enzyme activity of larvae of the rice leaffolderCnaphalocrocis medinalis (Guenée) (Insecta: Lepidoptera: Pyralidae) was investigated. Gut enzyme activities were affected by botanical insecticides and bacterial toxin individually and in combination. When fed a diet of rice leaves treated with botanical insecticides and bacterial toxins, in bioassays the activities of gut tissue enzymes — acid phosphatases (ACP), alkaline phosphatases (ALP) and adenosine triphosphatases (ATPase) — of rice leaffolder larvae were affected. When combined, the effect was more severe at a low concentration. Larvae that were chronically exposed to botanical insecticides and bacterial toxins showed a reduction in weight (59–89%) and exhibited a significant reduction in ACP, ALP and ATPase activities. The combination ofBacillus thuringiensis kurstaki and botanical insecticides caused a decrease of twofold in enzyme activity even at reduced concentration. A synergistic effect was found when botanical insecticides and bacterial toxins were combined at low doses. These effects were most pronounced in early instars. Clear dose-response relationships were established with respect to enzyme activity. In conclusion: (i) biopesticides are relatively safe and biodegradable; (ii) a synergistic effect of botanical insecticides and bacterial toxins was found; (iii) less expensive, readily available and naturally occurring biopesticides could be an alternative for organic and inorganic pesticides in controlling RLF. http://www.phytoparasitica.org posting Sept. 28, 2004.