98％棉隆微粒剂防治黄瓜根结线虫田间药效试验

以10％灭线磷GR为对照药剂,设98％棉隆MG 35、40、45 g/m2处理土壤防治黄瓜根结线虫.结果表明:98％棉隆MG 35、40、45 g/m2的3个处理,药后30 d土壤中2龄幼虫虫口减退率分别为89.45％、90.50％、92.05％,对照药剂10％灭线磷颗粒剂5 g/m2处理的虫口减退率为60.65％;药后90 d土壤中2龄幼虫虫口减退率分别为88.63％、89.73％、91.69％,对照药剂10％灭线磷5 g/m2处理的线虫虫口减退率为59.97％.98％棉隆MG各处理的防治效果分别为85.71％、88.80％、89.34％,而对照药剂为65.71％.表明98％棉隆MG可有效地控制黄瓜根结线虫的为害,有较好的推广应用价值.     

Lime-induced growth depression in Lupinus species: Are soil pH and bicarbonate involved?

In a series of experiments, the effect of elevated pH on root growth of different lupin genotypes and lime-tolerant Pisum sativum was assessed. Seedlings were cultivated in pH-controlled but unbuffered nutrient or test solutions with pH 5—8 under constant light or constant darkness. Moderately increased solution pH did not affect root elongation. At high pH, root elongation rates were reduced by less than 35%, L. luteus being most sensitive. In a further experiment, effects of 10 mM bicarbonate (HCO₃^-) and organic buffers (MES, TES) were examined. Bicarbonate severely affected root elongation of lupins, sensitivity increasing in the order Lupinus albus < L. angustifolius < L. luteus. Since the reduced root elongation was not accompanied by a decreased root weight, specific root weight was increased. Shoot growth was not affected by HCO₃^-. Addition of organic buffers to alkaline nutrient solution, similarly to HCO₃^-, reduced elongation of main roots, but not that of laterals. Both treatments increased citrate concentrations in roots of sensitive L. luteus, but not of tolerant L. albus. Other carboxylates were not related to growth inhibition. Xylem exudate pH was always below 5.8, indicating that HCO₃^- was probably not translocated to the shoot. It is concluded that HCO₃^- is a key factor for lime-induced growth inhibition of calcifuge lupins, with the roots, not the shoots, being primarily affected.     

Root renewal of sugar beet as a mechanism of P uptake efficiency

Sugar beet (Beta vulgaris L.) was grown in two different long‐term P fertilization experiments on a sandy and a loamy soil. The P supply levels of the soils were ”︁low”, ”︁sufficient”, and ”︁high”, according to the German recommendation scheme. The low P level decreased shoot and storage root yield only on the loam soil, where the recovery of the P‐deficient plants after a drought period was slower than at a sufficient P supply. The size of the living root system, as determined by a conventional auger sampling method, peaked at early July and decreased until harvest on the sandy soil without any influence of the P level. On loam, the living root systems were more constant and larger at P shortage. Total root production, as determined by the ingrowth core method, was about 120 km m^—2 in the well P supplied loam treatments and 200 km m^—2 at P deficiency, which was 3—4 times and 5 times higher than the average size of the living root systems, respectively. Hence, a rapid root renewal took place. On sand, where no P deficiency occurred, total root production was not different between the P supply levels but higher than in the well‐supplied loam treatments. Modelling P uptake revealed that this root turnover and the concomitant better exploitation of the soil facilitates P uptake at a low P level in soil, but is of no advantage at a sufficient P supply. The increase of root production at P shortage increased calculated P uptake by 25% compared to a calculation with the ”︁usual” root production at a sufficient supply.     

茄子/番茄嫁接植株根系分泌物对茄子黄萎病菌的化感作用

采用番茄为砧木嫁接茄子,研究了嫁接对茄子黄萎病的化感作用,并对嫁接茄子根系分泌物中的化感物质进行了GC-MS检测。结果表明,与自根茄相比,嫁接茄子田间表现出明显的抗病性;其根系分泌物能够抑制病原菌的生长,抑制率达15.43%。进一步对各处理根系分泌物进行检测,嫁接茄根系分泌物中物质种类和相对含量与对照相比均有变化。在嫁接茄子根系分泌物中检测出特征性化学物质：咔唑类、胺类、萸类、芴类、酮类、茚醇类、腈类,烃类和酯类物质相对含量增加,而苯类、茚类物质相对含量降低。     

0.5%阿维菌素颗粒剂防治黄瓜根结线虫病药效试验

以"津东8号"黄瓜为试材,以清水为对照,研究了泰安市现代农业科技有限公司生产的不同浓度的0.5%阿维菌素颗粒与深圳诺普信农化股份有限公司生产的0.5%阿维菌素颗粒剂对黄瓜根结线虫病的田间药效。结果表明:泰安市现代农业科技有限公司生产的0.5%阿维菌素颗粒剂2 000、3 000、3 500g/667m2对黄瓜根结线虫病的防效在66.61%～74.63%之间,3 000g/667m2相同剂量下的2个厂家的0.5%阿维菌素颗粒防效差异不显著。     

青藏高原东北部4种灌木主根和侧根抗拉力学特性比较

[目的]开展青藏高原东北部黄土区4种灌木植物主根和侧根抗拉力学强度试验,探讨主根和侧根抗拉力学特性关系,为深入研究植物根系固土护坡力学机理提供参考。[方法]选取西宁盆地长岭沟流域作为研究区,对生长期为3 a的柠条锦鸡儿(Caragana korshinskii)、中宁枸杞(Lycium chinense)、白刺(Nitraria tangutorum)和霸王(Sarcozygium xanthoxylon)4种优势灌木主根和侧根进行室内单根拉伸试验,确定其主根和侧根抗拉力、抗拉强度和杨氏模量及其与根径之间的关系;在此基础上,进一步分析了4种灌木主根和侧根根径、抗拉力、抗拉强度和杨氏模量之间的关系。[结果]柠条锦鸡儿、中宁枸杞、白刺和霸王主根抗拉力分别为侧根的28.45,13.21,11.01,7.35倍,主根抗拉强度分别为侧根的0.67,1.17,0.68,1.22倍,主根杨氏模量分别为侧根的2.00,2.39,2.82,2.48倍。[结论] 4种灌木植物主根抗拉力均显著大于侧根;柠条锦鸡儿和白刺主根抗拉强度小于侧根,而中宁枸杞和霸王主根抗拉强度大于侧根;4种灌木植物主根杨氏模量显著大于侧根,说明其主根相对于侧根不易发生形变,对边坡浅层稳定性贡献亦显著于侧根。     

Transformation of organic rhizodepositions by rhizosphere bacteria and its influence on the availability of tertiary calcium phosphate

This study assesses the influence of saccharides in the rhizodeposition on the phosphate solubilizing ability of rhizosphere bacteria. Water‐soluble rhizodeposits were analyzed of ¹⁴C‐labeled pea plants (Pisum sativum, cv. ‘Grapis’) which were grown at two different levels of P‐nutrition. The sugars produced were fed in vitro either as single compounds or as synthetic mixtures to three bacterial strains and the ability of the bacteria to mobilize Ca₃(PO₄)₂ was measured. The relative glucose proportion of pea exudates decreased under P deficiency while the content of galactose, ribose, xylose and fucose increased. In vitro feeding of single sugars and sugar mixtures showed that the ability of Pseudomonas fluorescens (PsIA12) to dissolve tertiary calcium phosphate was lower with pentoses and the mixed sugars of the P‐deficient plants than with glucose. On the other hand, the shifted sugar pattern observed under P deficiency increased the phosphate mobilization ability of Pantoea agglomerans (D5/23) and Azospirillum sp. (CC 322) considerably. This observation can only partly be explained by the acidification of the nutrient medium. Bacteria also produced different carboxylic anions depending on sugar supply. In addition to low‐molecular mono‐, di‐, and tricarboxylic acids which are known as P‐solubilizing substances, sugar acids also played an important role in cultures D 5/23 and CC 322.     

Carbon input by plants into the soil. Review

The methods used for estimating below‐ground carbon (C) translocation by plants, and the results obtained for different plant species are reviewed. Three tracer techniques using C isotopes to quantify root‐derived C are discussed: pulse labeling, continuous labeling, and a method based on the difference in ¹³C natural abundance in C3 and C4 plants. It is shown, that only the tracer methods provided adequate results for the whole below‐ground C translocation. This included roots, exudates and other organic substances, quickly decomposable by soil microorganisms, and CO₂ produced by root respiration. Advantages due to coupling of two different tracer techniques are shown. The differences in the below‐ground C translocation pattern between plant species (cereals, grasses, and trees) are discussed. Cereals (wheat and barley) transfer 20%—30% of total assimilated C into the soil. Half of this amount is subsequently found in the roots and about one‐third in CO₂ evolved from the soil by root respiration and microbial utilization of rootborne organic substances. The remaining part of below‐ground translocated C is incorporated into the soil microorganisms and soil organic matter. The portion of assimilated C allocated below the ground by cereals decreases during growth and by increasing N fertilization. Pasture plants translocated about 30%—50% of assimilates below‐ground, and their translocation patterns were similar to those of crop plants. On average, the total C amounts translocated into the soil by cereals and pasture plants are approximately the same (1500 kg C ha^—1), when the same growth period is considered. However, during one vegetation period the cereals and grasses allocated beneath the ground about 1500 and 2200 kg C ha^—1, respectively. Finally, a simple approach is suggested for a rough calculation of C input into the soil and for root‐derived CO₂ efflux from the soil.     

The acquisition of cadmium by Lupinus albus L., Lupinus angustifolius L., and Lolium multiflorum Lam.

Das Cadmiumaneignungsvermögen von Lupinus albus L., Lupinus angustifolius L. und Lolium multiflorum Lam. Mehrere Pflanzenarten mobilisieren Bodenphosphate (P) und Kationen wie Fe und Al durch die Exsudation organischer Anionen und Protonen. Deshalb untersuchten wir das Cd‐Aneignungsver‐mögen von P‐, Fe‐, Al‐mobilisierenden Arten (Lupinus albus L., Lupinus angustifolius L.) im Vergleich zu einer nicht mobili‐sierenden Pflanzenart (Lolium multiflorum Lam.). Die Pflanzen wuchsen in zwei stark unterschiedlichen Böden (saurer Humuspodsol, karbonathaltiger Lössunterboden). Die Cd‐Aufnahme in die Sprosse war bei Weidelgras 5 bis 10 mal höher als bei Blauen bzw. Weißen Lupinen. Dieses Ergebnis hat mehrere Ursachen: 1. Das Wurzellängen/Sprossmasseverhältnis des Weidelgrases ist 2—3 mal größer als das der Lupinenpflanzen. 2. Bei Weidelgras wird ein größerer Teil des aufgenommenen Cd in die Sprosse verlagert. 3. Die Cd‐Aufnahme bei Lupinen ist im sauren Boden (Podsol) und bei P‐Mangel auch im Kalkboden niedriger als bei Weidelgras. Während im Podsol die Cd‐Konzentration der Bodenlösung unter Lupine geringer war als in der Kontrolle (Gefäße ohne Pflanzen), war sie im Kalkboden höher. Bei den Lupinen war der Efflux organischer Säureanionen, vor allem Citrat und Malat, um den Faktor 10—100 höher als bei Weidelgras. Diese Exsudation kann zu einer hohen Cd‐Komplexierung, insbesondere durch Citrat, in der Rhizosphärenbodenlösung führen (˜ 85%). Diese Ergebenisse deuten darauf hin, dass das komplexierte Cd von den Wurzeln schlechter aufgenommen wird als das freie Cd.     

毛管间距对膜下滴灌棉花根系及植株生长的影响

在大田膜下滴灌条件下,对毛管间距影响棉花根系分布及植株生长的特点进行了试验研究。试验中滴灌毛管布置间距分别为130、90 cm;观测了棉花不同生育阶段的根系分布及单株株高、叶面积。试验结果表明,毛管间距大,导致灌水量也大,土壤易出现深层渗漏,而且土壤水分水平分布均匀性差,造成内、外行棉花长势不均匀,棉花根茎小,根长密度水平方向呈单峰抛物线分布,垂直方向14~28 cm土层处根长密度最大;而毛管间距小,土壤水分水平分布均匀,内、外行棉花长势均匀,棉花根茎大,根长密度水平方向呈双峰抛物线分布,垂直方向0~14 cm土层处根长密度最大。但2种毛管布置间距的棉花根系生长过程、株高及叶面积生长过程均符合相同的规律。试验结果为滴灌技术设计中选定土壤湿润比和毛管间距提供参考。