不同成熟期番茄热导率的测定

 采用微热探针法测定了同一品种不同成熟期番茄的热导率变化, 结果表明: 同一品种番茄热导率与其可溶性固形物含量存在着显著线性相关, 而与含水率和密度的相关性不显著。从这一结果可为番茄冷藏保鲜及制冷工业的定量研究参考。     

陇东地区不同生态型冬小麦抗旱性研究与适宜品种的筛选

在不同的播前底墒下,应用抗旱指数法、隶属函数法、模糊综合评判法研究了14个不同生态类型旱地冬小麦品种的抗旱性。结果表明,随着底墒的增加,旱地冬小麦产量和水分利用效率显著提高,相同底墒下品种之间产量与水分利用效率差异显著,不同生态型冬小麦对播前底墒的反应明显不同。抗旱指数法、隶属函数法、模糊综合评判法均能较好地评价旱地冬小麦的抗旱性,其评价结果基本一致。参试品种从来源分析,抗旱性表现为:甘肃陇东>山西地区>北京地区>渭北旱塬>黄淮地区。     

Effect of soil inoculum level and environmental factors on potato powdery scab caused by Spongospora subterranea

The effects of soil inoculum level and three environmental factors (soil type, soil moisture regime and temperature) on the incidence and severity of powdery scab caused by Spongospora subterranea were investigated in potato plants grown under controlled environmental conditions. Symptoms of powdery scab on tubers were assessed visually, after which DNA was extracted from tuber peelings and quantified in a real-time polymerase chain reaction assay using primers and a TaqMan® probe specific to S. subterranea to establish tuber infection levels. Soil inoculum concentration of S. subterranea did not significantly affect the incidence and severity of either tuber infection or powdery scab symptoms at maturity. No significant differences in disease incidence and severity were found between sandy, loamy and clay soils, although the two lighter soils yielded more powdery scab than clay soil. Constant dampness of the soil resulted in significantly more disease than a fluctuating moisture regime. Infection and disease levels were high at all three temperatures tested (9, 12 and 17°C), but symptoms were most severe at 12°C. The percentage of plants with infected tubers did not increase after tuber initiation, although the amount of S. subterranea DNA detected in tubers and the severity of powdery scab symptoms increased in mature plants. Latent tuber infections were found to be common, especially under conditions suboptimal for disease development. This new information may be important for the prevention of powdery scab in potato-growing areas around the world.     

柑橘果实膳食纤维的研究

以柠檬、玉环柚、椪柑、脐橙、温州蜜柑和胡柚为试材,测定了果皮和果肉中总膳食纤维(TDF)、不溶性膳食纤维(IDF)、水溶性膳食纤维(SDF)、中性洗涤剂纤维(NDF)、酸性洗涤剂纤维(ADF)、纤维素(CEL)、半纤维素(HC)、木质素(Lignin)、总果胶(TP)、原果胶(Protopectin)和水溶解性果胶(WSP)含量。以柚和温州蜜柑为试材,分别测定了不同的发育阶段膳食纤维及其具体组分的含量,总结了不同发育阶段果实膳食纤维的变化情况。结果表明,除柠檬和脐橙果肉的SDF含量稍多于果皮中含量外,其他各组分均是果皮中的含量大于果肉。除果皮中TDF和IDF的品种间变异较小外,其它组分在品种间的变异均较大。除HC外,各组分在果肉中的变异均大于果皮。柠檬果实中TDF、SDF、NDF、ADF、CEL、木质素和WSP含量都高于其它柑橘类水果。柚和温州蜜柑TDF和IDF随着果实的成熟而有所下降,但降幅不明显;而SDF则随着发育阶段的推移而渐渐增加。     

灌浆期复水对冬小麦根、冠生长及其相互关系的影响研究

以冬小麦品种北农6号为材料，研究了灌浆期复水对冬小麦生长的影响。结果表明，前期受旱程度不同的植株灌浆期恢复供水后，其株高、单株叶面积、生物量及产量等都超过相应的干旱对照，表现出明显的补偿生长效应。同时，各复水处理与对照相比，分配到冠部的干物质比例均增加，R／S下降。中度水分亏缺后充分供水的处理，可以在少减产的情况下节约大量用水，从而达到节水的目的。     

Deposition of spray liquid on the soil below cereal crops after applications during the growing season

The aim of this study was to investigate how big a proportion of the spray liquid applied in a typical application was deposited on the soil surface below the crop. From an agronomical point of view this part of the spray is an undesirable loss of foliar acting pesticides during application and it also constitutes a primary source of leaching and surface run‐off. The investigation was carried out during 1998–2001 in winter wheat and in spring barley. Applications were carried out at approximate intervals of 10 days during the whole growing season in the two cereal crops. The results showed that a high proportion of the spray liquid reaches the soil below the crop during applications at early growth stages corresponding to the growth stages where weed control on farms is carried out. At later growth stages soil deposition declined and reached values below 5% of the applied dose in winter wheat after inflorescence emergence (50–59 BBCH). The spring barley crops remained more open and minimum soil deposit values were approximately 15% of the applied dose at growth stages (50–59 BBCH). During ripening soil deposition values increased again as crop cover decreased.     

芦笋幼苗期和成苗期施肥技术分析探讨

芦笋是一种营养保健蔬菜,合理进行施肥对芦笋的产量和品质都起着决定性作用。分析探讨了芦笋幼苗期和成苗期的施肥技术。     

美洲黑杨×青杨等杨树无性系苗期选育试验初报

用美 5- 5等 15个杨树无性系与北京杨进行苗期对比试验 ,结果表明 :美 5- 5、美 6- 6、美 8-18、78- 2 5、美黑×欧黑均优于北京杨 ,其他无性系生长低于北京杨。     

黄连木不同育苗方式苗木质量的比较研究

用有序样本聚类分析法将黄连木1年生播种苗高生长过程划分为4个时期:出苗期(3月4日～4月10日)、生长初期(4月11日～6月30日)、速生期(7月1日～9月10日)、苗木硬化期(9月11日～10月10日)。进行种子处理和贮藏方法、播种期、播后苗床覆盖、苗木遮荫、合理密度、土壤追肥试验。结果表明:用草木灰或碱水对种子脱蜡去脂并进行混沙或黄心土贮藏,播种后及时覆盖稻谷皮或地膜均有利于提高种子发芽率;冬播比春播更有利于种子萌发和提高苗木生长量;全光育苗、保持60株/m2密度、土壤追施速效复合肥均是提高苗木生长量和质量的有效技术措施。     

关中地区危害杨树叶部的蛾类区系及其防治适期的模糊预测

本文论述了关中地区杨树食叶蛾类的区系结构,并从生态学角度出发,运用模糊分析方法,阐明了下旬/5月～中旬/6月,下旬/7月～中旬/8月为防治适期。