水稻黄矮病的研究概况及最新进展

1957年,广东省水稻上发生了一种稻叶发黄的病害,其症状与生理性早衰的稻叶发黄相似,当时被称为生理性黄叶枯病。经过十来年的研究,1965年范怀忠等证实该病为叶蝉传播的病毒病,并定名为水稻黄矮病(Rice     

人工饲草料地生产效能的研究

在牧区草料的匮乏严重阻碍着草地畜牧业的发展 ,牲畜头数增加 ,草地过牧 ,使生态环境遭受着严重破坏。选择了具有代表性的新疆天山北坡中段昌吉市阿什里哈萨克民族乡 ,对其畜牧业生产系统的草、家畜生产和能物流流转情况进行了研究。运用能物流高效持续利用原则和线性规划法 ,提出了切实可行的人工饲草料生产子系统的优化配置模式。结果表明 ,系统优化后 ,全年舍饲的载畜水平大大提高 ;人均年收入由现行系统的 1 70 2元增加到 5 4 86元 ;系统优化后不仅大大减轻了放牧对天然草地造成的压力 ,而且显著提高了土壤肥力 ,改善土质     

樟子松、赤松、油松在形态结构及生态生物学特性的比较研究

樟子松(Pinus sylvestrisvar.mongolica)、赤松(P.densiflora)、油松(P.tabulaefor-mis)均属于松科、松属、双维管亚属中的油松组。它们的共同特征是:叶二针一束,叶鞘宿存,针叶内有两条维管束,树脂道边生。但是,他们在形态特征、针叶内部结构及生态生物学特性方面也有显著的区别。根据这些区别,以准确辨认这三种松树,在生态环境的建设改造中不致于选错树种,从而造成人力和经济上的损失。     

棉花根腐病菌鉴定特征的快速培养条件

系统地研究棉根腐病菌的形态学特征及生理生化特性 ,总结出适用于检验检疫部门之快速、准确的鉴定方法 ,即无性器官快速形成条件。实验表明 ,病菌在 2 8℃ ,经过改进的No .70培养基上可生长出易于快速鉴定的典型的无性器官。     

中国龙游和越南Omon褐飞虱种群特性测定

根据褐飞虱对不同抗虫基因品种的致害和在不同抗虫基因品种上的存活率测定，中国浙江龙游种群以生物型Ⅱ为优势，越南Omon种群除有生物型Ⅱ的特性外还能致害ASD₇、Rathu Heenati、IR₃₆和Babawee等几个品种。短翅型成虫占总成虫比例，龙游种群17.1％，Omon种群76.1％。     

Comparative biology of Mallada desjardinsi (navas) and Chrysoperla congrua (walker) (Neuroptera: Chrysopidae), predators of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) and aphis gossypii (glover) (Homoptera: Aphididae) on cotton in eastern Tanzania

The developmental biology of Mallada desjardinsi (Navas) and Chrysoperla congrua (Walker) on the American bollworm, Helicoverpa armigera and the cotton aphid, Aphis gossypii was studied in the laboratory at 28–32°C. Total larva! periods of M. desjardinsi and C. congrua on H. armigera eggs were 14.4 and 14.8 days respectively. However, when reared on A. gossypii larval periods of M. desjardinsi and C. congrua were 14.9 and 13.5 days respectively. When reared on H. armigera 52.9% and 25% respectively of third instars of M. desjardinsis and C. congrua sp. died before pupation. However, when reared on A. gossypii 82.6% and 46.9% respectively of third instars of M. desjardinsi and C. congrua died before pupation. Thus, H. armigera eggs and A. gossypii nymphs were both adequate but not optimal diets for chrysopid larval development. The number of prey consumed by M. desjardinsi and C. congrua increased with instar. Total larval consumption of H. armigera by M. desjardinsi and C. congrua was determined to be 135.5 and 169.8 eggs respectively. However, total larval consumption of A. gossypii by M. desjardinsi and C. congrua was found to be 189.0 and 171.8 nymphs respectively. Because of its longer larval period, and higher consumption of A. gossypii, M. desjardinsi would be better suited for use against A. gossypii than C. congrua. In contrast, C. congrua whose consumption of H. armigera was higher than that of M. desjardinsi although their larval periods were similar, would appear promising for control of H. armigera.     

试论青藏高原隆升对中国沙漠形成演化的影响

第四纪期间中国北方风沙地貌发育的基本条件如风力、风向、沙漠、地形等随青藏高原的逐步隆升均发生相应变化。从探讨青藏高原隆升与中国沙漠形成演化出发，本文指出高原阶段性隆升与中国北方沙漠演化阶段上的因果关系。受高原隆升的地质、气候等综合效应影响，中国沙漠于第四纪初先在贺兰山以东、长城以北地区形成；１．６ＭａＢＰ以后高原北侧出现有利于风沙活动的干旱多风环境，沙漠扩展至西北地区；１．１ＭａＢＰ以后高原隆升对     

菌株Tu 49 代谢产物的分离及抗菌素活性的初步研究

从吐鲁番葡萄沟、苏公塔、五道林、交角沟等郊区采集的52种土样中筛选到一株能产生抗菌素活性的好气菌Tu49，革兰氏阳性，类群为黄色类群。所产生的抗菌素，对不同的微生物有明显的抑制作用。最适生长温度为30℃-32℃，最适pH为6．8－7．5，气生菌丝和孢子丝为无色，基丝体为黄色，产黄色可溶性色素。     

The effects of desiccation on broad‐leaved dock (Rumex obtusifolius) and curled dock (Rumex crispus) root fragment regeneration

Fresh root fragments of Rumex crispus and Rumex obtusifolius, which initially contain 65–70% moisture, progressively lose moisture when desiccated under conditions matching summer weather in southeast England. The likelihood of shoot emergence and the time it took in glasshouse conditions were both affected by desiccation, with R. crispus the most affected up to 48 hr and R. obtusifolius slower to emerge after 48 hr. These effects converged after longer desiccation periods, and R. crispus entirely failed to emerge after 120 hr. The dry weight of emerged shoots was not significantly different between the species until they were desiccated for 96 hr, after which R. obtusifolius dry weight was significantly reduced. In outdoor trials, desiccation for 24 or 48 hr had a lesser effect on emergence in either species when fragments were planted at the soil surface or at up to a depth of 10 cm, compared to deeper plantings, but emergence was significantly lower in plantings at 15 or 20 cm. Emergence delays were not significantly different between the species until they were planted at 15 or 20 cm, when R. obtusifolius was slower to emerge than R. crispus, an effect exacerbated by increasing desiccation. Similar interactions of increasing soil depth and desiccation were found in reductions in dry weight, number of tillers and leaf area, with R. obtusifolius generally, but not exclusively, better able to withstand more extreme trial conditions. Our findings suggest that control of these highly troublesome weeds can be assisted by appropriate agricultural practices, notably exposing cut fragments to drying conditions followed by deep burial.     

塔里木盆地周边灾害性洪水类型及特点

研究区位于新疆南部。这里气候干燥、降水稀少、各项自然要素和自然综合体无不带有干旱环境的影响和特点。灾害性洪水便是一例,其类型之多,成因之特殊为我国其它地区少见,具有干旱区水文现象的独特性和代表性。洪水给人类带来了巨大灾变。据统计,世界上每年由于洪泛造成的损失平均达4000亿美元,新疆仅1987年洪水损失也高达3亿多元(人民币)。研究区约占新疆国土面积的二分     

梭梭幼苗根系分泌物提取方法的研究

为了探讨梭梭根系分泌物中的化学成分,本文采用水浸提取和循环灌溉两种方法对梭梭幼苗根系分泌物进行收集和提取,结合气相色谱-质谱联用分析技术,分析梭梭幼苗根系分泌物中组分和含量的差异。实验结果表明:循环灌溉收集的梭梭幼苗根系分泌物中检测到35种化合物,包括酚醌类、醛酮类、醇类、酸类、脂类和胺类化合物;硅烷化处理后,主要增加部分强极性有机酸,如苯甲酸。水浸提取梭梭幼苗根系分泌物的中性相组分共检测出27种化合物,但未检测到酚醌类化合物;碱性相组分共检测出23种化合物,醛酮类化合物种类减少,烷烃类化合物种类增加;酸性相组分中仅检测到10种化合物,以醇类化合物为主,占检出化合物总量的72.62%。收集梭梭幼苗根系分泌物循环灌溉是一种有效的方法。