陕北枣树主要害虫防治对策

对陕北黄河沿岸枣树害虫的调查发现,原来的常灾性害虫枣尺蠖、枣镰翅小卷蛾、桃小食心虫、枣飞象等继续蔓延成灾,以往被认为次要的虫种如蚱蝉、大球胸象、黑绒金龟及日本蜡蚧等已上升为主要虫种。本文根据上述8种主要害虫的发生危害特点、已有的技术成果及群众的防治经验,结合陕北当前枣树生产的实际提出了相应的防治对策。     

Trichoderma harzianum produces nonanoic acid, an inhibitor of spore germination and mycelial growth of two cacao pathogens

An isolate of Trichoderma harzianum Rifai from an infected cacao pod produces and secretes nonanoic (pelargonic) acid into a liquid culture medium. Nonanoic acid (NA) was very inhibitory to spore germination and mycelial growth of two cacao pathogens, Crinipellis perniciosa Stahel and Moniliophthora roreri Cif. H.C. Evans. It was highly active causing 75% inhibition of spore germination in an in vitro assay at a rate as low as 0.09 μM for M. roreri and 0.92 μM for C. perniciosa. Mycelial growth was comparatively less sensitive to inhibition, but still there was a 75% reduction in growth with 0.62 μM in M. roreri and 151 μM NA in C. perniciosa. In contrast, NA did not affect Trichoderma mycelial growth or spore germination at concentrations that were inhibitory to the pathogens. 6-pentyl-α-pyrone was also produced and secreted into the medium by T. harzianum, however; it was not antagonistic to the cacao pathogens. Although a number of metabolites produced by Trichoderma spp. have been identified in the past, this is the first report of NA production and secretion by any Trichoderma. The results suggest that NA may play a role in the successful use of some Trichoderma spp. isolates in the biocontrol of fungal diseases of plants.     

枣新品种‘延川狗头枣’

 ‘延川狗头枣’为鲜食、制干兼用中晚熟枣新品种。果实大、卵圆形或锥形，似狗头状。单果平均质量18.7 g，最大25.4 g；果肉细脆，汁液中多，味酸甜；鲜食、干制品质优良。适宜平均气温10—11l℃ 、降雨量500 mm左右的北方地区栽培。     

早熟大果鲜食枣品种‘七月鲜''

‘七月鲜’是从合阳县农家品种中选出的早熟优良品种，比中熟品种‘梨枣’早熟20d以上；果大，整齐，平均单果质量29．8g，可溶性固形物含量28．9％，可食率97．8％，味甜，肉质细，极宜鲜食，不易裂果，早果性强，抗缩果病，节间短，树体矮小，适宜矮化密植和设施栽培。     

Comparison of Crinipellis perniciosa isolates from Brazil by ERIC repetitive element sequence-based PCR genomic fingerprinting

Fifty isolates of Crinipellis perniciosa originating from Theobroma cacao , Heteropterys acutifolia and Solanum lycocarpum , from six states within Brazil, were characterized through ERIC-PCR, representing the first application of this method for molecular characterization within C. perniciosa . Phenetic analysis of banding patterns revealed a separation of isolates on the basis of host of origin, with T. cacao -derived isolates showing only a 0·2 similarity level to a cluster comprising the isolates from H. acutifolia and S. lycocarpum . Considerable intraspecific variability was observed within C. perniciosa isolates from T. cacao , with distinct groups observed correlating with geographical origin. Given that a number of isolates from T. cacao from the Amazon region grouped with isolates from Bahia state, this work discusses the possibility that current C. perniciosa populations pathogenic on T. cacao in Bahia originated from the Amazon region, rather than from alternative host plants.     

Indole-3-acetic acid biosynthesis in <Emphasis Type="Italic">Aciculosporium take</Emphasis>, a causal agent of witches' broom of bamboo

 Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of bamboo plants. The symptoms of this disease are believed to be induced by plant hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in cultures of this fungus in an l-tryptophan-supplemented liquid medium. IAA production was confirmed on 30 isolates of A. take from various hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of IAA in A. take culture was examined by analyzing intermediate products and by feeding experiments. The results showed that the indole-3-pyruvic acid pathway (l-tryptophan → indole-3-pyruvic acid → indole acetaldehyde → IAA) was the dominant pathway in A. take. Received: June 3, 2002 / Accepted: July 25, 2002     

不同药剂处理对灵武长枣坐果与光合指标的影响

为了提高灵武长枣坐果率和单果质量,采用以色列专用肥(0.3%)、赤霉素(30×10-6)、爱乐壮(ALA、5-氨基乙酰丙酸)喷施处理大田种植的灵武长枣,测定其坐果率、光合速率、叶绿素含量、吊果量、单果质量等指标,分析不同药剂处理对灵武长枣坐果与光合作用的影响。结果表明:1‰ALA处理下的坐果率提高近1倍,且叶绿素含量、单果质量均高于对照;以色列肥处理下灵武长枣叶片的水分利用效率比对照高40%左右。因此推荐将1‰ALA和以色列专用肥应用于灵武长枣的生产实践中。     

遮雨棚设施结构对枣园温湿度的影响

笔者以7年生-10年生壶瓶枣树为试材，研究了遮雨棚栽培与大田栽培条件下温湿度变化规律和差异。结果表明：遮雨棚在晴天高温时有降温的作用，而阴雨天温度较低时则有保温的作用；遮雨棚阻碍了水分蒸发，使得相同条件下棚内湿度高于棚外；雨后棚内与棚外温度变化趋势基本一致，棚外湿度变化剧烈，棚内较为缓和。     

枣不定芽再生体系的研究

以枣优良品种骏枣为试材,研究了多种因素对其离体叶片及大田幼嫩茎段再生效率的影响.结果表明,幼嫩茎段再生较容易.叶片再生与生长调节物质种类和浓度及叶片成熟度有关.枣叶片不定芽再生的最佳培养基为1/2MS(大量元素减半)+TDZ0.5mg/L+IBA0.2m/L.不定芽再生率以上部叶片最高.     

陕北枣林土壤动物功能类群及其害虫生态调控

在陕北枣林研究区域内,以土壤动物为研究对象,采取野外调查取样、定点动态观测与室内鉴定分类的研究方法,选取了延安万花山、延川县、清涧县、佳县枣林4个样点7个样地,于2007年3月、6月、9月、11月,对土壤动物功能类群进行了初步研究。陕北枣林土壤动物可划分为植食性、捕食性、腐食性、枯食性、菌食性土壤、杂食性土壤动物6个功能类群,基于土壤动物功能类群与枣林病虫害生态调控的内在关系,建构陕北枣林害虫生态调控体系,为深入探讨土壤动物与枣林害虫生态调控的关系提供基础资料和理论依据。