Unsaturated fatty acids from zoospores of <Emphasis Type="Italic">Sclerospora graminicola</Emphasis> induce resistance in pearl millet

Downy mildew of pearl millet, caused by Sclerospora graminicola, is a devastating disease, resulting in high economic losses in the semi-arid regions of the world. Recently, induction of host plant resistance using biotic and abiotic inducers are included among disease management practices as an eco-friendly approach. Unsaturated fatty acids are considered as a new generation of plant disease resistance inducers. In the present study, six unsaturated fatty acids, viz. docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), arachidonic acid (AA), linolenic acid, linoleic acid and oleic acid, all originally detected in the zoospores of S. graminicola,were applied to seeds of susceptible cultivars of pearl millet to examine their ability to protect against downy mildew under greenhouse and field conditions. In greenhouse experiments, EPA and AA induced a maximum of 78.6% and 76.5% protection, whereas linoleic acid, DHA and linolenic acid provided up to 66.3%, 61.2% and 24.5% protection, respectively. Oleic acid was not effective in protecting pearl millet (only 5.1% protection). A time interval of four days between treatment of seeds and challenge inoculation was required to obtain optimum protection. Plants raised from treated seeds and challenge inoculated at the tillering and inflorescence stages showed enhanced resistance, resulting in higher grain yield compared to untreated plants of the same cultivar. Chitinase activity was found to be higher in susceptible seedlings of pearl millet after treatment with the fatty acids and pathogen inoculation than in seedlings only inoculated with the pathogen. This indicates that host defence responses are activated and thus that induced resistance is involved in the protection observed. The role of unsaturated fatty acids as activators of resistance against downy mildew in pearl millet is discussed.     

去毒桐籽粕饲用价值的探讨

桐籽粕含有多种醇、二萜脂等有毒物质,因而长期以来只能用于肥料。桐籽粕中含代谢能5.46MJ/kg,粗蛋白质约36.13%,赖氨酸1.43%及较多的铁。小白鼠、肉用仔鸡饲养试验及屠宰测定试验表明:在肉用仔鸡前期日粮中加入5%～8%的桐籽粕,虽然略逊于优质蛋白质饲料,但作为中、低档蛋白质饲料资源,仍具有开发价值。     

青皮种子主要储藏条件的研究Ⅰ.种子含水量与测控

水分是影响青皮(Vatica astrotricha Hance)种子活力最关键的内在因素,其中种胚含水量是决定因素。用含水量27—29％椰糠控制种胚含水量在50—52％,也就是控制种子含水量在30—36％,维持种子一定的呼吸强度(32℃下测定为50—60 O_2μl/g·h),种子活力保持最高,能延长寿命。找出了储藏中种子安全含水量的最佳点,此点处于安全含水量下限的内缘,可利用种子本身果翅与种子或大小种子之间含水量的内在关系来测定。这种测定方法准确、快速又简便。可考虑作为确定“顽拗型”种子安全含水量下限的新捷径。     

温度、光照和发芽床对假俭草种子萌发的影响

实验室内进行了假俭草种子净度检验样品最低限量和发芽检验方法的研究，探讨了光照（以黑暗为对照）、温度（分别包括２０℃恒温，１５／２５℃、２０／３０℃、２０／３５℃和２５／３５℃变温）和发芽床（分设纸上ＴＰ和砂中Ｓ）等因素对种子发芽的影响。结果表明：假俭草种子净度检验样品最低限量是３ｇ，送验样最低量以及计数其它植物种子检验样品最低量均为３０ｇ；最佳萌发条件为２０／３０℃或２０／３５℃变温（１６小时低温，８小时高温），高温时段设光照，和纸上（ＴＰ）发芽；发芽的初次和未次计数时间分别以第１０天和第２１天为宜；种子的幼苗发育可划分为单子叶植物子叶留土类型。     

中国东北部针叶林种实害虫调查报告

本文是1987年7—8月中法联合调查中国东北部针叶树种实害虫的初步结果,所调查地区有:黑龙江省小兴安岭的五营自然保护区、丰林林业局的母树林、东北林业大学凉水自然保护区;内蒙古大兴安岭的乌尔旗汗和库都尔人工,天然落叶松母树林以及黑龙江省植物园和东北林业大学哈。尔滨林场所调查树种有:兴安落叶松、红松、樟子松、黑松、红皮云杉、鱼鳞云杉及白皮冷杉。在球果内共发现15种害虫及其被害状,其中最主要的为害落叶松球果的Lasiomma属种类,落叶松球果被害率可达42—95％;其次是落叶松球果小卷蛾,球果被害率达6—2O％;第三位是球果螟,球果被害率达4—8％。 还发现冷杉球果花蝇[L.abietis(Huckett)]和冷杉球果小卷蛾(Barbara herrichiana Obraztsov),它们是我国的新记录。     

不同产地杉木种子游离氨基酸含量的初步分析

不同产地杉木种子均含有17种游离氨基酸，这与其它种子所含游离氨基酸种类基本一致。不同产地杉木种子游离氨基酸总量的变异趋势不同于杉木种子形态及发芽率的变异趋势。但其中某些氨基酸的变异趋势与种子发芽率呈负相关，表明杉木种子的发芽率可能与种子所含的某些游离氨基酸有关。不同产地杉木种子游离氨基酸总含量与干湿度指数呈负相关，说明杉木种子游离氨基酸总含量的地理变异亦可能是气候的差异所引起。     

“撒、矮、荪”配套模式制种技术研究——Ⅱ、理想株型的定向培育

本研究探讨了通过培育理想株型以克服母本撒播制种潜在的倒伏危机的技术途径。该文表述了3个主攻要素的集合:1.培育庞大、高活力的根系群,改善耕层土壤结构,提高稻株固着力。2.培育矮壮、竖立、紧凑型植株,保持良好的光合姿态,降低重心,提高稳定性能。3.应用生化调控手段,使之既解除包颈,又不使植株伸长超高。其技术途径可归纳为:起垄栽培、节水勘灌;适时、适量喷施植物生长调节剂多效唑(MET)、九二○(GA3)。它们之间促进与制约的交互作用,成功地实现了理想株型的塑造。     

油松种子园施肥与产种量关系研究

采用施肥的途径解决了促使油松母树开花结实的技术问题。试验结果表明：施肥可以使油松母树增产216％。该技术生产成本低、技术易掌握、施工方便，同时还可以促进母树的健康生长。     

籼型三系不育系水稻花时滞候解除研究Ⅱ 花时的温湿生态因子效应

对不同温湿度时域对不育系花时的生态效应进行了报道。试验结果表明，当不育系在温高湿大时域抽穗开花时，不育系的花时相对提早且较集中，与恢复系花时相遇率相对要好，不育系的柱头外露率增加，花粉萌发率提高。不育系的异交结实率得到明显提高（提高９．６２％～１１．４６％）。     

Oospores associated with tomato seed may lead to seedborne transmission of<Emphasis Type="Italic">Phytophthora infestans</Emphasis>

Tomato fruits at the green mature stage were inoculated with a mixed sporangial suspension of A₁ and A₂ isolates ofPhytophthora infestans. Other fruits were inoculated with either A₁ or A₂ sporangia. Seeds were extracted from the blighted fruits and sown in soil or on agar media to test for the transmission of late blight to the emerging seedlings. Only 23 (0.09%) of approximately 25,000 seedlings developed symptoms. All blighted seedlings originated from fruits inoculated with mixed A₁ + A₂ sporangia. Isolates ofP. infestans recovered from the emerging blighted seedlings were seemingly of oosporic origin, as they differed phenotypically (mating type, virulence, sensitivity to metalaxyl) from the parent isolates used to inoculate the fruits. The results suggest that transmission ofP. infestans might occur by seeds extracted from fruits carrying oospores and less probably by seeds extracted from fruits having no oospores. http://www.phytoparasitica.org posting April 30, 2004.