光敏核不育水稻选育与利用的几个问题讨论

对现有光敏核不育材料进行了分类,分为４种遗传类型;其中,温光弱感到光敏核不育系是最为理 想的遗传工具,并就其选育途径和选择“粳不籼恢”繁殖制种技术体系进行了论证．     

Genetic mapping and utilization of quantitative trichome-mediated insect resistance in potato

Introgression of trichome-mediated insect resistance from the wild speciesSolanum berthaultii has become a major focus of the potato improvement program at Cornell University during the past twelve years. Several quantitative characters are involved in this resistance which is effective against a wide range of pest types. Correlative biochemical assays have been developed to assay specific components of the resistance, and the effects of the resistance on the target pests have been studied. Quantitative laboratory assays and specific measurements of insect behavior and biology have increased the precision of selection and enable the investigation of the genetic control of the resistance.We are currently using restriction fragment length polymorphisms (RFLPs) for genetic mapping of factors controlling the trichome traits fromS. berthaultii. Backcrosses to both the wild and the cultivated species parents have been evaluated for phenotypes contributing to the resistance mechanism, including trichome density, sucrose ester and polyphenol oxidase production by the trichomes, and the enzymatic browning reaction responsible for insect entrapment. Genetic maps are being developed for these progenies, using RFLP markers previously mapped in potato. Field and greenhouse trials under insect infestations are also being conducted with the mapping progeny. Our goal is to locate genes responsible for quantitative insect resistance by correlating RFLP variation at mapped loci with the trichome phenotypes and insect resistance. Genetic markers for these traits will be useful in transfer of the effective wild chromosomal segments into and among tetraploid potatoes, and for a better understanding of the resistance mechanism.     

某类高阶非线性偏微分方程组弱解的正则性

本文研究一类2k阶非线性偏微分方程组之解的正则性,没有假定通常的椭圆性条件而只假定所谓"无穷远处"的椭圆性条件,证明了解的k-1阶导数为李普希兹连续的.     

瓜类嫁接栽培技术探讨

从6个瓜类砧木品种中，选出了黄瓜适宜砧木为黑籽南瓜，苦瓜适宜砧木为黑籽南瓜和本地肉丝瓜，西瓜适宜砧木为超丰F1和欣京砧一号。瓜类嫁接方法以顶插接法和劈接法为宜，嫁接时期在3月初为宜。重病地黄瓜嫁接苗比自根苗枯萎病发病率降低95．8％，产量提高34．9％；嫁接苦瓜发病率降低83．7％，增产16．9％；嫁接西瓜发病率降低88．9％，增产13．7％。     

中国山羊品种资源及其遗传多样性研究

本文论述了中国山羊的起源、品种遗传资源及其遗传多样性的研究进展。最新调查 显示中国的山羊品种达50个,其中43个为地方品种,4个培育品种,3个引入品种,许多品种 具有独特的生产性能或适应能力。大量研究表明,我国山羊遗传多样性较为丰富。     

Genetic variability within Phaeoisariopsis griseola from Central America and its implications for resistance breeding of common bean

The genetic and virulence variability of 112 isolates of Phaeoisariopsis griseola , collected from various locations in Central America, were studied using seven random amplified polymorphic DNA (RAPD) primers and 12 common-bean differential genotypes. Broad molecular diversity ( H  = 0·92) among isolates was found using RAPD markers. Fifty pathotypes were identified on 12 differential bean genotypes, 29 of which were represented by only one isolate. Only 18 pathotypes were found in two or more countries. Pathotype 63-63 was the most virulent and caused leaf spots on all 12 common-bean differential genotypes. Comparison of virulence phenotypes and RAPD profiles to known Andean P. griseola isolates confirmed that all isolates belonged to the Mesoamerican group. Pairwise comparison between individual RAPD loci showed that the majority were in gametic phase linkage disequilibrium, revealing that P. griseola maintains a genetic structure that is consistent with asexual reproduction. The molecular and virulence diversities of P. griseola isolates from Central America imply that using single resistance genes to manage angular leaf spot is inadequate and stacking resistance genes may be necessary to manage the disease effectively.     

库布齐沙漠穿沙公路沙害综合防治技术

库布齐穿沙公路修建在库布齐沙漠高大的流动沙丘区 ,风沙流侵袭与沙丘整体前移埋压公路是主要沙害形式。现有防沙措施是沙障保护下的人工植被及天然植被相结合的综合防护体系 ,固沙及阻沙效益明显。目前要解决的是尽快形成公路两侧稳定的植被群落 ,以保证公路的长期畅通     

钙素对叶用莴苣营养吸收和生长发育的影响

 采用NFT 栽培, 研究了叶用莴苣钙素与主要无机成分间的相互关系, 以及对叶用莴苣生长发育的影响。结果表明, 缺钙胁迫引起叶绿素含量降低, 缘腐病发病率上升, 叶片干、鲜样质量降低。生长中后期, 特别是新生内叶易发生钙素营养失调症。营养液中钙浓度过高会降低钾、镁的吸收, 而对氮、磷吸收影响不大。提高营养液中NH₄⁺ -N 比例会抑制钙吸收, 降低其有效性。