Cytology of tetraploid x hexaploid timothy (Phleum pratense L.)

Ten pentaploids were isolated from seedling populations developed from seed of tetraploid plants grown in association with hexaploid timothy. About 80% of the prophase sporocytes exhibited severe or moderate pycnosis. These pycnotic accumulations appear to arrest the meiotic processes and apparently result in sporocyte lethality. Surviving sporocytes at diakinesis possessed nuclei with configurations that varied from 1 VI+14 II+1 I to 9 II+17 I. It is suggested that the conventional sorts of irregularities (univalents, inversions and translocations) cannot account for the low percentages of stainable pollen. Pairing relations indicated that considerable duplication and/or autosyndesis occurred in the genomes combined, and suggest that even though the tetraploid (2n=28) and hexaploid (2n=42) forms of Phleum pratense are closely related they are not identical. A portion of the sterility observed may be due to nuclear-cytoplasmic interaction.Results of co-operative work of the Crops Research Division, A.R.S., U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station, Madison, Wis.Geneticist, Crops Research Division, A.R.S., U.S. Department of Agriculture, and Graduate Assistant, Department of Agronomy, Wisconsin Agricultural Experiment Station.     

Cytogenetics of a tetraploid form of Phleum pratense L.

A tetraploid form of Phleum pratense from southwestern Europe was found to behave cytogenetically as an autotetraploid. Inheritance patterns in inbred seedlings artificially inoculated with stem rust agreed with this interpretation if chromosome and chromatid assortment are assumed.Results of cooperative investigations of the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station.Geneticist, Crops Research Division, A.R.S., U.S. Department of Agriculture, and former Graduate Assistant, Agronomy Department, Wisconsin Agricultural Experiment Station, Madison, Wisconsin.     

魔芋组织培养中的褐变机理及防控措施

（云南农业大学魔芋研究所,昆明 650201）     

Genetic gains for yield after two back-crosses of the interspecific hybrid Libusta (Coffea canephora P. × C. liberica Bull. Ex Hiern) to C. canephora P.

The Libusta (Coffea canephora P. × C. liberica B.) programme initiated in the seventies in Côte d'Ivoire aims at improving the quality of coffee grown in low altitudes, with a yield comparable to current commercial C. canephora clones. The second generation of back‐crosses to the C. canephora (CAN) parent, BC2, are now likely to be commercially exploited as far as yield is concerned. The best BC2 progeny yielded 1386 kg of green coffee/ha/y, averaged over five harvest years. On average, the genetic gain for yield from BC1 to BC2 reached 22%. In a factorial mating design, no interaction was observed between BC1 and CAN parents, while both main effects were highly significant. This explained that observed genetic gains and further genetic gains may be achieved with appropriate strategies.     

美国山核桃在黔东南州的发展现状及展望

为进一步促进美国山核桃发展,分析了黔东南州主要气候因子、土壤因素,以及黎平、锦屏、三穗等县引种实践结果调查,提出了美国山核桃在黔东南州发展建议。     

阿维菌素与5种杀菌剂混配对苹果二斑叶螨杀虫效果的影响

为明确阿维菌素与杀菌剂混配后对杀虫效果的影响。利用玻片浸渍法室内测定了阿维菌素与5种杀菌剂混配后对苹果二斑叶螨的毒力变化。结果表明：甲基托布津、苯醚甲环唑、戊唑醇浓度分别在700~7.5 mg/L、200~12.5 mg/L、688~43 mg/L时,与阿维菌素混配表现出明显的增效作用;增大杀菌剂的量表现出一定的拮抗趋势;减少杀菌剂的量对死亡率则基本无影响。阿维菌素与噁酮?氟硅唑混配表现为相加作用;与多菌灵、代森锰锌混配对二斑叶螨为减效作用。     

天女木兰种子休眠原因的初步探讨

从天女木兰种子的形态、种皮透性、种子各部分抑制物质的生物测定等方面研究其休眠的原因，结果表明：天女未兰种子秋季采收后种胚尚未发育完全，是导致天女未兰种子深休眠的主要原因；种皮透气、透水性良好；种子不同部位都存在不同程度的发芽抑制物质，主要存在于假种皮和胚乳中。     

Identification of cultivars of pasture legumes (Centrosema macrocarpum,C. pubescens and C. sp.n.) by acid polyacrylamide gel electrophoresis of cotyledons storage proteins

Summary An electrophoretic procedure was developed for storage proteins which can discriminate cultivars of forage legumes, Centrosema macrocarpum, C. pubescens and C. sp.n. Proteins extracted from cotyledons were separated in 10% polyacrylamide gel containing 10% sucrose. Electrophoretic patterns are presented to illustrate the results that can be obtained with the procedure described. Cultivars of all three species were distinguishable based upon the variation in their acid soluble seed proteins.Joint publiccation of the Department of Food Science, University of Manitoba (No 101) and Centro Internacional de Agricultura Tropical-CIAT.     

海岛棉与澳洲棉、黄褐棉种间杂种F_1的细胞学研究

本文研究了四倍体栽培种海岛棉与二倍体野生种澳洲棉、四倍体野生种黄褐棉种间杂种Ｆ１的主要形态特征及Ｆ１花粉母细胞减数分裂中期Ⅰ的粱色体行为。结果，（海岛棉４１６×澳洲棉）Ｆ１有的性状趋向澳洲棉，如茎、叶的茸毛、花冠颜色、花的开放形式；有的象海岛棉，如叶形、叶色、花药和花粉之颜色；有的则为中间型，如苞叶形状、铃形等。（海岛棉７１２４×黄褐棉）Ｆ１趋向父本黄褐棉的性状有：腺体较多，茎秆、叶片暗绿色，有茸毛，叶片掌状。短日照性强；表现中间型的性状有：花瓣黄色，有红心。两个组合Ｆ１的花粉母细胞减数分裂中期Ⅰ的配对构型分别为３１．４Ⅰ＋３．９０Ⅱ＋０．０２Ⅲ＋０．０２Ⅳ和０．２４Ⅰ＋２５．７１Ⅱ＋０．０９８ｔⅠ″＋０．０３９Ⅳ，这一结果表明，海岛棉与澳洲棉的亲缘关系较远，与黄褐棉的亲缘关系较近，但海岛棉与黄褐棉的染色体间已有所分化，可能存在染色体结构上的差异。     

Clonal evaluation for increased seed production in two species of forage grasses,Festuca arundinacea Schreb. and Phleum pratense L.

Summary A study was made of the seed production characters of replicated single plants of two Aberystwyth varieties, S.170 tall fescue and S.48 timothy, and estimates were made of the total genetic variation and the heritability of each character. Six-plant selections were made from each of the two varieties, and performance trials indicated that seed yield had been increased by 20% in tall fescue and 47% in timothy. As indicated by the measurements on single plants, increases in seed weight per inflorescence were almost wholly responsible for the increase in seed yield, with the number of inflorescences remaining unaltered in the two new selections. The mean inflorescence size of both selections was similar to that of the two varieties, but floret fertility and 1000-seed weight were significantly increased. In S.48 timothy there was also an improvement in the facility with which seed could be threshed from the mature inflorescence.     

Resistance in Cucumis sativus L. to Tetranychus urticae Koch. 3. Search for sources of resistance

Summary After a first screening of 800 cucumber varieties, a laboratory test and a practical test, the following nine varieties have been selected for their distinguishable level of resistance to the twospotted spider mite: PI 220860, Hybrid Long Green Pickle, PI 178885, Ohio MR 200, Taipei no 1, Robin 50, Aodai, PI 163222 and PI 218036. Besides resistance tolerance for the twospotted spider mite also appears to occur. Related Cucumis species do not seem to possess higher levels of resistance than the most resistant C. sativus varieties. The resistance-parameters acceptance and reproduction appear to be positively correlated. On resistant varieties the metabolism of the spider mites is clearly disturbed, but this seems not to be caused mainly by bitter principles.     

Resistance in Cucumis sativus L. to Tetranychus urticae Koch. 4. The genuineness of the resistance

Summary For several generations subpopulations of the twospotted spider mite were reared on cucumber varieties previously selected as partially resistant. Subsequently resistance tests were carried out in the laboratory and the glasshouse with mites from these subpopulations and concurrently with mites from a basic population reared on a susceptible cucumber line. In these tests neither acceptance nor net reproduction or damage index on the partially resistant varieties depended on the kind of mite populations used as inoculum. Therefore it is concluded that the resistance is genuine. The stability of the resistance is discussed.     

Quality Characteristics and FTIR Research of Amorphophallus konjac K. Koch Cultivated under Forest

[Objectives]This study aimed to evaluate the quality characteristics of Amorphophallus konjac K.Koch and study the tubers of A.konjac K.Koch by infrared spectroscopy and second derivative method.[Methods]Referring to industrial standards of China for agriculture and related documents,the quality characteristics of A.konjac K.Koch were determined;and using potassium bromide tableting method and Fourier transform infrared spectroscopy,the infrared spectrum and second derivative spectrum of A.konjac K.Koch were studied.[Results]The drying rate,total ash content,acid-insoluble ash content,water extract content,ethanol extract content and crude polysaccharide content of A.konjac K.Koch were above 14.00%,4.57%-11.78%,0.04%-4.87%,26.31%-36.98%,2.20%-7.95%and 40.25%-61.18%,respectively.The infrared spectra of A.konjac K.Koch of different origins were relatively close,and the differences were mainly in peak intensity.The peaks at 1642,1322,1241,1154,1022,863,770 and 576 cm-1 were the main specific peaks.The main component was konjac glucomannan.[Conclusions]FTIR technology is simple and quick,and is suitable for quality control and sample identification of A.konjac K.Koch.This provides a scientific basis for the quality control and comprehensive utilization of A.konjac K.Koch cultivated under forest.     

6株拮抗酵母对梨毛霉菌(Mucor sp.)和青霉菌(Penicillium sp.)防效测定

采用稀释涂布平板法从拉萨市城关区的12种市售水果中分离酵母菌,并采用平板划线法对酵母菌菌株进行纯化;采用病斑法对皿内抑菌效果较强的6株拮抗酵母进行活体防效测定,并采用26S r DNA D1/D2区域序列测定法对酵母菌进行了分子鉴定。结果表明,193和233号两株酵母对梨毛霉菌(Mucor sp.)有明显的抑菌作用,其发酵液防效强于菌悬液;193号菌株对梨青霉菌(Penicillium sp.)有明显防效,其菌悬液抑菌作用大于发酵液。分子鉴定结果显示,6株酵母菌归为5个种,48号菌株为隐球酵母(Cryptococcus adeliensis),77号为葡萄有孢汉逊酵母(Hanseniaspora uvarum),193号为汉逊德巴利酵母(Debaryomyces hansenii),230和235号为禾本红酵母(Rhodotorula graminis),233号为胶红酵母(Rhodotorula mucilaginosa)。     

Interspecific hybridization between Coffea arabica L. and tetraploid C. canephora P. ex Fr. I. Fertility in F1 hybrids and backcrosses to C. Arabica

Summary The interspecific (C. arabica × tetraploid C. canephora) F₁ hybrid showed a low but highly variable fertility. An almost complete restoration to normal fertility was observed in individual trees of BC₁ and BC₂ generations with C. arabica as recurrent parent. From a comparison of various tests of fertility, it was found that pollen viability is a satisfactory measure of fertility.     

不同培养温度对金佛山方竹种子萌发的影响

对2个种源(产地分别为云南昭通市彝良县和贵州遵义市桐梓县)金佛山方竹(Chimonobambusa utilis (Keng)P.C.Keng)种子进行了培养箱内温度控制萌发试验。随机抽样测定了2个种源的种子千粒重。培养温度设置为8个梯度:16,18,20,22,24,26,28,30℃。结果发现,云南种源的种子长宽、千粒重显著大于贵州种源的种子。2个种源种子不同温度下的萌发率存在显著差异。贵州种源以24℃为最高萌发率,云南种源以26℃为最高,20℃与22℃下萌发率差异不显著。2个种源种子在26℃下胚根生长最快,与其它7个温度下的胚根长度相比呈显著性差异。金佛山方竹展叶时间随着温度的增加,表现为先减少后增加的变化趋势。总的来说金佛山方竹种子萌发喜低温。虽然不同温度下种子萌发所需时间不同,但其在18～22℃能够萌发且生长良好。而相对高温易引起幼苗白化,对幼苗生长不利。因此在金佛山方竹实生苗繁殖时,控制萌发温度能有效提高萌发率。     

Interspecific hybridization between Coffea arabica L. and tetraploid C. canephora P. Ex Fr. II. Meiosis in F1 hybrids and back crosses to C. Arabica

Summary Melosis was studied in Coffea arabica, in induced tetraploid C. canephora, in their F₁ hybrid (arabusta hybrid) and in backcross generations of the hybrid with C. arabica as recurrent parent. Irregularities were observed, consisting of univalents (especially in the arabusta hybrid), multivalents (especially in tetraploid C. canephora) and uneven distribution of chromosomes at first anaphase. Chromosome distribution was improved by backcrossing. Meiotic irregularities wer negatively correlated with pollen fertility.     

Cytology and morphology of the amphiploid Hordeum chilense × triticum turgidum conv. Durum

Summary The morphology and meitotic behaviour of the amphiploid Hordeum chilense × Triticum turgidum conv. durum are presented.The fertility, agronomic performance, chromosome stability and grain quality of the new amphiploid give it special value for plant breeding.