Classification of Azolla spp., section Azolla

Summary Azolla accessions (section Azolla) from the germplasm collections of the International Rice Research Institute and Washington State University were fingerprinted and classified by enzyme electrophoresis and leaf trichome morphology. A. filiculoides was enzymatically distinctive and also reliably identified by its prominent one-celled trichomes. Neotropical accessions labelled as A. filiculoides proved to be members of other species. Two groups of isolates were designated A. rubra, but those from Japan were identified as A. filiculoides. The A. rubra of Australia-New Zealand was biochemically unique and possessed less protuberant trichomes than A. filiculoides. A. microphylla, A. mexicana, and A. caroliniana were phenetically similar, but a. microphylla was identifiable from the others in the banding patterns of certain enzymes. A. mexicana and A. caroliniana were closely related enzymatically. The two-celled leaf trichomes of these three species were similar in size and shape.     

Numerical Simulation on Drying Characteristics of a Combined Microwave-convection Process

Combined microwave-convection drying characteristics are investigated by numerical simulation. Combined microwave-convection drying has advantage of swift drying and sterilization. Based on qualitative analyses on the mechanism of combined microwave-convection drying, the differential equations are established and the numerical simulation method is described. The humidity, vapor pressure and temperature, along the radius in a spherical pill, are calculated by the numerical simulation during drying process. The calculation results show the relationship between humidity, vapor pressure, temperature and drying time, and that drying process is greatly influenced by input microwave power. The calculation results are good consistent with the experimental datum.     

茶叶干燥技术研究现状及展望

干燥作为茶叶初制加工的重要工序,对茶叶感官品质的形成具有重要意义。干燥过程中,在热和力的作用下,随着水分的不断散失,在制品物理特性和内质成分发生剧烈变化,从而形成茶叶特有的感官品质。笔者阐述了中国茶叶初制各干燥技术原理及特点,指出茶叶干燥将由单一技术向联合应用技术发展的趋势,并提出要完善新型联合干燥技术的基础研究和干燥在制品含水量在线检测技术,为新型茶叶干燥机械研发和未来茶叶干燥技术提供一定的发展思路。     

Oligonucleotide fingerprinting of tomato DNA

Hinfl -digested DNA samples of wild and cultivated species of tomato were hybridized in gel to different oligonucleotide probes complementary to simple-sequence repeats. All motifs tested i.e. (GATA)₄, (GGAT)₄, (CA)₈. (CAG)₅, (GTG)₅, (GAAGTGGG)₂ and (CCTA)₄, produced multilocus fingerprints in all tomato species and cultivars. The extent of inter- and intraspecific polymorphism of the banding patterns varied considerably between different probes, with (GGAT)₄, (CCTA)₄, (GATA)₄ and (CA)₈ showing a much higher discriminatory potential than the other probes. Cluster analysis of band-sharing data yielded dendrograms which were consistent with the known history of tomato cultivation. (GATA)₄ was also successfully used for purity testing of breeding lines, as well as for analysing an F₁ progeny of a cross between two lines.     

DNA fingerprinting in soybean (Glycine max (L.) Merrill) with oligonucleotide probes for simple repetitive sequences

Summary Soybean DNA fingerprints were analyzed by digoxigenin-labeled oligonucleotide probes complementary to simple repetitive sequences. The clearest and most polymorphic patterns were obtained with (AAT)₆ as a probe, with which all 47 soybean cultivars tested could be distinguished. However, DNA fingerprints of individuals within cultivars showed the same pattern. Using (CT)₈, (GAA)₅ or (AAGG)₄ as probes, clear polymorphic patterns among cultivars and accessions in the subgenus Soja (Glycine max and Glycine soja) were not observed, while quite different patterns were found in accessions in the subgenus Glycine. The results suggest that G. max and G. soja are closer in their genome structure. DNA fingerprints of reciprocal crosses between cultivars and accessions in the subgenus Soja were similar, and contained bands of both parents. In an F₂ population from these crosses, such bands segregated in a Mendelian fashion.     

Strawberry-cultivar Identification using Randomly Amplified Polymorphic DNA (RAPD) Markers

Accurate and rapid cultivar identification is important for breeders'-rights protection, especially for vegetatively propagated plants. The objective of this study was to test the feasibility of developing cultivar-specific RAPD markers in commercial strawberries (Fragaria ananassa Dutch). Efforts were focused on distinguishing between two newly developed Volcani cultivars, ‘Ofra’ and ‘Dorit’, and six other cultivars, ‘Douglas’, ‘Chandler’, ‘Oso Grande’, ‘Dover’, ‘Nurit’ and ‘Parker’. Reproducible RAPD fingerprints were generated, each containing at least one polymorphic DNA product. A combination of 10 polymorphic DNA products exhibited cultivar-specific patterns enabling the distinction between closely related varieties, such as ‘Ofra’ (which is the progeny of ‘Dorit’ and ‘Parker’) and ‘Dorit’ (which is the progeny of ‘Nurit’ and ‘Dover’). This study shows that RAPD markers can help in the protection of breeders’ rights to strawberry cultivars.     

Suitability of mapped sequence tagged microsatellite site markers for establishing distinctness, uniformity and stability in aromatic rice

At present, testing for distinctness, uniformity and stability (DUS) of crop varieties relies on a set of morphological characters. These characters suffer fromthe limitations of number, interaction with the environment in which the variety grows and subjectivity in decision-making. The potential of DNA-based markers such as sequence tagged microsatellite site (STMS), for establishing DUS merits investigation. In the present study, a set of 55 mapped STMS markers, selected from 12 linkage groups of rice genome, was used to examine distinctness of 23 aromatic rice genotypes including the commercially important Basmati varieties. Forty-one of these markers (74.5%) showed polymorphism between the varieties. The number of alleles per locus ranged from 2–4 with an average of 2.3. The polymorphism information content (PIC) of the markers varied from 0.083 to 0.665 with an average of 0.338. All the varieties could be differentiated from each other at a low probability (0.07×10^-13) of identical match by chance. The marker-based clustering of the varieties corresponded with the known phenotypic classification, thereby providing confidence in the distinctness established by the mapped STMS markers. The utility of these markers to study uniformity and stability was analysed using a commercially important crossbred Basmati rice variety Pusa Basmati 1(IET-10364) that contributes about 40–50% of Basmati rice export from India. Genotyping of twenty individual plants, grown from the nucleus, breeder, foundation, certified and farmer's saved seed samples using all the 55 markers revealed no variation among the plants. These observations suggested that the set of mapped markers employed in this study could be further used for establishing distinctness of aromatic rice varieties and for studying DUS of the important commercial variety Pusa Basmati 1. This revised version was published online in July 2006 with corrections to the Cover Date.     

有机无机肥料配合施用对玉米根系的影响

以玉米品种四密21为材料,通过土柱模拟试验研究了有机无机肥料配合施用对玉米根系的影响.结果表明:有机无机肥料配合施用,提高了玉米各土层特别是中、下层根系干重和比率;增加根系伤流量;延缓根系活力下降;降低根系MDA含量;提高根系SOD活性.所以能够延缓玉米根系器官的衰老,从而使玉米产量提高.     

不同基因型刺梨及其近缘种亲缘关系的RAPD分析*

采用RAPD标记，对刺梨(Rosa roxburghii Tratt)7个基因型及8个近缘种(类型)进行鉴定和亲缘关系分析。结果表明，筛选出的16个随机引物可扩增出137条480bp到3.3kb大小的清晰。DNA片段，其中95条为多态性片段，为总数的69．3％；每个引物平均产生8．6条。由OPB-11、OPAF-16和OPW-02扩增的14条特异DNA片段，可有效地将普通刺梨7个基因型和无籽刺梨区分开来。基于遗传距离矩阵，采用IJPGMA法对15个供试样品的亲缘关系进行了聚类分析，文中还就无籽刺梨及重瓣刺梨的可能来源进行了探讨。     

渠井用水比对灌区降水响应及其环境效应分析

渠井结合灌区适宜渠井用水比例关系灌区地下水环境和区域农业可持续发展。该文以人民胜利渠灌区为例,集合了灌区1954-2014年农业用水量及降水量、研究区域2008-2014年渠井用水比、地下水埋深、地下水水化学特征数据,分析了降雨量、地下水动态特征与渠井用水比例的相关性,以期探明渠井结合灌区渠井用水比对降雨的响应及其对土壤和地下水环境的影响。结果表明,典型渠井结合灌区渠井用水比与年降水量呈线性正相关;渠系上游地下水水位变化较下游更为剧烈,在用水水平、用水方式一致条件下,渠井用水比例越大,地下水埋深超过11 m区域增幅越小,较大的渠井用水比例对于上游地下水位下降减缓效果明显;平水期、枯水期,由于渠井用水比例不合理,地下水无序开采且超采严重,区域地下水碱化趋势明显;受气候变化影响,近5 a渠灌水量仅为多年均值的75.52%,未来区域降水量具有减小趋势,这势必进一步加剧农业水资源紧缺的形式。为了满足农业的正常生产,增加灌区地下水开采成为唯一解决途径,这势必加剧地下水的碱化趋势及地下水超采区的扩大。因此,确定灌区适宜的渠井用水比例对于灌区水资源的科学利用与农业的可持续发展具有重要意义。