陆地棉高品质纤维种质基因库的拓建

采用远缘杂交,开展了棉属野生种的高强纤维潜力基因向陆地棉品种转育研究,以构建高纤维品质的种质基因库.在适宜的自然条件和人工条件下,陆地棉分别与异常棉(Gossypium anomalum)、辣根棉(G.armourianum)、雷蒙德氏棉(G.raimondii)等杂交,克服杂交不可交配性、杂种一代的高度不育性等,通过多年的回交选择和纤维品质测定筛选,     

EXPERIMENTAL INVESTIGATION ON BOILING HEAT TRANSFER OUTSIDE THE LOW FINNED TUBE WITH SHROUD

Based on analysis of pool boiling characteristics outside low finned tube, this paper describes a simple method, using enhancing shroud to improve the performance of boiling heat transfer outside the low finned tube. The experiment results show that the boiling heat transfer coefficient can be 7-up to 10-fold enhanced by using shroud. The efficiency of a shroud is related to the size of two windows, heat flux and physical characteristics of test fluids.     

Genetic diversity of Brassica carinata with emphasis on the interspecific crossability with B. rapa

Brassica carinata (BBCC, 2n = 34) possesses many good agronomic characters and, to provide more genetic information about this species and utilize it further, 110 accessions of B. carinata were tested for genetic variation by using 233 amplified fragment length polymorphism markers, so that a dendrogram could be constructed. To combine the good traits of B. carinata and B. rapa (AA, 2n = 20) with those of B. napus (AACC, 2n = 38) which is the major rapeseed variety in China, interspecific crosses between these two species have been made which have resulted in 276 doubled hybrids (AABBCC). These hexaploids combine positive characters and can be used for crossing with B. napus . Brassica carinata as the female parents exhibited extensive differences in interspecific crossability and 20 high crossability accessions were identified. The Poisson Regression Model analysis result (P < 0.0255) indicated that such differences were due to the genotype of the accessions. Accessions with high crossability could promote gene flow within the genus Brassica .     

Recent advances in alien gene transfer in wheat

Summary The recent advances in alien gene transfer from distantly-related species into wheat are reviewed in the present paper. The main achievements during the last ten years include the great expansion of the range of wide hybridization and development of new techniques for production and characterization of wheat-alien chromosome translocations. Updated results of wide hybridization since 1983 and comprehensive characterization of wheat-alien translocation lines in our laboratory are compiled. The future outlook for alien gene transfer in wheat is also discussed.     

Variation in relation to geographical distribution of wild oats-seed traits

Summary A sample of 457 wild oats (Avena sterilis L.) from the world collection maintained at the Germplasm Laboratory, Beltsville, Maryland, USA, was studied for variation of six seed characters via means, ranges, variances, and frequencies from various geographical areas. It was concuded that region-specific adaptations are responsible for occurrence of certain trait(s) in specific geographical regions; e.g., Libyan and Iraqi collections had high protein percentage, Israeli strains had high oil percentage, and the Middle East and Central Asian lines had a high number of spikelets per panicle. The main conclusion of interest here is that, within the same species, estimates of the amount of variation may vary widely, depending upon the area sampled, geographical scale of sampling, etc., presumably due to the complex interrelationship between genetic and ecological factors.Journal Paper No. J-12670 of the Iowa Agric. and Home Econ. Exp. Stn., Amers, Iowa, Project 2447.     

Sources of resistance to angular leaf spot (Phaeoisariopsis griseola) in common bean core collection, wild Phaseolus vulgaris and secondary gene pool

Angular leaf spot (ALS) is one of the most devastating diseases of common bean (Phaseolus vulgaris L.) in tropical and subtropical countries. The causal fungus, Phaeoisariopsis griseola(Sacc.) Ferr. is highly variable and a diverse source of resistance genes is required to manage this disease. We evaluated a common bean core collection,primary and secondary gene pools and lines derived from inter-specific crosses of P. vulgaris and P. coccineus or P. polyanthus (secondary gene pool) for resistance to angular leaf spot. Of the 1441 accessiones in the core collection, only 2.2% were resistant to both Andean and Mesoamerican races of P. griseola, 28% were resistant only to Andean and 9% to Mesoamerican races. Of the 32 resistant accessions, 68%originated from Bolivia, Colombia,Guatemala and Mexico. More accessions from these countries should be examined for P. griseola reaction. Very few wild P. vulgaris accessions (4%), were resistant to ALS. In contrast, high levels of resistance (62%) were found in the secondary gene pool. Among the 1010 lines from inter-specific crosses, 109 lines were highly resistant. These genotypes from the primary and secondary common bean gene pools resistant to Andean and Mesoamerican races of P. griseola offer a potential for developing broad and durable ALS resistance. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic diversity of wheat gene pool of recurrent selection assessed by microsatellite markers and morphological traits

Abstact An agronomic gene pool of wheat (Triticum aestivum L.) was constructed through recurrent selection. In present research, 24 wheat SSR markers determining 25 loci on 14 different chromosomes were used to evaluate the gene pool. Thirty parents used as original materials in recurrent selection were also assessed. In total, 115 alleles were detected in gene pool with an average of 4.6, ranging from 2 to 9 alleles per locus. Statistical test showed that genetic diversities had no significant difference between the gene pool and the 30 parents. Principle coordinates analysis revealed that the individuals of the gene pool were mainly divided into three groups, which was consistent with the result of cluster analysis based on genetic distance matrix of the gene pool. Cluster analysis was carried out based on Euclidian distance calculated upon five morphological trait values and the results showed that most individuals were in a group while the others scattered. Correlation analysis of genetic distance matrix and Euclidian distance matrix showed no significant correlation between two matrices. The results suggest that the gene pool is improved after several cycles of selection, while genetic variation is still maintained. Therefore, the gene pool is suitable for further breeding program.     

小麦抗赤霉病基因库研究 Ⅲ.不同基础群体组建方法及其轮回选择探讨

利用太谷核不育小麦,进行多亲本杂交,按不同的方式组建基础群体。采用不同的选择方法和选择强度,分别进行轮回选择。对长期库 GPO 和近期库 GPⅠ、GPⅡ,GPⅢ等4个不同轮选群体,于1989/1990和1990/1991年在南京进行了研究。群体平均抗赤霉病性 GPⅢ较强,GPⅡ较弱。各群体当选优良可育株平均病粒数(率)GPⅢ较低,但其后代抗赤性与其他3个群体间无明显差异。与 GPO 相比,GPⅠ、GPⅡ、GPⅢ平均株高分别矮12.2,11.4和6.7厘米,达显著或极显著水平;穗粒重和千粒重分别高9.79—17.20%和2.76—9.91%;穗粒数、小穗数明显较多。当选优良单株平均株高3个近期库比长期库矮7—10厘米,单株粒数多40—70粒,单株粒重高1.5—4.5克,穗粒数多2—6粒,穗粒重高0.2—O.55克。表明 GPⅠ、GPⅡ的组群方法较 GPO 好,3个近期库的改良效果显著优于长期库。各群体遗传变异均较大,进一步选择仍然有效。     

Long-Term Crop Rotation Effects on Organic Carbon,Nitrogen, and Phosphorus in Haplustoll Soil Fractions

Soil organic matter (SOM) or carbon (SOC) consists of a number of fractions (which can be separated by granulometric wet sieving) having different properties among them. Information on fraction nutrient distribution and long-term crop rotations is lacking for semiarid environments. The objective of this research was to study the agronomic effects on soil OC, N, and P fractions. The humified OC was the largest and least variable fraction of the SOC. Soil under continuous mixed pasture had higher OC contents than under annually tilled treatments. Similarly, soil total nitrogen under the cropped treatments decreased from 1.7 g N kg-¹ in noncultivated soils (reference plots) to 1.0, 0.7 an 0.7 g N kg-¹ under mixed pasture, pasture-crop, and wheat-crop respectively, in the fine soil fraction. The reference plots also showed significantly lower levels of organic phosphorus (P o ) in comparison to the other treatment (from 67.1 w g P o g-¹ to greater than 100 w g P o g-¹ in the fine fraction of the treatments and years). The noncultivated soil showed larger values of P o and inorganic P in the large-size granulometric fraction (0.1-2 mm) than in the soil fine fraction (0-01 mm). However, the rotation treatments had greater concentrations of P in the fine fraction. The P o from the coarse fraction appears to be the most labile and sensitive fraction to tillage and environmental conditions, and may be closely related to P availability.     

Effect of inorganic phosphatic fertilizers on the efficacy of an arbuscular mycorrhiza fungus against a root-knot nematode on pyrethrum

Effects of triple super phosphate (TSP) and single super phosphate (SSP) fertilizers on efficacy of a Glomus sp. (isolate KS 14) against Meloidogyne hapla were determined. The fertilizers were applied at 150 and 300 kg ha -1 at the time of fungus inoculation. Two months later, plants were inoculated with the nematodes. Plant growth and nematode disease parameters were determined 2 months after nematode inoculation. The fertilizers at both levels improved plant growth in all treatments. In general, the fungus improved plant growth on its own or in the presence of nematodes, but not in the presence of fertilizers. Both fertilizers at both levels were more effective in improving plant growth than the fungus. The fungus showed sensitivity to inorganic P fertilizers in that the fertilizers significantly reduced fungal root colonization and its pyrethrum growth stimulative effects. The fungus suppressed nematode disease severity unlike the fertilizers. The suppressive effects of the fungus on the nematodes were in most cases reduced by the fertilizers. The nematodes, unlike the fertilizers, did not have any significant effects on root colonization by the fungus or on its ability to improve pyrethrum growth. The presence of nematodes in fertilizer or fertilizer-fungus-treated plants, however, significantly reduced pyrethrum growth.