生长调节剂和肥料对案头菊组培苗综合评分的影响

通过设立有关的主要经济性状(植株高矮和花朵直径大小)指标和案头菊质量评分标准,采用生长调节剂(B9)和肥料(尿素+磷酸二氢钾混合物)作为处理因子,对案头菊组培苗综合评分的影响进行探讨,并总结出了一套适合武汉地区案头菊生产的技术措施。     

Chromosome constitution in G2 and G3 progenies of 6x-triticale × T. turgidum L. hybrids

Summary Rye chromosome constitution and stability in a series of plants of G2 and G3 generations obtained after the cross between hexaploid triticale and durum wheat (F1: 2n=5x=35; genomes AA BB R) are studied using the zymogram phenotype expression for the following isozyme marker genes: Mdh-2c1 (1R), Cpx-c2 (2R), Got-3-c1 (3R), Pgm-c1 (4R), Est-c6 (6R), Got-2-c1 (6R), Acph-c1 (7R) and Got-1-c1 (7R). The results were corroborated using C-banding in a sample of the plant population studied and make clear the utility of biochemical methods in quick cytogenetic analysis. From the results, a different rate of transmission for each rye chromosome is inferred.     

A comprehensive multisite recurrent selection strategy in perennial ryegrass

Summary As the seed market for forage grasses in France is rather limited, proposed varieties should have a broad adaptation to a range of different environment. Therefore a comprehensive strategy of multisite recurrent selection has been devised for perennial reyegrass. It is based on an experimental cooperative network between National Institute for Agronomic Research (INRA) and private companies. A pragmatic approach has been retained that gives a compromise between theoretical and practical considerations. The method is illustrated by results from a breeding population consisting of 33 half-sib families derived from a local germplasm. Family selection with an intensity of 30% was applied to yield and persistence data from sward plot trials. The strategy was based on a multisite index where trait x location combinations are considered as different traits and given equal economic weights. Improvements of 10–15% were expected for summer-autumn production and persistence. For spaced plant nursery traits, a subset of locations was chosen according to a multiplicative model decomposition of G x E interaction, where a 10% mass selection was practised. This leads to interesting progress on crown rust tolerance, growth scores, leafiness and persistence. Moreover, the expected indirect responses from selection on spaced plant traits to sward traits and vice-versa are almost all favourable. As significant improvements are expected for most traits in all locations, this programme should allow to increase the general adaptation of ryegrass varieties for France.     

Directed search for plant constituents: a case study concerning flavonoids in Norway spruce

The reported content of flavonoids in the needles of Norway spruce, Picea abies, has been used as a basis for a directed search for compounds previously undetected in this species. Combined with advanced chromatographic methods and sensitive detection techniques, the directed search approach assisted in the identification of the novel flavonols, myricetin 3- O- (6-acetylglucoside) and syringetin 7- O-glucoside, and several other flavonoids isolated for the first time from this species.     

Variation and covariation of agronomic traits and quality in triticale at low nitrogen input

The use of high nitrogen (N) inputs is becoming restricted in many countries due to environmental and economic considerations and reliable information is needed about parameters pertinent for breeding N-use efficient triticales (x Triticosecale Wittmack). This study reports estimates of variances, heritabilities, correlations, and regression for 36 triticales, grown at three locations for 2 years with two N regimes (zero and normal N supply). Eleven traits were assessed. A 45% mean reduction in grain yield by low N input was mainly the result of a 25% lower number of tiller-bearing spikes per m2 and 17% fewer kernels per spike, whereas 1000-kernel weight was little affected. Genotype-nitrogen interaction was of importance only in some environments and for certain traits. Heritability estimates at both N levels were similar and moderate to high. Correlations between N levels were high for nearly all traits. Regression analysis for grain yield revealed only few N-efficient triticales with lower than unity slope together with a high grain yield. Based on the genetic parameters, it is concluded that a special low input breeding programme does not appear to be necessary in triticale. The breeder can select at either of the N levels with similar response. But he should include tests in low productivity environments at some early stages in the breeding process to avoid loss of genetic variation for N-use efficiency.     

Stability and genetic improvement of maize yield in Argentina

Summary Yield stability and the genetic improvement of maize (Zea mays L.) grain yield in the humid pampas of Argentina were evaluated.Stability parameters were computed for 15 varieties grown in 35 environments. To analyze genetic improvement of grain yield, data were obtained from trials grown in four locations and twelve years. Two locations represented the typical maize area, while the remaining two were considered marginal. Simple correlation and linear regression coefficients were computed to study the relationships between yield, stability parameters, number of days to 50% tassel emergence, and year of release. Genetic improvement of grain yield was analyzed from linear regression of the average yield of the three highest-yielding varieties (as percentage of the average yield of five common checks) on year of trial.Yield differed significantly among varieties. Significant variety x environment (linear) interaction was also detected. Significant linear relationships were found between regression coefficient for yield (stability parameter 1) and days to tassel emergence, stability parameter 1 and yield, year of release and days to tassel emergence, and year of release and stability parameter 1. Thus, newer maize varieties tended to flower later and had greater responsiveness to favorable environments than did older varieties. Yields have increased for both the typical and marginal areas, with average yearly increases of 114 and 182 kg/ha, respectively.Breeding programs with nurseries located in the typical maize area have raised yield potential in both areas studied. However, if present trends continue, future releases could prove inadequate in low-yielding or short season environments.     

Natural triploid hybrids between Solanum acauleBitter and S. infundibuliformePhilippi in the province of Jujuy,Argentina

Summary The occurrence of natural triploid hybrids between tetraploid Solanum acauleBitter subsp. acaule and diploid S. infundibuliformePhilippi both tuber-bearing Solanums, in the Puna region of Jujuy, is reported. The natural hybrids, which are morphologically intermediate between their putative parents and completely male sterile, have a somatic chromosome number of 36. The artificial hybrids, obtained by crossing both parental species, closely resemble the natural ones thereby confirming their parentage. It is proposed to designate the natural hybrids Solanum x viirsooi hybr. nov.     

Genotype environment interactions and sib content in F1 hybrid —brussels sprouts

Summary Sib content of F₁ hybrid seed lots obtained from crossing four highly self incompatible brussels sprout lines was examined at two locations for four years. Parental combinations accounted for by far the greatest proportion of the total variation observed. Significant second and third order interactions terms suggest complex interactions between parental genotype, years, and locations. Attempts to interpret these data in terms of the regression model of Finlay & Wilkenson (1963), were unsuccessful.     

Analysis of genotypic and environmental variation in international mungbean trials

Summary Two-way classification analysis, combined with analysis of variance and linear regression techniques, was applied to a set of yield data from twenty-one genotypes grown at twelve locations for two years in International Mungbean Nursery trials. Genotypes and environments with similar yield response patterns were grouped and differences between groups identified. Genotypes were also grouped on the basis of flowering time and the relation between days to flower and yield was examined. It was concluded that cluster and associated analyses are of value in determining response patterns of mungbean genotypes to a wide range of environments, and a useful aid in the selection of materials and locations for mungbean evaluation. In particular we note the adaptation of genotypes M409 and M1134 to high elevation locations, and the positive yield response of M374 (MG50-10A) to high yielding environments. Highest yielding lines were also the earliest to flower. Disease resistance was considered the most important breeding objective for mungbean yield improvement.     

Regression analysis of genotype x environment interaction in sweet potato

Summary Two experiments, each involving a set of 10 sweet potato clones, were conducted for three years at 4 sites (Ekona, Ebolowa, Nkolbisson, and Bambui Plain) in Cameroon. Data obtained were subjected to analysis of variance to determine the presence of genotype x environment (G x E) interactions, and to regression analysis to assess the performance of clones across anvironments. Environments were assessed in two ways: (i) the mean response of all clones (dependent assessment), and (ii) the average performance of a different set of clones (independent assessment).The first experiment (Expt 1) produced higher yields but had fewer stable clones than the second (Expt 2).The analysis of variance revealed that the clones interacted significantly with environments for all traits.The study has identified high yielding and stable sweet potato clones for distribution to growers in the major areas of cultivation in the tountry. Despite slight differences in numbers of clones judged stable by the various regression indices in the two methods of environmental assessments, the rankings of clones on the basis of their linear regression coefficients were similar. In a developing country like Cameroon, with limited resources and where sophisticated equipment for obtaining physical or biological measures of the environment may be lacking, the mean performance of genotypes may still be the most reliable measure of environment in evaluating the stability of performance of crop cultivars.