Diploids and natural autotetraploids in the predominantly vegetatively propagated Brassica oleracea L. var. ramosa DC and their cytology

Summary Perennial kale is a rare vegetable and forage crop in the Dutch province of Limburg where it is disappearing. It may be a relic of a primitive kale form which could have been grown on a large scale in West-Europe. The crop is predominantly vegetatively propagated.Cytological investigations indicated that a number of accessions are autotetraploid with 2n=4x=36. The origin and age of these autotetraploid accessions are not known, but they may stem from adventitious buds on wounded tissue during the vegetative propagation.     

Effect of Induced Autotetraploidy on Response to Sclerotinia Clover Rot in Trifolium pratense L.

The effect of induced autotetraploidy on the response of red clover to Sclerotinia clover rot (SCR) was studied under laboratory, glasshouse and field conditions. To assess the response in the laboratory, the detached leaf technique was employed, whereas in the glasshouse and in the field, 6—14 weeks old seedlings and adult plants, respectively, were artificially inoculated with the pathogen grain inoculum. The results of the studies showed that great genotypic variability occurs within diploid (2×)and tetraploid (4×)red clover in response to that disease. Generally, tetraploid red clover, in comparison to diploid, is more resistant to SCR. The laboratory, glasshouse and field experiments showed that the effect of induced autotetraploidy on SCR resistance is positive. The hardening of plant with light and temperature enlarged the differences in reponse to SCR between ploidy levels, family pairs and individual strains with every testing method. Other factors, like plant age and flowering time, influencing red clover response to SCR are also discussed.     

Performance of Diploids and Induced Autotetraploids of Catharanthus roseus under Different Levels of Nitrogen and Plant Spacings

Two bulk experimental strains of induced autotetraploids,‘Purple tetraploid bulk’ (PTB) and ‘White tetraploid bulk’ of Catharanthus roseus were evaluated along with the diploid ‘Purple’ variety (PDB) and a diploid pure line selection PS-3 in four environments consisting of combinations of two levels each of plant spacing and nitrogen at Bangalore and Hyderabad during 1983—84 and in two additional environments at Bangalore during 1984—85. PTB, in general, performed better than PDB at closer plant spacings, especially in the absence of nitrogen application. The highest increase in economic yield (leaf + root yield) over PDB was recorded by PTB with 45 × 30 cm plant spacing and no nitrogen fertilization. The highest economic yield of PTB (obtained with 30 × 30 cm spacing and 100 kg N per ha) was 26 % higher than the highest economic yield of PDB. There were no significant differences between PTB and PDB for content of total alkaloids in leaves within all the environments during both years. Strain × environment interactions were significant for content of total alkaloids in roots during 1983—84. During 1984—85, PTB and PDB did not significantly differ from each other for content of total alkaloids in roots.     

诱导番茄同源四倍体的研究

人工诱导番茄四倍体,当作遗传传递的工具,有重要的育种用途。籍助染色体重组工程,诱导番茄多倍化,实现基因转移,不仅可获得座果多而品质好的番茄新品系。还可克服远缘杂交中的不亲和性、杂种不孕性等,从而培育新品种。试验结果表明:用中等剂量的秋水仙素处理减数分裂前的细胞,并结合涂抹幼苗生长点的方法,产生番茄四倍体的频率大,植株茎部粗壮,叶色深而宽厚,座果多而果实大。但需加强田间管理,才可在生产中应用。     

Three-Way and Four-Way Recurrent Selection in Plant Breeding

Three or four-way recurrent selection is proposed for the development of three or four-way crosses. In term of genetic effects, it could be justified if there are interactions between more than three genes, whether alleles or not, if autopolyploids are also considered. For autotetraploids, in particular with tetragenic interaction, four-way recurrent selection could be more effective than reciprocal recurrent selection (two-way selection). According to the types of progenies used to develop the tests, different selection procedures are considered, the two extremes being called method 1 and method 3. With method 1 (selection for three or four-way general combining ability) a plant from a population is used to produce three-way or four-way progenies with the other populations used as testers. With method 3 (selection for three or four-way specific combining ability) three-way or four-way crosses are developed with one plant from each population. To study the genetic advance, the theory is developed to consider either diploidy or autotetraploidy. It is shown that method 3 will allow a greater genetic advance than method 1 for low heritability and low selection intensity. The way towards hybrid development with three and four-way pedigree selection is discussed: again selection can be for general or specific three or four-way combining ability. It is emphasized that an advantage of recurrent selection for three or four-way specific combining ability is that it allows direct varietal development with pedigree selection on three or four-way specific combining ability. Some other practical aspects are also considered.     

Thebaine content and yield in induced tetraploid and triploid plants of Papaver bracteatum Lindl.

Summary The effect of colchicine induced autotetraploidy on the thebaine content and yield of the capsules of Papaver bracteatum was studied. A significant increase in the thebaine content of the capsules was found in tetraploid plants during two consecutive growing seasons, but the thebaine yield per plant was slightly reduced in the autotetraploids. Autotriploid plants showed a very high concentration of thebaine (8.8%) only in the first growing season.Preferential bivalent pairing and a relatively high pollen fertility were observed in the tetraploids, thus making possible the stabilization of tetraploidy by selfing.Tetraploidy seems a most promising approach for developing clones (by vegetative propagation) or lines rich in thebaine.     

Autotetraploidy in caraway (Carum carvi L.) for the increase of the aetheric oil content of the seed

Summary An autotetraploid population of caraway (Carum carvi L.) was produced by treating the growing points of young plants with a 0.2% colchicine solution. Selection on morphology, pollen size and pollen shape, followed by a selection on seed size proved to be an effective way to identify the mixoploid C₀ plants. Three percent of the treated plants produced a tetraploid progeny. Moderate selection in the C₁ and the C₂ population resulted in an improvement of the average seed-set to the amount of 50% of the diploid control, with a range of 21–78%. The 1000-kernel weight of the tetraploid material was 7 g, compared to 3 g in the diploid control. The oil content of the autotetraploid seed was increased with 35.6%; the increase in carvone amounted to 6.9%. The results of the experiment indicate that breeding work in autotetraploid caraway may result in a new cultivar.