Aiuminium tolerance of durum wheat germplasm

Summary Aluminium tolerance of Macedonian durum wheat (Triticum turgidum L. conv. durum (Desf.) MacKey) germplasm was evaluated in nutrient solutions containing 0, 74 or 148 M of total Al. Relative root length (148 M Al/0 Al) of various genotypes ranged from 41 to 72% (from moderately sensitive to moderately tolerant to Al). No genotype with Al tolerance close to that of very tolerant T. aestivum cultivar Atlas-66 was found. Seed Ca concentration was positively (r=0.64, P0.05) and seed Fe concentration negatively (r=–0.71, P0.05) related to the relative root growth. Such a significant correlation was not obtained for seed concentrations of other nutrients or seed protein content.Abbreviations HSD Tukey's Honestly Significant Difference - RRL-2 relative root length, in % (74 M total Al/0 M Al) - RRL-4 relative root length, in % (148 M total Al0 M Al)     

Pollen grain size in four ploidy levels of genusAvena

Summary Pollen grain size in many genera positively correlated with chromosome number. In this study, oat (Avena) pollen grain size was examined in diploids (2×=14, one species, for accessions), tetraploids (4×=28, five species, 20 accessions), hexaploids (6×=42, one species, eight cultivars), and in 10 octoploid (8×=56) accessions. Mature anthers ready to dehisce pollen were sampled from one to six plants per accession, and pollen grains were squeezed out of the anther with tweezers. Oat pollen grains are slightly elliptical, and the length of the major axis was found to be highly correlated with the minor axis width (r=0.94^**). Pollen grain length, 39.3 m for diploids, 41.3 m for tetraploids, 47.0 m for hexaploids, and 48.8 m for octoploids, was positively correlated (r=0.86^**) with ploidy level. No genomic or species effects appeared to influence this trait. Only tetraploidAvena vaviloviana accession PI 412767 produced two distinct class sizes of pollen grains, 99% normal (43.0 m) and 1% large (52.7 m).     

Evaluation of Triticum aestivum germplasm from Croatia and Yugoslavia for aluminium tolerance

Summary Aluminium tolerance of 90 genotypes of Triticum aestivum L. germplasm from the breeding programmes of eight Croatian and Yugoslav institutions was evaluated in nutrient solutions having Al³⁺ activities of 0, 12.5 and 25M. Overall distribution of Al tolerance of wheat genotypes was skewed toward lower tolerance rankings. Average Al tolerance differed among gene pools created at different breeding institutions. Genotypes tolerant enough to be useful in the breeding programmes aimed at selecting cultivars with improved Al tolerance are identified in germplasm from four institutions. No correlation was found between chemical characteristics of soils used over the years by breeding institutions for their field trials and the Al-tolerance ranking of the corresponding germplasm material.Abbreviations HSD Tukey's Honestly Significant Difference - RRL-4 relative root length, in % (25M Al³⁺/0 Al)     

The black currant leaf curling midge,Dasyneura tetensi Rübs.; its host range,and the inheritance of resistance

Summary Established Western European black currant cultivars are susceptible to Dasyneura tetensi but the Scandinavian Sunderbyn II, Kangosfors and Hedda, and 10 out of 33 Russian cultivars showed very slight or no leaf symptoms of midge attack in the field.Of species within the black currant Section Eucoreosma, Ribes dikuscha, R. pauciflorum (probably=syn R. ussuriense), and R. americanum were not attacked, but an accession of R. bracteosum proved very susceptible. Species within other sections of the genus were not attacked.A strong dominant resistance gene in R. dikuscha, designated Dt, appeared to be linked with (a) gene(s) controlling resistance to American gooseberry mildew, Sphaerotheca mors-uvae. Resistance in Sunderbyn II and, probably, in R. pauciflorumwas oligogenic and dominant.     

High frequency somatic embryogenesis with a pampeana-derived genotype of alfalfa (Medicago sativa L.)

Summary Somatic embryos of genotype R11 of the alfalfa variety Pampeana were produced from embryogenic calli derived from leaf sections. They were induced by an auxin shock and its development was attempted on six different media. The best condition for somatic embryo production was inducing callus on MS medium plus 10 M 2,4-D and 4,6 M KIN and transferring them, after the auxin shock, to MS with 10–20 mM NH₄ ⁺ and 30 mM proline. More than 500 somatic embryos per plate were produced. Embryos were grown to plants on MS or half strength MS media and all regenerated plants resembled the original R11 genotype. This technique could be useful in alfalfa Pampeana improvement using genetic modification.     

Heritable tissue culture induced variation in Zinnia marylandica

Summary Adventitious shoots of Zinnia marylandica, an amphidiploid with limited genetic segregation, were regenerated from cotyledonary tissue on Murashige-Skoog (MS) media containing 0.2 or 22.2 M thidiazuron (TDZ) and grown through flowering. Fisher's Test for Equal Variance indicated tissue culture induced plants had more variation than seed-derived control plants. Twelve of 149 (8%) plants derived from 0.2 M TDZ and three of 23 (13%) plants from 22.2 M TDZ had variant characters. Aberrant characteristics in self-pollinated variants included plant height, fertility, flower color and morphology, and were sexually transmitted, indicating genetic change had occurred. Aberrant characteristics not observed in regenerated plants arose in progeny.Abbreviation TDZ thidiazuron     

A breeding method for accelerated development of cold chipping clones in potato

Summary The development of potato cultivars having acceptable chipping quality after cold storage is important because it reduces costs to growers while ensuring continuity of supply to processors throughout the year. Over 5100 single-hill progenies were planted to select for cold chippers. A breeding procedure for selecting and evaluating these progenies for cold chipping ability was used, and 38 desirable genotypes were identified. These selections were increased in the second clonal generation and evaluated for yield, specific gravity, and seven chipping treatments of varying storage duration/temperature/reconditioning duration and were compared to standard chipping cultivars Atlantic, Monona, Norchip, and Snowden. Twenty-two selections yielded Norchip the highest yielding cultivar, while 15 selections had a specific gravity Atlantic, the highest specific gravity cultivar. Snowden was the best chipping cultivar overall and some selections were not significantly different than Snowden. Overall, nine selections combined high yield and specific gravity with the ability to produce attractive chips from 4° C. Single-hill selection for cold chipping could potentially save four years in the breeding process by the identification of good parents, the recycling of good parental cross combinations, and the evaluation of progeny for chipping earlier in the breeding program.     

Genetics and histology of powdery mildew resistance in apple

Summary Eight scab-resistant cultivars and selections along with eight commercial apple cultivars were evaluated for powdery mildew resistance in greenhouse and nursery tests. Dayton, Liberty, Delicious and Tolman Sweet were rated moderately resistant to infection in both greenhouse and nursery tests. Segregation of seedlings among 14 progenies for mildew reaction indicated that mildew resistance is polygenically controlled in this material with additive gene effects. Recovery of mildew resistant seedlings from crosses involving a scab-resistant parent(s) suggested that this material can be useful in developing scab- and mildew-resistant apple cultivars. Histological investigations were conducted to describe mildew symptoms of infected leaves.     

Genetic base of Indian potato selections as revealed by pedigree analysis

Pedigree analysis of the 77 advanced Indian potato selections showed that their origin could be traced to only 49 ancestors out of which 29 were exotic, which accounted for 69.52% of the total genomic constitution and maximum contribution (40.65%) was by 10 ancestors from U.K. Breeders tendency was to involve adapted advanced clones as immediate parents. Coefficient of relationship between pair of selections ranged from 0 to 0.68. The success of the parents used was not related to region-specific choice of parents. The findings are discussed in the context of genetic uniformity and the relevance of having separate breeding programmes for the three major areas of potato cultivation in India. Attempt has also been made to give some directions for choosing selections for use as parents and release as cultivars based on their coefficient of relationship so as to broaden the genetic base of the future potato cultivars.     

Interspecific hybrids of Cucumis metuliferus × C. anguria obtained through embryo culture and somatic embryogenesis

Summary Interspecific crosses between Cucumis metuliferus Naud. and C. anguria L. were obtained through embryo culture. Embryos in the rabbit-ear to advanced fluke-shaped stages were rescued 34–99 days after pollination. Plants were obtained through direct embryo culture, and through somatic embryogenesis from immature embryos. For direct embryo culture, fluke-shaped embryos were stored in sterile water in darkness for three days at 25C prior to transfer on Murashige and Skoog (MS) culture medium plus 1.0 M 6-benzylamino-purine. Multiple plants were obtained from single embryos through somatic embryogenesis of rabbit-ear stages on MS plus 10 M indole-3-acetic acid and 5 M 6-benzylamino-purine. Evidence of hybridization included leaf shape intermediate between the two parents, penduncle shape prior to fertilization which resembled the male parent, low pollen viability and isoelectric focussing of protein bands for acid phosphatase of leaf extracts.     

Diallel analysis of yield components of snap beans exposed to two temperature stress environments

Ten snap beans (Barrier, Brio, Carson, Cornell 502, CT 70, HB 1880, Hystyle, Labrador, Opus and Venture) were selected for differential temperature tolerance and used as parents in a complete diallel mating design. The 45 F₁ hybrid lines (with reciprocals) and parents were screened at 32 C day/28 C night, and in a separate experiment, 16 C day/10 C night, during reproductive development in replicated controlled environments. Variation for yield under temperature treatments was observed among parents and hybrids, with certain hybrids exceeding parental performance. Significant (P 0.0001) general combining ability (GCA), and significant (P 0.05) specific combining ability (SCA) were observed for yield components including pod number, seed number, and seeds per pod. There was evidence that pod number and seeds per pod under temperature stress are under separate genetic control. Reciprocal effects and heterosis were not significant. GCA could not be predicted from parental performance. The breeding line Cornell 502 had the highest GCA under high temperature, and the cultivar Brio had the highest GCA under low temperature. The cross Brio × Venture was high yielding in both temperature treatments. Heat tolerance and chilling tolerance were associated in certain parents and hybrids. However, performance under high and low temperature treatments was not generally correlated in the parents and hybrids, indicating that these traits should be selected separately.     

Genotypic differences in wheat Al tolerance

Summary Aluminium tolerance of 83 genotypes from Croatian and Yugoslav Triticum aestivum germplasm was evaluated in nutrient solutions having Al³⁺ activities of 0, 12.5 and 25 M. Relative root length (25 M Al³⁺/0 Al) of various genotypes ranged from 2 to 97% (from very sensitive to tolerant to Al). No genotype with Al tolerance close to that of very tolerant cultivar Atlas-66 was found. Soil, climatic, fertilization, and liming effects that wheat plants giving seeds for the nutrient solution Al-tolerance screening had been subjected to during their growth cycle did not influence the Al-tolerance ranking. Significant correlation was found between screening wheat for Al tolerance in nutrient solutions and in acid Pseudogley soil amended with five rates of limestone in a greenhouse experiment. Seed protein concentration was significantly related to the Al-tolerance ranking (r² = 0.962). Such a significant correlation was not obtained in a case of rheological and other quality characteristics of seeds. Al-tolerant wheat genotypes identified in this study will be used in breeding for improved Al tolerance.Abbreviations HSD Tukey's Honestly Significant Difference - RRL-2 relative root length, in % (12.5 M Al³⁺/0 Al) - RRL-4 relative root length, in % (25 M Al³/0 Al)     

Inheritance of firmness in raw cucumber (Cucumis sativus L.) fruit

Summary Inheritance of raw cucumber fruit texture (Magness-Taylor Fruit Pressure Tester firmness) was investigated over a 4-year period from 1971–1974. Results from 2 separate but related experiments suggested that firmness was quantitatively inherited with sufficient additive effects to permit gain from selection. In a selection study within 4 F₂ populations derived from crosses between firm (Chipper and Gy3) and soft (Mincu and Green F) fruit type cultivars, variation among and within F₃ and F₄ families was significant but overall family means were not significantly higher than the high parent in any of the 4 crosses. Narrow sense heritability estimates for fruit texture were 0.80 in the Mincu × Chipper population and 0.77 in the Green F × Chipper, Mincu × Gy3, and Gy3 × Green F crosses. In a separate experiment, generation means analysis was used to assess the mode of gene action in 2 crosses: Green F × Chipper, and Gy3 × Green F. Additive genetic effects accounted for 98.8% and 99.3% of the total genetic variation within each cross, respectively.Scientific Journal Series Paper No. 9794.     

Disomic alien chromosome substitution and addition in hexaploid oat

Summary True-breeding, leaf rust (Puccinia coronata Cda. f. sp. avenae Fraser and Led.) resistant oat lines with somatic chromosome numbers of 42 and 44, were recovered in the advanced generations of a pentaploid hybrid from the cross between C.I. 7232, a leaf rust resistant and dark lemma colored derived tetraploid and Clarion, a susceptible hexaploid oat. Microsporocyte observations and breeding behaviour of these lines and their F₁ hybrids with susceptible hexaploid oat cultivars indicated that the 42- and 44-chromosome lines are disomic substitutions (20+1A) and disomic additions (21+1A), respectively, of the same alien chromosome which carries genes for dark colored lemma and leaf rust resistance. The substitution and addition lines possess good field resistance to leaf rust. Plants of substitution lines were less vigorous, shorter, with poor straw and reduced fertility. Addition lines had reduced tillering ability, plant vigour, culm thickness, leaf width and fertility and were late maturing. Progeny tests for resistance indicated that substitution lines are more stable than addition lines. It is suggested that these lines may be of value in a program of radiation-induced gene transfer.     

Quantitative genetics in an apple breeding strategy

Summary Open-pollinated seed of 500 genotypes of commercial cultivars, breeding selections and wild species of apples (Malus × domestica) was collected from overseas mixed-clone repositories. This is to generate the first generation of the new Apple Breeding Population.Subsequent generations will be intercrossed in a pair-crossing design. Recurrent selection for general combining ability (GCA) is the breeding method used for genetic improvement of the Breeding Population. Every parent in the control-pollinated breeding population is tested for GCA using a polycross mating design.The best individuals of the Breeding Population, intensively selected between families using the polycross GCA estimates, and also within families are intermated to produce a Cultivar Production Population. Trees selected from this have then to be evaluated in grafted clonal tests before commercial release.Each generation, a new Breeding Population of 500 genotypes is selected from the pair-cross families, based on parental GCA values (from polycross tests), full-sib family means and individual performance and then intercrossed. Greatest emphasis will be on within-family selection not between-family, so as to avoid reducing the effective population size.     

The influence of cytokinins and ionic strength of Anderson's medium on shoot establishment and proliferation of evergreen azalea

Shoot-tip explants of evergreen azalea cv. Fuchsia grown on Anderson's medium and containing different cytokinins produced the highest proliferation rate on a medium containing thidiazuron (TDZ). TDZ concentrations ranging from 0.23 to 2.3 M resulted in both good bud-break rate (4 to 5) and shoot quality (> 0.5 cm in length). Adding 2.3 M zeatin to Anderson's medium containing 0.23 or 2.3 M TDZ increased the number of axillary shoots/explant. However, increasing the zeatin concentration to 4.6 M resulted in a reduced shoot proliferation rate. A medium containing 1.15 M TDZ and 2.3 M zeatin resulted in an 18-fold increase for 'Fuchsia' and a 9-fold increase for 'Hino Crimson' after 6 weeks of culture. It was found that explants grown on a half-strength Anderson's medium with 87.6 mM sucrose generally had better shoot proliferation rate and shoot quality than at higher ionic strength.     

Limited but specific variations of seed storage proteins in Japanese common wheat (Triticum aestivum L.)

The electrophoretic banding patterns ofgliadin in common wheat lines derived fromJapan were determined byacid-polyacrylamide gel electrophoresis. For the 107 wheat lines used in our study,27 different patterns were identified, 13corresponding to the -gliadin, 8 tothe , -gliadin and 6 to the-gliadin. The gliadin patterns ofJapanese wheat cultivars and landracesgreatly differed from the patterns of wheatlines from other countries, and thevariation seen in wheat lines from Japanwas limited to 46 patterns. Sevencollection or breeding areas in Japanshowed different frequencies in theirgliadin patterns. Combining the gliadinpatterns with high molecular weightglutenin subunit compositions, 67combinations were observed. One gliadinpattern consisting of -gliadinpattern F, , -gliadinpattern H and -gliadin pattern Dwas frequently found in many Japanese wheatlines, though the other patterns werelimited to only one or two wheat lines.     

A tissue culture technique for vegetative propagation and low temperature preservation of Beta vulgaris

Summary A tissue culture technique for clonal propagation of Beta vulgaris is described. Flower buds or flower bud clusters formed adventitious shoots on half-strength Murashige & Skoog's medium supplemented with 10 mol/l benzyladenine (BA). The shoots were multiplied by axillary bud proliferation on a medium with 1 mol/l BA and rooted on a medium with 10 mol/l indolebutyric acid. The plants were vegetative. No mutations were observed. Genotypic variation was found in shoot formation, shoot multiplication and rooting. Some genotypes showed leaf malformations which were attributed to BA. Rooted plants in culture tubes could be stored for one year at 2 or 5°C and a low light intensity.     

Partial self-compatibility in ‘Tombul’ and ‘Montebello’ hazelnuts

Summary Self-pollination of hazelnut (Corylus avellana L.) cultivars in 1988 and 1990 revealed the existence of partial self-compatibility in Tombul and Montebello. Percent cluster set in these cultivars averaged 44 and 20%, respectively, but was less than 10% in 8 other cultivars investigated. Percent cluster set from pollination with Segorbe averaged 62 and 41% in 1988 and 1990, respectively. Self-pollination produced 40% fewer nuts per cluster and twice as many blanks as cross-pollination. All cultivars and selections have an active sporophytic incompatibility system.Evaluation of self-compatibility in seedlings from the cross Montebello × Compton revealed that the partial self-compatibility of the maternal parent was transmitted to some of the progeny. Self-pollination resulted in greater than 10% cluster set in two selections, OSU 41.134 and OSU 43.025, in both years, but only in 1988 in OSU 42.089 and Willamette. Three other selections had very low set in both years. Results of incompatible crosses with standard testers were generally in agreement with those of self-pollination, except that the S₂ tester induced greater set on 3 genotypes in 1988 and the S1 tester on 2 genotypes in 1990 than self-pollination. The partial self-compatibility of Montebello, OSU 41.134, and OSU 43.025 appears to be due to a failure of their stigmas to prohibit pollen tube growth in incompatible crosses. There is no evidence of a pollen-part mutation in Montebello, nor is there evidence that partial self-compatibility is due to the interaction of S-alleles, as Barcelona, which has the same alleles as these three genotypes, failed to set nuts in all incompatible crosses.     

Effects of salicylic acid on cold preservation and cryopreservation of encapsulated embryonic axes of Persian lilac (Melia azedarach L.)

Embryonic axes of Persian lilac (Melia azedarach L.)encapsulated into calcium alginate beads with sucrose (0.75 M) and salicylicacid (0, 50 M, 200 M) were subjected to cryopreservationtechnique with dehydration and freezing in liquid nitrogen or to coldpreservation by stocking alginate beads in empty petri dishes for 4 monthsat 4 °C. In these two cases 200 M salicylic acid enhancedsignificantly the percentage of viability of encapsulated embryonic axes andthe role of salicylic acid in increasing tolerance to dehydration is discussed.