Showing papers on "Plant breeding published in 1981"

Tolerance of commercial cultivars and breeders' lines of wheat to Heterodera avenae Woll

Abstract: Many commercial cultivars and breeders' lines of wheat were ranked for tolerance to cereal eelworm by comparing their yield of grain on a site heavily infested with Heterodeva avenae with their average yield on five other areas of South Australia. Different methods for assessing tolerance were examined. A range from tolerance to intolerance was obtained, but most commercial cultivars were intolerant. Many breeders' lines were highly tolerant. A visual system for rating early growth was strongly correlated with final yield. Resistance and tolerance were not related.

The Reproductive Efficiency of Cultivated Peanuts. IV. The Influence of Photoperiod on the Flowering, Pegging, and Fruiting of Spanish-Type Peanuts1

Abstract: The time of flowering and pegging during the early development of the peanut plant are heritable and correlated This research was designed to determine the effects of photoperiod on the periodicity of flowering and subsequent peg growth within specific portions of the life cycle of the peanut plant. A Spanish-type peanut, Arachis hypogaea L., C2 (PI 262000), was used in the investigations. Plants exposed to long-day treatments (light interrupted 15-hour dark period) in growth chambers of the North Carolina State University Phytotron Unit, produced 1.84 times more flowers per plant than those grown in 9 hour photoperiods. Plants in short-day treatments reached flowering peaks earlier than those in long-day chambers and produced 134.4 shellable fruit per plant in contrast to 34.1 fruit per plant for long-day treatments. The reproductive efficiency, relative to other plant traits, was also enhanced by growing the plants in short-day photoperiods. Twenty-seven percent of the flowers on plants grown under short days produced shellable fruit resulting in 106.5 g of seed per plant. Only 3.8% of the flowers on plants in long-day chambers produced shellable fruit resulting in 12.1 g of seed per plant. The proportion of seed weight to plant top weight was 59.6% in short-day regimes compared to 3.0% in long-day regimes...

Biosystematic studies of cultivated plants as an aid to breeding research and plant breeding

Abstract: The value of biosystematics to the breeder is shown by reference to examples taken from potato breeding.

Phenotypic variation in plants regenerated from protoplasts: The potato system

Abstract: Regeneration of whole plants from isolated protoplasts (plant cells devoid of cell walls) provides a novel capability that is potentially useful for crop improvement efforts. Such a regeneration capacity has been developed for the commercial potato cultivar 'russet Burbank,' currently the most popular cultivar in production. Due to fertility problems of this cultivar, the improvement of 'russet Burbank' by classical breeding procedures has been limited. Examination of a large population of protoplast-derived clones has revealed that variation for a number of traits can be observed. Variation observed under laboratory conditions and in field trials includes changes in plant morphology and tuber-setting characteristics, as well as alterations in response to environmental and pathogen stress. A brief description of the cloning process and the potential for application of cloning technology in crop plant improvement will be presented. (Refs. 41).

Pasture species and cultivars for regions

Abstract: The origin of the pasture species grown in New Zealand and the development of ecotypes are briefly described. The effects of environmental factors such as rainfall, temperature, soil type, soil fertility, grazing pressure, and pests and diseases on plant breeding objectives and choice of species in different regions of the country are discussed. The value of incorporating plant material from Mediterranean sources into New Zealand-bred cultivars of ryegrass, white clover and Lotus is illustrated, but the importance of local plant collections in the development of cultivars such as Nui and Ellett ryegrass and a hill country white clover is also emphasized. The possibility of breeding cultivars specifically for overseas markets is discussed.

Adaptation of the glasshouse cucumber to lower temperature in winter by breeding

Abstract: The Institute for Horticultural Plant Breeding (IVT) has in 1974 initiated a program to select slicing cucumbers that grow and produce well at lower temperatures in winter. The goal was set at 20°C day, and 15°C night from the time of planting, while soil heating kept the root temperature around 20°C. The resulting saving of fuel costs amounts to 30–40°with cropping beginning at the usual time. Few out of hundreds of varieties from all over the world exhibited good growth in the selection environment. After four cycles of breeding and incorporation of Dutch slicer germplasm over 30 were developed with superior growth and fruit production, which were made available to the interested private breeding firms in The Netherlands in 1978. Early harvest of the best breeding lines at the low temperature equalled that of the control varieties at normal temperature. Most lines also gave promising yields in a 1979 trial with 12°C night temperature. Measurements of early growth at controlled fixed and alternating temperatures confirmed that outstanding lines grew faster than the control variety Farbiola. Changes in plant type may partly be responsible for the observed differences. Leaf area ratios (LAR) of the breeding lines were generally higher than those of the control variety at 20°C D/12°C N. Selection of fast growing plants at an early growth stage appeared to be possible.

Shoot Fly Resistance in Sorghum

Abstract: The present diallel analysis were undertaken to study combining ability for shoot fly (Atherigona soccata Rondani) resistance and other related characters in sorghum. General combining ability variances were higher than sea variances for dead heart (%), eggs/plant, plant recovery and yield/plant. These results indicated predominance of additive gene action for these traits. The nature of gene action for seedling height, tillers/100 plants, effective tillers and yield/productive plant was predominantly non-additive. All resistant parents recorded desirable gca effects for dead heart (%), eggs/plant and plant recovery. IS 5490 and IS 5604 were observed to be desirable general combiners for most of the characters. The parent 168 is also promising within the group of dwarf parents. Significant positive association between per se performance of parents and gca effects indicated that lines for breeding can be selected on the basis of parental performance. Predominance of additive genetic variance for shoot fly resistance indicated that exploitation of IS 5490, IS 5604 and 168 through biparental approach may be rewarding.

Increase of numbers of cereal aphids by insecticide application as an aid to plant breeding

Abstract: Increase of pest populations to abnormal levels following application of pesticides is a well-known phenomenon which has been turned to advantage in work on host-plant resistance to insect pests. For example, increases in numbers of aphids followed treatment of potato with carbaryl (Sevin), DDT and other chemicals which killed aphid predators (Peterson, 1963) and carbaryl has been used where enhancement of populations of Myzus persicae was achieved deliberately (Radcliffe & Lauer, 1971; Tingey & Van de Klashorst, 1976). Interest in the possibility of breeding for resistance to cereal aphids, especially Sitobion avenae (F), has increased as more examples of differences between varieties have been reported (e.g. Kolbe, 1969; Hinz & Daebeler, 1974; Lowe, 1978, 1980; Stokes, Lee & Wratten, 1980). This aphid occurs sporadically in the field and natural enemies, notably predaceous and parasitic insects, may contribute significantly to this variation (Vickerman & Wratten, 1979), so the use of insecticides to reduce the effects of the latter appears a promising technique in the development of reliable field screening methods for plant breeding.

Genetic analysis in the pasture grass Setaria sphacelata. I. Dry matter yield and flowering

Abstract: The progeny of a 7 x 7 diallel cross between plants randomly selected from a segregating tetraploid setaria population (S. sphacelata var. sevicea and var. splendida) was studied at Lawes, south-east Queensland, over a two year period in two spaced plant replicates. Plants were harvested at 6-week intervals (9-10 week in winter), and dry weight and flower head number were recorded. Two additional replicates were allowed to grow uninterrupted, and date of flowering and flower head number were recorded. Damage caused by the fungus Pyricularia gvisea was scored on all four replicates. Genetic analysis indicated a high order of general combining ability variance for yield in the population and strong positive genetic correlation between seasons for yield (rg = 0.72-1.26). Variance estimates derived from analysis of variance and parent offspring regression were comparable. Genetic variance was strongly and consistently additive for days to flower and flower head number. Positive genetic correlations between seasons and years for days to flower (rg = 0.31-1.09) indicated that genetic differences in flowering were not strongly confounded by environmental effects. Dry matter yield was genetically correlated with flower head number and hence earliness to flower (rg = 0.79-1.16). Days to flower was genetically correlated with flower head length (rg = 0.71-0.91). Resistance to the pathogen Pyricularia grisea was shown to be under genetic control. The data suggested that resistance may be controlled by a gene exhibiting tetrasomic inheritance with two alleles necessary for expression of a high order of resistance.