Showing papers on "Plant breeding published in 1968"

Mineral elements in temperate crop and pasture plants. II. Calcium

Abstract: Twenty-five annual crop and pasture plant varieties from 21 species were grown on a lateritic gravelly sand at Gidgegannup in Western Australia. Plant tops were sampled at three stages during the growing season and at maturity. This paper presents data for calcium contents of the tops. Calcium concentrations varied widely among species, and to a smaller extent with age and among plant parts at maturity. Species rankings varied only slightly among harvests. Herbs and all legumes except lupins maintained high calcium concentrations throughout the growing season. By contrast, the concentrations in grasses, and even more markedly in the cereals, were low in the young plants and declined further as the season progressed. Concentrations in lupins were intermediate in the first two harvests, but fell precipitously towards maturity to levels similar to those in grasses. Despite low overall levels in the mature plant, seeds of lupins were generally higher in calcium concentration than other legume seeds and several times as high as cereal grains. Calcium concentrations of plant tops correlated reasonably well with published data on cation exchange capacities (CEC) of roots when taken over the whole range of species, but within major plant groups the correlation was poor. It is suggested that, rather than signifying a causal relationship between root CEC and calcium concentration in the tops, the results may merely indicate that dicotyledonous plants tend to have high calcium concentrations and CEC values while monocotyledonous plants have low. It is also suggested that if any such causal relationship does exist, its origins are more likely to lie in the CEC properties of the tops than in those of the roots.

Heritability and genotypic and environmental correlations of creeping root and persistency in Medicago sativa L.

Abstract: This study examines the relationships between creeping-rootedness, plant diameters, and persistency in lucerne. Highly significant positive genetic correlations were found between all three plant characters among families under continuous grazing. The investigations disclosed several trends in genetic and environmental correlations, the significance of which is discussed. The heritabilities for the proportion I of creeping plants (0.41), plant diameter (0.32–0.45), and survival (0.23–0.46) were all high, indicating that response to selection is possible. The results showed that plant density decreased under continuous grazing; 66% of the creeping-rooted plants but only 8% of Hunter River plants survived after 17 months of continuous grazing.

Mutation Induction in Melilotus Alba Annua by Chemical Mutagens 1

Abstract: !,!ydroxylamine (HA), 2-aminopnrine (AP), 5-bromourani (BU), and ethyl methanesulfonate (EMS) were tested for mutagenic activity on seeds of Melilotus alba annua. ~lutants ~ere c!assif~ed into the following categories: o-hydroxycinnamic acid (o-HCA) content and J3-glucosidase activity, chlorophyll deficiency, dwarf growth habit, and miscellaneous morphological variations. Due to difficulties in classification, the o-HCA and J3-glucosidase category and the dwarf category were unreliable for determining ~utation rates. Based on the chlorophyll-deficient and misceltaneous morphological categories, mutation rates for HA, AP, and BU treatments did not differ from the control rates, but EMS at 0.003M and 0.004M concentrations was highly effective in inducing mutations in the~e. categories. Mutation rates based 'on chlorophyll deficiency were somewhat higher and more sensitive to EMS concentration than were mutation rates based on the miscellaneous categ.ory. Large numbers of chlorophyll, dwarf, and morphological variants, several more vigorous than the controls, were isolated from the EMS treatments, bnt no new o·HCA or J3-glucosidase mutants were obtained. Additional index words: sweetclover, ethyl methanesulfonate. G IC variability is essential for the work of . th~ ge.n~ticist and plant breeder. In higher plants this vaJylbJlrty l~as most often been achieved through plant introduction, the collection of spontaneous mutants and hybridization. Certain present-day mutagens are highly efficient (8), and advances in the llndel:standin~of mutation as a celluar process have pel:nutted shifts in the proportion of different IlIUational types through variations in treatment conditions (I). Thus, another potentially valuable wurce of genetic variability has become availible. The mutagenic action of ethyl methanesulfonate in plants .has ~een. adeq~ately demonstrated in barley (5), Arabidopsis ({J), maize (7), wheat (9), and Vicia 'Contribution from the Crops Research Division, Agricultural Research Service, U. S. Department of Agriculture, and the Nebraska Agricultural Experiment Station, Lincoln, Nebr. 68503. ~upported in part by the National Science Foundation (Grant No, GB-1l48). Published with the approval of the Director as Paper No, 2308, Journal Series, Nebraska Agr. Exp, Sta. Received March 23, 1968. 'Formerly Instructor in Agronomy, University of Nebraska (now AssI~tant Professor of Agronomy and Genetics, Washington ltate Ull1ver~Ity, Pullman, Wash.), Research Geneticist, Crops Research DIVISIOn, ARS, USDA, Lincoln Nebr.; and Bert Rodgers Professor of Agronomy, University of Nebraska, Lincoln, reIpectively. (2). However, mutagenic activity in higher plants has not been demonstrated for the base analogs, 5-b~-omour~cil and ~-aminopu~ine, nor for hydroxylaml1le.' which are hIghly effective mutagens in microorgamsms. The present paper deals with the mutagenic activity of these four chemicals on seeds of sweetclover (Melilotus alba ann.ua Desr.). Materials and Methods A small, annual, white-flowered strain of sweetclover which originated as a plant introduction from India (1'.1. 165554) was used in this study. The small size, short life cycle, autogamous habit, and prolificacy of this strain made it a nseful experimental plant for mutation and genetic studies. Also, unlike the j lowers of most other }VI. alba strains, the flowers of this strain nndergo self-pollination without mechanical tripping. The seed used in these experiments was derived by bulking the selfed seed from 95 plants, all of which were grown from the selfed seed obtained from a single plant. All seed was machine scarified prior to treatment. Concentrations of the mutagens were selected on the basis of solubility of the compounds together with the results of several preliminary experiments designed to determine the maximum concentration of each mutagen which would be used without destroying seed v~ability or inducing excessive sterility in the resulting plants. The following treatments were chosen: ethyl methanesulfonate (EMS), 0.003M and 0.004M; hydroxylamine (HAl 0.002M; 2-aminopurine ((\1') 0.OO?6M; 5-bromouracil (BU) O.OOIM. J<.MS and HA were dissolved in 0.05M potassium phosphate buffer, pH 7.0. AI' and BU were dissolved in water. Distilled water and O,(J5M potassium phosphate, pH 7.0, were used as controls. Air-drv seeds were immersed in the treatment solutions (0.1 ml per seed) and were shaken at room temperature for 24 hr on a rotary shaker set at approximately 190 rpm. Immediately after treatment of all except the .EMS-treated seeds, seeds were rinsed three times with distilled water and planted in soil contained in I-pint (\i2-liter), plastic-coated milk cartons in a greenhouse kept free of pollinating insects. In the case of the EMS treatments, a 2-hr washing with distilled water was interposed between the chemical treatments and the three water rinses. Selfed seed was harvested from individual plants of the M, generation. A sample of 25 selfcd seeds from each M, plant was planted in a row in a greenhouse flat. to produce an M 2 line. As the late bud or early flowering stage was reached, each M 2 plant was examined, and mutant plants were assigned to categories according to the following procedure: (A) u-Hydroxycinnamic acid (a-HCA) and J3-glucosidase mutants. New mutants of this category were sought because of their possible genetic and metabolic relationships to existing a-RCA and J3-glucosidase mutants (4). A qualitative paper test, designed to detect mutant plants that were low in a-HCA content or lacking in J3-glucosidase activity, was performed on all plants as previously des~ribed for unheated samples (3). Plants giving a negauvc test were retested using a somewhat more elaborate qualitative procedure" which permitted the separation of plants low in a-RCA content from those lacking in 13glucosidase activity. (B) Chlorophyll-deficient mutants. All degrees of chlorophyll deficiency were included in this category. Initial readings of chlorophyll deficiency were made at the seedling stage to permit detection of lethals. (C) Dwarf mutants. Plants approximately 1/3 or less of the height of normal plants were classified as dwarf mutants. (D) Miscellaneous morphological mutants. This category included all obviously altered plants that could not be classified into one of the other groups and consisted primarily of alterations in leaf and flower morphology or in growth habit. ~1utants of interest were transplanted to individual l-pint milk cartons and grown to maturity. In the case of lines carrying lethal mutants, enough normal plants were saved to insure that a heterozygote would be isolated. The purity and homozygosity of all viable mutants were increased by selecting and self-Iertiliz"Corz, R. J., and r. A. Haskins. Unpublished procedures. 632 CROP SCIENCE, VOL. 8, SEPTEMBER-OCTOBER 1968 Table 1. Influence of seed-applied mutagens on mutation rates as measured in M2 lines of sweetclover.