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Search Results: 1 - 10 of 462082 matches for " A.;Krug "
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Observa??es citológicas em citrus: IV. números de cromos?mios na sub-família Aurantioideae com referência especial ao gênero Citrus
Krug, C. A.;
Bragantia , 1944, DOI: 10.1590/S0006-87051944000200003
Abstract: 1. the chromosome number of fourteen species (twenty forms) belonging to five different genera of the subfamily aurantioidex. are reported. all determinations available in the literature on chromosome numbers made in this subfamily are tabulated. the basic chromosome number is x = 9 for all forms so far investigated. about 40 triploids, some 190 tetraploids (including 19 in poncirus, 1 in triphasia, and 1 wild form in fortunella), 1 pentaploid, 1 hexaploid, and 14 or 15 aneuploids have been reported. 2. all these polyploids, except the 21 tetraploids just mentioned and several triploid hybrids between citrus and fortunella, belong to the genus citrus. considering the genetic similarity of the chromosome complements of several genera of the subtribe citrinx, it is suggested that some of these might perhaps better be considered mere species of a single genus.
Melhoramento do cafeeiro: V - Melhoramento por hibrida??o
Krug, C. A.;Carvalho, A.;
Bragantia , 1952, DOI: 10.1590/S0006-87051952000200003
Abstract: artificial hybridization in coffee breeding offers possibilities that are still unexplored. inter-varietal hybridization has been used in coffea arabica in order to get information about the genetic constitution of the varieties, and occurrence of heterosis, to breed without changing the morphological characters of the varieties and also to synthesize new genetic types of economic value. inter-specific hybridization has been employed for improvement of cup quality and to furnish data about the relationship of various coffee species and the behaviour of known genetic factors of one species in the genetic background of other coffee species. about 2500 inter-varietal and inter-specific artificial hybridization have been made in campinas during the last 20 years. the economic value of some of these hybrids has been stressed in this paper and special attention has been called to the inter-specific hybrids involving the tetraploid c. arabica and other known diploid species as c. canephora, c. dewevrei and c. congensis. after chromosome doubling of these triploid hybrids, the resulting allopolyploids may be of economic value.
Genética de Coffea: XII - Hereditariedade da c?r amarela da semente
Carvalho, A.;Krug, C. A.;
Bragantia , 1949, DOI: 10.1590/S0006-87051949000300005
Abstract: the known species of coffea can be grouped into two categories according to the color of their endosperm which is either green or yellow. the commercially cultivated varieties of coffea arabica l. and coffea canephora pierre ex froehner are well known for the green color of their seed while the less known varieties of coffea liberica hiern and coffea dewevrei de wild, et th. dur. have yellow feed. in 1935, however, a yellow seeded type of c. arabica, was found in brazil and has been described as coffea arabica l. var. cera k.m.c. ; it is believed to have originated by mutation from coffea arabica l. var. typica cramer. in this paper the authors present the results of a genetic study of the yellow seeded mutant known as "cera". it has been found that in c. arabica, yellow endosperm is controlled by one pair of recessive factors cece. hybrid seeds containing a cece embryo were green (xenia), their endosperm being either cecece or cecece. cera is a tetraploid variety and when it was crossed with diploid coffea species having yellow endosperm, it was found to produce only yellow hybrid seeds. the cera, which is a yellow seeded mutant has been useful not only for definitely showing that the bulk of the coffee seed is true endosperm, but it has also proved useful is study of the biology of the coffee flower.
Genética de Coffea: XIII - Hereditariedade do caraterístico erecta em Coffea arabica L.
Carvalho, A.;Krug, C. A.;
Bragantia , 1950, DOI: 10.1590/S0006-87051950001100001
Abstract: in the present paper the authors present the results of a genetic study concerning the erecta type of growth of the lateral branches of coffea arabica l. the erecta mutant, which probably originated in java, differs from normal coffee plants by having upright growing lateral branches instead of plagiotropic ones. however, in spite of the fact that both, the main shoot and the lateral branches grow in the same direction, the dimorphic nature of the branches still persists. the genetic studies carried out since 1933, which included the study of progenies of f1, f2 generations and backcrosses, have revealed that the erecta character is conditioned by one pair of dominant genes er er. it is not yet known whether all erecta plants, of different origins, have the same dominant gene, but investigations already in progress are expected to yield information on this matter. of all genes so far studied in c. arabica, er is the most completely dominant, the heterozygote being indistinguishable from the homozygote. the erecta gene has been found to show complete penetrance and a constant expressivity.
Agentes de poliniza??o da flor do cafeeiro (Coffea arabica L
Carvalho, A.;Krug, C. A.;
Bragantia , 1949, DOI: 10.1590/S0006-87051949000100002
Abstract: this paper describes the methods used and presents an analysis of the results obtained from three years of study, to determine the separate and inter-related effects of various agents such as gravity, wind and insects, in the pollination of flowers of coffea arabica l. observations were made and data obtained from several thousands of normal and castrated flowers that were maintained under natural and controlled conditions. it has been found that the importance of gravity, wind, and insects in pollination of the flowers may vary appreciably in relation to local environmental influences. the data obtained, however, indicate certain trends that are of definitive interest. based on the total number of ovules, it was found that in 1228 normal flowers observed, 62 percent produced seed. this value is believed to represent in general the percentage of fertilization that might be expected to occur naturally. in tests designed to exclude the influence of wind, insects, and gravity, it was found that an average of 24 percent fertilization (within flowers) occurred. in measuring the effects of the combined agents of wind, insects and gravity it was found that 18.5 - 32.7 percent fertilization occurred as a result of self-pollination and 4.1 to 5.2 percent was due to cross-pollination. analysis of the data also show in all except one case, the percentage of fertilization resulting from self-pollination was higher than that from cross-pollination. these findings show the importance of self-pollination in coffea arabica. the use of castrated flowers was particulary helpful in determining the maximum effect of each of the pollinating agents studied under isolated controlled conditions. the general analysis of all data indicates that in the case of self-pollinated normal flowers the influence of wind and insects are about equal and that the effect of gravity is relatively less and likely to be of variable importance. in the case of factors affecting cross-pollination of normal flo
Genética de Coffea: IX - Observa??es preliminares s?bre quimeras genéticas em Coffea arabica L.
Carvalho, A.;Krug, C. A.;
Bragantia , 1946, DOI: 10.1590/S0006-87051946000600001
Abstract: after a short discussion on plant chimeras, the effects of the na na alleles in coffea arabica l. are presented and attention is called to the frequent appearance of somatic-mutations of these genes, which are very unstable under the influence of certain genetic backgrounds. the analysis of some of these somatic mutants is then presented in detail. the first case deals with a nana plant (na na), which produced a murta branch (na na): the results of selfing and crossing seemed to indicate that at least the second germ layer, which produces the gametes, was affected by the mutation. two murta plants (na na) produced bourbon (na na.) branches, which proved to be of a chimerical nature, as their second germ layer was not affected by the mutation, maintaining its original genetic constitution (na na). the exact structure of these chimerical branches has not been established, as it is not known yet how many germ layers exist in coffea arabica l. and which of them are responsable for the morphology of the leaf. it is however concluded from the analysis of the above mentioned cases, that the second germ layer takes no essential part in determining leaf morphology. combining the results of the 3 analysis, it is concluded that the first of the above mentioned plants must therefore have at least two modified germ layers.
Genética de Coffea: XI - A influência do gen recessivo na s?bre a produtividade do cafeeiro (Coffea arabica L.)
Krug, C. A.;Carvalho, A.;
Bragantia , 1946, DOI: 10.1590/S0006-87051946001100001
Abstract: in the present paper the difference in yielding ability of two genotypes which differ by only one single gene is compared : na na (bourbon) and na na (murta). 20 plants of each of 14 murta (na na) progenies were used for comparison after discarding all na na plants which are dwarfed and practically unfruitful; each progeny was made of 10 na na and 10 na na individuals. the individual yields were recorded during 8 years (1939 to 1946) and it was shown that the na allele, besides its well known effect on the morphology of the leaves, has a remarkable influence on the yielding capacity of the na na plants, reducing it, in average, to only 55,9% as compared with the na na genotype. the bartlett's test of homogeneity of variance when applied to study the variability between the plants of the bourbon and murta groups has shown that both groups are homogeneous, but a significant difference between their variances was found, the bourbon one being larger. the same test when applied to study the variation between the annual yields of the same groups of plants has led to the same conclusion. the na na plants however were more suceptible to the die-back of the lateral branches after harvest, which even caused the death of several plants. considering that fruit size and weight of both varieties (bourbon and murta) are practically identical, it is concluded that the lower fruit number of the murta genotype is responsable for its lower yields. as its flowers are normally fertile, pollen being produced in abundance, it is supposed that a lower number of internodes, or a lower number of flowers in the inflorescences or even a lower total number of flowers in each leaf axil is responsable for the decrease in yield of the murta variety. the results of this study are also of practical importance suggesting the elimination of all murta plants in a coffee plantation and their replacement by bourbon.
Genética de Coffea: XV - Hereditariedade dos característicos principais de Coffea arabica L. Var. semperflorens K.M.C.
Carvalho, A.;Krug, C. A.;
Bragantia , 1952, DOI: 10.1590/S0006-87051952000200005
Abstract: under normal environmental conditions coffee plants in the state of s?o paulo flower two to four times during the period of july to november. only rarely do they flower beyond these limits. in 1934 a few coffee plants of the species c. arabica were found which flower almost at any period of the year. this mutant was named semperflorens. the results of the gene tical analysis here presented indicate that the characteristics of this mutant are controled by one pair of recessive factors (sf sf). this pair of genes controls the growth habit of the plant and leaf characters, its almost continuous flowering habit and its marked drought resistance. the f1 plants (semperflorens x normal) are entirely normal, the f 2 segregatir g into 3 normal and 1 semperflorens. by crossing semperflorens with the testers murta and nana, it was concluded that the new variation probably originated as a mutation from the bourbon variety. the fruits of the semperflorens plants ripen almost throughout the whole year; at two periods however, yields are higher, one of them corresponding with the normal harvest period of coffee (march-april-may), the other occuring in october-november-december. its total annual yield is of the same magnitude as that of the bourbon variety. as the semperflorens also seems to be of certain economic value for small intensive plantations, an attempt is being made to improve its yielding capacity through regional breeding work.
Genética de coffea V: hereditariedade da colora??o bronzeada das folhas novas de coffea arabica L.
Krug, C. A.;Carvalho, Alcides;
Bragantia , 1942, DOI: 10.1590/S0006-87051942000600001
Abstract: in the present paper the authors are publishing the results of the genetical analysis of three color types occurring in young leaves of coffea arabica l : green ; dark bronze and light bronze. based on extensive data obtained from progenies, fi and f2 hybrids and back-crosses, it is concluded that only one pair of allelomorphic genes control these colors for which the symbols br-br are proposed : br br, the double recessive, constitutes the green type, br br, the heterozygote, the light bronze one and br br, the double dominant, the dark bronze one. the dark bronze colour is therefore incompletely dominant over green, the fi between the two being light bronze. in the group of homozygote dark bronze plants a certain variability of the maximum intensity of the bronze colour is noticed, which is most probably due to modifyers which intensify or dilute the expression of this character. two papers, respectively by stoffels (8) and narasimha swamy (7) dealing with the same subject are critically discussed.
Genética de coffea VI: independência dos fatores xc xc (xanthocarpa) e br br (bronze) em coffea arabica L.
Krug, C. A.;Carvalho, Alcides;
Bragantia , 1942, DOI: 10.1590/S0006-87051942000600002
Abstract: in two previous publications (1,2) the authors demonstrated that in coffea arabica l. yellow fruit color and bronze color of young leaves are each controled by one pair of genes (respectively xc xc and br br). the f1 hybrids, in the first instance between plants with yellow and red fruits and in the second instance between plants with bronze and green colored young leaves, showed incomplete dominance of both characters, the f1 fruits being of a light red color and the f1 young leaves of a light bronze one. as some of the crosses involved both pairs of genes, it was possible to find out wether they are linked or independent. in the present article the authors are publishing the results obtained with several f2 populations and also with 2 types of back crosses. the data demonstrate clearly that the two pairs of genes are independent, a fact which was expected, considering that the varieties of coffea arabica l, used in the present analysis, have as many as 22 pairs of chromosomes.
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