Plant Pathology Commons^™

Modifying Environmental Stress To Increase Discrimination Among Genotypes, P W. Voigt, C L. Dewald

IGC Proceedings (1977-2023)

The difficulty of selection for resistance to environmental stress is increased by year-to-year climatic variation. Management practices, e.g., fertilization and mowing can increase winter or drought injury. Improved discrimination among genotypes for resistance to stress can result. In northwestern Oklahoma winter survival of Eragrostis curvula (Schrad.) Nees tillers was decreased by autumn defoliation. The mowing date causing maximum injury varied from year-to-year but was usually in October. Multiple autumn defoliations were sometimes necessary to decrease survival to desired levels in relatively winter-hardy germplasm. More research is needed on the use of management to increase stress and discrimination among genotypes for …

Selection For Resistance To Snow Mould, H A. Jonsson, C Nilsson

IGC Proceedings (1977-2023)

The snow mould fungi (Fusarium nivale, Typhula incamata and T. ishikariensis) are limiting grass production in cool temperate areas. A programme was initiated to improve the resistance to snow mould in perennial ryegrass (Lolium perenne) and meadow fescue (Festuca pratensis). Hardening and artificial inoculation were performed in controlled environment chambers. A single strain isolate of pink snow mould (Fusarium nivale) was more aggressive in meadow fescue than a mixture of isolates.

he progenies from surviving plants after one test were used for the next cycle of selection. After one cycle of selection in meadow fescue a moderate improvement and after …

Resistance Of Red Clover Cultivars To Clover Rot In Pure And Mixed Stands With Reference To Breeding Work, M Matsuura, N Matsumoto, A Sawai, M Gau, S Ueda

IGC Proceedings (1977-2023)

The poor persistency of red clover ( Trifolium pratense L.) is the most serious problem for hay production in the Hokkaido district. Clover rot ( causal agent Sclerotinia trifoliorum Erikss.) is one of the virulent diseases which kill red clover during winter. We made the quantitative analysis of the damage due to clover rot and clarified the types of resistant red clover from 1982 to 1984. Three treatments, consisting of control, fungicide (thiophanate-methyl) application and inoculation with pathogens, were applied on pure and mixed stands of three cultivars and one seed lot of red clover. The dry matter yield in …

Characteristic Differences Of Survival Plants Under Grazing From The Original Varieties In Orchardgrass (Dactylis Glomerata L.), Y Tsurumi, T Yoshiyama, K Nakashima, H Yamaguchi

IGC Proceedings (1977-2023)

Survival plants of five varieties of orchardgrass (Dactylis glomerata L.) under grazing for four years at Shibetsu-cho in Hokkaido pref. ( 44°N, 50m), Iwadeyama-cho in Miyagi pref. (39°N, 52m) andAso-cho in Kumamoto pref. (33°N, 850m) were collected and their 13 characters were observed, comparing with those of the original varieties. Significant differences were found in many characters between the survivals and the originals and among the locations. Survivals ofKumamoto were found to be more different from the originals when compared with those of the other locations and were estimated to be useful materials for breeding a variety of persistency …

A New Method For Selection Of Mutants In Cross-Fertilizing Species, Y Ukai

IGC Proceedings (1977-2023)

A method was proposed for selection of mutants in cross-fertilizing plant species. It is composed of taking seeds separately from each spike of the mutagen-treated population, sowing the seeds in hill plots in the next generation, isolating each hill from the others by bagging all the plants of each hill at flowering time, taking seeds for the next generation from each hill, and sowing them in hill progenies for selection of mutants. The procedure will be called "Crossing-within-Spike-Progeny" method, or simply CSP method. To increase the frequency of mutant genes and to enlarge the mutated sector within spike in the …

Breeding For Increased Forage Yield In Reed Canarygrass, Irving T. Carlson

IGC Proceedings (1977-2023)

This research was undertaken to advance the knowledge of breeding for improved forage yield in reed canarygrass (Phalaris arundinacea L.), a cross-pollinated, perennial, cool-season grass. The relative yield of F1 hybrids and advanced­generation synthetics formed from clones selected for high general combining ability (GCA) for yield was investigated. In addition, effects on synthetic performance of excluding the parent clone with high inbreeding depression were studied. Experimental strains were evaluated in dense stands harvested at least three times each year. The highest-yielding two-clone cross yielded only 2% more than the highest-yielding, advanced-generation synthetic. This superiority would be insufficient for commercial …

Effect Of Long-Term Subfreezing Seed Storage On Forage Production Of Eight Grass Cultivars, Clarence M. Rincker

IGC Proceedings (1977-2023)

Grass seeds stored 20 years at subfreezing temperatures germinated well under sterile laboratory conditions in earlier studies. This study was conducted to determine whether forage yields from seeds stored 22 to 26 years at subfreezing temperatures were comparable to those from fresh seeds. Included were seed of eight cultivars: three cultivars of orchardgrass (Dactylis glomerata L.), two of smooth bromegrass (Bromus inermis Leyss.), two of timothy (Phleum pratense L.), and one of meadow fescue (Festuca elatior L.). Fresh_ and stored seed of each cultivar was planted in field plots in April 1984. Each entry was …

Improved Handling Of Chaffy Grass Seeds Through Cone Threshing, D S. Loch, W.A T. Harding, G L. Harvey

IGC Proceedings (1977-2023)

Chaffy grass seeds have handling problems which detract from their commercial usefulness. They are relatively light and bulky, and do not flow freely because individual units tend to become entangled. Cone threshing was investigated as a means of processing chaffy grass seeds to improve their handling characteristics. In Andropogon gayanus cv. Kent, Bothriochloa insculpta cv. Hatch, and Bothriochloa pertusa, processing removed awns, sterile florets, and some surface hairs from the normal dispersal units. This facilitated cleaning to increase analytical purity with little or no reduction in viability, even after storage for up to 20 months. About 50-60% of …

Deviation From Expected Association Between Dry Matter And Crude Protein Production In 36 Lucerne Cultivars, V D. Wassermann, B E. Eisenberg

IGC Proceedings (1977-2023)

The generally held belief that there is a direct quantitative relationship between the amount of top growth and the level of nitrogen fixation in lucerne was tested in this study. Dry matter and crude protein production were determined on 36 cultivars in an irrigated field trial over two growing seasons. The relationship between dry matter and crude protein production was determined for the cumulative yields as well as for all individual cuts. Some 14 cul ti vars were found to deviate significantly (0.1 % level) from expectation. Therefore, all cultivars did not respond to the same degree to the nitrogen …

Induction Of Cytoplasmic Mutation On Male Sterility In Beta Vulgaris L., T Kinoshita

IGC Proceedings (1977-2023)

First cytoplasmic male sterility ( abbreviated as CMS) was induced by chemical mutagens. By treating dried seeds of type-0 strains with an aqueous solution of acriflavine, streptomycin, acridine orange and ethidium bromide, at various concentrations and by raising M1 plants from the above seeds, the authorswere able to find certain male sterile variants (S.S.b and C.S. type) in the M1 lines. Moreover, this male sterility was transmitted from the M1 plants to their M2 lines at relatively high frequencies, i.e., over 50%. It was demonstrated that the normal cytoplasm converted to the sterile cytoplasm which is equivalent with S cytoplasm …

Inheritance Of Cytoplasmic Male Sterility In Orchardgrass, S Sato, S Kawabata, F Ikegaya

IGC Proceedings (1977-2023)

A source of male sterility in orchardgrass (Dactylis glomerata L.) was selected. These plants were classified into four types; male sterile (S2), partially male sterile (S1), partially fertile (S0) and normal (N). Evidence of the effects of S ( sterilizing) cytoplasm on expression of male sterility was suggested by reciprocal differences in the crosses of S0 x N. Two models were assumed for genotypes of male sterility and data obtained from progeny test of the experimental crosses were applied to the models. Expression of male sterility appeared to be induced mainly by an interaction of S cytoplasm and a dominant …

Variation In Plants Regenerated From Tissue Culture Of Bahiagrass And Rhodesgrass, O Doi, Y Tsurumi, T Nagatani

IGC Proceedings (1977-2023)

A program was designed to obtain variation of bahiagrass (Paspalum notatum Fliigge) and rhodesgrass ( Chloris gayana Kunth) by tissue culture. Callus was obtained from seeds of bahiagrass and rhodesgrass or panicles of rhodesgrass on callus formation mediums. Regeneration of complete plants was accomplished by transferring callus to regeneration mediums. Variation of regenerated plants was observed in such characters as plant type, leaf width, anthocyanin coloration, grain length etc. One variant of bahiagrass showed wider leaves, darker green leaves and larger grains than the original and tetraploid (2n =40). One variant of rhodesgrass showed wider leaves, thicker stems and …

Tiller Development In Relation To Seed Production Of Tropical Grasses, D S. Loch

IGC Proceedings (1977-2023)

Intensive management of tropical grass seed crops aims to maximize the number of tillers producing inflorescences and to reduce the spread of maturity between individual tillers. Success depends on the number of tillers, synchronization of their development, the proportion that survive, and the percentage which produce inflorescences. These aspects are reported for established seed crops of 13 cultivars of six perennial grass species grown in replicated field experiments near Gympie in southern Queensland, Australia. Maximum tillering occurred during early vegetative growth. Tiller density varied for different grasses and generally began to decline before inflorescences emerged, so that substantial numbers of …

The Potential For Seed Production Of Tropical Pasture Species In Zambia, J Kulich

IGC Proceedings (1977-2023)

One of the major constraints for forage development in Zambia is the shortage of seeds of the desired species. It has been necessary to import seed using scarce foreign exchange. A three-year study was conducted at the National Irrigation Research Station, Mazabuka, Zambia, to identify potential seed yields for seven tropical forage legumes and three forage grasses. The promising species were established in replicated pure stands. Basal (PK) fertilisers were applied, including nitrogen for the grasses. Seed was harvested by hand each time a seed crop matured. The weight of clean dry seed was recorded and the seed was assessed …

The Genetic Improvement Of Panicum Maximum Jacq. For The Seed Production, M Noirot

IGC Proceedings (1977-2023)

The genetic improvement of P.maximum for the seed production is based on two features : the number of spikelets and, especially, the number of every-day new panicles. With this purpose, we have set a topcross between an apomictic and four sexuals. The floral behavior is split into three independant factors and the heritabilities are estimated for this ones. This study has led to the choice of suitable methods of selection.

Isolation Of Sexual Plants In Guineagrass And The Potential Of Its Hybridization Breeding In Japan, K Nakajima

IGC Proceedings (1977-2023)

Guineagrass (Panicum maximum J acq.) is the most promising warm-season grass in the southwest areas of Japan, but its cultivation is limited because of its slow growth at initial growth stage and low seed-yield. As the mode of reproduction o( this grass is apomixis, its genetic improvement is restricted to selection or induced mutation. Sexual plants were screened in two trials to develop the hybridization breeding. In the second survey, 15 completely sexual accessions were isolated by embryo sac analysis from new African collections. They were added to 4 completely sexual plants, already obtained in the first survey, as …

Improvement Of Range Grasses Through Interspecific Hybridization With Quackgrass (Elytrigia Repens L. Neveski), K H. Asay, D R. Dewey

IGC Proceedings (1977-2023)

The USDA-ARS at Logan, Utah has developed breeding populations from hybrids between quackgrass [Elytrigia repens (L.) Nevski] and several range grasses of the tribe Triticeae. The most promising of these is the quackgrass X bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Love] hybrid (designated RS). The RS hybrid was only partially fertile, meiotically irregular, and of limited agronomic merit in the F1 generation. However, after eight generations of selection, it is as fertile as the parental species and has responded in a positive manner to selection pressure for degree of rhizome development, forage yield, vegetative vigor, and plant type. It …

Development Of Chromosome Substitution Triticale Lines And Their Utility Value As Feed, M Sasaki, Y Yasumuro, N Nakata

IGC Proceedings (1977-2023)

An effective method for producing chromosome substitutional triticale lines was proposed. Selection was made on hypoaneuploid plants from primary octoploid triticale population by use of the nature of spontaneous chromosome elimination owing to its meiotic instability. Five lines selected by this method were tested for their performance as grain feed and supplemental forage to other triticale, wheat, rye and barley cultivars. The selected lines S78 and S591 produced higher grain yield than other small grains, though not significant with other triticale cultivars. Lysine contents of the selected lines were intermediate between parental crops. S78 was the most promising line having …

Breeding Tropical Grasses For Ease Of Vegetative Propagation And For Improved Seed Production, J B. Hacker

IGC Proceedings (1977-2023)

Four case studies are briefly described in which seed production or ease of propagation of tropical grasses has been improved by genetic manipulation, viz:

I. Hybridization of a sterile tussock-forming Digitaria smutsii accession with a stoloniferous accession D. milanjiana produced an F1 hybrid which combined high yield with stolon development

ii., iii. Seed production has been successfully introduced into sterile D. smu"tsii and Setaria sphacelata var. splendida iv. Seed production of frost-tolerant Setaria sphacelata var. sericea has been doubled by doubling tiller fertility.

Interspecific Transfer Of Apomixis In Pennisetum, W W. Hanna, M Dujardin

IGC Proceedings (1977-2023)

Apomixis is a vegetative means of reproduction through the seed. It provides an opportunity to increase production, reduce production costs, simplify breeding methods and fix unique gene combinations in many of our major world food crops such as Pennisetum americanum L. Leeke, Zea mays L., and Triticum L. Genes controlling apomixis may not be present in the cultivated species but can be found in related wild species. The long-term objectives of this research are: 1) to transfer genes for obligate apomixis from the tertiary gene pool to pearl millet, a sexual species, and 2) to develop methods and principles that …

Interploidy Transfer Of Germplasm In Red Clover 2n Gametes, R R. Smith, W A. Parroti, M M. Smith

IGC Proceedings (1977-2023)

A program was designed to sexually produce tetraploid red clover, Trifolium pratense L. adapted to the northern zone of the United States using 2n gametes to effectively transfer diploid (2x) germ plasm to the tetraploid ( 4x) level. Both unilateral (2x-4x and 4x-2x) and bilateral (2x-2x) crosses were conducted using diploid parents which produced 2n gametes. Red clover genotypes were isolated which produced an average of 0.21 2n eggs per 1000 and 12 and 16% tetraploids in unilateral and bilateral crosses, respectively. Genotypes were also identified which either produced 2n pollen exclusively or at a high frequency. Tetraploid and fertile …

Methodology And Breeding Of Tetraploid Red Clover, N L. Taylor, E O. Wiseman

IGC Proceedings (1977-2023)

Research is underway to develop tetraploid cultivars of red clover (Trifolium pratense L.) for use in the United States that will be more resistant and higher yielding than presently used diploid cultivars. Cultivars have been produced by use of colchicine, nitrous oxide, and unreduced gametes (2X-4X and 4X-2X crosses). Nitrous oxide treatments have produced up to 71 percent tetraploids which is much higher than that from colchicine (about 4 percent). This nitrous-oxide developed tetraploids population from the cultivar 'Kenstar' has been used as one parent in 2X-4X and 4X-2X crosses. The former yielded a high percentage of tetraploids whereas …

Application Of Ovule Culture To Interspecific Hybridization Between Trifolium Repens And T. Ambiguum, T Yamada, H Fukoka

IGC Proceedings (1977-2023)

The objective of the present study was to apply the ovule culture for the production of interspecific hybrids between Trifolium repens and T. ambiguum. Significant ovary development occurred only when T. ambiguum was used as the female parent. After interspecific fertilization, almost all hybrid ovules fail to develop from about 7th day after pollination. Observation of the growth pattern of hybrid ovules suggests that these should be excised and transplanted to the culture medium by the 5th day after pollination, A medium containing minerals of the minor modified Nitsch (1951), Vitamines (Murashige and Skoog 1962), 7% sucrose, 0.2% Casein …

Chromosome Differentiation In Several Species Of The Genus Melilotus (Sweetclover), F Kita, M Maekawa, K Ise, Y Uehara

IGC Proceedings (1977-2023)

Examining 10 species of the subgenus Micromelilotus, the interspecific cross compatibility is recognized among 5 species, M.infesta, M.macrocarpa, M. messane.nsis, M.segetalis, and M. sulcata. Chromosome behaviors at meiosis of the F1 hybrids reared to maturity are investigated. It is revealed that structural differentiation of chromosomes due to a reciprocal translocation and a complex of paracentric inversions play a significant role in speciation. These basic informations are also useful for sweetclover breeding program using interspecific hybridizations.

The Alfalfa Anthracnose Resistance Success Story, J H. Elgin Jr

IGC Proceedings (1977-2023)

In the past 18 years since anthracnose was first recognized as a serious disease of alfalfa, breeders and pathologists have been highly successful in developing cultivars with high resistance. The availability of these resistant cultivars has resulted in a 10% annual increase in yield in areas of the USA where anthracnose is a problem and has an estimated value in excess of $240 million. This paper reviews the research which contributed to that successful effort.

Breeding Alfalfa For Southern Blight Resistance, S Inami, M Kanbe, F Fujimoto, K Nakashima, Shinji Suzuki

IGC Proceedings (1977-2023)

Difference in disease occurrence was observed in the reaction of seven varieties of alfalfa, Medicago sativa L., to southern blight, Corticium rolfsii, which is an important disease in warm region of Japan. The varieties were tested in space planted condition under inoculation in 1972 and 1973 in Aichi-ken Agricultural Research Center. The correlation coefficient in percentage of the dead plants between the first and the second test was 0.930**, and the varietal difference in analysis of variance for dead plant percentage was highly significant. Based on these results, breeding of resistant alfalfa to southern blight, was started from 1973, …

Key Factors In The Rapid Development And Seed Increase Of Alfalfa With Insect Resistance, W F. Lehman, V L. Marble, M W. Nielson

IGC Proceedings (1977-2023)

The development of alfalfa cultivars with insect and disease resistance and the subsequent seed increase is usually a relatively slow process, but it can be rapid if certain key factors are followed as was done in the development of CUF 101, the first cultivar with resistance to the blue alfalfa aphid (Acyrthosiphon kondoi) (BAA). The BAA was identified as a new, damaging aphid species in about March, 1975. A severely damaged field of a well adapted cultivar was soon located and in April the parent plants of the new cultivar had been selected after a careful, systematic selection …

Some Results Of Selection For Disease Resistance In Herbage Legumes At Svalof, Sweden, Bengt Andersson

IGC Proceedings (1977-2023)

Herbage legumes are very important for forage production in Sweden. One of the main problems when growing red clover and lucerne is their susceptibility to diseases of which the most important are stem nematodes, verticillium wilt, clover rot and root rot. Breeding for improved disease resistance has for a long time been one of the principal objectives in breeding programmes. The first successful result was obtained when a red clover cultivar resistant to stem nematodes was released. By the development of efficient laboratory, screening methods it is nowadays possible to introduce nematode resistance in all new cultivars of red clover …

An Interdisciplinary Approach To Breeding Bloat-Safe Forage Legumes, B P. Goplen, R E. Howarth, G L. Lees, K J. Cheng, W Majak

IGC Proceedings (1977-2023)

This paper reviews the progress of bloat research carried out in Canada over the past 20 years to clarify the etiology of bloat, identify bloat-safe characteristics in forage legumes, and develop techniques to breed a bloat-safe cultivar of alfalfa. To this end a number of research institutions have been involved and a number of diverse and complementary disciplines have contributed.

Mean Aspects Of Lucerne Breeding Work Practiced At The Forage Crop Institute In Lodi, P Rotili

IGC Proceedings (1977-2023)

The choice of mother plants and the progeny test had to be made in dense sward. This proposition is most important chiefly when the construction of the new cultivars concerns an intensive forage system like that of the Northern and Central Italy plains. In these conditions, being possible to control the major part of natural environment factors, the effects of artificial factors introduced by the farmer, become predominant. Among these, the high number of cuttings (six per year) is the most important. The major point for a breeder is to improve the lucerne meadow structure. The choice of the plant …