The present work describes a method for the testing of the resistance of winter cereal varieties to Fusarium nivale, Typhula ishikariensis and T. incarnata. The shooting of the plants was carried out in greenhouses and after a period of 3 weeks of coldhardening the plants were infected, covered with cellulose wadding and placed in a temperature of 2°C. Once the varieties with the highest susceptibility were severely infected by the fungi the test was suspended and the plants were given some 2 weeks to recover prior to being analysed. The tested varieties were well known from field trials during a number of years. The results agree in the main with those obtained in the field. The Finnish winter wheat and winter rye varieties showed a greater degree of resistance to the above fungi than the Swedish ones. The injury inflicted by F. nivale on winter rye was more severe than that on the winter wheat varieties. T. ishikariensis and T. incarnata were considerably more pathogenic to wheat than F. nivale, and the tested varieties showed varying degrees of resistance to these fungi. The results likewise point to a correlation existing in the resistance to the three low temperature parasitic fungi.

Competition between downy brome (Bromus tectorum) and winter wheat causes serious economic losses to growers in the Pacific northwest. On a site which received 25 cm average annual rainfall and had a light soil (very fine sandy loam) winter wheat yields were reduced 28% by fewer than 54 downy brome plants per m² (5 plants/ft²). On a site which received 55 cm average annual precipitation and had a silt loam soil, winter wheat yields were reduced 92% by more than 538 downy brome plants per m² (50 plants/ft²). Downy brome seed-to-straw ratios were indicative of a tremendous yield potential. Seed-straw ratios of 1:4 are probably an exception but ratios of 1:1 and 1:2 were common. Chemical fallow studies at three sites showed that nonselective downy brome control can be obtained by the use of herbicide combinations such as 3-amino-l-2, 4-triazole-ammonium thiocyanate (amitrole-T), plus chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) or amitrole-T plus 2,4-dichlorophenoxyacetic acid (2,4-D). Amitrole-T plus atrazine was more effective when used as a fall treatment. Amitrole-T plus 2,4-D was more effective in the spring. These chemicals reduced tillage requirements and decreased downy brome growth by 90%.

The present work describes a method for the testing of the resistance of winter cereal varieties to Fusarium nivale, Typhula ishikariensis and T. incarnata. The shooting of the plants was carried out in greenhouses and after a period of 3 weeks of coldhardening the plants were infected, covered with cellulose wadding and placed in a temperature of 2°C. Once the varieties with the highest susceptibility were severely infected by the fungi the test was suspended and the plants were given some 2 weeks to recover prior to being analysed. The tested varieties were well known from field trials during a number of years. The results agree in the main with those obtained in the field. The Finnish winter wheat and winter rye varieties showed a greater degree of resistance to the above fungi than the Swedish ones. The injury inflicted by F. nivale on winter rye was more severe than that on the winter wheat varieties. T. ishikariensis and T. incarnata were considerably more pathogenic to wheat than F. nivale, and the tested varieties showed varying degrees of resistance to these fungi. The results likewise point to a correlation existing in the resistance to the three low temperature parasitic fungi. | Artikkelissa on kuvattu menetelmä, jolla tutkittiin syysruis- ja syysvehnälajikkeiden kestävyyttä Fusarium nivalea, Typhula ishikariensista ja T. incarnataa. vastaan. Kokeet suoritettiin kasvihuoneessa. Koekasvien orastumisen jälkeen kasvit karkaistiin vähitellen alenevissa lämpötiloissa, infektoitiin sienien puhdasviljelyksillä, peitettiin selluloosavanulla (kuva 1) ja sijoitettiin talvehtimaan +2°C asteen lämpötilaan. Koe keskeytettiin silloin kun altteimmat lajikkeet olivat pahasti sienten saastuttamia, ja kasvien annettiin olla ennen analysointia toipumassa n. kaksi viikkoa korkeammassa lämpötilassa. Kokeissa olleiden vehnä- ja ruislajikkeiden (taulukko 1 ja 2) suhtautuminen talvituhosieniin on tunnettu monivuotisten kenttäkokeiden perusteella. Lajikkeiden alttius talvituhosienille oli kasvihuonekokeissa suurimmaksi osaksi samantapainen kuin kenttäkokeissa. Suomalaiset syysvehnä ja syysruisjalosteet olivat kestävämmät kokeiltavana olleita sieniä vastaan kuin ruotsalaiset. F. nivalen aiheuttamat vauriot olivat syysruislajikkeissa pahemmat kuin syysvehnälajikkeissa. T. ishikariensis ja T. incamata olivat vehnälle huomattavasti patogenisempia kuin F. nivale. Eri lajikkeiden kestävyys Typhula-sieniä vastaan oli vaihteleva. Kokeet osoittivat että syysviljalajikkeiden kestävyydessän kokeiltavana olleita sieniä vastaan on olemassa korrelaatio.

Rates of surface straw litter were shown to influence the location of the crown node in four varieties of winter wheat (Triticum aestivum). As the rate of surface straw was increased, the node formed farther from the seed; however, there was a strong variety) ✕ straw rate interaction. At low straw rates, winter-hardy varieties formed their nodes closer to the seed than did nonhardy varieties. Both light and temperature influenced the location of the crown node. As light decreased or temperature increased, the node formed farther from the seed, but the node location was strongly affected by a variety ✕ temperature ✕ light intensity interaction. Adventitious roots formed but did not elongate when the soil water content around the crown node was air dry; however, at water contents at or above 15 bars adventitious root growth appeared normal.

The F₂ progeny from a diallel cross involving seven winter wheat parents along with the parents were grown at the Hyslop Agronomy Farm near Corvallis, Oregon to determine the influence of three plant densities on gene action estimates for yield and its primary components. The plant densities were designed to provide different levels of competitions involving solid, six and 12 inch spacing within the rows with one foot spacing between the rows. Gene action estimates were obtained by the combining ability analysis as well as narrow sense heritability estimates. In addition, path-coefficient analysis was utilized to investigate the direct and indirect associations of the primary components of yield under different stresses of competition resulting from the changes in population densities. The morphological characters measured were 1) total yield per plant, 2) kernel weight 3) number of kernels per spikelet, 4) number of spikelets per spike, 5) tiller number and 6) plant height. A small additive gene action for yield was noted in the six inch spacing while additive gene action effects could not be detected in the 12 inch and solid plantings. Yield being a complex trait seems to be affected by the environmental changes resulting from different plant densities. Consistent general combining ability estimates were observed for kernel weight and plant height in all the plant densities, indicating a small genotype-environment interaction. In the spaced plantings additive gene action estimates were obtained for tiller number and spikelets per spike while there was no evidence of additive gene effects in the solid planting. No additive gene action was noted for kernels per spikelet in the 12 inch planting while six inch and solid plantings revealed considerable genetic variability. These results would suggest that the genotypes are susceptible to environmental fluctuations for the traits tiller number, spikelets per spike and kernels per spikelet. The correlation coefficients reveal that in spaced plantings tiller number, spikelets per spike and kernels per spikelet are significantly and positively related to yield. In the solid seeding only spikelets per spike was significantly associated to yield. When the four variables were considered in terms of their associations with yield it was observed in the F₂ that in spaced plantings all the four components of yield have direct positive influence on yield. In the solid seedings however, spikelets per spike and kernels per spikelet had high positive direct effects on yield while tiller number and kernel weight showed a negative direct influence on yield. The data revealed that spikelets per spike and kernels per spikelet are the most important traits contributing towards yield. However, the results obtained with correlation coefficients indicate that a negative association existed between these two traits as well as between kernels per spikelet and tiller number suggesting the possible existence of a biological limitation between these components of yield. The results indicate that a breeding program with emphasis on the selection of plants in competitive conditions in the early generations may make the selection work more efficient. Moreover, increases in yield which considers each of the components separately or in combination of two or more would offer the most promise. By this procedure the breeder would take advantage of the large amount of additive genetic variances associated with each of the components and at the same time take into consideration any biological limitations which may exist.

A seven-parent diallel cross of winter wheat was grown in the F₁ generation in hills for 2 years and in the F₂ generation in hills and in nursery yield plots the second year. Heritability estimates for earliness of flowering, height, number of spikes, kernels per spike, kernel weight, and grain yield were obtained from regression of F₁ or F₂ means on mid-parent values. Simple correlations were calculated among all variables. The correlations were analyzed further by the path coefficient technique to determine direct and indirect effects. Heritability estimates from data from hills for earliness, height, number of spikes, and kernels per head were high and those for kernel weight and grain yield were intermediate or low. Estimates in the F₁ and F₂ generations from data obtained from hill plots were reasonably similar. Estimates of heritabilities for the six characters from the F₂ generation, were very similar for hills and thick-seeded nurseries. The three components of yield were highly correlated with grain yield. The path-coefficient analysis indicated that each of the components had large direct effects on grain yield but important indirect effects resulting from negative correlations among yield components.