The effects of competition on yield of grain was studied in mixed populations of a winter and a spring wheat (Triticum aestivum L.) cultivar sown in their respective planting seasons. Viable and nonviable seeds of the two cultivars, winter ‘Genesee’ and spring ‘Justin’, were mixed in 26 planting ratios. Separate nurseries were sown for the fall and spring planting seasons, respectively. The nature of the cultivars was such that only Genesee was harvested in the fall-sown experiment and only Justin in the spring-sown experiment, that is, fall-sown Justin winterkilled and spring-sown Genesee remained in the vegetative stage. In the fall-sown nurseries there was root or underground competition and a low level of aerial competition throughout the season. The results showed that winter wheat yields depended largely upon the density and vigor of the post-winter population stand. The Genesee plants showed excellent ability through tillering and vigor to compensate for stand differences. The yields of spring wheat were depressed by the presence of winter plants in their midst and this effect was approximately in proportion to the planting ratios. Conclusions from the study point towards the importance of breeding winter wheats with superior post-winter plant establishment.

Winter injury of small grains often results in severe yield reductions. This study was conducted to determine how planting date and fall fertilization interact to affect winter survival and performance of winter wheat (Triticum aestivum L.). In 1975 ‘Arrow’ wheat was planted in central New York on eight dates ranging from 21 August to 24 October. In 1976 five plantings were made from 31 August to 14 October. In both years 75 kg/ha of K was disked in and then four fertility treatments were band applied at each planting date. These were 0 N and 0 P, 0 N and 20 kg/ha P, 22 kg/ha N and 0 P, and 22 kg/ha N and 20 kg/ha P. At harvest measurements were taken for grain yield, plant height, grain moisture, test weight, and components of grain yield. Wheat planted in mid to late September had greater winter survival and produced significantly more grain with a higher test weight than did later planted wheat. The effects of earlier planting varied between years because of different weather conditions. Grain moisture content increased with planting delay. Planting after the optimum time decreased the number of spikes per square meter both years. This component was closely related to yield and was an indication of the degree of winterkilling. Planting date had variable effects on the number of kernels per spike and kernel weight. Phosphorus alone or with N significantly increased wheat yields and winter survival. This effect was reflected in an increased number of spikes per unit area and increased kernel weight. Nitrogen alone had little effect on yields when compared to unfertilized wheat; and when N was applied with P the results were similar to those from P alone. Test weight generally increased with P but not with N. Phosphorus also hastened grain maturation, while N had no beneficial effect. Nitrogen also did not increase any yield component. As planting date was delayed, the value of P for increasing winter survival, grain yields, and grain maturation became increasingly important, resulting in significant planting date ✕ fertilization interactions for these characteristics.

Cold hardiness is the primary factor restricting the area of winter wheat (Triticum aestivum L. em Thell.) production in North America. Related species are potential sources of genetic variability that could be used in the improvement of winter wheat cold hardiness. Among these relatives, rye (Secale cereale L.) has shown the greatest ability to tolerate cold. However, exploitation of this source would be feasible only if the genes for cold hardiness in rye were expressed when in association with the wheat genomes. To determine the level of this expression seven octaploid triticales were produced. These triticales and their parental winter wheat and rye cultivars were then assessed for cold hardiness in artificial freeze tests. In all instances the triticales achieved only the cold hardiness of their parental wheat cultivars. The effect of increasing ploidy level on the expression of cold hardiness in rye was also investigated. The cold hardiness of seven autotetraploid rye populations was compared with the cold hardiness of their parental diploid populations. All autotetraploid populations were not as cold hardy as the corresponding diploid populations, indicating that polyploidy has an adverse effect on the expression of genetic systems controlling cold hardiness in rye. Based on these observations, it appears that rye is an unsuitable source of genes for the improvement of cold hardiness in polyploids such as common wheat.

In a five-year field experiment on a well-limed sandy soil five nitrogen fertilizers were compared. They were urea, ammonium sulphate, calcium nitrate, calcium ammonium nitrate and a mixture of ammonium sulphate and calcium nitrate. The crops in successive years were spring wheat, winter rye, winter wheat, spring wheat and winter rye. The average yield level was not different because of different fertilizers, but in individual years some differences were found. Average contents of nitrogen and calcium in grain and straw, however, showed a slight superiority of calcium nitrate to ammonium sulphate. Other fertilizers did not deviate significantly from either of these. Placement vs. broadcasting, application time and rate of fertilizer nitrogen were also investigated. These factors did not affect the differences between fertilizers. The soil-acidifying effect of the fertilizers decreased in the order: ammonium sulphate, urea, mixture of AS and CN, calcium ammonium nitrate. Calcium nitrate had no effect on soil acidity.