The economically optimum yield for INIA 66 wheat was obtained by using 150 lbs of nitrogen and 30 lbs of phosphorus per acre in these tests. Nitrogen had greater effect on yields than phosphorus, however, maximum yields were realized by using a combination of nitrogen and phosphorus as a fertilizer. Darker green color intensity was obtained with higher rates of fertilizer. Higher rates of phosphorus have a tendency to suppress the bushel weight. The highest net dollar return was obtained by using 150 lbs of nitrogen and 30 lbs of phosphorus per acre.

Durum wheat (Triticum durum Desf.) varieties grown in the United States are not adapted to the short-day conditions of the middle latitudes (between 28°N and 28°S). Introduction of a gene or genes for daylength insensitivity could broaden the adaptability of these varieties, but the effects of insensitivity on agronomic and quality performance in northern latitudes are not well known. Fifty-two F₃ durum wheat bulks homozygous sensitive to daylength and 52 bulks homozygous insensitive to daylength were selected from 4 crosses between northern varieties and a daylength-insensitive selection (‘Zenati’/‘Bouteille’) introduced from Israel. These 104 F₃ bulks were compared for agronomic and quality performance in North Dakota in 1967 and 1968. Ten pairs of lines, near isogenic except for daylength response, were developed from three of the four crosses by selecting heterozygous plants from F₃ through F₆. The F₃ pairs were compared in a split-plot arrangement in four environments. Insensitive lines tended to be significantly earlier (1 to 3 days) and shorter (3 cm) than the sensitive lines. Genotype ✕ environment interactions were significant for yield. The insensitive near-isogenic F₆ lines yielded slightly more grain than the sensitive lines in two environments, five of the senstive lines yielded as much as 20 to 40% more grain than the insensitive lines in one environment, and the two response types yielded essentially alike in one environment. We conclude that durum wheats for the North Central States can be converted to the insensitive condition without loss in productivity or quality. Insensitive lines must be thoroughly tested over a wide range of temperature and daylength conditions to assure that only the most stable ones are released for commercial production.

The semi-dwarf, stiff-strawed soft winter wheat variety ‘Bineboy’ (Triticum aestivum L.) was released in 1965 by the North Carolina State University Agricultural Experiment Station. Presumably, its greater straw strength would allow producers to use higher rates of nitrogen without as much risk of lodging. Information was needed, however, on the nitrogen requirements of this new type of wheat and the most beneficial time for these applications. Field experiments were conducted on two soil types (Davidson clay loam and Lynchburg fine sandy loam) for 2 years to determine the response of Bluehoy wheat to nitrogen rates of 56, 112, 168, and 224 kg/ha applied at seeding in October or partly in October at seeding (56 kg/ha) and partly in February as.topdressing rates of 56, 112, and 168 kg/ha. Applying all the nitrogen at seeding on the Davidson clay loam was just as effective for high grain yields and high test weight as the split applications. The 112 kg/ha applied in October (seeding) on this soil type was sufficient for maximum yields. Grain yields were lower on the Lynchburg fine sandy loam soil for October applications than for February applications at nitrogen rates of 112 and 168 kg/ha. No difference in yield was obtained for the two dates at the highest rate of nitrogen (224 kg/ha). Test weights were significantly lower both years when the nitrogen was applied in February on the Lynchburg fine sandy loam as compared to the same total rate applied at seeding. A similar trend was also found for the February nitrogen applications on the Davidson clay loam. This study shows that Blueboy wheat producers can apply all of the nitrogen fertilizer to clay loams and fine sandy loam soils at the time of seeding rather than splitting the application into a small amount at seeding followed by a topdressing in February. A higher level of nitrogen fertilization will be required, however, to offset possible losses from leaching on soils with a sandy surface texture. On these soils producers must weigh the cost of using a higher nitrogen rate at seeding against the possibility of producing a lower-quality wheat and the cost of an extra trip over the field in February when fields may be wet.