Response of Winter Wheat to Date of Planting and Fall Fertilization

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.