Protein Content of Winter Wheat Grain as Related to Soil and Climatic Factors in the Semiarid Central Great Plains
1973
Smika, D. E. | Greb, B. W.
Protein content of wheat (Triticum aestivum L.) grain has decreased in recent years in the Central Great Plains. Conflicting reports concerning the causes for this decrease prompted this investigation. Protein content data from North Platte, Neb.; Akron, Colo.; and several south-western Nebraska locations were shown to be negatively correlated by linear regression with total precipitation >1.25 cm for a 15-day period 40 to 55 days before maturity (r = −0.70**) or with available soil water at seeding to a depth of 1.2 or 1.8 m (r = −0.79**). Grain protein levels were shown to be positively correlated by linear regression with total soil NO₃-N to depths of 1.2- or 1.8-m (r = 0.82**) and by curvilinear regression with maximum air temperature for a 5-day period 15 to 20 days before maturity (R = 0.74**). With all four factors combined, R² = 0.96. With available soil water at seeding plus NO₃-N in the soil profile at seeding and protein content of wheat grain, R² = 0.86. Maximum yield was obtained with 28 cm of soil water available at seeding, and at least 106 kg/ha of NO₃-N at seeding was needed to obtain grain with 12% protein.
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