The uptake and utilization of potassium by corn inbreds and hybrids

This investigation was conducted on a Hartsells loam to study the effects that potash, genotypes and seasonal variation had on yield, K, Ca, Mg, and P concentrations in Dixie 29 inbreds, F1 hybrids, and double-cross hybrids over a three-year period (1966-1968). Cation interactions in leaf tissue and the above ground plant removal of K, Ca, Mg, and P were also considered. The experimental design was a split plot with K₂O levels (0, 60, 120 and 240 pounds K₂O/A) as the main plots and genotypes as the splits. Leaf tissue samples were taken at approximately 38, 55, and 86 days after planting all three years. Whole stalk samples were taken in 1968 at 110 days after planting. All tissue samples were wet ashed and the K, Ca, Mg, and P content were determined from the digestate using the Technicon Autoanalyzer. Yields increased due to the addition of potash up to the 60 pounds K₂O per acre level for the inbreds and up to the 120 pounds K₂O per acre level for the hybrids. In 1967 the yields were greatly reduced due to a cool, cloudy and wet growing season. Using regression models for predicting yields and accounting for variation in yields proved to be more useful for hybrids than inbreds. Shifts in K, Ca, and Mg occurred due to the application of potash, sampling date, and seasonal variation. The yields increased as the meq/100 grams K/Ca, K/Mg, and K/Ca + Mg ratios increased in the ear leaf tissue. Regression prediction equations were useful in accounting for variations in percent K in ear leaf tissue for both inbreds and hybrids. Differences in yield, percent K, Ca, Mg, and P occurred among the genotypes. The inbreds transmitted their high or low affinity for the various elements on to the F1 hybrids. In the above ground part of the mature corn plant about 25 percent more K and 75 percent more Ca, Mg, and P was removed by the F1 hybrids than the inbreds.