Root Characteristics of Corn Genotypes as Related to P Uptake¹

Abstract Plant utilization of P applied to soils is usually low. Utilization may be increased by having more roots present or by improving P uptake characteristics of the roots. The objective of this research was to determine the effect of varying corn ( Zea mays L.) root characteristics, by using different genotypes, on P uptake and to determine if the Claassen‐Barber simulation model predicted these differences accurately. Five corn genotypes were grown in the growth chamber in soil at two levels of P and harvested a three ages. Increasing P level increased shoot yield of all genotypes, but had little effect on the amount of roots. The root surface area per unit of shoot weight varied between genotypes at low soil P but not at high soil P. Wih high soil P here was a linear correlation with r = 0.98 and a slope of 0.97 between P uptake predicted by the simulation model and observed P uptake. At low soil P observed P uptake was double the predicted uptake, however, the correlation was r = 0.90. Root hair effects, not included in the simulation model, were probably the reason for the greater observed P uptake at low soil P. Differences between genotype in morphological and physiological root characteristics in. fluenced the amount of P absorbed by corn plants. It appears that genotypes could be developed that would be more efficient in absorbing P from soil.