Differences Among Genotypes of Corn in the Kinetics of P Uptake¹

Abstract

Abstract Many plant species utilize fertilizer or soil P inefficiently. Hence, development of corn genotypes ( Zea mays L) that are more efficient in absorbing P from soil would be valuable. A survey of 12 inbreds grown in water culture indicated a 1.8 to 3.3‐fold variation in root weight, root length per unit of plant weight, root length per unit of root weight, and maximal net P influx. Some aspects of the role of genetics were elucidated by comparing the P absorption parameters of five inbreds with those of four single‐cross hybrids made from these inbreds. Five single crosses were grown at low and high P levels in the field on a Raub silt loam (Aquic Argiudoll) to test the significance of the measured root parameters on P uptake. Plants were harvested 22, 38 and 51 days after planting. Phosphorus uptake was also simulated by a model using soil and plant root parameters related to P uptake. The correlation between predicted and observed P uptake was r 2 = 0.90 for the 22 to 38‐day time interval and r 2 = 0.98 for the 22 to 51‐day time interval. Hence, observed differences among corn single crosses in their plant root parameters were reflected in their P uptake when grown in the field.