Differential Phosphorus Uptake by Phosphorus‐Stressed Corn Inbreds1

The corn (Zea mays L.) inbreds Pa36 and WH (reported to be high and low P accumulators, respectively, when grown in soils) were tested for differences in P uptake from nutrient solutions. Phosphorus efficiency for the two inbreds was tested by inducing P stresses in two ways: 1) by varying the amount of P added to the nutrient medium, and 2) by adding varied quantities of A1 to the nutrient medium at a given level of P. The more P‐efficient inbred Pa36 took up and accumulated higher amounts of P than WH when grown separately or together with WH in the same container. Dry matter yields for WH were comparable or higher than Pa36 when grown at various levels of P, but under Al‐induced P stress conditions, Pa36 yielded higher than WH. Regardless of the method of P stress, Pa36 yielded more dry matter than WH when both inbreds were grown together in the same container. WH roots decreased the solution pH faster than Pa36 roots under all P stress conditions. The increased amount of active A1 at the lower solution pH affected WH roots more adversely than Pa36 roots. Intact Pa36 roots exhibited higher phosphatase activity than WH roots when grown at various levels of P.