PHOSPHORUS RESPONSE OF MAIZE HYBRIDS AND THEIR PARENTAL LINES

The leaf area, and dry root and shoot masses of two maize hybrids (Nor ma and Mv 444) and of their parental inbred lines were studied in the Martonvasar phytotron at three phosphorus supply levels. As the result of greater rates of phosphorus, increases were observed in the leaf a rea and in the dry root and shoot mass of both the hybrids and their p arental lines. The leaf area of the maternal line of Norma exceeded th at of the hybrid at all three phosphorus levels, while the leaf area o f Mv 444 was greater in all treatments than that of either parent. Par tial dominance was observed for Norma and overdominance for Mv 444 as regards the leaf area, and this was not affected by the quantity of ph osphorus. The data indicated complete dominance in the dry shoot and r oot masses of Norma, while overdominance was observed for Mv 444. For the characters examined the heterosis percentage declined in general a s the result of increasing rates of phosphorus, indicating differences in the phosphorus responses of the hybrids and their parental inbred lines.