The Evolution of Physiological Characteristics of Maize Root during Varieties Replacing in China, 1950 s to 1990 s I. Changes of Root Vigor & ATPase Activity

Root vigor change of maize commercial varietes planted in 1950 s to 1990 s could be satisfactorily simulated by Gaussian Model. The total root vigor in varieties of 1990 s was much higher than that in varieties of 1970 s and 1950 s. This difference became more evident in 40~100 cm depth soil and reached maximum at the grain filling stage (67 to 74 day after sowing). The daily accumulation of root vigor curve could be calculated by Gaussian equation, and called root vigor daily integral (RVDI). The RVDI was much higher in 1990 s maize varieties than in 1970 s and 1950 s, and this different was especially distinct during grain filling period(from 67day to 90day after sowing). As variety replacement continued, the soluble protein contents ATPase activity in roots increased, especially in the roots around the plant 10~15 cm horizontal soil. The special ATPase activity in roots around plant 10~25 cm horizontal soil in 1990 s maize varieties was also much higher than that in other varieties.