田间试验表明,玉米制种产量及其母本农艺经济性状随连作年限的延长呈递减、降低趋势。连作3～5年的产量递减率低,达1.24%～3.50%,农艺经济性状降低不明显;连作5年以上递减幅度逐年加大,农艺经济性状降低趋势明显,其中连作7～ Field experiments showed that corn seed yield and female agronomic economic traits decreased with the extension of the continuous cropping years and decreased. The decreasing rate of yield in successive 3 to 5 years was low, reaching 1.24% -3.50%, agronomic economic traits decreased insignificantly; the declining rate of continuous cropping for more than 5 years increased year by year, the agronomic economic traits decreased significantly, of which 7 ~