Effect of the interval between ploughing and sowing on growth of continuous cropping alfalfa

Autotoxicity often causes poor establishment of continuous cropping alfalfa, therefore reducing the autotoxicity will benefit successful alfalfa regeneration in continuous cropping. A field experiment was conducted in the Beijing regions to determine effect of the interval between ploughing and reseeding on growth of continuous cropping alfalfa in 5years field. The treatments included 0, 15, 30, 45 and 90 days of interval between ploughing and reseeding. The results of this study showed that less interval between ploughing and reseeding reduced the length of root and shoot and the weight of root and shoot of the alfalfa plants. The root length, shoot length, root weight and shoot weight in plots with 0 day interval reduced the 10%-23%, 16%-26%, 58%-71% and 38%-62%,respectively when compared to those in plots with a interval of 15, 30, 45 and 90 days. The changes of the interval did not affect chlorophyll content while the activities of SOD and POD increased with the decrease in interval between ploughing and reseeding.