The vertical distribution and its change of root quantity and activity of the inter-planted winter wheat

In the winter wheat‖early spring maize/summer maize cropping system(‖ and ∥ menas intercropping and relay cropping respeclively), the vertical distribution and its change of root quantity and activity of the interplanted winter wheat were studied. The main results are as follows: (1) The maximum rooting depth of the interplanted wheat was about 200 cm, and the root quantity in 160-200 cm soil layer continued to increase till to the grain filling stage and even to waxripe stage. (2) The moisture content of fresh root increased from top to deep soil layers, and decreased with the advance of growing stages. (3) With the advance of growing stages, the weight of fresh root in 0-80 cm soil layer showed a decreased trend after jointing; that of the 80-160 cm soil layer reached its maximum at flowering stage and then decreased; and the fresh root weight in 160-200 cm deep soil layer increased continuously and reached its maximum at waxripe stage. The total weight of dry root in 0-200 cm soil layer reached its maximum at the grain filling stage and then began to decrease. (4) The percentage ( average of the four stages of jointing, flowering, filling and waxripe) of the fresh and dry root weight of 0-20 cm, 0-40 cm, 0-80 cm, 0-120 cm soil layer to the 0-200 cm total were 4690% and 47.63% ,57.90% and 59.89%, 77.00% and 78.62%, 92.26% and 93.07%, respectively, and 120-160 cm occupied less than 10%. According to the root weight density, 0-20 cm, 20-120 cm, 120-160 cm and 160-200 cm soil layers were classified as high, mid and lower and rare root density area, respectively. (5) The root activity (TTC reducing capacity) decreased from top to deep soil. The root activity decreased with the growing stage advance from jointing to flowering and filling stage, and increased a little at waxripe stage. (6) The percentage (average of the four stages of jointing, flowering, grain filling and waxripe) of root TTC reducing quantity of 0-20 , 0-40 , 0-80 , 0-120 and 120-160 cm soil layers to the 0-160 cm total were 53.84%, 66.01%, 83.40%, 94.77% and 5%, respectively. According to the density of root TTC reducing quantity, 0-20 , 20-120 and 120-160 cm soil layers could be classified as high, mid and lower density areas, respectively.