间作冬小麦根系数量与活性的空间分布及变化规律

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

在冬小麦‖早春玉米/夏玉米种植体系("‖"与"/"分别表示间作和套作)中,研究了小麦根系数量与活性的空间分布特征及变化规律。主要结果:(1)高产田间作冬小麦最大根深200cm左右,160～200cm深层土壤根量持续增长至灌浆蜡熟期。(2)根系含水率自上而下由低向高变化,随生育进程推进,呈下降趋势。(3)根系鲜重自拔节期以后,0～80cm土层随生育进程推进呈减低趋势;80～160cm于开花期达最大值,之后下降;160～200cm土层到灌浆期和蜡熟期值最大。0～200cm土体总根干重于灌浆期值最大,之后下降。(4)拔节、开花、灌浆和蜡熟4次结果平均,0～20cm土体根鲜重和干重分别占到0～200cm总重的46.90%与47.63%,40cm以上占到57.90%与59.89%,80cm以上占77.00%与78.62%,120cm以上占到92.26%与93.07%,120cm以下土体占不足10%。根系重量密度自上而下可划分为0～20cm高密度区、20～120cm中密度区、120～160cm低密度区及160～200cm稀密度区。(5)根系TTC还原强度呈上大下小变化,0～160cm土体平均根活力拔节期较高,开花灌浆期下降,蜡熟期反弹上升。(6)拔节、开花、灌浆和蜡熟期四次结果平均,0～20cm土壤根系TTC还原总量占到0～160cm土体的53.84%,40cm以上占到66.01%,80cm以上占到83.40%,120cm以上占到94.77%,120～160cm深层土壤占5%左右。

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.