条带深松对不同密度玉米群体根系空间分布的调节效应

摘要

For exploring the regulation effect of strip subsoiling (SS) on spatial distribution and amount of maize population root system, a field experiment was conducted with three planting densities (LD: 45 000 plants ha–1; MD: 67 500 plants ha–1; HD: 90 000 plants ha–1) and two soil tillage practices (SS: strip subsoiling tillage, NT: no tillage). The spatial distribution of maize indi-vidual and population roots and its response to planting density and soil tillage were studied using small cubic root soil sampler through the “3D monolith” root space sampling method. The result indicated that individual root length was significantly affected by planting density. In 0–50 cm soil layers (each layer was 10 cm), individual roots length was decreased by 110.31, 43.18, 15.73, 10.49, and 17.45 m under high planting density compared to that under low planting density. Under the condition of high planting density, strip subsoiling increased individual roots length by 13.32%, 19.80%, 47.20% in 20–30, 30–40, and 40–50 cm soil layers, respectivelty, compared to no tillage. The effects of planting density were not significant on population total root length, while significant on spatial distribution of population root system. The root length density around single plant centre was decreased by 3.82 cm cm–3, 0.62 cm cm–3 in 0–10 cm, 10–20 cm soil layers, while root length density between two plants was increased by 1.13, 0.18, 0.06, and 0.05 cm cm–3 in 0–10, 10–20, 20–30, and 30–40 cm soil layers under high planting density compared to that under low planting density. Under the condition of high planting density, compared to no tillage, strip subsoiling decreased root length density around single plant centre by 16.10% in 0–10 cm soil layer, while increased it by 47.45%, 13.37% in 10–20 cm, 20–30 cm soil layers. Meanwhile, strip subsoiling increased root length density between two plants by 50.26%, 30.72%, 106.15% in 20–30, 30–40, and 40–50 cm soil layers, respectively. The significant change of spatial distribution of population root system increased the index of root surface area and root dry matter in high planting density and strip subsoiling tillage treatment. The increments in leaf area and shoot dry matter resulted in an increment of maize final yield. The results of this study suggest that the distribution of root between two plants is improved with the increment of planting density. The treatment of high planting density and strip subsoiling regulates the spatial distribution of population root system by increasing the root quantity in deep soil layer and be-tween two plants, and weakening the crowding of roots in upper soil layer, which promotes the increment of maize yield.%为探究条带深松耕作(SS)对密植玉米群体根系空间分布与容纳量的调节效应,本试验设置3个种植密度(低密：4.50万株 hm–2、中密：6.75万株 hm–2、高密：9.00万株 hm–2),以土壤免耕(NT)为对照,利用小立方原位根土取样器,通过“3D monolith”根系空间取样方法,比较研究玉米个体与群体根系的空间分布对种植密度与土壤耕作方式的响应。结果表明,单株根长受种植密度影响显著,在0~50 cm 土层中(每10 cm 为一土层),高密种植的单株根长较低密种植减少110.31、43.18、15.73、10.49和17.45 m；在高密种植条件下,与土壤免耕比,条带深松耕作增加20~30 cm、30~40 cm、40~50 cm 土层中的单株根长13.32%、19.80%、47.20%；单株根干重与单株根长的变化一致。种植密度对群体总根长的影响不显著,却显著影响群体根系的空间分布。与低密种植比,高密种植的植株中心根长密度在0~10 cm、10~20 cm 土层中分别降低3.82 cm cm–3、0.62 cm cm–3,但植株之间的根长密度在0~10、10~20、20~30和30~40 cm 土层中分别增加1.13、0.18、0.06和0.05 cm cm–3；在高密种植条件下对土壤进行条带深松耕作,与土壤免耕比,植株中心的根长密度在0~10 cm 土层中降低16.10%,在10~20 cm、20~30 cm 土层中却分别增加47.45%和13.37%,植株之间的根长密度在20~30、30~40和40~50 cm 土层中分别增加50.26%、30.72%和106.15%；条带深松耕作显著提高密植玉米群体下层根系的容纳量。高密条件下条带深松耕作增加了群体根干重、深层根系量、植株间根系分布及根表面积,进而增加了地上部群体叶面积指数及地上部干重,最终促进产量显著提高。说明密植群体通过条带深松耕作改善了群体的根系空间分布,减弱了上层根系的拥挤,通过增加深层土壤根系量及植株之间根系量增加了群体根系容纳量,发挥了密植群体根系功能,实现了密植群体的高产。