不同耕作方式对玉米根系特性及养分吸收转运的影响

【目的】耕作方式影响玉米根系的生长发育及养分吸收,比较东北中部雨养区不同耕作制度下玉米根系生长和养分吸收特征,为建立合理的耕作方式提供理论依据和技术支撑。【方法】2011―2012年,在吉林省连续进行了2年的田间定位试验,设置4种耕作方式:浅灭茬后直接播种(对照,T1),苗带深松后镇压(T2),行间深松且苗带镇压(T3),苗带行间全部深松(T4)。在6展叶期、吐丝期和生理成熟期,取0-60 cm土层的植株根系样品,分析玉米产量、养分吸收转运及根系生长发育特征。【结果】不同耕作方式下玉米产量差异显著(P <0.05),两年平均值表现为T3> T2> T1> T4,T2处理和T3处理的产量分别比T1处理增加8.1%和10.2%。与T1处理相比,T2和T3处理均增加了玉米吐丝后氮磷钾养分累积量,吐丝后累积养分对籽粒的贡献率显著增加(P <0.05)。T2和T3处理下的氮、磷、钾累积量对籽粒的贡献率分别比T1处理增加了0.4%~3.6%、16.9%~33.8%、70.5%~82.1%,T3处理增幅高于T2处理。T2和T3处理显著增加了玉米各生育期的总根干重、总根长和总根表面积(P <0.05),其中,6展叶期至成熟期,总根干重、总根长、总根表面积的增幅分别为9.8%~22.8%、16.1%~33.1%、19.9%~38.2%。T2和T3处理在各土壤剖面的根系形态均优于T1处理,其中以T2处理最佳,且在20-40 cm土层间差异最为显著(P <0.05)。与T1处理相比,T3处理下各生育时期在20-40 cm土层的根干重、根长、根表面积平均增幅为34.1%、48.3%、47.8%,根直径平均增幅为22.1%。【结论】与浅灭茬后直接播种相比,苗带行间全部深松不利于根系发育,而行间深松且苗带镇压方式促进了根系的生长发育和纵向延伸,尤其是在20-40 cm土层根系干重、根长和根表面积明显增加,有利于根系对深层土壤养分的吸收利用,进而提高玉米花后累积养分对籽粒的贡献率,增加产量。

Effect of soil tillage modes on root morphology and nutrient uptake and translocation of maize

  【Objectives】  Tillage affects the development of maize root system and the utilization of plant nutrients. We compared the root development and morphology of maize under different tillage practices in the rain-fed areas of northeastern China, in order to provide technical support for the establishment of reasonable tillage modes.  【Methods】  A field experiment was conducted for two years (2011–2012) in Jilin Province. Four sets of tillage were set up, including seeding following light stubble (T1), deep loosening and compaction in seedling belts (T2), deep loosening between rows and compaction in seedling belts (T3), deep loosening in both intra- and inter-seedling rows (T4). At the 6-leaf stage, silking stage and maturity stage, both plant and root samples in 0–60 cm soil layer were collected for the analysis of yield, nutrient uptake and root system indexes.  【Results】  Tillage modes had significant effects on maize yield. The average grain yields in two years were in order of T3 > T2 > T1 > T4. Compared with T1 treatment, the grain yields in T2 and T3 treatments were increased by 8.1% and 10.2%, respectively. The accumulation of N, P and K and their contribution to grain were all increased significantly at the post-silking and maturity stage (P < 0.05), and which were increased by 0.4%–3.6%, 16.9%–33.8%, 70.5%–82.1% significantly in T2 and T3 treatments at the post-silking stage (P < 0.05), and all above increment in T3 treatment were higher than those in T2 treatment. Compared with T1 treatment, the total root weight, total root length, and total root surface area in T2 and T3 treatments were increased by 9.8%–22.8%, 16.1%–33.1% and 19.9%–38.2% from 6 leaf stage to maturity stage, respectively. The root morphology in T2 and T3 treatments were better than those in seeding following light stubble treatment (T1), especially in 20–40 cm soil layers (P < 0.05). Compared with T1 treatment, the root dry weight, root length, root surface area and root diameter in the 20–40 cm soil of T3 treatment were increased by 34.1%, 48.3%, 47.8% and 22.1%, respectively.  【Conclusions】  Deep loosening in both intra- and inter-seedling rows without compacting is adverse to the root growth. Deep loosening between rows and compaction in seedling belts treatment could promote the deep development and longitudinal extension of roots, especially in the 20–40 cm soil layer, which is beneficial to absorb the soil nutrients, and thus increase the nutrient accumulation after silking and the allocation to the grains, and achieve higher grain yield.