基于玉米-大豆轮作的不同施肥体系对大豆开花后根系形态及产量的影响

探讨玉米-大豆轮作条件下,降低生产成本、减少环境污染的大豆施肥模式,是目前东北大豆生产需要解决的技术问题。本研究基于建立的玉米-大豆轮作体系设置了5种施肥处理,分别为：T1：玉米施用化肥,大豆不施肥;T2：玉米施用化肥,大豆施用有机肥;T3：玉米施用化肥,大豆施用1/2量的化肥;T4：玉米施用化肥,大豆施用化肥;T5：玉米与大豆所需化肥总量一次性全部施入到玉米种植年份,大豆不施肥。分析了不同施肥模式对大豆不同生育期0~10、10~20、20~30cm土层深度内大豆根系干物质积累、根系形态特征时空变化以及与产量的关系。结果表明,经两个轮作周期,T2处理大豆产量最高为 2959kg·hm-2,比T4处理显著高出7.3%,产量提高主要体现在大豆的株高、主茎节数、单株荚数和单株粒数等性状的改善,而T1、T3、T5处理的大豆产量比T4处理显著低出15.4%,8.5%和5.0%。T2处理显著增加了大豆R6期0~10cm土层的根重密度,比T4处理显著高出42.3%,且与产量呈显著正相关,相关系数为0.655(p < 0.01);T2处理也明显增加了大豆R1期0~10、10~20cm土层以及R6期20~30cm土层的根长密度,分别比T4处理显著高出25.3%、71.3%和27.6%,且与产量呈显著正相关,相关系数为0.692 (p < 0.01)。与T4处理相比,尽管T3处理显著增加了大豆R1期10~20、20~30cm土层的根重密度和R6期10~20cm土层的根长密度及根表面积密度,但均与产量呈显著负相关。T4处理只显著增加R1期单位体积的根表面积,而对大豆根平均直径和其它时期单位体积的根表面积的影响不大。因此,不同施肥措施影响大豆根系特征及其产量的关系问题比较复杂。施用有机肥可通过增加表土层根的重量以及深土层根的长度从而提高大豆的产量。因此在有机肥源供应充足的地区,玉米、大豆两区轮作基础上,玉米收获后秋施15t·hm-2有机肥,是提高大豆产量,降低生产成本,减轻化肥应用负面环境影响的替代措施。

Effects of different fertilization systems on characteristics of roots after flowering and yield in soybean based on corn-soybean rotation

Exploring fertilization patterns under corn-soybean rotation is a technological solution to minimize production costs and environmental pollution in soybean production in Northeast China. The present study investigated the effects of fertilization patterns under corn-soybean rotation on root dry matter accumulation and morphological characteristics at soil depths of 0-10cm, 10-20cm and 20-30cm, in different growth stages and the relationship with yield. The fertilization patterns were (1) applying chemical fertilizers in corn and no fertilizers in soybean (T1); (2) applying chemical fertilizers in corn and cattle manure only in soybean (T2); (3) applying chemical fertilizers in corn and half rate of fertilizers in soybean (T3); (4) applying chemical fertilizers in both corn and soybean (T4); (5) applying all fertilizers used for corn and soybean in corn only and no fertilizers in soybean (T5). The results showed that the highest soybean yield of 2959 kg•ha-1after two rotations was obtained in the treatment (T2), which was 7.3% higher than treatment (T4). The increased yield was mainly due to the improvement in plant height, number of main stem nodes, number of pods per plant and number of seeds per plant. Compared to T4 treatment, yield in T1, T3 and T5 treatments was reduced by 15.4%,8.5% and 5.0% respectively. T2 treatment significantly increased root biomass density at R6 stage with 42.3% greater than the T4 treatment in 0-10 cm soil depth, which was positively related to yield with a coefficient of 0.655(p < 0.01). Compared to T4 treatment, the T2 treatment increased the root length density by 25.3%, 71.3% in 0-10cm and 10-20cm depth at the R1 stage, and 27.6% in 20-30 cm at the R6 stage, which was significantly correlated to yield with a coefficient of 0.692(p < 0.01). Although T3 treatment significantly increased root biomass density in 10-20, 20-30 cm soil depth at R1 stage, and root length density and root surface area density in 10-20 cm at R6 stage, soybean yield was negatively correlated with them. T4 treatment only significantly increased root surface area, and had no effects on root average diameter and root surface area at other stages. Therefore, the effects of fertilization system on the relationship between soybean root properties and yield was complex. The increased yield in manure application might be due to the increase in surface root biomass density and greater root length. In areas where manure resources were available, the application of 15t/ha cattle manure after corn harvest under corn-soybean rotation, could be an alternative approach in increasing soybean yield, reducing production costs and negative impact on environment from chemical fertilizers.