间作对玉米根系分泌物及团聚体稳定性的影响

通过田间小区试验种植玉米(玉米单作、玉米∥大豆、玉米∥马铃薯),测定3个生育期(拔节期、大喇叭口期、抽雄期)玉米根系分泌总糖含量、总有机酸含量和土壤团聚体状况,分析间作对玉米根系分泌物及团聚体稳定性的影响。结果表明:玉米根系分泌总糖含量和总有机酸含量随生育期的推移而增加,间作显著提高玉米根系分泌总糖含量和总有机酸含量,玉米∥马铃薯玉米∥大豆。在抽雄期,玉米∥大豆、玉米∥马铃薯相比玉米单作0.25mm水稳性团聚体含量(R_(0.25))分别显著提高6.19%,8.17%;平均质量直径(MWD)分别提高5.04%,10.08%;几何平均直径(GMD)分别提高6.12%,12.24%;分形维数(D)分别显著降低0.72%,1.09%;团聚体破坏率(PAD)分别显著降低16.77%,26.08%。在根系分泌物最大的抽雄期,玉米根系分泌总糖含量、总有机酸含量与R_(0.25),GMD,D,PAD呈极显著相关关系(P0.01)。因此,间作可通过增加玉米根系分泌总糖含量和总有机酸含量,进而提高土壤团聚体的稳定性。

Effects of Intercropping on Maize Root Exudates and Soil Aggregate Stability

The field experiment with different planting patterns (maize monoculture, maize//soybean intercropping and maize//potato intercropping) of maize was carried out, and root exudates of total sugars and total organic acids and soil aggregates at jointing, bell-mouthed, and tasseling stages of maize growth were measured. The influence of intercropping on maize root exudates and soil aggregate stability was explored. The results showed that root exudates of total sugars and total organic acids increased with maize growth. Intercropping significantly increased maize root exudates of total sugars and total organic acids. Maize//potato intercropping was better than maize//soybean intercropping. Compared with maize monoculture, maize//soybean intercropping and maize//potato intercropping have increased >0.25 mm water stable aggregate (R_0.25) by 6.19% and 8.17%, mean weight diameter (MWD) by 5.04% and 10.08%, geometric mean diameter (GMD) by 6.12% and 12.24%, have significantly decreased fractal dimension (D) by 0.72% and 1.09%, and portion of aggregate destruction (PAD) by 16.77% and 26.08%, respectively at tasseling stage. At tasseling stage with maximum root exudates, total sugars content and total organic acids content were significantly correlated with R_0.25, GMD, D, and PAD (P<0.01). These results indicate that intercropping can enhance maize root exudates of total sugars and total organic acids and thus improve soil aggregate stability.