糜子绿豆带状种植下糜子的氮素积累、代谢及产量变化

禾豆间作是一种高效的生态种植模式,为明确糜子-绿豆合理间套作种植模式下糜子对养分高效利用的机制,于2017—2018年在榆林小杂粮综合试验示范站,以单作糜子(SP)为对照,设糜子(P)-绿豆(M)4种间作模式[2∶2(2P2M)、4∶2 (4P2M)、4∶4 (4P4M)、2∶4 (2P4M)],分析糜子开花期和成熟期不同器官干物质积累、氮素含量及植株氮积累量,以期探讨叶片和根系氮素代谢的变化规律,进一步挖掘不同间作模式对糜子产量及其构成因素的调控效应。结果表明,糜子-绿豆间作可显著增加糜子开花期根系、茎秆、叶片和鞘的氮素含量,使成熟期穗的氮含量比单作增加10.9%～15.9%;间作有利于促进糜子器官的生长发育,与单作相比,间作模式下糜子成熟期干物质积累量两年试验平均提高11.6%～32.1%,植株氮素积累量增加12.8%～36.9%,其中糜子叶片和茎秆的氮素转运量分别比单作增加51.7%～78.9%和24.1%～55.6%,叶片对于穗的氮素贡献率增加40.6%～66.9%。糜子-绿豆间作模式可显著调节糜子旗叶和根系的氮素代谢,硝酸还原酶活性、谷氨酰胺合酶活性、可溶性蛋白含量及游离氨基酸含量均有不同程度的增加,2P4M处理下达到最大值。植株生理代谢、氮素营养的合理调控显著改善了糜子产量及其构成因素,产量表现为2P4M4P4M2P2M4P2MSP。综上所述,糜子-绿豆间作模式可促进糜子生育后期的氮素积累、转运及氮素代谢,延缓了植株的衰老,提高糜子产量,表现出明显的间作优势。本试验条件下,2P4M是陕北地区糜子-绿豆最佳的间作配比。

Nitrogen accumulation,metabolism, and yield of proso millet in proso millet- mung bean intercropping systems

Cereal-legume intercropping is a ecological and efficient planting pattern. To investigate the effects of proso millet- mung bean intercropping on nitrogen accumulation, metabolism and yield of proso millet from the flowering to maturity stage, we designed four patterns of proso millet (P) to mung bean (M) including 2:2, 4:2, 4:4, and 2:4 in 2017 and 2018 in Yulin, Shaanxi province. The intercropping significantly improved the nitrogen contents in root, stem, leaf and sheath of proso millet at the flowering stage. The nitrogen content in panicle at the maturity stage increased by 10.9%-15.9% compared with the sole cropping of proso millet. Intercropping increased the dry matter accumulation by 11.6%-32.1% and the nitrogen accumulation of proso millet by 12.8%-36.9%. The nitrogen transportation from leaves and stems to panicles increased by 51.7%-78.9% and 24.1%-55.6%, respectively. The proso millet-mung bean intercropping significantly promoted the nitrogen metabolism of proso millet flag leaves and roots. The nitrate reductase activity, glutamine synthase activity, soluble protein content and free amino acid content increased to a different degree, with the maximum in 2P4M treatment. The productivity and yield were enhanced in intercropping by boosting physiological metabolism and nitrogen assimilation. Overall, these results suggest that proso millet-mung bean intercropping pattern enhances the nitrogen accumulation, metabolism, and yield of proso millet, and 2P4M treatment is optimal to improve nitrogen uptake and yield under proso millet/mung bean intercropping systems in Yulin, Shaanxi.