Boosting proso millet yield by altering canopy light distribution in proso millet/mung bean intercropping systems

AbstractWhile crop rotations improve soil quality indicators and crop yields in humid temperate regions, much less information is available under harsher arid tropical and subtropical conditions. A field experiment conducted from 1990 to 1993 compared the effect of continuous pearl millet and pearl millet-fallow systems with six rotations of pearl millet that included one, two, or three years of a legume (cluster bean or mung bean). Data were collected on several soil quality indicators and pearl millet yield. Continuous pearl millet monoculture for three y ears did not affect soil organic C, NaHCO3-soluble P, DTPA extractable Fe, Cu, Mn, or Zn, or several soil organic N fractions, but slightly increased activity of dehydrogenase and acid and alkaline phosphatase enzymes. Similar trends were observed for fallow-based cropping systems, except that enzyme activities were lower. Cropping systems containing mung bean or cluster bean improved availability of soil N and other nutrients and increased enzyme activity. These effects increased with number of years of legume. Improvements from cluster bean generally were greater than from mung bean. The lowest pearl milkt yield was obtained with continuous pearl millet and no N, and yields f or fallow-based cropping systems were 13% greater than with continuous pearl millet. Grain yields of pearl millet with two or three years of mung bean in the cropping system were, respectively, 37 and 65% greater than for continuous pearl millet; with cluster bean the corresponding increases were 68 and 101%. Pearl millet yield increased with N applications up to 40 kg/ha under all cropping systems, and up to 60 kg/ha for some cluster bean-based systems. Yield of pearl millet following cluster bean was nearly double that of continuous pearl millet. These results indicate that in hot, dry climates cropping systems that include a legume, especially cluster bean, are more productive, use the limited water supply and fertilizer N more effectively, and improve several soil quality indicators more than do cropping systems without legumes.

Download Full-text

Intercropping Alters the Soil Microbial Diversity and Community to Facilitate Nitrogen Assimilation: A Potential Mechanism for Increasing Proso Millet Grain Yield

Frontiers in Microbiology ◽

10.3389/fmicb.2020.601054 ◽

2020 ◽

Vol 11 ◽

Author(s):

Ke Dang ◽

Xiangwei Gong ◽

Guan Zhao ◽

Honglu Wang ◽

Aliaksandr Ivanistau ◽

...

Keyword(s):

Grain Yield ◽

Microbial Diversity ◽

Mung Bean ◽

Rhizosphere Soil ◽

Potential Mechanism ◽

Microbial Composition ◽

Soil Microbial Diversity ◽

Soil Microbial ◽

Proso Millet ◽

N Assimilation

Intercropping of cereals and legumes has been used in modern agricultural systems, and the soil microorganisms associated with legumes play a vital role in organic matter decomposition and nitrogen (N) fixation. This study investigated the effect of intercropping on the rhizosphere soil microbial composition and structure and how this interaction affects N absorption and utilization by plants to improve crop productivity. Experiments were conducted to analyze the rhizosphere soil microbial diversity and the relationship between microbial composition and N assimilation by proso millet (Panicum miliaceum L.) and mung bean (Vigna radiata L.) from 2017 to 2019. Four different intercropping row arrangements were evaluated, and individual plantings of proso millet and mung bean were used as controls. Microbial diversity and community composition were determined through Illumina sequencing of 16S rRNA and internal transcribed spacer (ITS) genes. The results indicated that intercropping increased N levels in the soil–plant system and this alteration was strongly dependent on changes in the microbial (bacterial and fungal) diversities and communities. The increase in bacterial alpha diversity and changes in unique operational taxonomic unit (OTU) numbers increased the soil N availability and plant N accumulation. Certain bacterial taxa (such as Proteobacteria) and fungal taxa (such as Ascomycota) were significantly altered under intercropping and showed positive responses to increased N assimilation. The average grain yield of intercropped proso millet increased by 13.9–50.1% compared to that of monoculture proso millet. Our data clearly showed that intercropping proso millet with mung bean altered the rhizosphere soil microbial diversity and community composition; thus, this intercropping system represents a potential mechanism for promoting N assimilation and increasing grain yield.

Download Full-text