Abstract
Cereal/legume intercropping is likely to achieve the optimal exploitation of soil and atmospheric nitrogen (N) sources to maintain high production and quality levels with low N inputs, as an attempt to eliminate underlying environmental effects. Nevertheless, the extent of the effect of cereal/legume intercropping on nodulation and N fixation of intercropped legumes in root interaction requires extensive verification. In the present study, root interaction of alfalfa/triticale intercropping was simulated in pots with the use of root separation types (pot with no barrier (A-T), pot with nylon mesh barrier (NA-T), pot with plastic barrier (PA-T), and alfalfa alone (SA)) in pots. Moreover, the experiment was measured at a range of N levels (N21, N210) and growing stages (branching, budding and initial flowering stages) in growth chamber. As alfalfa was growing, the total nodule number (TNN), effective nodule number (ENN) and nitrogenase activity (NA) of alfalfa with A-T and other cropping systems more noticeably differed from each other at higher N levels, whereas their diversification was reduced at lower N levels. As alfalfa was growing continuously, fresh nodule weight per plant (PNW) and single fresh nodule weight (SNW) with A-T and other cropping systems were amplified more significantly. The nodulation and N fixation ability under N21 were more significant than those under N210. Dry weight of plant per pot (TDW) and nitrogen accumulation of plant per pot (TNA) with A-T were obviously higher than those with other systems in the initial flowering stage, except for TNA under N21. The parameters regarding the nodulation and N fixation ability were significantly positively correlated on the whole. However, SNW and TNA were not significantly correlated, neither were SNW and TDW. According to the mentioned results, the closer root interaction, the better the nodulation form and N fixation ability of alfalfa will be, and the higher the biomass and N accumulation of all plants in pots will be. Interspecific facilitation in alfalfa/triticale intercropping system resulted in a greater yield and N accumulation; it also ultimately enhanced nodulation and N fixation ability, which can be applied in sustainable systems to avoid N loss to the environment and enhance N use efficiency.
Highlights
Cereal/legume intercropping is likely to achieve the optimal exploitation of soil and atmospheric nitrogen (N) sources to maintain high production and quality levels with low N inputs, as an attempt to eliminate underlying environmental effects
No difference in effective nodule number (ENN)/total nodule number (TNN) was witnessed in four cropping systems at branching stag
ENN, effective nodule number/total nodule number (ENN/TNN), PNW, single fresh nodule weight (SNW) and PNF were significantly impacted as the different N concentrations by alfalfa
Summary
Cereal/legume intercropping is likely to achieve the optimal exploitation of soil and atmospheric nitrogen (N) sources to maintain high production and quality levels with low N inputs, as an attempt to eliminate underlying environmental effects. The root interaction of alfalfa/triticale with NA-T was weaker than that with A-T, so the nodulation and N fixation ability with NA-T were lower than those with A-T. As revealed by the mentioned results, the closer the crop roots interact, the better the nodulation form and N fixation ability of alfalfa in alfalfa/triticale cropping systems will be.
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