Arbuscular mycorrhizal fungi and rhizobium facilitate nitrogen uptake and transfer in soybean/maize intercropping system

Abstract

The tripartite symbiosis between legumes, rhizobia and mycorrhizal fungi are generally considered to be beneficial for the nitrogen (N) uptake of legumes, but the facilitation of symbiosis in legume/non-legume intercropping systems is not clear. Therefore, the aims of the research are as follows: (1) to verify if the dual inoculation can facilitate the N uptake and N transfer in maize/soybean intercropping systems and (2) to calculate how much N will be transferred from soybean to maize. A pot experiment with different root separations [solid barrier, mesh (30 μm) barrier and no barrier] was conducted, and the 15N isotopic tracing method was used to calculate how much N transferred from soybean to maize inoculated with arbuscular mycorrhizal fungi (AMF) and rhizobium in a soybean (Glycine max L.cv. Dongnong No. 42)/maize (Zea mays L.cv. Dongnong No. 48) intercropping system. Compared with the Glomus mosseae inoculation (G.m.), Rhizobium SH212 inoculation (SH212), no inoculation (NI), the dual inoculation (SH212+G.m.) increased the N uptake of soybean by 28.69, 39.58, and 93.07% in a solid barrier system. N uptake of maize inoculated with both G. mosseae and rhizobium was 1.20, 1.28, and 1.68 times more than that of G.m., SH212 and NI, respectively, in solid barrier treatments. In addition, the amount of N transferred from soybean to maize in a dual inoculation system with a mesh barrier was 7.25, 7.01, and 11.45 mg more than that of G.m., SH212 and NI and similarly, 6.40, 7.58, and 12.46 mg increased in no barrier treatments. Inoculating with both AMF and rhizobium in the soybean/maize intercropping system improved the N fixation efficiency of soybean and promoted N transfer from soybean to maize, resulting in the improvement of yield advantages of legume/non-legume intercropping.

Nitrogen Fixation and Transfer in Agricultural Production Systems

“…Proportion of fixed N 2 transferred from faba bean to wheat (Triticum aestivum L.) was 50% when inoculated with AMF compared 15% in uninoculated stands [52]. Similar results were also reported in garden pea-barley (Hordeum vulgare L.) and soybean-maize (Zea mays L.) intercropping studies [48,53]. The AMF-mediated transfer of N can be both unidirectional and bidirectional [48,54] and often along with a concentration gradient [47].…”

Allocation of Nitrogen and Carbon Is Regulated by Nodulation and Mycorrhizal Networks in Soybean/Maize Intercropping System

“…In the maize/soybean intercropping system, the yield advantage of maize has been also reported (Tang et al, 2005; Meng et al, 2015). In the present study, we demonstrated that the high competitive ability of maize relative to soybean can be partly ascribed to the contribution of AMF and rhizobia.…”

“…One common intercropping scheme is to pair a cereal crop with a legume that can supply N through biological N 2 fixation. Yield advantages of intercropping legumes with non-N 2 fixing crops have been found in many intercropping systems, including ryegrass-subclover (Ledgard et al, 1985), rice-peanut (Shen and Chu, 2004), wheat-faba bean (Xiao et al, 2004), Millet-cowpea (Laberge et al, 2011), rapeseed-faba bean (Jamont et al, 2013), and maize-soybean (Tang et al, 2005; Meng et al, 2015). Despite the prevalence of such cropping systems, the mechanisms underlying yield advantages of intercropping compared with monocropping systems have not been fully explored.…”

“…It has been demonstrated that intercropped crops may benefit from symbiotic associations with both rhizobia and AMF. Nitrogen fixed by legume plants can be transferred to non-legumes via root contact or CMNs in many intercropping systems (Xiao et al, 2004; Sierra and Nygren, 2006; Laberge et al, 2011; Meng et al, 2015). However, net N transfer from legumes to non-legumes through CMNs has been sparsely documented.…”

Efeito do cultivo intercalar de adubo verde com minitomateiro orgânico em ambiente protegido na produtividade, qualidade e transferência de nitrogênio

“…A transferência de N entre as plantas leguminosas e não leguminosas pode ocorrer pela rizodeposição (exsudados radiculares) das raízes das leguminosas, por intermédio das micorrizas associadas às plantas leguminosas e não leguminosas, e liberação do gás amônia pelos adubos verdes (Hanstein, Mattsson, Jaeger, & Schjoerring, 1999;Lesuffleur, Salon, Jeudy, & Cliquet, 2013;Meng et al, 2015;Peoples, Chalk, Unkovich, & Boddey, 2015).…”