Green manure effects on zinc and cadmium accumulation in wheat grains (Triticum aestivum L.) on high and low zinc soils

Abstract

Background and aims Zinc (Zn) deficiency is a global problem in human nutrition due to imbalanced diets based on staple foods of low Zn contents. This study investigated the potential of using clover (Trifolium alexandrinum L.) and mustard (Sinapis alba L.) green manure crops to increase soil Zn uptake by wheat (Trifolium aestivum L.) without enhancing cadmium (Cd) accumulation. Methods A factorial pot experiment with wheat was performed with three green manure treatments (clover, mustard or no green manure) and three soil treatments which were a high-Zn soil (FYM), a low-Zn soil (TURK) and the TURK soil with mineral Zn fertilization (TURK+ZN). Green manure crops were grown first and then incorporated into the soils before wheat. Results In contrast to mustard, clover increased grain Zn concentrations in the FYM and TURK+ZN soils, but not in the TURK soil. The effect appeared to be due to high soil nitrogen inputs and concurrent pH decrease, root biomass increase, and the release of organic ligands mobilizing soil Zn and Cd. However, the high N inputs also induced Cd accumulation above critical thresholds. ConclusionsThe study suggests that on Zn sufficient soils or in combination with Zn fertilizer, leguminous green manure can increase soil Zn accumulation by wheat.

Green Manure Effect on The Ability of Native and Inoculated Soil Bacteria to Mobilize Zinc for Wheat Uptake (Triticum Aestivum L.)

“…In line with this and in agreement with several other studies(Cakmak et al 2010;Kutman et al 2010), we found positive correlations between wheat shoot and grains N and Zn and Cd concentrations (Table7). Similarly as inGrüter et al (2017b), we found more wheat root and shoot (excluding grains) biomass production in the LOW Zn soil than in the HIGH Zn soil, which may partly be atttributed to the poor soil structure of the HIGH Zn soil (observed by high soil density and distribution of the roots along the pot walls). Low aggregate stability was con rmed by a low Ca content (1.68 g kg − 1 ), which is known to improve aggregate stability through building Ca bonds between clay and humus particles(Blume et al 2016).…”

Green manure effect on the ability of native and inoculated soil bacteria to mobilize zinc for wheat uptake (Triticum aestivum L.)

“…3 and 10 mg Zn kg −1 , respectively), considered as critical for wheat growth (White 1993). Contrasting results were obtained in a recent pot experiment conducted by Grüter et al (2017b) using the same two soils, as well as the same clover and wheat variety, but under different growing conditions (climate chamber with higher air temperature and a different lighting system). In their study, the incorporation of clover green manure increased aboveground wheat Zn uptake by almost a factor of two in the LOW Zn and of five in the HIGH Zn soil.…”

“…R. leguminosarum was also inoculated in LOW Zn where no green manure was grown. The HIGH Zn Table 1 Physicochemical and biological properties of the two soils used in this study Soil analyses were performed before green manure sowing as an initial soil characterization a Apart from total soil N, DGT extractable Zn and Cd, basal soil respiration and microbial C and N biomasses, the rest of the soil parameters given in this table was obtained from Grüter et al (2017b) b IUSS Working Group WRB (2014) c Below limit of detection (< LOD) d For LOW Zn, the DTPA extractable Zn was below 0.5 mg kg −1 , commonly considered as the Zn deficiency threshold (Cakmak et al 1996 soil was not inoculated with this rhizobium as preliminary tests highlighted infectious potential of this soil. Nodules were found on clover roots in both soils after 6 weeks of growth.…”

“…Table 3 summarizes the various soil analyses performed at each time point and how the soil samples were prepared for analysis. Clay content, soil texture, cation exchange capacity, maximum water holding capacity, soil organic and inorganic C content, total element concentrations, DTPA extractable Zn and Cd and Olsen P data were obtained from Grüter et al (2017b), where the analytical methods can also be found. The methods used for the remaining soil analyses (soil pH, total soil N, DGT extractable Zn and Cd, soil respiration, microbial C and N contents and soil mineral N concentrations) can be found in the supplementary material (Sect.…”

New Insights to Zinc Biofortification of Wheat: Opportunities to Fine-tune Zinc Uptake, Remobilization and Grain Loading

“…Increases in plant Zn can be achieved through fertilizer application (soil and/or foliar) and appropriate crop rotation (De Valença, Bake, Brouwer, & Giller, 2017). Green manure applications increase Zn content in wheat grain, and nutrient release follows decomposition rate (Gruter, Meister, Schulin, & Tandy, 2018). Soil applications of Zn fertilizer can raise grain Zn concentration in wheat three or four-fold (Cakmak, 2008), and one-off soil amendments give persistent benefits in many soil types.…”