Is it really organic? – Multi-isotopic analysis as a tool to discriminate between organic and conventional plants

Compound-Specific δ15N and δ13C Analyses of Amino Acids for Potential Discrimination between Organically and Conventionally Grown Wheat

“…This corresponds with results from bulk tissue analysis in previous studies 1. This stomatal conductance of leaves [14][15]…”

“…11 Thus, the use of legumes represents a common and 54 valuable strategy for improving soil fertility in organic agriculture. However, legumes have a 55 nitrogen isotopic composition similar to that of synthetic fertilisers 1 Also the stable isotope ratio of carbon 13 C/ 12 C (expressed as δ 13 C) has also been investigated for 66 organic authentication. In C3 plants, δ 13 C is affected by water availability and drought stress, but 67 also shows significant interactions with nutrient availability and fertilization 14,15 , which frequently 68 can be systematically different between organic and conventional systems.…”

“…Moreover we considered δ 15 N and δ 13 C values of bulk tissue wheat grain samples, taking the data 344 from the literature for DK1 and measuring the samples from IT to conduce a direct comparison with 345 the compound specific data.Figure 3shows the distribution of δ 15 N and δ13 C values of Danish and 346 Italian bulk tissue samples, while Figure 4 shows the same distribution for δ 15 N and δ 13 C values of 347 Glx. The bulk tissue analysis allowed separation between wheat plants grown with the use of animal 348 manure (OSA) from plants grown using synthetic fertilizers (CS), but it was impossible to 349 distinguish the agricultural system based on legumes as green manures (OSB) from the 350 conventional one, as discussed above.…”

Nitrate dynamics in natural plants: insights based on the concentration and natural isotope abundances of tissue nitrate

“…Since then, the application has been expanded widely to accommodate isotopic analysis of NO − 3 in fresh water (e.g., groundwater, stream water, precipitation), soil and sediment water, soil extracts, as well as dissolved organic N (DON) in seawater and DON bound to diatoms as described by Koba et al (2010a) and McIlvin and Casciotti (2011), respectively. This method has recently been used for measurements of NO − 3 in natural plants and crops (Liu et al, 2012a, 2013a; Laursen et al, 2013; Bloom et al, 2014; Mihailova et al, 2014). The established protocol facilitates the Δ 17 O (Δ 17 O = [1 + δ 17 O] / [1 + δ 18 O] 0.5247 − 1; Kaiser et al, 2007) analysis of leaf NO − 3 to diagnose atmosphere-derived NO − 3 in leaf uptake (Mukotaka, 2014).…”

How to understand the complexity of product quality and the challenges in differentiating between organically and conventionally grown products—exemplified by fresh and heat-processed carrots (Daucus carota L.)

“…However, these techniques are expensive and their use is challenging due to the diversity of fertilization practices used in organic and conventional production. In another paper, it was concluded that nitrogen isotope analysis could discriminate the use of animal manure from synthetic fertilizer but was unable to discriminate between plants that were fertilized with synthetic nitrogen fertilizers or green manure derived from nitrogen-fixing legumes (Larusen et al 2013). Since farmers often mix different types of animal manure and green manure, it seems unlikely that the nitrogen isotope method can be used to differentiate organic from conventional products.…”