Screening stably low cadmium and moderately high micronutrients wheat cultivars under three different agricultural environments of China.

Heavy metal-contaminated farmland, especially for cadmium (Cd), is being used for agricultural production in large scale due to the increasing food demand. Thus, minimizing the influx of Cd to the human food chain is urgently needed. Screening for stably low Cd and moderately high micronutrient wheat cultivars is one of the most feasible and effective approaches to ensure food safety and quality. Here, the Cd accumulation by 72 wheat cultivars was identified in field 1, and the stability of Cd accumulation in these cultivars was tested in fields 2 and 3. The effects of Cd on micronutrient (zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), and boron (B)) uptake in grains were also investigated. Nine of the 24 low-Cd wheat cultivars identified by screening showed stably low-Cd and moderately high micronutrient concentrations in grain. Nine cultivars exhibited unstable low-Cd accumulation characteristics, and another five cultivars contained significantly lower Zn concentrations in grain in at least two experimental fields. One low-Cd cultivar also had low Zn, Cu and Mn concentrations in grain. The accumulation of Cd in wheat grain had little effects on the uptake of Fe. Grain Cd concentration correlated positively with the dry weight of stem and root, and negatively with the spike length. There was no correlation between grain Cd concentration and wheat yield. The selected cultivars with stably low-Cd accumulation and moderately high micronutrient concentrations in grain are recommended for cultivation in slightly to moderately Cd-contaminated farmland to ensure food safety for the growing human population.

Liu N ，Huang X ，Sun L ，Li S ，Chen Y ，Cao X ，Wang W ，Dai J ，Rinnan R ... -  《-》

Zinc fertilisation increases grain zinc and reduces grain lead and cadmium concentrations more in zinc-biofortified than standard wheat cultivar.

Given that plant uptake and transport systems for metals have some similarities, zinc (Zn)-biofortified cultivars may concurrently accumulate non-essential toxic heavy metals in grains. However, Zn-biofortified cultivars have never been tested for heavy metal accumulation in grains. In a pot experiment, we compared Zn-biofortified wheat (Zincol-2016) with a standard wheat (Faisalabad-2008) cultivar on heavy-metal-contaminated soils for yield response and grain accumulation of Zn, lead (Pb) and cadmium (Cd), without or with Zn fertilisation (8mgZnkg-1). The soils, collected from agricultural fields in (i) industrial zone and (ii) peri-urban area, had been receiving industrial and city effluents for >20years. In the two soils, Zn fertilisation significantly (P≤0.05) increased grain yield of both cultivars. Zinc fertilisation increased grain Zn concentration of Zincol-2016 and Faisalabad-2008 by respectively 32 and 18% in industrial-zone soil, and by 15 and 2% in peri-urban soil. Averaged across Zn rates, Zincol-2016 accumulated in grains more than double the Zn amount than Faisalabad-2008 in industrial-zone soil. At 0mgZnkg-1, grain Pb and Cd concentrations were respectively 26 and 33% greater in Zincol-2016 than Faisalabad-2008 in industrial-zone soil, and 86 and 50% greater in Zincol-2016 than Faisalabad-2008 in peri-urban soil. Zinc fertilisation significantly (P≤0.05) decreased concentration of Pb and Cd in grains of both cultivars. In industrial-zone soil, a toxic level of Pb in grains (0.24mgkg-1) was attained at control rate of Zn by Zincol-2016, and was decreased to a safe level (0.07mgkg-1) by application of 8mgZnkg-1. Therefore, biofortified cultivars should not be grown in contaminated soils, and/or sufficient Zn must be applied, to decrease accumulation of non-essential toxic heavy metals in grains. Moreover, future breeding efforts should be directed toward selection of biofortified cultivars that would selectively accumulate Zn in grains, but not the contaminants.

Qaswar M ，Hussain S ，Rengel Z 《-》

Agronomic and ionomics indicators of high-yield, mineral-dense, and low-Cd grains of wheat (Triticum aestivum L.) cultivars.

The accumulation of toxic and essential nutrient elements in wheat grain influences wheat yield, grain nutritional quality, and human health. Here, we assessed the potential for breeding wheat cultivars to combine high yield with low cadmium and high iron and/or zinc concentrations in grains, and we screened appropriate cultivars. A pot experiment was conducted to explore differences in grain cadmium, iron, and zinc concentrations among 68 wheat cultivars, as well as their relationships with other nutrient elements and agronomic characters. The results showed 2.04-, 1.71-, and 1.64-fold differences in grain cadmium, iron, and zinc concentrations, respectively, among the 68 cultivars. Grain cadmium concentration was positively correlated with grain zinc, iron, magnesium, phosphorus, and manganese concentrations. Grain copper concentration was positively correlated with grain zinc and iron concentrations, but not with grain cadmium concentration. Therefore, copper has a potential role in regulating grain iron and zinc accumulation without influencing cadmium concentration in wheat grain. There were no significant relationships between grain cadmium concentration and four important wheat agronomic characters (i.e., grain yield, straw yield, thousand kernel weight, and plant height), indicating that the breeding of low-cadmium-accumulating cultivars with dwarfism and high yield characteristics is possible. On cluster analysis, four cultivars (Ningmai11, Xumai35, Baomai6, and Aikang58) exhibited low-cadmium and high-yield characteristics. Among them, Aikang58 contained moderate iron and zinc concentrations, while Ningmai11 had relatively high iron but low zinc concentrations in the grain. These results imply that it is feasible to breed high-yield dwarf wheat with low cadmium and moderate iron and zinc concentrations in the grain.

Yi Q ，Wang Y ，Yi C ，Li L ，Chen Y ，Zhou H ，Tong F ，Liu L ，Gao Y ，Shi G ... -  《-》

Selection of low-cadmium and high-micronutrient wheat cultivars and exploration of the relationship between agronomic traits and grain cadmium.

The cadmium (Cd) and micronutrient contents in grains were used as screening indicators through a pot experiment, and the hierarchical cluster analysis was used to select wheat cultivars with low Cd and high micronutrient contents. The potential human health risks caused by wheat intake and the relationship between the Cd concentration in wheat grains and 12 agronomic traits were also investigated using the risk assessment model and logistic equation fitting, respectively. Yannong-23, Zhongmmai-175, and Luyuan-502, the main wheat cultivars promoted in the Huang-Huai-Hai region of China, were screened for low Cd accumulation and high micronutrient. Health risk assessment results demonstrated that children showed a high noncarcinogenic risk and that adults posed a high carcinogenic risk. The results of the agronomic trait analysis showed that low-Cd accumulation wheat cultivars had high spikelet number and fresh and dry weights of root, stem, and leaf (p < 0.05). Logistic curve fitting results showed that among all agronomic traits, the root dry weight was the most suitable factor with remarkable goodness of fit and showed a significant negative correlation. The Cd concentration in wheat grains could be predicted by the logistic curve equation obtained by fitting this trait. Results provided theoretical support for the safe use of slightly to moderately contaminated farmland, formulation of health risk management policies for different populations, and breeding of high-quality wheat.

Li S ，Huang X ，Liu N ，Chen Y ，He H ，Cao X ，Dai J ... -  《-》

[Blocking Effects of Foliar Conditioners on Cadmium, Arsenic, and Lead Accumulation in Wheat Grain in Compound-contaminated Farmland].

Xiao B ，Wang QS ，Gao PP ，Zhao QL ，Yang W ，Wang Z ，Liu WJ ，Xue PY ... -  《-》