Objectives The study aims to elucidate the zinc (Zn) concentration in grains, flour, and bran of newly developed wheat cultivars (lines) in the major wheat-growing regions in China, and investigate the influence of yield composition, nutrient absorption, and soil factors on Zn concentration in grain. It is of significant importance in providing supports for Zn biofortification of wheat in China.

Methods Based on multi-point trials of 104 newly developed wheat cultivars (lines) conducted in 17 provinces (municipalities) in the major wheat production regions of China during the two wheat growing seasons of 2021−2022 and 2022−2023, the study determined Zn concentration in wheat grain and its flour and bran, wheat yield and yield components, Zn absorption and distribution in grain, as well as soil physicochemical properties and fertilizer application rates, Zn concentration in different parts of the grain of newly developed wheat cultivars (lines) in China, as well as the absorption and distribution of Zn and environmental influencing factors.

Results The Zn concentration in grains of newly developed wheat cultivars (lines) ranged from 14.3 to 54.7 mg/kg, with an average of 27.6 mg/kg in the major wheat regions of China. The Zn concentration in flour ranged from 1.4 to 30.2 mg/kg, with an average of 9.0 mg/kg, while the Zn concentration in bran ranged from 23.2 to 107.6 mg/kg, with an average of 55.9 mg/kg. Wheat cultivars (lines) in the southern wheat regions exhibited higher Zn concentrations in grains and their various parts compared to those in the northern regions. The Zn concentration in wheat grain showed a negative correlation with the grain yield, biomass, and spike number per area. For Zn uptake and distribution in plant parts, the grain Zn concentration was positively correlated with Zn absorption and distribution in the grain, but negatively correlated with Zn absorption in the straw, glume and bran. Furthermore, the Zn concentration in grain showed a negative correlation with calcium and sulfur concentrations, and a positive correlation with iron and copper concentrations in grain. The grain Zn concentrations of the newly developed wheat cultivars (lines) varied among locations, with soil pH, available Zn and available Fe being the primary factors influencing Zn concentration in wheat grain. A negative correlation was found between the grain Zn concentration and soil pH, while a positive correlation was found with the available Zn and Fe in soils. Regression analysis suggested that when the soil pH be lower than 6.3 and soil available Zn higher than 1.7 mg/kg, the grain Zn concentration could be higher than 40.0 mg/kg.

Conclusions The average Zn concentrations of newly developed cultivars (lines) in China were 27.6, 9.0 and 55.9 mg/kg for grain, flour and bran, respectively. The main crop factors regulating Zn nutrition include yield, number of spikes and Zn accumulation in straw, glumes and bran, and main soil factors are pH, available Fe and Zn. In the selection and breeding of high-yield and high-quality wheat cultivars, attention should be paid to cultivating cultivars with strong root absorption of Zn, high number of spikes and large thousand-grain weight, while also promoting Zn nutrition in flour fortified through fertilization.