Grain zinc concentration, yield components, and zinc uptake and utilization of different high-yielding wheat cultivars in dryland fields

Objectives Grain zinc (Zn) concentration varies among cultivars of wheat. The uptake and utilization of Zn are also different from one cultivar to the other. Studying the characteristics of cultivars in Zn nutrition will provide valuable information for improving wheat yield and grain Zn contents through breeding.

Methods A split field experiment was conducted for three growing seasons in the typical dryland area of the Loess Plateau from 2013 to 2016. 123 wheat cultivars, collected from the main wheat production areas in China, were grown under two treatments of no fertilizer control and applying N 150 kg/hm² and P₂O₅ 100 kg/hm². The Zn concentrations in grain and their relationship with dry matter accumulation, yield components, Zn uptake and utilization were investigated.

Results Significant differences were found in grain zinc concentration among high-yielding wheat cultivars under fertilization. Grain Zn concentration was not correlated with the grain yield, but was positively and significantly correlated with thousand-grain-weight, Zn uptake, Zn harvest index and grain Zn formation efficiency, negatively and significantly correlated with grain number per spike. Among the cultivars, high-Zn cultivars had significantly higher Zn concentration than low-Zn cultivars regardless of fertilization. Moreover, fertilization led to higher grain Zn concentration in high-Zn cultivars, but the opposite was true for low-Zn cultivars. Under fertilization, there was no difference between high-Zn cultivars and low-Zn cultivars in grain yield, biomass, and harvest index, but the former had lower spike number, and higher Zn uptake in grain and aboveground part, Zn harvest index, and grain Zn formation efficiency than the latter. High-Zn cultivars had greater fertilizer effects than low-Zn cultivars on grain yield, biomass, spike number, grains number per spike.

Conclusions The key to increase wheat grain zinc concentration through breeding or crop management is to promote zinc uptake and its allocation to grains in low-Zn soils in the typical dryland area of the Loess Plateau.