Objectives Trace element Zn is essential for human health. Without sufficient Zn nutrition, the development of human body might be affected, be more vulnerable to the invasion of pathogenic bacteria and susceptible to diseases, and less tolerate to oxidative stress. Zn supplement of human body is mainly from food intake, however, about 50% of the world’s arable land is deficient in Zn, and the Zn contents in edible parts of main food crops are generally low. In this paper, we discussed the response of main grain crops to Zn fertilizers for providing a theoretical basis for future research on Zn enrichment.
Major advances Deficiency of Zn in grain parts of main food crops could be improved by soil application and forliar spraying of Zn fertilizers, and both the two ways showed significant effects in improving the Zn contents in edible parts of main food crops (wheat, rice and maize) and the yields, the effectiveness of soil application of Zn fertilizers is low and the applied rate is high, due to the influence of soil physicochemical properties, such as soil pH, organic matter content, the apparent utilization rates of soil application of Zn fertilizers are lower than those of leaf spray, the leaf spray of Zn fertilizers could not increase yields as high as soil application did; interactions between the nutrient elements affect the application effect of Zn, Zn is antagonistic to P and Fe, synergistic to Cu; Zn is not evenly distributed in the different grain components, the contents of Zn gradually become lower in bran, grain and flour of wheat, the same in rice grain, brown rice and polished rice, and Zn contents in the main consumables flour and rice are low; Zn in grain part derives from both the root absorption and the redistribution of stems and leaves in wheat, and mainly from root absorption in rice.
Suggestions and expectations At present, the migration and distribution of Zn in the fertilizer-soil-crop systerm is not clear, the cost of the application of Zn fertilizer is high, the optimal input and the ration of the different nutrient elements is still uncertain. In view of problems existing in the application of Zn fertilizers and its causes, this future researches should focus on the following six aspects: 1) Study the uptake and distribution of Zn in the fertilizer-soil-crop system, clearify the enrichment and allocation of Zn in the fertilizer-soil-crop system, and establish a database of Zn in major farmland soils throughout the country and build a response model between yield and Zn content and Zn fertilizer; 2) Research of effective Zn feitilization technology and cost effective Zn fertilizers; 3) Study the synergistic and antagonistic effects of Zn with other nutrient elements, so as to find satisfactory input way and achieve the best nutritional value of food crops as a whole; 4) Improve soil physicochemical properties, so to alleviate the effectiveness and durability of Zn fertilizers; 5) Screening grain crop cultivars with both high yield and high Zn content; 6) Study the Zn-rich molecular biological mechanism of the main food crops, serving breeding of crop cultivars.
DownLoad: