How Could Agronomic Biofortification of Rice Be an Alternative Strategy with Higher Cost-Effectiveness for Human Iron and Zinc Deficiency in China?

BACKGROUND: Iron and zinc deficiencies affect human health globally, especially in developing countries. Agronomic biofortification, as a strategy for alleviating these issues, has been focused on small-scale field studies, and not widely applied while lacking of cost-effectiveness analysis (CEA). OBJECTIVE: We conducted the CEA of agronomic biofortification, expressed as USD per disability-adjusted life years (DALYs) saved, to recommend a cost-effectiveness strategy that can be widely applied. METHODS: The DALYs were applied to quantify the health burden due to Fe and/or Zn deficiency and health cost of agronomic biofortification via a single, dual, or triple foliar spray of Fe, Zn, and/or pesticide in 4 (northeast, central China, southeast, and southwest) major Chinese rice-based regions. RESULTS: The current health burden by Fe or Zn malnutrition was 0.45 to 1.45 or 0.14 to 0.84 million DALYs for these 4 regions. Compared to traditional rice diets, the daily Fe and/or Zn intake from Fe and/or Zn-biofortified rice increased, and the health burden of Fe and/or Zn deficiency decreased by 28% and 48%, respectively. The cost of saving 1 DALYs ranged from US$376 to US$4989, US$194 to US$2730, and US$37.6 to US$530.1 for the single, dual, and triple foliar Fe, Zn, and/or pesticide application, respectively, due to a substantial decrease in labor costs by the latter 2 applications. CONCLUSIONS: Agronomic biofortification of rice with the triple foliar spray of Fe, Zn, and pesticide is a rapidly effective and cost-effectiveness pathway to alleviate Fe and Zn deficiency for rice-based dietary populations.

Harvesting more grain zinc of wheat for human health.

Increasing grain zinc (Zn) concentration of cereals for minimizing Zn malnutrition in two billion people represents an important global humanitarian challenge. Grain Zn in field-grown wheat at the global scale ranges from 20.4 to 30.5 mg kg-1, showing a solid gap to the biofortification target for human health (40 mg kg-1). Through a group of field experiments, we found that the low grain Zn was not closely linked to historical replacements of varieties during the Green Revolution, but greatly aggravated by phosphorus (P) overuse or insufficient nitrogen (N) application. We also conducted a total of 320-pair plots field experiments and found an average increase of 10.5 mg kg-1 by foliar Zn application. We conclude that an integrated strategy, including not only Zn-responsive genotypes, but of a similar importance, Zn application and field N and P management, are required to harvest more grain Zn and meanwhile ensure better yield in wheat-dominant areas.

Long-term fertilisation causes excess supply and loss of phosphorus in purple paddy soil.

BACKGROUND: Phosphorus (P) loss from cropland is accelerating the eutrophication of waters around the world such as the Three Gorges Reservoir (TGR) in China. We investigated whether purple paddy soil under long-term P applications was a major source of P efflux to the TGR. RESULTS: Substantial surplus P in the plough layer (0-20 cm) was evident after 15-year P applications. Available P (Olsen-P) in the plough layer ranged from 1.9 to 42.4 mg kg(-1) and some of which will exceed the threshold of 30 mg kg(-1) for environmental concern within 7 years of P application (inorganic NPK with or without organic fertiliser). Between 30 and 70% of Olsen-P was leached out of the 0-30 cm soil layer. Surplus P resulted in high P concentrations in the surface water during the rice cropping season, and these concentrations exceeded those in most waters of the TGR and exceeded the critical level for eutrophication (0.1 mg L(-1)) during the first 10 days after rice planting. Furthermore, total P in run-off due to rainfall events exceeded the level for eutrophication, with a total loss of 43.2-147.9 g P ha(-1) depending on the fertilisation. CONCLUSION: Current agronomic P management in purple paddy soil is environmentally unsustainable in terms of the adverse impact on surface water quality. Integrated P management practices are urgently required to optimise crop yield while minimising P loss in order to protect surface water quality in the TGR region.

Genotypic differences in zinc efficiency of Chinese maize evaluated in a pot experiment.

BACKGROUND: Zinc (Zn) deficiency, a major problem limiting crop production worldwide, is common on calcareous soils of China. Using such a Zn-deficient soil supplied adequately with plant mineral nutrients, with or without Zn, 30 Chinese maize genotypes were grown for 30 days in a greenhouse pot experiment and assessed for Zn efficiency (ZE), measured as relative biomass under Zn-limiting compared with non-limiting conditions. RESULTS: Substantial variation in tolerance to low Zn nutritional status was observed within the maize genotypes. Tolerant genotypes did not show Zn deficiency symptoms at the studied early seedling growth, and there was a well-defined relationship between shoot dry matter and the ZE trait. ZE values ranged on average from 45 to 100% for shoot dry weight. Under low available soil Zn conditions, shoot and root dry weights, shoot Zn concentration and content, leaf superoxide dismutase (SOD) activity, leaf area and plant height were all correlated with ZE. Shoot Zn and phosphorus (P) concentrations were negatively correlated. CONCLUSION: Three genotypes (L55 × 178, L114 × 178 and Zhongnong 99) were identified as highly Zn-efficient and three (L53 × 178, L105 × 178 and L99 × 178) as very low in ZE. This selection allows further work to evaluate ZE based on grain yield and grain Zn concentration, including field experiments likely to benefit farmers producing maize on Chinese soils low in available Zn.