Submitted to: Agronomy for Sustainable Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2009
Publication Date: 4/15/2010
Citation: Khoshgoftarmanesh, A.H., Schulin, R., Chaney, R.L., Daneshbakhsh, B., Afyuni, M. 2010. Micronutrient-Efficient Genotypes for Crop Yield and Nutritional Quality in Sustainable Agriculture: A Review. Agronomy for Sustainable Development. 30:83-107. Interpretive Summary: Grains differ in microelement concentrations dependent on the soil where they were produced, the genetics of the cultivar, and management conditions. Variation in microelement composition of seeds has become increasingly recognized as important both in yield of the crop grown from the seeds and the nutritional quality of the seeds as human or livestock feed. Iron and zinc deficiency of humans is a significant problem for perhaps 40% of humans, especially those in developing countries. Improvement of the concentration of bioavailable Zn and Fe in seeds is believed to be the only practical way to improve health of the populations who depend on grains for the bulk of their diets. In both cases, genetic variation in plant uptake of the element from soil and transport of the element to seeds, varies enough that breeders are working to improve crop genetics to solve human nutrition problems. This paper reviews the evidence on the need for such breeding programs, and the effectiveness. Testing the bioavailability is the most difficult part of this crop improvement program. In the case of improving crop yields when the crops are grown on soils with low plant available levels of iron, zinc, manganese and some other micronutrients, crop breeding is also needed. Breeding can both improve utilization of absorbed elements within the plant, and transport more of the element to the edible grain. In some cases, spraying plants with soluble Mn or Zn during seed filling can increase seed levels of these elements enough to substantially improve growth of the next generation from the seed produced. Thus seed quality can be improved to improve yields by “seed priming”. Ultimately, improving the genetics of crops so that the plants can produce higher quality edible grain and high yields from soils with normal levels of micronutrients is an important goal toward which progress is being made.
Technical Abstract: Micronutrient deficiency is a limiting factor for crop productivity in many agricultural lands worldwide. Furthermore, many food systems in developing countries can not provide sufficient micronutrient contents to meet the demands of their people, especially low-income families. Several approaches (e.g., soil fertilization) are possible to correct micronutrients deficiency. Considering ecological concerns, sustainable agriculture is looking for more environmental-friendly and cost effective approaches. Cultivation and breeding of micronutrient-efficient genotypes in combination with proper agronomic management practices seems to be the most sustainable solution to combat micronutrient deficiency. Nutrient efficiency has been defined in different ways. In most cases, the crop yield has been considered as the main basis for separating micronutrient-efficient and inefficient genotypes, while micronutrient-efficient genotypes may even contain lower micronutrient concentrations in their edible parts than micronutrient-inefficient genotypes. In programs for selecting or breeding micronutrient-efficient cultivars, the stability in response to nutrient efficiency in different environments and relationships between crop productivity, mineral concentrations and other nutritional quality factors (e.g., concentrations of promoter and antinutrients) have to be considered. Combining crop productivity and grain quality aspects (total content and bioavailability of nutrients) in developing new micronutrient-efficient genotypes is necessary. The stress tolerance index, STI, can be used to identify genotypes that produce high yields under both non-stress and stress environments.