[permaculture] Fwd: [SANET-MG] Improving the nutritional quality of crops

Lawrence F. London, Jr. venaurafarm at bellsouth.net
Tue May 10 11:44:52 EDT 2011

-------- Original Message --------
Subject: [SANET-MG] Improving the nutritional quality of crops
Date: Tue, 10 May 2011 11:36:56 -0400
From: Joel Gruver <jgruv at HOTMAIL.COM>

Hello folks,

the following abstracts are a small window into current research on 
improving the nutritional quality of crops.

Gregorio GB. 2002. Progress in breeding for trace minerals in staple 
crops. J Nutr. 132(3):500S-502S.

Staples are not considered an important source of minerals in the diet. 
  However, because of high staple consumption, any increase in mineral 
concentration might well have a significant effect on human nutrition 
and health. The nutritional quality of staple crops (rice, cassava, 
wheat, maize and beans) can be improved by breeding. Studies have shown
the potential to exploit the genetic variation in seed concentration of 
iron and other minerals without the general negative effect on yield of 
adding new traits. The relationship between yield and mineral 
concentration may be positive, particularly in mineral-deficient soil. 
Initial evaluations have shown that some crop varieties have high Fe, Zn 
and carotene in their edible portions. The next step for conventional 
breeding will be to study the genetics of trace mineral inheritance to 
determine the best selection technique. Initial investigations of the
genetics for high iron in rice have indicated a complex mode of 
inheritance, demonstrating additive and dominant gene and environmental 
effects. Breeding strategies have been developed based on these genetic 
findings. The use of biotechnological tools, such as molecular 
marker-assisted selection, will significantly increase the pace and 
prospects of success for breeding to improve the nutritional value of 
staple food crops.

Holtz C. 2009. The potential to improve zinc status through 
biofortification of staple food crops with zinc. Food Nutr Bull. 30(1 

Biofortification is an agricultural strategy that aims to increase the 
content of select micronutrients, including zinc, in staple food crops 
such as rice,  wheat, maize, pearl millet, and others. When consumed 
among zinc-deficient populations, zinc-biofortified staple foods should 
  improve the adequacy of zinc intakes and hence reduce the risk of 
dietary zinc deficiency. Several conditioning factors will contribute to 
the potential for this strategy to meet its goal, including the 
additional amount of zinc that can be bred into the staple crop food, 
the amount of zinc that remains in the staple crop food following usual 
  processing methods, and the bioavailability of zinc from the staple 
crop food in the context of the usual diet. Reduction of the phytate 
content of cereals with the use of agricultural techniques is a 
potential  complementary strategy for improving the bioavailability of 
zinc. The feasibility of biofortification to result in a meaningful 
increase in the adequacy of population zinc intakes and to reduce the 
consequences  of zinc deficiencies still needs to be determined through 
efficacy trials. At the program level, the ability to widely disseminate 
biofortified crop varieties and the willingness of farmers to adopt them 
will also affect the magnitude of the impact of this strategy.

Alloway BJ. 2009. Soil factors associated with zinc deficiency in crops 
and humans.  Environ Geochem Health. 31(5):537-48.

Zinc deficiency is the most ubiquitous micronutrient deficiency problem 
in  world crops. Zinc is essential for both plants and animals because 
it is a structural constituent and regulatory co-factor in enzymes and 
proteins involved in many biochemical pathways. Millions of hectares of 
  cropland are affected by Zn deficiency and approximately one-third of 
  the human population suffers from an inadequate intake of Zn. The main 
soil factors affecting the availability of Zn to plants are low total Zn 
contents, high pH, high calcite and organic matter contents and high 
concentrations of Na, Ca, Mg, bicarbonate and phosphate in the soil 
solution or in labile forms. Maize is the most susceptible cereal crop, 
  but wheat grown on calcareous soils and lowland rice on flooded soils 
are also highly prone to Zn deficiency. Zinc fertilizers are used in the 
prevention of Zn deficiency and in the biofortification of cereal

Broadley MR et al. 2006. Biofortification of UK food crops with 
selenium. Proc Nutr Soc. 65(2):169-81.

Se is an essential element for animals. In man low dietary Se intakes 
are associated with health disorders including oxidative stress-related 
conditions, reduced fertility and immune functions and an increased risk 
of cancers. Although the reference nutrient intakes for adult females 
and males in the UK are 60 and 75 microg Se/d respectively, dietary Se
intakes in the UK have declined from >60 microg Se/d in the 1970s to 35 
microg Se/d in the 1990s, with a concomitant decline in human Se status. 
This decline in Se intake and status has been attributed primarily to 
the replacement of milling wheat having high levels of  grain Se and 
grown on high-Se soils in North America with UK-sourced wheat having low 
levels of grain Se and grown on low-Se soils. An immediate solution to 
low dietary Se intake and status is to enrich UK-grown food crops using 
Se fertilisers (agronomic biofortification).
Such a strategy has been adopted with success in Finland. It may also be 
possible to enrich food crops in the longer term by selecting or 
breeding crop varieties with enhanced Se-accumulation characteristics 
(genetic biofortification). The present paper will review the potential 
for biofortification of UK food crops with Se.

Johnson CC et al. 2010. Symposium on 'Geographical and geological 
influences on nutrition': Factors controlling the distribution of 
selenium in the environment and their impact on health and nutrition. 
Proc Nutr Soc. 69(1):119-32.

Se is essential to human and animal health but can be toxic in excess. 
An interest in its geochemistry has developed alongside a greater 
understanding of its function in a number of health conditions. Geology 
exerts a strong control on the Se status of the surface environment; 
low-Se rock-types (0.05-0.09 mg Se/kg) make up the majority of rocks 
occurring at the Earth's surface, which in turn account for the 
generally low levels of Se in most soils. However, there are exceptions 
such as associations with sulfide mineralisation and in some types of 
sedimentary rocks (e.g. black shales) in which contents of Se can be 
much higher. Baseline geochemical data now enable a comparison to be 
made between environmental and human Se status, although a direct link 
is only likely to be seen if the population is dependent on the local 
environment for sustenance. This situation is demonstrated with an
example from the work of the British Geological Survey in the 
Se-deficiency belt of China. The recent fall in the daily dietary Se 
intake in the UK is discussed in the context of human Se status and 
declining use of North American wheat in bread making. Generally, US 
wheat has ten times more Se than UK wheat, attributed to the fact that 
soils from the wheat-growing belt of America are more enriched in Se to 
a similar order of magnitude. In agriculture effective biofortification 
of crops with Se-rich fertilisers must be demonstrably safe to the
environment and monitored appropriately and baseline geochemical data 
will enable this process to be done with confidence.

Joel Gruver
School of Agriculture
Western Illinois University
jgruv at hotmail.com

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