By Dr. Mohammed Sa’id Berigari, Senior Soil and Environmental Scientist, USA, June 15/ 2012.
Agronomy is a highly integrative group of sciences using several disciplines of crop and soil sciences including plant breeding, physiology, transgenic crop improvement, soil chemistry, fertility, physics, microbiology, and other related genetic and environmental aspects of crop and soil managements. The primary objective of such integrated disciplines is to develop improved varieties of agronomic, turf, and forage crops to continuously produce sufficient food, feed, fuel, and fiber for the growing world population.
In spite of great scientific achievements in these areas, the world today faces growing challenges of large scale food insecurity and malnutrition, adverse impacts of climate change, environmental degradation, and heavy reliance on fossil fuel energy. Solutions to these challenges will be found with sustained investments globally from both public and private sectors at all levels to address such challenges. The agronomists will provide the tools, essential technologies, and solutions required to address these challenges.
Crop Adaptation to Climate Change: Drought is number one limitation to crop productivity worldwide. With climate change, the incidence and duration of drought and other abiotic and biotic stresses on major crops will increase in many areas of the globe, adversely affecting crop yields and food supply. Solutions to such a complex problem can best be addressed by research teams of scientific expertise-breeders, physiologists, molecular geneticists, and soil and environmental scientists.
The majority of the progenitors of most crops were developed under periodical dry conditions when drought tolerant genes already existed in most crop germplasm or in their wild relatives. However, these important genes have not all survived in modern cultivars because agriculture has concentrated on breeding varieties adapted to favorable environments and to irrigation. The need is urgent to incorporate genes for drought tolerance with predictions of more widespread and severe droughts. Agronomists must produce more of “crops-per-drop” of water and develop sound strategies to share water resources at the rural and urban interface where water can be bought and diverted to nonagricultural sectors.
Crop Resistance to Biotic Stresses: Organisms that cause stresses in crops continually adjust their pathogenic mechanisms to further invade plant’s limited defenses. The rate of adjustment by some pathogens has accelerated with new adopted intensive management practices and climate change that adversely affect environmental conditions. Moreover, crop uniformity can increase genetic susceptibility to various pests. For instance, US soybean cultivars are almost uniformly susceptible to new biotic stresses of aphids and soybean rust.
The management practices that retain plant residues on the field result in increased soil organic matter, improved soil properties, and additional sequestered carbon; however, they also create an environment where pathogens can prosper and cause reductions in crop yields. Examples include pathogens like gray leaf spots of corn whose inoculum grows on previous crop residue. And also, aflatoxins carcinogens are produced by fungi whose proliferation increases in stress environments of drought, high temperatures, and /or high humidity. Therefore, there is urgent need for plant genomic tools that can identify novel resistance genes and rapidly incorporate them into improved cultivars.
Management Practices for Resource-Limited Systems: Agricultural productivity is limited in many parts of the world by poor soil conditions and high fertilizer prices. However, soil tilth issues including high soil pH, Al toxicity, and salinity increases are not easily overcome by conventional high-input practices. Consequently, new crop varieties and management practices are needed that reduce reliance on agricultural inputs and remedy common soil problems.
Research teams with multidiscipline will be the key to solutions of those problems because they have the expertise to improve N fixation in legume crops and improve nutrient uptake and use and can develop crop varieties that are tolerant to such limitations. Research teams should focus on efficient and reliable methods to identify desirable crop germplasm that has the right genetic makeup to deliver these improvements. Coupled with technology transfer, these efforts will increase yields and quality of food crops and enhance food security and alleviate nutritional deficiencies worldwide.
Crop Management Systems: Agriculture always adapts to change. Consider the revolutionary changes in agriculture resulting from such practices as irrigation, fertilizer, weed, insect, and disease control, and modern tillage systems. There is a need to make similar changes to cropping systems as we face future changes in climate and an increased need for efficient use of resources. Nearly 80-90% US food is produced on large scale farms, commonly operated by family entities.
To maintain greatest advances and productivity, environmental sustainability, and profitability new crop management information and technology systems are required to be adopted for various farms. Such innovations should enhance integrated pest management and water and soil conservation in ways that are practical and convenient for large scale farms. There are numerous tools that can make this possible, like remote sensing and other off site-site monitoring. The synergy between variety development and crop management research has resulted in yield increases for the last half century. The interplay between genetics and environment must be optimized continually to produce food, feed, fiber and fuel worldwide.
Biofuel Production: Biofuel production from crop plants is expected to increase in the coming years. Crops in addition of being sources of oils and proteins, they are also, sources of various carbohydrates including sugars, starches, and cellulose that can be converted to biofuel ethanol. All biofuel crops should be grown in a way that optimize biomass yield while minimizing inputs of fertilizer, irrigation, and pesticides.
It is essential to minimize the competition between biofuel crops and human food crops. Thus, ethanol-based biofuel crops will be and should be grown on marginal soils and to leave more arable soils for human food crops. Since biodiesel is produced from seed oil, biofuel must be produced from existing seed crops. Therefore, biofuel research needs to concentrate on oil seed crops that are used less for feedstock but very productive such as peanuts. The composition of biofuel crops will need to be modified to make them easy to convert to energy use, but these modifications may make more vulnerable stresses and pests.
As a result there is a need 1) modify crop composition relative to requirement of processing, 2) increase yield in low-input production systems, 3)understand plant response to changes in the environment , in tandem with changes to composition for accurate modification, 4) understand the ecosystem services (carbon sequestration, water quality, wild life habitat, etc.) from perennial bioenergy crop production on arable and marginal soils, and 5) develop new production systems that thrive in low-input conditions.
Grand Challenge of Bioresources: Germplasm Collections are excellent treasure of genetic diversity and the foundation for all crop improvement programs. A germplasm collection for a single crop species may contain greater than 50, 000 distinct genetic plant types, yet the genomic profiles are not readily available, limiting application of information contained in the collections. However, new inexpensive technologies offer a low-cost remedy for developing detailed genetic profile to entire collection. As a result, new genomics information will enhance our ability to correlate plant’s genotype with its agricultural performance for plant breeding purposes in a way never before possible.
To translate the economically important diversity of germplasm collections into food and other agricultural products, it is critical to integrate the new genomics information with a series of field-breeding positions specifically targeted at “mining” germplasm collections. Field breeders will use hybridization and selection informed by genomics to produce novel, agronomically important genetic types that work effectively in agriculture. As a result, development of crops will be accelerated to avoid famines and market-place catastrophes resulting from fluctuations in rainfall, and pests, therefore enabling greater food security around the world.
1. Lauer, J.G.; et.al. 2012. The scientific grand challenges of the 21st century for the Crop Science Society of America. Crop Sci.Soc.Amer., 52(3): 1003-1010.
2. Lauer, J.G.; et al. 2012. Grand challenges for crop science. CSA (Crops, Soils, Agronomy) News, Magazine, Crop Sci.Soc.Amer., Soil Sci.Soc.Amer., and Amer. Soc. Agron.: 4-11.
Dr Berigari’s article is very interesting as he outlines the challenges that we face today in agriculture and food production in the face of climatic change, disease resistance etc., and increasing population demands. To compound the problem is the all too common loss of good agricultural land to urban and industrial development while less fertile land, or land that had been previously used for industry and is now waste, is ignored. Throughout the world there is a finite amount of agricultural land and it should be safeguarded for generations to come. I have always had an interest in genetics and in producing my own vegetables I try new F1 varieties that have been bred to be more suited to the warmer weather we now have. The recognition that old strains and varieties of crops offer a wealth of genetic variation that can be utilised in the production of new crops that are better suited to changing conditions. This valuable genetic resource can be maintained in seed banks such as the Millenium Seed Bank Partnership, Kew Gardens, London which works with numerous institutions throughout the world. As Mesopotamia saw the birth of agriculture I would suggest that efforts should be made to record the region’s domesticated and wild varieties of plants, not only to conserve them but in order to evaluate their potential use in the breeding of new crops that are adapted to local conditions.