Preamble

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Ralph Slatyer

Visiting Fellow, Research School of Biological Sciences, ANU, Canberra

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Professor Ralph Slayter, AC, FAA, FRS, FTSE

Green plants provide the biological energy for a dynamic biosphere. All organisms depend upon green plants for their livelihood.

Nowhere is this dependence more evident than with human beings since nearly half the products of global photosynthesis are channeled directly through human populations or used indirectly by us for the myriad of activities that we undertake.

Our overall impact on the environment is the product of the total number of people and the average impact of each person. Continued growth in population, and in the demands of individual people, are not only increasing the overall impact but are resulting in a reduction in the area of arable land and in land degradation, thereby reducing the scope to provide for human needs.

In many regions of the world, particularly those already overpopulated in terms of rural productivity and the carrying capacity of their land, these factors are resulting in political, economic and social upheaval.

Clearly this increasing overall impact must be reined in. But for the next few decades at least, global population will inevitably continue to grow, by which time it may be double the present level. There is therefore a pressing need to reduce the impact per person and this applies more to agriculture than to many other human activities.

To provide for future generations agricultural ecosystems will have to be ecologically sustainable and the total sustainable production must be adequate for our increased numbers. It follows that sustainable yields from existing agricultural eco-systems will need to increase, and soils and climates now regarded as marginal or unsuitable for agricultural production may need to be brought into cultivation.

Climate change is an additional issue. On the positive side it may lead to more favorable climatic conditions and increased yields in some existing agricultural areas and may result in some areas now regarded as climatically marginal for agriculture being brought into cultivation. On the negative side it may result in the climate of some existing arable areas becoming marginal or unsuitable for agriculture. Furthermore, climate change may shift favourable climatic zones into areas of less fertile soils.

Conservation of biodiversity is an essential requirement for ensuring ecosystem function at a local, regional and global level. Biodiversity is threatened by habitat destruction and modification, and by fragmentation of areas of natural habitat. Gene pool erosion and species extinction can occur as a direct result of these changes and indirectly as fragmentation and isolation of previously intact areas reduce habitat requirements below the minimum needed for population and species viability.

Climate change exacerbates this situation since habitat modification and fragmentation hinder, and may prevent, natural migrations which have been a primary mechanism by which species have adapted to altered environments and gene pools have evolved.

These complex issues present a major challenge to plant scientists, particularly since the solutions must endure not just for one or two generations but indefinitely if human beings are to live on earth in peace and harmony.

The title and subtitle of this book, Plants in Action: Adaptation in Nature, Performance in Cultivation, succinctly summarise the challenge to plant scientists for the future. For plant scientists to respond to this challenge and to play a role in improved rural production and biological conservation, we need to understand better the mechanisms by which changes in the physical environment affect physiological processes, the manner in which genetic control over physiological processes is exercised, and the means by which genomes can be modified to produce cultivars which can be successful in modified environments.

And for ecological sustainability, it will also be necessary to understand better the mechanisms by which changes in the physical environment affect the interactions between species and determine the range and limits of species distribution.

There is a wealth of genetic material in the world’s biodiversity to draw upon in modifying the genomes of existing and future cultivars, thus providing a basis for better adapted cultivars and sustainable agricultural ecosystems in climates and on soils at present regarded as unsuitable for agriculture. There is also the prospect of modifying the genomes of native species with a view to ameliorating the effects of fragmentation and degraded habitats on gene pool erosion.

Can the plant science community meet these challenges? There is clearly much to be done and much to be learned, but already there have been substantial achievements. Among these are the success stories in nutritional physiology associated with the discovery of trace elements. Research into salinity tolerance and the development of forest and crop cultivars which can tolerate saline substrates has shown the potential for addressing what were thought to be intractable environmental conditions.

There also continue to be major advances in the portability and accuracy of instruments used for physiological research so that experiments and observations previously restricted to laboratories can now be conducted directly in the field. This is enriching the whole field of ecophysiology and is opening the way for physiological information to be applied more directly to agricultural and ecological problems.

On the other hand, major challenges remain. Much remains to be learned about morphogenesis and the effect of water and heat stress and enhanced CO2 levels on plant growth and development. The control of floral initiation remains elusive yet has enormous consequences for the development of cultivars with different times to maturity. Such developments would open the possibility of multiple cropping in favourable environments with obvious implications for yield improvement.

Stomatal function is a vital factor in mediating the response of plants to water stress and to high CO2 environments and offering scope for enhanced water use efficiency. Yet our present understanding of stomatal function is not adequate to explore the possibilities of utilising genetic variation as a tool in modifying the stomatal characteristics of cultivars. Even our understanding of the effect of environmental factors on photosynthesis and respiration, probably the most studied and best understood of all physiological processes, requires strengthening.

This book will be of particular value to students, and to the plant science community generally, because genotype × environment interaction is a pervasive theme and it gives special emphasis to plant responses to environmental conditions and to stress environments generally. Its Australasian roots will ensure that it is relevant not just to the problems of developed countries but also to those of developing countries.

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