|Author:||Turner, N. C.|
|Book Group Author:||NA|
Mediterranean environments are characterized by cool wet winters and hot dry summers. While native vegetation in Mediterranean-climatic zones usually comprises a mixture of perennial and annual plants, agricultural development in the Mediterranean-climatic region of Australia has led to the clearing of the perennial vegetation and its replacement with annual crops and pastures. In the Mediterranean environments of southern Australia, this has led to secondary (dryland) salinization. To slow land degradation, perennial trees and pasture species are being reintroduced to increase the productivity of the saline areas. The annual crops and pastures that form the backbone of dryland farming systems in the Mediterranean-climatic zone of Australia are grown during the cool wet winter months on incoming rainfall and mature during spring and early summer as temperatures and rates of evaporation rise and rainfall decreases. Thus, crop and pasture growth is usually curtailed by terminal drought. Where available, supplementary irrigation in spring can lead to significant increases in yield and water use efficiency. To sustain production of annual crops in Mediterranean environments, both agronomic and genetic options have been employed. An analysis of the yield increases of wheat in Mediterranean-climatic regions shows that there has generally been an increase in the yields over the past decades, albeit at a lower rate than in more temperate regions. Approximately half of this increase can be attributed to agronomic improvements and half to genetic improvements. The agronomic improvements that have been utilized to sustain the increased yields include earlier planting to more closely match crop growth to rainfall distribution, use of fertilizers to increase early growth, minimum tillage to enable earlier planting and increase plant transpiration at the expense of soil evaporation, rotations to reduce weed control and disease incidence, and use of herbicides, insecticides and fungicides to reduce losses from weeds, insects and disease. Genetic improvements include changing the phenological development to better match the rainfall, increased early vigour, deeper rooting, osmotic adjustment, increased transpiration efficiency and improved assimilate storage and remobilization. Mediterranean environments that are subjected annually to terminal drought can be both environmentally and economically sustainable, but to maximize plant water use efficiency while maintaining crop productivity requires an understanding of the interaction between genotypes, environment and management.
|Pages:||139 - 147|
|Journal:||Annals of Applied Biology|
annuals, arid lands, assimilation, chemical control,climatic factors, crop yield, cultural control, drought, dry farming,fertilizers, fungicides, genetic improvement, growth, herbicides, insectpests, insecticides, irrigation, Mediterranean climate, osmosis, pastureplants, pastures, phenology, plant disease control, plant diseases,plant pests, plant water relations, planting date, rain, rooting,rotations, sustainability, tillage, transpiration, vigour, water stress,water use efficiency, weed control, weeds, Australia, insects, plants,Hexapoda, arthropods, invertebrates, animals, eukaryotes, Australasia,Oceania, Developed Countries, Commonwealth of Nations, OECD Countries,crop rotation, dryland farming, grazing lands, rainfall, rotationalcropping, soil cultivation, vigor, watering, weedicides, weedkillers,Field Crops (FF005) (New March 2000), Forage and Fodder Crops (FF007)(New March 2000), Plant Breeding and Genetics (FF020), Plant WaterRelations (FF062), Plant Production