Crop improvement for tropical and subtropical Australia: Designing plants for difficult climates

• Published in: Field crops research 1991, Vol.26 (2), p.113-139
• Main Authors: Lawn, R.J., Imrie, B.C.
• Format: Article
• Language: English
• Subjects: AMELIORATION DES PLANTES; AUSTRALIA; AUSTRALIE; BREEDING METHODS; CLIMA; CLIMAT; CLIMATE; ESTRES; FISIOLOGIA VEGETAL; FITOMEJORAMIENTO; GLYCINE MAX; METHODE D'AMELIORATION; METODOS DE MEJORAMIENTO; PHYSIOLOGIE VEGETALE; PLANT BREEDING; PLANT PHYSIOLOGY; SORGHUM BICOLOR; STRESS; VIGNA MUNGO; VIGNA RADIATA
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/0378-4290(91)90032-Q

The use of physiological understanding in crop breeding in northern Australia is discussed, and is illustrated with examples from several summer grain crops including soybean ( Glycine max — an oilseed). mungbean ( Vigna radiata/V. mungo — a grain legume) and sorghum ( Sorghum bicolor — a cereal). These, and most of the summer grain crops being developed in the region, are relatively recent additions to Australian agriculture, and in some cases to the tropics, or to mechanized agriculture in the tropics. Most are strongly sensitive to photoperiod and temperature. A primary aim, therefore, has necessarily been to improve their adaptation and subtropical environments characterized by generally warm temperatures and relatively short photoperiods. At the same time, constraints imposed by stressful temperature extremes, and frequent water-deficits as a result of limited and highly variable seasonal rainfall, have had to be addressed. The latter constraint has been compound by soils that often have limited water-storage capacity. Genetic improvement has been confounded by large and often nonsystematic genotype X environment ( g×3) interaction, which increases the testing necessary as a basis for selection. The most valuable contribution of physiological understanding has been to interpretation of g× e interaction in terms of biological, as opposed to statistical, models. Physiological interpretations have been both qualitative and quantitative in nature, and ‘models’ range from simple to complex, but nonetheless enable predictive inference to be drawn of the performance of particular genotypes in specific environments. Physiological research is thus being used to identify the key physiological and climatic constraints to productivity confronting crop improvement, to establish strategies for agronomic and breeding research, and to formulate ‘dynamic’ ideotypes to assist the breeder to match crop life-cycles to the sources and constraints of target environments. Physiological understanding also offers the potential to exploit traits conferring resistance to specific stresses but, to date that potential remains largely unrealized.