Constitutive traits affecting plant performance under stress
1997
Blum, A.
The final integrated plant response to drought stress in terms of total biomass or economic yield is conditioned by genes which are expressed constitutively and genes which are stress-responsive and stress-adaptive. Genes expressed constitutively may be stress-responsive, but they are not, by definition, stress adaptive. This brief review discusses the impact, whether positive or negative, of several major plant constitutive traits on plant production under drought stress. For most crop plants there is a genotype x drought stress interaction for yield which is expressed when stress is severe enough, Besides well-watered conditions, a high yield potential is expressed also under moderate levels of stress. However, a high yield potential may be negatively affecting yield under severe stress. The possible reasons for this negative association are discussed. Plant phenology has been widely implicated in plant production under drought stress. Phenology determines plant characters which may impact plant water-relations, crop assimilation and reproductive integrity under drought stress. The roles of plant size, vigor and potential growth rate in affecting productivity under stress are not well resolved. Some of the positive and negative implications of plant size towards plant productivity under drought stress are considered. Carbon assimilation, storage and utilization are expressed constitutively and their impact on stress adaptation is becoming evident, such as the case of plant reserve utilization. Finally, molecular techniques are now used to achieve the constitutive overexpression of stress adaptive genes. The few available examples and their implications are mentioned.
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