Genetic variation and changes with ontogeny of osmotic adjustment in sunflower (Helianthus annuus L.) |
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Authors: | C. A. Chimenti A. J. Hall |
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Affiliation: | (1) IFEVA, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, 1417 Buenos Aires, Argentina |
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Abstract: | Summary Intraspecific variation for osmotic adjustment in sunflower was examined using a collection of 33 genotypes of different origin which were exposed to water stress at the 8-leaf stage. Changes in osmotic adjustment with ontogeny were also evaluated in the pre- and post-anthesis phases using seven genotypes drawn from this collection. Estimates of osmotic adjustment were derived from measurements of leaf relative water content (RWC) and osmotic potential () during a period in which the soil was allowed to dry out gradually. The degree of osmotic adjustment, expressed as the value of RWC for a of –1.7 MPa (RWCe), was derived from the ln RWC/ln relationship. Both monophasic and biphasic ln RWC/ln relationships were found. Irrespective of the form of the relationship, all genotypes at the 8-leaf stage showed some degree of osmotic adjustment. This was also true for the cultivars included in the subset examined in pre- and post-anthesis phases. Significant differences (P=0.05) in RWCe were found between extreme genotypes in all three phases.Significant (P=0.05) linear relationships were found between RWCe measured in the 8-leaf stage and that measured in the pre- and post-anthesis phases, establishing the viability of measurements in the 8-leaf stage as a means of selection for osmotic adjustment in later developmental stages. Genotype rank order was stable (P=0.01) across the three ontogenetic phases examined.Abbreviations ETp potential evapotranspiration - osmotic potential - RWC relative water content - RWCe value of RWC for a of –1.7 MPa |
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Keywords: | sunflower Helianthus annuus osmotic adjustment genetic variation ontogenetic changes |
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