Sampling Stomatal Density in Alfalfa1
- J. R. Carlson,
- R. L. Ditterline,
- J. M. Martin and
- R. E. Lund2
Sample size requirements for stomatal density studies in alfalfa (Medicago sativa L.) are not documented. This study was conducted to refine sampling techniques and to determine whether the sampling required to estimate stomatal density is too extensive to use this trait as a possible rapid screening criterion for drought resistance in alfalfa.
Stomatal and epidermal cell counts were made on abaxial and adaxial leaflet surfaces sampled at three nodes from 10 stems of five alfalfa plants. These plants differed significantly in stomatal densities on abaxial and adaxial leaflet surfaces. Leaflets from the uppermost node sampled had higher stomatal densities than those from lower nodes.
Variability from counts on leaflets from stem to stem rather than variability in counts from microscopic field to microscopic field within a leaflet contributed most to overall imprecision in estimation of mean counts per plant. To increase precision and efficiency, efforts should thus be directed toward sampling leaflets on more stems and not toward more fields on a leaflet. Number of stem samples required to detect given differences between plants at specified probability levels have been tabulated.
Due to the large level of within-plant variability for stomatal density in alfalfa, we decided that the sampling required was too extensive to pursue this trait in a breeding program for drought resistance.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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