|Abstract or Summary
- A study of the SH and SS content levels during vernalization of
wheat was made. In order to carry out the study, a rapid analytical
technique was worked out which allowed fast sequential analyses of
the samples of wheat tissue.
Two techniques were used: a) an amperometric titration
method and b) a fluorescence quenching method.
The amperometric titration method consisted of adding aliquots
of samples of wheat tissue homogenate to the system and noting the
decrease in current, due to a tie-up of Ag⁺ by the SH groups of the
sample. The system consisted of a rotating platinum electrode connected
to a mercury-mercuric oxide reference cell. The supporting
electrolyte was a 0.14M solution of tris at pH 7.4.
The fluorescence quenching method consisted of adding aliquots
of sample to a solution of fluorescien mercuric acetate (FMA) in a
1N NaOH media. The SH and SS groups reacted with FMA in a one:one ratio. The reacted FMA was unable to fluoresce, thus
making possible a quantitative assay for SH and SS groups in solution.
Red Bobs, a spring wheat, and Elgin, a winter wheat, were
grown in the dark at 3° C. and at 20° C. The SH and SS contents
of the shoots were measured throughout a period of five weeks in
the group grown at 3° C. and a period of 48 hours in the group grown
at 20° C.
The results of the analyses showed that the SH, SS, and SH+SS
contents based on fresh weights were present in greater quantities
in the tissues of Red Bobs grown at 20° than in the Elgin tissues
grown at 20°. The high SH and SS concentrations present in the
warm-grown Red Bobs tissues were due to a high concentration of
protein extracted from that tissue. The SH, SS, and SH+SS contents
per fresh weight were quite similar in the cold-grown tissues of
both varieties during the growth period. These constituents present
in the cold-grown tissues occurred in quantities that were less than
those found in warm-grown Red Bobs tissues and greater than those
present in the warm-grown Elgin tissues. Both varieties grown at
both temperatures showed a similar decrease in SH and SS contents
based on fresh weights as maturation progressed.
The analyses indicated that SH, SS, and SH+SS contents based
on protein levels were similar in Elgin and Red Bobs tissues grown
at 20°. Both varieties grown at 3° contained greater concentrations of SH, SS, and SH+SS groups based on protein levels than those present
in the tissues grown at 20°. The Elgin tissues at 3° underwent a
fluctuation of these values as growth progressed, while the Red
Bobs tissues at 3° maintained relatively constant levels of SH, SS,
and SH+SS contents based on protein levels present during the growth
It was concluded that the levels or patterns of SH and SS groups
in young spring and winter wheat shoots were not correlated with
the capacity of these plants to flower.