Shapiro, N. and A. B. Burdick
In vitro pollen studios concerned with evaluating radiation damage must strive for optimum conditions for germination and growth if interpretations are to be of value. A single, uniform pollen producing line (206) of L. pimpinellifolium was used. Fresh pollen samples were collected from greenhouse and control room grown plants. The greenhouse was maintained at 68 deg. F; the control room was equipped with artificial light of high intensity and tained at 70 deg. F - 57% RH. Maximum growth was obtained with a 17 hour day lenght. The table shows the results obtained during the summer of 1960.
Germination of line #206 pollen in various sugar or sugar-boron solutions (hanging drop method) when plants were grown under greenhouse and control room conditions
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Average per cent germination pollen at 3 hours^1 and
presence of bursting ()^2 in:
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Experi- 20% S^3 and 25% S and
ment 25 Bo^3 50 Bo 60 Bo 70 Bo 25 Bo 50 Bo 60 Bo 70 Bo
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Greenhouse
1 80(2) 80(1) 80(1) 85(0)
2 80(1) 55(0) 90(0) 55(l)
3 40(3) 80(2) 85(2) 85(2)
4 25(3) 55(3) 75(3) 20(3)
5 80(1) 75(0) 80(0) 80(0)
6 50(1) 40(2) 85(0) 80(1)
60(0) 65(0)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Control Room
1 85(2) 80(0) 80(0) 85(0) 90(1) 85(0) 90(0) 85(0)
2 90(2) 90(0) 70(1) 90(0) 90(0)
3 90(0) 90(0) 90(0)
4 85(l) 85(1)
5 80(2) 80(1)
6 90(0) 95(1)
7 85(0) 85(0)
8 85(1) 80(0)
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^1 Average % germination based on 2 slides, 100 grains per slide.
^2 Bursting of grains and pollen tubes, scaled as:
0 = little or none, 1 = some, 2 = moderate, 3 = severe.
^3 Bo = ppm boric acid. 20% S, 25% S = sucrose. Sucrose alone at
concentrations from 5% to 20% produced severe bursting and no
germination.
Line 206 was chosen for the experiment because it appeared to have pollen that
would germinate well under a variety, of conditiones. The differences shown
in the table are probably not significant, but the bursting differences
suggest that 50-60 ppm Bo gives best results. Pollen tube growth appeared to
be best using 25% sucrose + 60 ppm boron. Greenhouse grown samples were lees
reliable than those produced in the control room. Control room samples
germinated in 25% sucrose + 60 ppm boron were particularly uniform will tube
growth was generally better.