The results obtained indicate that morphological characters of pollen grain of the 346 and 502 inbred lines and their counterparts varied insignificantly (coefficient of variation (V)<10%). However, the variability range of such pollen grain characters as perimeter, area, and eccentricity in R1, MR1, and MR2 generations was significant (V>20%). In addition, the higher coefficients of variation were noted for waxy counterparts.
Analysis of variance revealed that variability of pollen grain characters studied was either genotype or gamma radiation dependent (Table 1).
Table 1. Share of variability of pollen
grain characters, %.
|genotype||gamma radiation||their interaction|
*** - P<0.001; * - P<0.05
However, the variability of width and eccentricity was to a large degree gamma radiation dependent. It is worth noting that variability of such a character as form factor proved to be mostly determined by the interaction of factors studied. For waxy counterparts the average values of such characters of pollen grain as perimeter, area, and eccentricity were found to be higher (Table 2).
Table 2. The average values of morphological
characters of pollen grain.
|Least significant difference (LSD 0.001 )||7.04||237.28||1.63||2.73||1.93||0.16|
In generations of regenerants derived from inbred lines studied the average values of perimeter, form factor, and eccentricity proved to be decreasing in comparison with control (Table 3).
Table 3. Pollen grain morphological
characters variability in generations of regenerants.
It was also found that morphological character variability of vegetative and generative cell nuclei in MR1 and MR2 generations was higher (14%<V<47%) in comparison with control and R1 generation. Analysis of variance showed the reliable dependence of variability of these characters on genotype, gamma radiation and their interaction. It should also be noted that the variability of characters studied (except eccentricity of generative cell nuclei) was more gamma radiation dependent (Table 4).
Table 4. Morphological character variability
of vegetative (V) and generative (G) cell nuclei of pollen.
|the share of variability determined by:|
|Characters||genotype||gamma radiation||their interaction|
|Form factor V||35.99***||51.68***||4.89*|
|Form factor G||9.44***||77.68***||5.46*|
p<0.05; **p<0.01; ***p<0.001
The average values of such characters as perimeter, width of vegetative cell nucleus and all morphological characters of generative cell nucleus were found to be decreasing for regenerants of waxy counterparts (Table 5).
Table 5. The average values of morphological
characters of vegetative (V) and generative (G) cell nuclei in dependence
|Form factor V||21.88||19.69||16.18||17.93||1.73|
|Form factor G||26.68||23.31||22.03||18.48||3.18|
In MR1 and MR2 generations the average values of characters studied proved to be increasing in comparison with control and R1 generation. In addition the plants of MR2 generation had the highest average values of male gametophyte characters studied (Table 6).
Table 6. Morphological character variability
of vegetative (V) and generative (G) cell nuclei of pollen among plants
of different generations.
|Form factor V||15.85||17.39||18.96||21.15||1.5|
|Form factor G||19.49||20.89||22.34||31.02||2.76|
In general, according to the results
obtained the pollen of regenerants and their progeny (especially those
derived from irradiated embryos) was found to differ from the male gametophyte
of inbred lines by the range of morphological characters studied.
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