Induced colchiploidy in Petunia hybrida Hort. Morphocytogenetical studies.

Abstract

Increase in the productivity or improvement in the quality of a plant by the use of fertilizers has limitations while these aspects can be achieved with greater assertion and to a long range advantage by genetical means. Of these the application of the methods of selection, hybridi zation and polyploidy had been most fruitful in bringing about all round betterment in many cases of agricultural, horticultural or even wild plants. Petunia hybrida Hort. is a common ornamental plants grown for its beautiful flowers which range in colur from white to deep red or purple (Bailey 1958). With the increase of the ploidy level all or most of these can be achieved although they may be associated with some disadvantage such as poor seed setting. However, reduce seed setting or such disabilities may assume lesser importance in this orna mental because the plant has too many seeds per capsule. In the present experiment, P. hybrida (pink) has been selected to induce autoploidy to observe the following objectives: Lengthening of flowering period, increasing the colour diversity and improving the size and keeping quality of flowers. Materials and methodsThe seeds of Petunia hybrida Hort. (pink) Vilm. has been utilized in the present study and collected from the plants grown for several successive generations in the botanical graden of the university. Tested for their diploid character and normal feature of meiosis. The col chicine treatment was applied on apical portion of the plant (See Singh and Roy 1984).After treatment, the dimension of the plant parts changed and these were documented after measuring the plant height, internodal length, leaf (L/W), stomatal size, flower size and seed setting (Average of 10 plants in each case).For meiotic studies, flower buds of different treatment plants were fixed in acetic-alcohol (1:3) with a few drop of ferric chloride in it to improve staining. Squashes were made per manent by t-butyl alcohol schedule.Heating the pollen grains in a drop of 1% acetocarmine solution, those which suitably stained were taken as fertile and the empty shrunken ones as sterile. Fertility percentage was scored on the average of 200 pollen grains. ObservationsVarious concentration of colchicine (0.20-0.50%) was applied on the apical bud and the 0.25% concentration was found effective in inducing the maximum number of tetraploid plants. Out of thirty plants were treated with above solution, 63.33% plants were survived and only 30% turned out as tetraploid (Table 1). Seeds obtained from induced tetraploids by selfing were sown in the field and plants of C2 generation were also found to be tetraploid on being cytologically investigated. Observations on induced autotetraploidy in P. hybrida was extended over first (C1) and second (C2) generation using suitable parameters.

Induction and Identification of Polyploidy by Colchicine Treatment in <i>Lilium regale</i>

“…The results of survival rate agree with the work of Heo et al (2016) who reported the negative effect of high colchicine concentration on survivability in L. leichtlinii plantlets. However, Singh and Roy (1988) also reported high colchicine concentration can cause the death of plantlets by damaging to several parts of cells. Many other researchers demonstrated colchicine had a negative toxic effect on explants and decreased the survival and regeneration rate of cultures (Jähne and Lörz 1995, Cohen and Yao 1996, Van Duren et al 1996, Song et al 1997.…”

Meiotic Behaviour and Pollen Fertility in Colchiploid Zea mays L.

“…It is generally assumed that, the number of quadrivalents is governed by the size of the chromosomes, chiasma frequency and excess of chromosomes within the cell which interfare with normal pairing. The less number of quadrivalents have been also reported in sunflower (Dhesi and Saini, 1973), Verbnea (Arora, 1940), Portulaca (Singh, 1979), Helianthus annuus (Gupta and Roy, 1986), Petunia hybrida (Singh and Roy, 1988), Solanum Khasianum (Bhatt, 1977), Gossypium (Beasley, 1940). The chiasma initiation at telomeric sites are possible and interdependence of chiasmata in a bivalent (as evident from dominance of rod bivalents in autotetraploids) reduces the chances of quadrivalent formation in tetraploids leading to cytogenetic diploidization of colchiploids (Lavania, 1986).…”