Morphological and Cytological Studies on a Radiation Induced Polyploid in <i>Capsicum annuum</i> Linn

Abstract

In the course of mutation induction studies on Capsicum annuum Linn., an autotetraploid plant was observed in the M2 population raised from gamma ray irradiated seeds.The present paper deals with morphological and cytological studies on this polyploid. Material and methodsThe variety of Capsicum annuum Linn. used in this study is characterized by attractive purple fruits (Fig. 1). Genetically pure seeds were obtained by selfing for three generations. These were subjected to gamma rays at dose levels ranging from 10 to 15kR. The treated seeds were sown in pots and later transplanted to the field. The resulting M, plants were selfed. Each plant was harvested sepa rately and its progeny (M2) raised in the field. Among the progenies of the 10kR treated plants, one plant was found to be an autotetraploid. Observations on growth, morphological features, flowering and fruit setting of the polyploid were recorded.Cytological studies were carried out from flower buds fixed in 1:3 acetic-alcohol and smeared in acetocarmine.Studies on pollen mitosis were carried out from hematoxylin stained preparations.Pollen sterility was determined from aceto carmine-glycerine mounted slides. Results Morphological studiesThe polyploid was characterized by slower and stunted growth (Fig. 2). The leaves were thicker, broader, large sized (Fig. 3) and deep green in colour as compared to those of the controls. As in other polyploids, the epidermal cells of the palisade and spongy parenchyma as well as the stomata were larger.Flowering was delayed in the polyploid. The flowers borne on the polyploid were conspicuously larger and a general enlargement of the floral structures was noticeable (Fig. 4). Increase in the number of petals and stamens was also observed in many cases. Abnormal flowers showing dissected floral parts or rudimentary structures were also present (Fig. 5).The tetraploid was sterile. Though many flowers were produced, only two fruits were formed. The fruits were much smaller than those of the control plants

Colchiploidy in Lindernia crustacea (L.) F. Muell.

“…In addition to quadrivalents trivalents were also observed in few pollen mother cells. Pre sence of trivalent configuration in tetraploids have also been reported by Raghuvanshi and Singh (1977) and Indira and Abraham (1977).…”

Cytomorphological studies in an induced polyploid of Hevea brasiliensis Muell. Arg.

“…1976). The length of the petiole of polyploid was comparatively more, especially in the base of the storey, enabling more exposure of the leaves to sunlight, The floral parts were also larger than those of the normal plants as in the case of induced polyploids of Capsicum (Indira and Susan Abraham 1977) and Matricaria (Arora and Mad -husoodanan 1981).…”

Induction, identification and genetics analysis of tetraploid Actinidia chinensis

“…Tetraploid plants show some typical morphological characteristics, like stunted growth and presence of larger, thicker, dark green and larger stomata [67,68]. Morphological difference was also found between diploid plants and their tetraploid plants in the other research of kiwifruit [8,60].…”