Study of in vitro propagation of male sterile chili pepper (Capsicum SP.)

Abstract

Chili pepper is a member of capsicum species, in which male sterile chili pepper is rarely found in the nature; however, it has been commercially used for F1 hybrid seed production. Chili pepper has been known to be recalcitrant to differentiation and regeneration under in vitro conditions. In this thesis, seeds of male sterile chili pepper were used as a source to produce in vitro plants. The micropropagation of these plants has been studied using both photomixotrophic (conventional) and photoautotrophic methods and designed in four experiments. Firstly, chili fruits were surface sterilized by javel (25-100%, v/v) or burned on the flame of alcohol lamp, then cultured under different lighting conditions (light or dark). No contamination rate and the highest survival rate (66.7%) were found in the treatment where fruits were burned on the flame of alcohol and cultured under lighting condition was the best. Secondly, nodal cuttings, with no leaf, were cultured onto the agar-based MS medium supplemented with sucrose (30 g L-1), Morel vitamins, 2 mg L-1 AgNO3, BA (3-4 mg L-1), IAA (0-0.2 mg L-1). Most shoots were induced in the MS medium supplemented with BA 4 mg L-1 and IAA 0.2 mg L-1. Thirdly, different culture methods (photoautotrophic or photomixotrophic) and different supporting materials (agar or vermiculite) affecting the growth of in vitro chili plants were studied. Chili plants were proved to grow well under photoautotrophic condition on agar as supporting material. Fourthly, macro elements in MS medium was altered to promote the photosynthetic ability and growth of in vitro chili plants; 2 levels of total nitrogen contents (40 or 60 mmol L-1) was combined with 3 different ratios of NH4+/NO3- (1:2, 1:3, 0:1). Among chili plants grew the best on the MS medium that contains 40 mmol L-1 total nitrogen contents with a ration 1:3 of NH4+/NO3. The results showed that male sterile chili pepper could be successfully multiplied under photoautotrophic condition. Keywords Chili pepper, javel, photoautotrophic methods of male sterile chili pepper, net photosynthetic rate, nitrogen content.