WATER STRESS IN TWO CAPSICUM SPECIES WITH DIFFERENT DOMESTICATION GRADE

Abstract

Seeds' germination is usually affected by water stress. The aim of this study was to compare the effect of water stress on the final germination percentage, mean germination rate, and epicotyl and hypocotyl lengths, and root:shoot ratio index of semi-domesticated Capsicum frutescens L. and cultivated C. annum L. pepper species. Seeds were exposed to eight levels of water potential (Y) induced by polyethylene glycol (PEG) 8000. Seed germination is usually affected by water stress. The aim of this study was to compare the effect of water stress on the final germination percentage, mean germination rate, epicotyl and hypocotyl growth, and root:shoot ratio index of semi-domesticated, Capsicum frutescens L., and cultivated, C. annuum L., pepper species. Seeds were exposed to eight levels of water potential (Ψ) induced by polyethylene glycol (PEG-8000). Capsicum annuum showed final germination percentage of 73%; however, no significant differences (P =0.01) were observed among Ψ treatments between species. Mean germination rate was lower for C. frutescens than for C. annuum. Variation in epicotyl and hypocotyl growth was observed between treatments, but no clear pattern was observed across Ψ treatments. Root:shoot ratio index was higher for C. annuum than for C. frutescens. Root:shoot ratio index differences were significant among Ψ treatments in the case of C. annuum, while for C. frutescens differences were not significant. Root:shoot ratio index was a reliable drought tolerance indicator for both pepper species. An increase in root:shoot ratio as a function of water stress levels suggest a priming effect on C. annuum improving seedling growth under water stress. In the case of C. frutescens, no decrease effect on root:shoot ratio index was evident suggesting an adaptive characteristic to growth under arid and semiarid climatic conditions in Baja California Sur.