Responses of Cyperus brevifolius (Rottb.) Hassk. and Cyperus kyllingia Endl. to varying soil water availability

Different responses of Cyperus brevifolius and Cyperus kyllingia to varying soil water regimes were examined to explain their successful existence in a diverse range of habitats throughout the year in Indonesia. Thirty 43-day sprouts of each species were grown in three soil conditions, namely drought, field capacity, and flooding under greenhouse conditions. Plant height, leaf length, tiller number, and flower number were measured twice a week, from 45 to 98 days after sowing (DAS), while the other 12 traits were recorded at the end of the observation time. Ten out of the twelve traits were substantially influenced by the soil water content. Both species exhibited their best growth, production, and reproduction under field capacity conditions, and these traits were greatly subdued under drought conditions. Under drought conditions, both species manifested reduced growth and leaf expansion; however, stomatal aperture and frequency did not exhibit strong response to the soil water content. C. brevifolius showed a significantly greater biomass production and reproductive traits in field capacity and flooded conditions, but under drought conditions, growth was greatly hampered and only vegetative propagation occurred. On the other hand, C. kyllingia showed a higher tolerance to drought conditions, indicated by both a higher biomass and a higher number of flowers. The results obtained suggest that survival ability when faced with drought conditions was more apparent in C. kyllingia than in C. brevifolius, but where there was sufficient soil water, C. brevifolius was more prolific. This could be the explanation for the dominance of C. brevifolius in flooded areas and during the rainy season, and the occurrence of C. kyllingia in a wider range of habitats throughout the year.