Abiotic Stress Elicitation on Secondary Metabolites of Red Betel (Piper crocatum Ruiz and Pav.) Leaves as Potential Repellent for Rice Bug (Leptocorisa oratorius (F.)

Abstract

Rice bug, Leptocorisa oratorius (F.), is the main pest of rice plants which can reduce rice productivity significantly. Natural insecticide from plant extract compounds, such as Red Betel (Piper crocatum Ruiz and Pav.), is an alternative to reduce the attack of these pests and environmental friendly. This research aimed to study the effect of abiotic stress on plant growth and secondary metabolites profiles of P. crocatum leaves that have potential compounds as an insecticide. The research design used a split-split plot design with three factors, namely drought stress 100, 50 and 25% Field Capacity (FC) light treatment (without shade, shade net 65% and shade net 75%) and fertilizer application (guano and NPK). Data analysis used ANOVA and Duncan Multiple Range Test (DMRT) for growth data, also GC-MS test for profile metabolites analysis. The research showed that the combination of 100% FC, guano and without shade (W1F1L1) treatment produced the best plant growth. The combination of 50% FC, NPK and without shade (W2F2L1) had the highest potential to increase the type of insecticide compounds, while the treatment of 100% FC, NPK and shade net 75% (W1F2L3) produced the highest insecticide total compounds. There were 32 types of compounds potentially acted as an insecticide in the red betel leaf chloroform extracts. The compound groups covered terpene, monoterpene, sesquiterpene, diterpene and others. The combination of abiotic stress in the form of drought stress, light treatment and fertilizer application affected the growth of P. crocatum in terms of plant morphology and biomass. It also could increased the type and content of bioactive compounds in leaves of P. crocatum. The W2F2L1 was the best treatment to increase the type of insecticide compounds and the growths of red betel.