Weed interference results in increased synthesis of reactive oxygen species (ROS). High accumulation of ROS causes oxidative stress and stimulates the activation of the antioxidant defense system in plants. Weed interference causes biotic stress in the form of allelochemicals and abiotic stress in the form of competition for plants which results in the inhibition of growth and development in plants. Ageratum conyzoides is an annual weed in plantations and can cause biotic and abiotic stress on surrounding plants. This study aims to determine the effect of A. conyzoides interference on antioxidant content in the form of total phenol and total proline in patchouli leaves [Pogostemon cablin (Blanco) Benth cv. Sidikalang] as well as the percentage of essential oil yield from P. cablin. The study was conducted with a Complete Randomized Design (CRD) with a single factor of A. conyzoides interference levels in as many as four treatments (0, 2, 4, 6 individuals of A. conyzoides per treatment). The results concluded that higher levels of A. conyzoides interference led to an increase in total phenol and total proline in P. cablin leaves, but decreased the percentage yield of P. cablin essential oil.

Soybean plant [Glycine max (L.) Merr.] Is a food crop that is a source of fat, protein, and minerals. Drought stress is a major obstacle in the cultivation of soybean plants, which causes the synthesis of excessive amounts of Reactive Oxygen Species (ROS) which triggers oxidative stress. Hydrogen peroxide (H2O2) is the most stable ROS, in low concentrations it can act as a signaling molecule and activate an antioxidant defense system to protect plants from oxidative stress. The study was conducted at the Plant Structure and Function Biology Laboratory of Diponegoro University. The study aims to determine the effect of H2O2 treatment on the condition of different levels of water availability on the vegetative growth of soybean plants variety Deja 1. Research using a completely randomized design (CRD) 4x2 factorial pattern. The first factor is H2O2 concentration (0 0.5 1 and 2 mM). The second factor is the level of water availability (100 and 35% of field capacity). Each treatment was repeated 5 times. Quantitative data were analyzed by Analysis of Variance (ANOVA) followed by DMRT test at 95% confidence level. The results showed that there was an interaction between the H2O2 concentration factor and the level of water supply to the canopy fresh weight. The 2 mM H2O2 treatment at 100% water availability and 1 mM H2O2 with 35% water availability increased vegetative growth as indicated by the canopy and root fresh weight parameters, number of leaves, stomata opening width, relative water content. Based on the results of the study it can be stated that the exogenous H2O2 treatment of leaves with certain concentrations at all different levels of water availability can increase the vegetatif growth of soybean variety of Deja 1.