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Several species of the genus Oxalis, such as Oxalis corniculata and Oxalis latifolia, are part of the Oxalidaceae family which have the ability to produce allelopathic compounds against horticultural crops and other weeds. To determine the relationship and interaction between grass weeds that cover the land and Oxalidaceae weeds, observations were made on species diversity, coverage, and distribution of land cover crops in the area around the sampling site for Oxalidaceae weeds. Results show that the three species with the highest cover are Axonopus compressus, grass in the family Poaceae, and Oxalis corniculata, with 23.18, 17.57, and 7.97%, respectively. Among the 33 species observed, there are 2 species of Oxalidaceae from the genus Oxalis, namely, O. corniculata and O. latifolia. In contrast to Oxalis corniculata, Oxalis latifolia (Broadleaf Wood sorrel) only cover 5,41% of the garden area. O. corniculata or Creeping wood sorrel is the only ground vegetation and weed found in 80% of the observed plots. In conclusion, Oxalis weed is a cosmopolitan weed and its potential as a biological control for other weeds can be further investigated. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa) is the main food crop in Indonesia. One of the ways to increase rice productivity is by using external compounds that have a function to affect growth. In addition to its usefulness as a biopesticide, tobacco plants also can be used as Plant Growth Regulator (PGR) due to containing allelopathic substances, organic matter, and other phenolic compounds that affect plant growth, especially the production of terpenoid secondary metabolites at appropriate application intervals. The study was conducted to identify the effect and optimum treatment of concentration and intake-time interval combination within tobacco extract (Nicotiana tabacum). The parameters to observe were the shoot-root ratio of paddy growth and dense grain percentage. The research consists of 10 variables comprising of 9 experimental subjects and 1 control (non-tobacco extract). There were a combination of tobacco extract solution (1, 2, 3 m/L) with intake-time interval (one week, two-weeks, three-weeks), triplicate. The preliminary result indicated that the experiment delivered significant impact to treatment with a combination of concentrated 2 mL/L of nicotine within an interval intake time of 1 week, showing 80% percentage of dense grains which categorized as fertile plant. [ABSTRACT FROM AUTHOR]

The domestic consumption of rice (Oryza sativa) in Indonesia are increasing because of the population growth. One of the ways to increase rice productivity is by using external compounds such as plant growth regulators (PGRs) or phytohormones that function to affect growth. Tobacco plants can also be used as PGR because they contain allelopathic substances, organic matter, and other phenolic compounds that can affect plant growth. This study aims to determine the effect of intervals of tobacco extract application on the growth and yield of rice plants of the Inpari 32 variety. The study was conducted in a Randomized Block Design (RBD) with 4 interval treatments (control F0; once a week F1, once every two weeks F2, and every three weeks F3). One-Way ANOVA test was done at a 5% level and continued with a DMRT test, with variables of plant height, number of leaves, number of tillers, growth rate, phytohormones (auxin IAA; and gibberellic acid GA3), flowering age, harvest age, shoot and root dry weight, stover shoot root ratio, 1000 grain weight, the ratio of pithy rice grain to rice grain. Total, seed weight per clump, grain weight per plant, and productivity (tons/ha). The study results were that the application interval treatment did not show a significant effect on all test parameters, but the treatment interval of application of tobacco extract once a week (F1) showed a tendency for better results especially in the number of leaves. [ABSTRACT FROM AUTHOR]

In this paper we study the dynamics of predator-prey model with allelopathic effect on prey. We find that the model has four equilibrium points that are extinction of prey equilibrium, the extinction of predator equilibrium, the extinction of both predator and prey, and the coexistence equilibrium. It is shown that the extinction of predator equilibrium and the extinction of both predator and prey equilibrium are unstable, while the extinction of prey equilibrium is conditionally stable. The coexistence equilibrium is unconditionally stable. The analytical results are confirmed by numerical simulations. [ABSTRACT FROM AUTHOR]

A laboratory experiment was conducted to study the allelopathic effects of the aqueous extract of the leaf and seed of Leucaena leucocephala. The aqueous extracts were individually tested on three selected weed species, namely goatweed (Ageratum conyzoides), coat buttons (Tridax procumbens) and lilac tasselflower (Emilia sonchifolia). The allelopathic effects of the leaf and seed extracts on germination, shoot length, root length and fresh weight of each of the selected weed species were determined. Germination of goatweed, coat buttons and lilac tasselflower were inhibited by the aqueous extracts of both the leaf and seed of L. leucocephala and was concentration dependent. Different concentrations of the aqueous extracts showed various germination patterns on the selected weeds species. Seedling length and fresh weight of goatweed, coat buttons and lilac tasselflower were reduced in response to respective increasing concentrations of the seed extracts. Maximum inhibition by the aqueous seed extract was observed more on the root rather than the shoot growth. The aqueous seed extract at T3 concentration reduced root length of goatweed, coat buttons and lilac tasselflower by 95%, 86% and 91% (of the control) respectively. The aqueous seed extract showed greater inhibitory effects than that of the aqueous leaf extract. [ABSTRACT FROM AUTHOR]