Allelopathic and competitive interactions between native and alien plants

The novel-weapons and homeland-security hypotheses are based on the idea that aliens and natives are not adapted to each other’s allelochemicals as they did not co-evolve. However, as only a few studies have tested this, it remains unclear how important co-evolutionary history is in determining the strength of allelopathic interactions between aliens and natives. Here, we tested for potential pairwise allelopathic effects on each other of five alien and five native herbaceous species in China. We did a germination experiment and a competition experiment. In the germination experiment, we tested whether aqueous extracts of the ten study species had allelopathic effects on each other’s seed germination. In the competition experiment, we tested whether the alien and native species differed in their competitive effects and responses, and whether these were changed by the presence of activated carbon—a presumed allelopathy neutralizer– in the soil. Plant extracts had negative allelopathic effects on seed germination. This was particularly the case for extracts from the native species. Moreover, aqueous extracts had slightly stronger negative effects on germination of the aliens than on germination of the natives. In the competition experiment, on the other hand, the natives suffered more from competition than the alien species did, but we could not relate this to allelopathy. Alien plants had negative competitive and allelopathic effects on native plants, but the reverse was also true. These alien-native interactions, however, were not consistently stronger or weaker than native-native or alien-alien interactions.

Volunteer potato interference and removal timing in sugar beet

Field studies were conducted from 2005 to 2009 in Idaho and Oregon to 1) evaluate the competitive effect of volunteer potato on sugar beet yield (volunteer potato competition experiment), and 2) determine the optimum timing of volunteer potato removal from glyphosate-tolerant sugar beet fields using glyphosate (volunteer potato removal timing experiment). The volunteer potato competition experiment consisted of eight potato densities, including the untreated check: 0, 6,741, 10,092, 13,455, 16,818, 20,184, 26,910, and 40,365 tubers ha−1. The volunteer potato removal experiment consisted of 10 removal timings (including the untreated check) ranging from the 10-cm rosette stage to mid-tuber bulking. There was a linear decrease in sugar beet root and sucrose yield as volunteer potato density increased (P < 0.001) such that with every volunteer potato tuber per square meter, sugar beet root yield decreased by 15% and sucrose yield decreased by 14%. At the highest volunteer potato density (40,365 tubers ha−1), sugar beet root yield was 29,600 kg ha−1 (compared to 73,600 kg ha−1 for the untreated), representing a 60% reduction in sugar beet root yield. In the removal timing study, a one-time application of glyphosate at the 10-cm rosette, hooking, and tuber initiation stages provided 74% to 98% reduction in volunteer potato tuber biomass. Delaying volunteer potato removal beyond the tuber initiation stage reduced sugar beet root and sucrose yield (12% to 20%), resulting in an economic loss of $104 to $161 per hectare. The best potato removal timing that optimizes the trade-off between improved control and potential for sugar beet yield reductions is before or at the tuber initiation stage.

Allelopathic and Competitive Interactions Between Native and Alien Plants

The novel-weapons and homeland-security hypotheses are based on the idea that aliens and natives are not adapted to each other’s allelochemicals as they did not co-evolve. However, as only a few studies have tested this, it remains unclear how important co-evolutionary history is in determining the strength of allelopathic interactions between aliens and natives. Here, we tested for potential pairwise allelopathic effects on each other of five alien and five native herbaceous species in China. We did a germination and a competition experiment. In the germination experiment, we tested whether aqueous extracts of the ten study species had allelopathic effects on each other’s seed germination. In the competition experiment, we tested whether the alien and native species differed in their competitive effects and responses, and whether these were changed by the presence of activated carbon –a presumed allelopathy neutralizer– in the soil. Plant extracts had negative allelopathic effects on seed germination. This was particularly the case for extracts from the native species. Moreover, aqueous extracts had slightly stronger negative effects on germination of the aliens than on germination of the natives. In the competition experiment, on the other hand, the natives suffered more from competition than the alien species did, but we could not relate this to allelopathy. Alien plants had negative competitive and allelopatic effects on native plants, and the reverse was also true. These alien-native interactions, however, were not consistently stronger or weaker than native-native interactions or alien-alien interactions.

The Competition between of invasive Hydrilla verticillata L.f. and native Ceratophyllum demersum L. in monocultures and mixed cultures experimental

The present study aims to assess inter-specific competition between Hydrilla verticillata and Ceratophyllum demersum. A competition experiment design has five treatment combinations to terminal shoots of C. demersum only, terminal shoots of H. verticillata only and three different treatment combinations of C. demersum and H. verticillata together. Our results showed parameters growth of C. demersum were decreased of which, total chlorophyll, protein, and biomass while Superoxide dismutase (SOD), and Catalase (CAT) enzymes increase were significantly (p<0.05) compare with control treatment. While H. verticillata were increased total chlorophyll, biomass, CAT and little increase in protein and SOD were significantly (p<0.05) compare with control treatment. Therefore, due to the competition, with the introduction of C. demersum, the performances growth of H. verticillata were increased. Based on our result, showed H. verticillata and C. demersum species were coexist, C. demersum will have a competitive advantage over H. verticillata. Therefore, this study suggests, H. verticillata could out-compete for C. demersum in many situations, that despite the similar ecology.

Affinity analysis between trypsin and aptamers using surface plasmon resonance competition experiments in a steady state

A surface plasmon resonance (SPR) competition experiment in a steady state was developed to determine the binding dissociation constants between a protein and its DNA aptamers.