This study aimed to investigate whether different doses of specific phenolic acids (chlorogenic acid, caffeic acid, ferulic acid, gallic acid, protocatechuic acid,
-hydroxybenzoic acid, syringic ...acid, vanillic acid, and
-coumaric acid), alone or in combination, can inhibit the early growth of the common ragweed (
L., Asterales: Asteraceae). A seed bioassay was performed in Petri dishes and placed in a climate chamber to assess the effects of five dose levels of phenolic acids to radicle and shoot length, as well seedling biomass of
. The lowest dose of phenolic acid corresponded to the natural phenolic acid concentration previously reported in dry plant tissue samples from Brassicaceae cover crop plants. Results show that the inhibition of the early growth of
depends strongly on phenolic acid. Across different treatments, high doses of phenolic acids significantly shortened shoots and radicles, as well as reduced seedling biomass. Treating seeds with ferulic acid alone, vanillic acid alone,
-hydroxybenzoic acid alone, or a mixture of all phenolic acids significantly reduced all early growth parameters. The estimated effective dose for the 50% inhibition (ED
) of radicle growth in
seedlings was 368.39 ± 59.85 × 10
mol with ferulic acid, 135.41 ± 17.65 × 10
mol with
-coumaric acid, 810.36 ± 134.15 × 10
mol with
-hydroxybenzoic acid, and 160.11 ± 12.30 × 10
mol with the combination of all phenolic acids.
Weeds can be one of the most severe threats to crop production, especially when they are widespread and highly adaptable. Part of the adaptive strategy of plants is the ability to germinate in ...different conditions. Germination is the first developmental phase of plant life and is fundamental for its establishment. In this work, the germination of two populations of
L. at two different sites in Croatia (one cropped, the other non-agricultural) was tested under a wide range of salinity stress, 4, 8, 12, and 16 dS/m, and pH stress, values 1-9, at two temperature ranges of 15-25 °C and 18-30 °C. The results show that this species can tolerate high salinity, with a high number of seeds germinating, even under the highest level of saline stress and especially at higher temperatures: 21.7% of seeds germinated at 15-25 °C and 51.2% at 18-30 °C.
also appears to be quite acid tolerant, with a significant reduction in germination only at pH 2, and no germination only at pH 1. Germination was always higher at higher temperatures, independently of abiotic stress. Although there were some differences between the two populations in the final germination percentages, they were similar in their responses to the abiotic stresses.
Herbicides are the most commonly used means of controlling the growth of Ambrosia artemisiifolia L. Their constant use has led to the development of resistant populations. They can be evaluated by ...studying seed germination and the corresponding grown plants, but A. artemisiifolia exhibits seed dormancy, preventing germination and delaying research. Here, we developed a simple and rapid method to stimulate germination of freshly collected or stored A. artemisiifolia seeds. The germination of A. artemisiifolia freshly collected/stored seeds was evaluated after storage, stratification, and chemical treatments (ethephon, gibberellic acid (GA3), thiourea, KNO3). Ethephon or ethephon + GA3 improved freshly collected seed germination by 88 and 95%, respectively, and germination of stored seeds by 78 and 80%, respectively. In addition, placing the seeds of A. artemisiifolia in ethephon, GA3, ethephon + GA3, or thiourea solutions caused the freshly collected seeds to germinate faster than stored seeds or nontreated seeds. In contrast, the conditioning of seeds in these solutions favored germination of stored seeds, especially when ethephon + GA3 or GA3 was used. Imbibition of the freshly collected A. artemisiifolia seeds in a mixture of ethephon and GA3 can effectively overcome primary dormancy when rapid experimental results are needed. For seeds requiring prolonged storage, conditioning in ethephon, GA3, or thiourea solutions may be applied to promote germination.
Echinochloa crus-galli (L.) P. Beauv. is the most common monocotyledonous weed in maize crops in Croatia. Crop–weed interference is influenced by weed emergence patterns, and knowledge of the timing ...of weed emergence is crucial for the development of an efficient integrated weed-management program. Therefore, two-year field experiments were conducted in a maize crop sown in early May in continental Croatia to determine the emergence pattern of E. crus-galli from natural seedbank. In laboratory studies, the estimated base temperature and base water potential for the Croatian ecotype of E. crus-galli were 10.8 °C and −0.97 MPa, respectively. Then, the estimated germination parameters were compared with the values embedded in the AlertInf model from Italy (Veneto) to calibrate this hydrothermal model. The estimated hydrothermal units were around 28 for the onset (10%) and 93 for the middle (50%) emergence of E. crus-galli. Our findings showed that the AlertInf model satisfactorily simulated the emergence of E. crus-galli in maize crop in Croatia (EF = 0.97 in 2019 and 0.98 in 2020), indicating its potential use in other geographical areas
Effective weed management depends on correct control timing, which depends on seedling emergence dynamics. Since soil temperature and soil moisture are the two main factors that determine weed ...germination, the hydrothermal time model can be used to predict their emergence. The aim of this study was to estimate the base temperature (Tb) and base water potential (Ψb) for the germination of Chenopodium album, Amaranthus retroflexus, Setaria pumila, and Panicum capillare collected from fields in continental Croatia and then to compare these values with those of Italian populations embedded in the AlertInf model. Germination tests were performed at seven constant temperatures (ranging from 4 to 27 °C) and eight water potentials (0.00–1.00 MPa). The estimated Tb and Ψb were 3.4 °C and −1.38 MPa for C. album, 13.9 °C and −0.36 MPa for A. retroflexus, 6.6 °C and −0.71 MPa for S. pumila, and 11.0 °C and −0.87 MPa for P. capillare, respectively. According to the criterion of overlap of the 95% confidence intervals, only the Tb of C. album and the Ψb of A. retroflexus of the Croatian and Italian populations were similar. Further field experiments should be conducted to monitor the weed emergence patterns of C. album and calibrate the AlerInf equation parameters.
The aim of the research was to determinate the degree of variation in morphological (seed weight) and functional polymorphism (final germination, dormancy, seed mortality and germination dynamic) ...within two seed populations of Ambrosia artemisiifolia L. Seeds were collected separately from 20 plants/population in Jastebarsko (45°40'18˝N; 15°39'03˝E), population-J and Popovača (45°34´1˝N; 16°40´43˝E), population-P in 2014. Seed weight of J and P populations had weak variability (CV-J = 18.2%, CV-P= 29.8%) with an average of 4.05 g (J) and 4.54 g (P). Estimated variability was strong for amount of death seeds in the J (CV = 67.6%), but weak for geminated (CV = 4.9%) and moderate for dormant seeds (CV = 51.0%). Variability within P population was moderate for both germinated and dead seeds (CV = 34.5%; 34.1%), while variability within amount of dormant seeds was weak (CV = 14.2%). Variability in medium germination (T50) was relatively low for both experimental populations (CV – J = 12.0%; CV – P = 22.4%). Despite determined intrapopulation variation, degrees of variability between researched parameters (final germination, dormancy and medium germination – T50) were weak or moderate and therefore acceptable for further experiment base on seed testing.
Huds. is an important pinoxaden-resistant grass weed in many countries of Europe. Recently, the low efficacy of pinoxaden was reported in winter cereals in Croatia, but a preliminary dose-response ...trial showed no herbicide resistance for the investigated weed population. Therefore, a two-year experiment was conducted under greenhouse conditions to determine the efficacy of various pinoxaden doses (20, 40 and 80 g a.i. ha
) on weed visual injuries and biomass reduction after herbicide application at different growth stages. As expected, the maximum weed biomass reduction (97.3%) was achieved by applying the highest dose (80 g a.i. ha
) at the earliest growth stage (ZCK 12-14). A pinoxaden dose of 20 g a.i. ha
resulted in satisfactory weed biomass reduction (88.9%) only when applied at ZCK 12-14. The recommended dose (40 g a.i. ha
) also provided sufficient weed control up to the growth stage ZCK 21-25. Slightly delayed (ZCK 31-32) application of the recommended dose brought about a low weed biomass reduction (60.1%). Double than the recommended dose also failed to provide satisfactory weed control at the advanced weed growth stages (ZCK 31-32 and ZCK 37-39). Thus, reported low efficacy of pinoxaden is most likely because of delayed herbicide application when
is overgrown.
Several cover crops (CCs) exert allelopathic effects that suppress weed growth. The aim of the present study was to evaluate the effects of aqueous extracts containing different concentrations 0, ...0.5, 1, 2.5, 5, 7.5 and 10% (
/
) of Brassicaceae CCs (
and of the CCs
and
on germination and early growth of
L. The allelopathic effects were species and concentration-dependent.
, for example, caused the greatest potential to inhibit germination, shoot, radicle length and fresh seedling weight, whereas
and
inhibited germination and early growth of
only at concentrations ≥7.5%. In contrast, no inhibition was observed when aqueous extracts of
and
were added at any of tested concentration. Liquid chromatography-tandem mass spectrometry detected 15 phenolic compounds in Brassicaceae CCs with the highest content (µg/g) of vanillin (48.8), chlorogenic acid (1057), vanilic acid (79), caffeic acid (102.5) and syringic acid (27.3) in
. Our results suggest that
is the most allelopathic CCs and that the fruits of
are the plant organs richest in allelochemicals.
Poljska ljubica (Viola arvensis Murr.) jednogodišnja je vrsta koja zakorovljuje usjeve gustog sklopa te nasade bobičastog voća i povrćarskih kultura. Potječe s prostora Euroazije, a zbog svojstva ...adaptibilnosti proširila se i na ostale kontinente. Često je moguća zamjena s vrstom V. tricolor L. (maćuhica) od koje se razlikuje po boji cvjetova i obliku gornjih listova. Razmnožavanje V. arvensis generativno je. U laboratorijskim uvjetima najveća klijavost ostvaruje se pri temperaturi od 15 °C u trajanju od 8 sati te pri temperaturi od 5 °C u trajanju od 16 sati. Preferira pjeskovita tla reakcije od blago kisele do lužnate. Tolerantna je na zasjenjivanje i sušu. Prezimljuje u formi rozete, a visinom biljka može dosegnuti prosječno 30 cm. Zbog niskog habitusa izravne štete uzrokovane korovnom vrstom V. arvensis nisu toliko značajne koliko neizravne koje se javljaju nakon žetve usjeva kada biljno tkivo zahvaćeno pri žetvi usjeva može utjecati na povećanje vlage sjemena usjeva. V. arvensis vrsta je koja se prilagodila utjecaju čovjeka te se uspješno razvija na obrađivanim tlima. Forma rozete smatra se tolerantnom prema primjeni herbicida te je zbog toga otporna na primjenu kemijskih mjera suzbijanja.
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