The objective of this study was to evaluate the release rate, duration, and biological efficiency of yeast volatile compounds associated with olive fruit flies in slow-release dispensers, ...polypropylene vials, and rubber septa attached to yellow sticky traps under different environmental conditions in order to protect the environment, humans, and nontarget organisms. Isoamyl alcohol, 2-octanone, and 2-phenethyl acetate were placed in dispensers and tested over a four-week experiment. The weight loss of the volatile compounds in both dispensers was measured, and a rapid, inexpensive, and simple HS-GC/FID method was developed to determine the residual amount of volatiles in the septa. 2-Phenethyl acetate stood out in the rubber septa and showed a statistically significant difference in the release ratio compared to the other volatiles under all conditions tested. Our results showed that the attraction of olive fruit flies increased with decreasing concentrations of the tested volatiles. Regarding the number of flies attracted by rubber septa containing 2-phenethyl acetate, significantly better results were obtained than for septa containing isoamyl alcohol and 2-octanone, in contrast to the attraction of olive fruit flies to polypropylene vials containing these compounds but without significant difference. Since the presence of all tested chemicals was detected during the experiment, this opens the possibility of using more environmentally friendly and cost-effective dispensers with a significantly lower amount of semiochemicals.
Rhizobia are an important component of sustainable agricultural production. In symbiosis with legumes, they provide adequate amounts of nitrogen for their growth and leave nitrogen in the soil for ...crops that follow in the rotation. One of the major threats to symbiotic nitrogen fixation are herbicides. The effect of herbicides on symbiotic nitrogen fixation can be positive or negative. The positive effect is manifested in the stimulation of growth and development of rhizobia. When symbiosis is negatively affected, the efficiency of nitrogen fixation is reduced, resulting in lower legume growth and yield. Herbicides can contact rhizobia immediately after application or, in the case of persistent herbicides, later in the growing season. Herbicides may affect the rhizobia, the host plant, or the establishment and development of the symbiosis. This paper reviews previous research on the effects of herbicides on rhizobia.
The olive fruit fly, Bactrocera oleae (Rossi) is economically the most important olive pest, causing yield losses in all olive growing areas where is detected. Considering that EU requires the ...reduction of pesticide use by up to 100% by 2050, more effective non-pesticide lures for B. oleae monitoring and/or controlling are needed. This research was aimed at investigating the attractiveness of different blends of olive fruit fly-associated yeast volatiles toward B. oleae. Three blends of olive fruit fly-associated yeast volatiles: isoamyl alcohol and 2-phenethyl alcohol; isoamyl alcohol, 2-phenethyl alcohol and 2-phenethyl acetate; and isoamyl alcohol, 2-phenethyl acetate and isobutyl acetate were selected and tested on yellow sticky traps for attraction of B. oleae in olive orchard. Results showed that traps containing all tested blends of olive fruit fly-associated yeast volatile compounds, in total, were significantly more attractive to B. oleae and were not significantly attractive to green lacewings, compared to the control. Among them, the most promising was the one containing the blend of isoamyl alcohol, 2-phenethyl acetate and isobutyl acetate because its attractiveness was constantly significant during investigation compared to the others. This blend in the future could lead us to the discovery of a new attractant for the monitoring and/or controlling of B. oleae.
Rhizobia are an important component of sustainable agricultural production. In symbiosis with legumes, they provide adequate amounts of nitrogen for their growth and leave nitrogen in the soil for ...crops that follow in the rotation. One of the major threats to symbiotic nitrogen fixation are herbicides. The effect of herbicides on symbiotic nitrogen fixation can be positive or negative. The positive effect is manifested in the stimulation of growth and development of rhizobia. When symbiosis is negatively affected, the efficiency of nitrogen fixation is reduced, resulting in lower legume growth and yield. Herbicides can contact rhizobia immediately after application or, in the case of persistent herbicides, later in the growing season. Herbicides may affect the rhizobia, the host plant, or the establishment and development of the symbiosis. This paper reviews previous research on the effects of herbicides on rhizobia.
Rod Panicum obuhvaća veći broj vrsta (370 - 600) raširenih u svijetu, a podrijetlom je iz tropskih i suptropskih krajeva. U RH su prisutne četiri vrste iz ovog roda: Panicum capillare L., Panicum ...dichotomiflorum Michx., Panicum miliaceum L. i Panicum riparium H. Scholz od kojih se prve tri pojavljuju kao korovi okopavinskih usjeva. Panicum capillare i Panicum dichotomiflorum invazivne su vrste na području RH: P. capillare prvi put zabilježen u RH 60-ih godina, Panicum dichotomiflorum 70-ih, a Panicum miliaceum 90-ih godina prošlog stoljeća. Ovisno o različitom vremenu pojave na prostoru RH, u usjevima je kao korovna vrsta najrasprostranjeniji P. capillare kojeg slijedi P. dichotomiflorum te potom P. miliaceum . Navedene su vrste prema životnom ciklusu jednogodišnje te se šire isključivo sjemenom. Sjeme se najčešće širi poljoprivrednim strojevima i oruđem, ali je znatno prisutna epizoohorija te anemohorija . Za razliku od ostalih monokotiledonih korovnih svojti čije sjeme u banci sjemena brzo gubi klijavost, sjeme P. dichotomiflorum može sačuvati klijavost i do 20 godina, čineći perzistentnu banku sjemena u tlu. Sve su navedene vrste kasnoproljetne s temperaturnim minimumom za klijanje od 10 °C i više te optimumom od 30 °C. Suzbijanje vrsta roda Panicum najčešće se provodi herbicidima. Ipak, zbog kasnog nicanja u usporedbi s drugim korovnim travama u kukuruzu, često izbjegnu aplikaciju herbicida, što se potom pogrešno tumači lošom učinkovitosti. No, poznavanjem biologije i ekologije vrsta moguća je uspješna integrirana zaštita te primjena nekemijskih mjera poput zasjenjivanja, odnosno korištenja pokrovnih kultura, smanjenja razmaka sjetve te korištenja plodoreda i obrade tla.
Cilj istraživanja bio je primjenom digitalnog mikroskopa utvrditi utjecaj i dinamiku učinka različitih koncentracija herbicida pendimetalina na rast bakterije Bradyrhizobium japonicum. Istraživane ...koncentracije pendimetalina iznosile su 0,00; 0,165; 0,33; 0,66; 1,32 i 2,64%. Koncentracija 0,66% odgovara količini pendimetalina koja se uobičajeno primjenjuje u praksi (registrirana dozacija). Utjecaj pendimetalina na rast bakterija utvrđivan je mjerenjem širine zone inhibicije oko filter-diskova tretiranih istraživanim koncentracijama pendimetalina 5, 7, 10 i 12 dana nakon nacjepljivanja (DNN) bakterija na hranjivu podlogu. Najmanji inhibitorni učinak utvrđen je kod prvog mjerenja (5 DNN), kad se prosječna širina zone inhibicije kretala od 0,18 mm kod najniže (0,165%) do 0,97 mm kod najviše (2,64%) istraživane koncentracije. Pri svakom sljedećem mjerenju utvrđena je progresija inhibitornog učinka pendimetalina na rast bakterija. Najveći inhibitorni učinak utvrđen je kod posljednjeg mjerenja (12 DNN) kad je širina zone inhibicije kod koncentracije pendimetalina od 0,165% iznosila 0,61 mm. Povećanjem koncentracije znatno se povećavala, te je kod koncentracije od 2,64% iznosila 2,46 mm. Rezultati istraživanja ukazuju na negativan učinak herbicida pendimetalina na rast bakterija B. japonicum čak i kod koncentracija manjih od preporučene koja se primjenjuje u praksi.
The objective of this study was to determine the effect of different concentrations of herbicide pendimethalin on the growth of nitrogen-fixing bacteria Bradyrhizobium japonicum using a digital microscope. Pendimethalin was applied at concentrations of 0.00; 0.165; 0.33; 0.66; 1.32 and 2.64%, where the concentration of 0.66% presents the amount of herbicide which is usually applied in the field (recommended dose). The influence of pendimethalin on the growth of B. japonicum was determined by measuring the width of the inhibition zone around the discs 5, 7, 10 and 12 days after inoculation (DAI) of bacteria on a nutrient medium. The lowest inhibitory effect of pendimethalin for all concentrations determined was 5 DAI, when the average width of inhibition zone was between 0.18 mm for the lowest (0.165%) to 0.97 mm for the highest (2.64%) concentration. The progression of the inhibitory effect of pendimethalin occurred with every following assessment. The highest inhibitory effect determined was 12 DAI, when the width of the inhibiton zone at a concentration of 0.165% was 0.61 mm. The width of the inhibition zone significantly increased with increasing the pendimethalin concentrations and at a concentration of 2.64% it was 2.46 mm. The results of this study indicate the negative effect of herbicide pendimethalin on bacteria B. japonicum, even at concentrations lower than recommended concentrations that are applied in the field.
Kvržične bakterije važan su dio održive poljoprivredne proizvodnje. Uspostavom simbiotskog odnosa, osiguravaju leguminozama, kao i kulturama koje slijede u plodoredu, dostatne količine dušika za rast ...i razvoj. Jednu od najvećih prijetnji uspješnog uspostavljanja simbiotskog odnosa predstavljaju herbicidi. Učinak herbicida na simbiotsku fiksaciju dušika može biti pozitivan ili negativan. Pozitivan učinak očituje se u poticanju rasta i razvoja kvržičnih bakterija. U slučaju negativnog djelovanja herbicida na simbiozu, fiksacija dušika biti će reducirana što će rezultirati reduciranim rastom i prinosom leguminoza. Herbicidi mogu doći u kontakt s kvržičnim bakterijama odmah nakon primjene ili u slučaju perzistentnih herbicida, kasnije u vegetaciji. Herbicidi mogu utjecati na same kvržične bakterije, biljku domaćina ili na uspostavu i odvijanje simbioze. U radu je dan pregled dosadašnjih istraživanja utjecaja herbicida na kvržične bakterije.
Simbiotska fiksacija dušika najznačajniji je tip biotičke fiksacije. Nastaje kao rezultat simbiotskog odnosa između kvržičnih bakterija (rizobija) i korijena leguminoza. Budući da je primjena ...herbicida neizostavna mjera u tehnologiji uzgoja leguminoza i zbog činjenice da se nakon primjene najveći dio herbicida zadržava u sloju tla u kojem je i najveća aktivnost mikroorganizama, upravo se herbicidi navode kao jedni od glavnih činitelja koji utječu na uspostavu simbiotskog odnosa, a time i na učinkovitost kvržčnih bakterija. Cilj ovog istraživanja bio je utvrditi utjecaj različitih koncentracija herbicida imazamoksa na rast soja bakterije Bradyrhizobium japonicum. Istraživanje je provedeno u laboratorijskim (in vitro) uvjetima. Za istraživanje je korišten pripravak Pulsar 40 koji sadrži 40 g a. t. l-1 pripravka. Utjecaj imazamoksa na rast soja bakterije B. japonicum utvrđivan je filter-disk metodom. Istraživane koncentracije imazamoksa iznosile su 0; 0,2; 0,4; 0,8 i 1,6 mg a. t. ml-1 vode. Koncentaracija od 0,2 mg imazamoksa ml-1 vode odgovara koncentraciji imazamoksa koja se uobičajeno primjenjuje u praksi (1,0 l pripravka u 200 l vode ha-1). Nijedna istraživana koncentracija nije iskazala inhibitorni učinak na rast bakterije B. japonicum. Stimulativan učinak imazamoksa na rast soja istraživane bakterije najizraženiji je bio pri koncentraciji od 0,4 mg a. t. ml-1, dok je pri ostalim koncentracijama (0,2; 0,8 i 1,6 mg ml-1) utvrđen sporiji rast bakterijskih kolonija u odnosu na kontrolnu varijantu.
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