SPECIES COMPOSITION OF WEEDS IN RAPESEED CROPS IN GEOGRAPHICALLY REMOTE REGIONS ON THE EXAMPLE OF LIPETSK AND SVERDLOVSK REGIONS

The aim of the study is to identify differences in the species composition of weeds in spring rapeseed crops in two geographically remote regions of the Russian Federation – Lipetsk (Central black earth region) and Sverdlovsk (Ural region). The analysis was carried out using methods of comparative Floristics and distribution of species by classes of constancy of occurrence. Differences between segetal weed flora elements in the agrophytocenoses of canola compare regions, as in floral structure, consisting of the first two "triads" of the floristic spectra and confirmed the low rate coefficient of species similarity. Species differences are represented by species that pollute rapeseed crops only in one of the compared regions. Among the species common to the agrophytocenoses of rapeseed in the two regions are such species as, Chenopodium album L., Echinochloa crusgalli (L.) Beauv., Silene praténsis (Rafn) Godr., Euphorbia helioscopia L, Fallopia convolvulus (L.) A. Loeve, Viola arvensis Murr. they are characterized by higher rates of occurrence in the Lipetsk region, and Capsella bursa-pastoris (L.) Medik., Cirsium setosum (Willd.) Bess, Erodium cicutarium (L.) L. Her., Thlaspi arvense L. – in the Sverdlovsk region. The dominant species in the Lipetsk region are Raphanus raphanistrum L., Chenopodium album L., Echinochloa crusgalli (L.) Beauv., Silene praténsis (Rafn) Godr., and in the Sverdlovsk region - Galium vaillantii DC., Stellaria media (L.) Vill., Capsella bursa-pastoris (L.) Medik., Thlaspi arvense L., Chenopodium album L., Cirsium setosum (Willd.) Bess. To protect rapeseed crops from weeds in different regions that differ in terms of heat and moisture availability, it is necessary to develop regional protection systems, preceded by mandatory monitoring studies.

Intraspecific differentiation in seed flooding tolerance of Echinochloa crusgalli var. zelayensis population in shores of a giant reservoir along altitudinal gradients

Aims In a large dam-regulated reservoir with regular hydrological pattern and strong flooding gradients across shore elevations, plants inhabiting in different shore elevations have to confront long-lasting flooding of differential intensities every year. Such persistent stress may lead to intraspecific differentiation of flooding tolerance in seeds. Echinochloa crusgalli var. zelayensis is a dominant annual plant in the shores of the Three Gorges Reservoir (TGR), which plays an important role in the shore vegetation. The objective of this study is to check whether intraspecific differentiation of seed flooding tolerance has occurred among E. crusgalli var. zelayensis populations in the TGR shores and whether such differentiation is associated with weak seed dispersal. Methods We collected seeds of E. crusgalli var. zelayensis from different populations in the TGR shores, and then placed them at four elevations in the shores flooded by reservoir impoundment. Parameters reflecting seed flooding tolerance including post-flooding percentage of intact seeds, seed germinability and seedling emergence rate were investigated for the seeds from different populations and undergoing flooding of different intensities. Floating time of seeds and speed of water level rise during impoundment were examined, and used to quantify dispersal potential of seeds in the shores of the TGR when flooded. Important Findings Both intact seed percentage and final seedling emergence rate after flooding significantly declined with increasing shore elevations where the seeds were collected, indicating that intraspecific differentiation in seed flooding tolerance has occurred among E. crusgalli var. zelayensis populations in the TGR shores after 7-year operation of the reservoir. The distance of seeds transported by rising water during reservoir impoundment was limited due to short-floating time of the seeds and relatively low speed of water level rise in the reservoir. This would be favourable to the development of intraspecific differentiation in seed flooding tolerance.

Interação das espécies Echinochloa crusgalli e Pistia stratiotes para fitorremediação de Levonorgestrel

Os contaminantes emergentes provenientes dos avanços tecnológicos, industriais, agropecuários e farmacêuticos estão cada vez mais presentes na natureza, ameaçando à saúde humana e ao meio ambiente. O levonorgestrel (LNG) é um exemplo desses contaminantes que são encontrados em concentrações extremamente baixas, dificultando a remoção por técnicas convencionais de tratamentos de água e esgoto. Portanto, surgem métodos alternativos de remoção desses compostos, como o uso da fitorremediação. Essa técnica se baseia na remoção de contaminantes emergentes através de plantas. Diante disso, objetivou-se remover o LNG de solução aquosa através das espécies Echinochloa crusgalli e Pistia stratiotes juntas e separadamente. Utilizou-se 3 tratamentos de estudo (0,16 mg L-1 de Levonorgestrel), controle positivo (com hormônio, sem plantas) e controle negativo (com plantas, sem hormônio), seguido de 3 condições de plantas (apenas E. crusgalli; apenas P. stratiotes; ambas as espécies) em duas repetições, totalizando 30 experimentos. Analisou-se as soluções por Cromatografia Líquida de Alta Eficiência com detector de arranjo de diodos (HPLC/DAD). As determinações de LNG nas plantas foram realizadas através de Cromatografia acoplada ao Espectrômetro de Massas (GC/MS). No geral, os resultados obtidos apresentaram um desempenho satisfatório, pois na segunda semana todos os tratamentos de estudo obtiveram uma concentração de LNG abaixo do limite de quantificação do método (0,025 mg L-1). As análises macroscópicas das plantas não apresentaram diferenças significativas, indicando que ambas as espécies desenvolveram-se bem nesse meio. Assim, conclui-se que essas espécies podem ser utilizadas em programas de biomonitoramento e fitorremediação, tanto juntas quanto separadas para complemento de purificação de água e esgoto

Echinochloa crusgalli var. Mitis metabolism as resistance mechanism to imazapyr and imazapic

Selection pressure caused by continuous use of imazapyr and imazapic herbicides in rice fields without crop rotation, has selected for resistant biotypes of Echinochloa crusgalli var. mitis. To know the mechanism of resistance involved becomes important in order to define effective management strategies. Therefore, the objective of this work was to verify if enhanced metabolism of herbicide is responsible for imazapyr and imazapic resistance in Echinochloa crusgalli var. mitis biotypes from Rio Grande (ECH38 resistant and ECH44 susceptible), Pelotas (ECH1 resistant and ECH14 susceptible) and Arroio Grande (ECH27 resistant) in the state of Rio Grande do Sul. For this purpose, forty-nine biotypes were collected from the southern region of the state in areas with barnyard grass control difficulties with ALS inhibitor herbicides. The treatments of study consisted of application of malathion (1000 g a.i. ha-1) and piperonyl butoxide (525 g a.i. ha-1), inhibitors of the cytochrome P450 mono-oxygenase enzymes and after 60 minutes, preceding herbicide application (73.5 + 24.5 g a.e. ha-1. Visual control evaluations were taken at 14 and 28 days after treatments (DAT) and shoot dry mass (SDM) determination at 28 DAT. The results indicate that the application of inhibitors does not alter the control response of the ECH38, but shows a significant increase in phytotoxicity in 28 DAT, with values of 78% for the ECH1. The use of Malathion associated with the herbicide provided a reduction in the SDM of 1.34 g.plant-1 in relation to the isolated application of herbicide and for piperonyl butoxide (PBO) of 1.28 g.plant-1 for the resistant biotype from Pelotas. For ECH27, the SDM reduction was lower than the values of 0.87 g.plant-1 for Malathion and 1.04 g.plant-1 for PBO. The resistance mechanism to imazapyr + imazapic herbicide in Pelotas and Arroio Grande biotypes is related to increased metabolism of the herbicide, and it cannot be stated that this mechanism is involved in the resistance of the ECH38 biotype.

Видовой состав сорных растений в агрофитоценозах зерновых культур в географически отдаленных областях: Ленинградской (Северо-Западный регион) и Липецкой (Центрально-Черноземный регион)

Цель исследования – выявление различий в видовом составе сорных растений в посевах зерновых культур в географически отдаленных регионах (СЗР и ЦЧР). Произведен сравнительный анализ данных обследования 30 полей зерновых культур в ряде районов Ленинградской области в 2014-2016 гг. и 29 полей в районах Липецкой области в 2016-2018 гг., осуществленных по оригинальной методике автора. Использованы традиционные методы флористического анализа, а также распределение видов по классам постоянства встречаемости. Различия между сегетальными элементами флоры зерновых культур двух областей заключаются в более высоких показателях флористического богатства и таксономического разнообразия в Ленинградской области, а также различной очередностью семейств в первых двух «триадах» сравниваемых флористических спектров. Более глубокие отличия заключаются не только в наличии дифференциальных видов (63 вида в посевах зерновых культур только в Ленинградской области и 45 видов в посевах зерновых только в Липецкой области), но и в разных показателях встречаемости одинаковых видов, засоряющих посевы зерновых культур в обоих регионах. К более высоким классам постоянства встречаемости в Ленинградской области, чем в Липецкой, относятся виды: Chenopodium album L., Tripleurospermum inodorum (L.) Sch. Bip., Matricaria discoídea DC., Taraxacum officinale Wigg., Thlaspi arvense L., Stellaria media (L.) Vill., Elytrigia repens (L.) Nevski, Capsella bursa-pastoris (L.) Medik., Fumaria officinalis L. и Fallopia convolvulus (L.) A. Loeve, Achillea millefolium L., Artemisia vulgaris L., Sonchus arvensis L., Myosotis arvensis (L.) Hill., Silene vulgaris (Moench) Garcke, Plantago major L., Persicaria lapathifolia (L.) S.F. Gray, Polygonum aviculare L. На территории Липецкой области такими видами являются – Silene praténsis (Rafn) Godr,. Echinochloa crusgalli (L.) Beauv., Galeopsis tetrahit L., Galium aparine L., Convolvulus arvensis L. В засоренности посевов ячменя в разных областях также выявлены различия: зарегистрировано 42 вида сорных растений в посевах ячменя только Ленинградской области (среди которых доминирует Matricaria discoídea DC.) и 31 вид в посевах ячменя только в Липецкой области (среди которых доминируют Echinochloa crusgalli (L.) Beauv., и Amaranthus retroflexus L.). Из 29 одинаковых видов в посевах ячменя обеих областей, в Ленинградской области преобладают Chenopodium album L., Fumaria officinalis L., Tripleurospermum inodorum (L.) Sch. Bip., а в Липецкой Convolvulus arvensis L., Galeopsis tetrahit L., Raphanus raphanistrum L. Следовательно, фитосанитарный прогноз распространения видов сорных растений в посевах зерновых культур в целом, и в посевах ячменя, в частности, как и системы защиты от сорных растений будут отличаться в двух сравниваемых регионах.