Acetolactate synthase (ALS) inhibiting herbicides are commonly used to eliminate weeds from mature turfgrasses. Field trials were conducted from 2004-2006, testing ALS herbicides for preemergence and early postemergence activity on newly seeded turfgrasses, using four species: Riviera bermuda, Zenith and Companion zoysia, L- 93 creeping bentgrass, and Poa annua L. Data collected were phytotoxicity and percent turf cover. Bermuda and zoysia herbicides were metsulfuron-methyl (42 g ha-1), trifloxysulfuron (29 g ha-1), flazasulfuron (53 g ha-1), foramsulfuron (30 g ha-1), bispyribac-sodium (112 g ha-1), and rimsulfuron (35 g ha-1). Treatments occurred the day of seeding and two-three weeks after seeding. Flazasulfuron, trifloxysulfuron and bispyribac-sodium caused significant damage in all treatments. Data suggests that bermuda and zoysia are tolerant of seedling treatments of foramsulfuron, rimsulfuron, and metsulfuron-methyl at these rates. Bentgrass and P. annua herbicides were foramsulfuron (15 and 30 g ha-1), siduron (2803 g ha-1), bispyribac-sodium (49 g ha-1), and paclobutrazol (281 g ha-1). Treatments occurred the day of seeding, two and four weeks after seeding. Foramsulfuron at 15 and 30 g ha-1 caused significant damage regardless of when it was applied. Data suggests that bentgrass and P. annua are tolerant of seedling treatments of siduron, paclobutrazol, and bispyribac-sodium at these rates.

Manganese (Mn) in excess of crop requirements is a serious problem when manganiferous soils become acid, waterlogged or amended with organic materials. We investigated the dynamics of manganese phytotoxicity and tested management options for growing crops in acid soils with excess Mn. We hypothesized that Mn phytotoxicity is governed by water use and expressed as continuous negative interaction between current plant/leaf growth rate (RGR PLant/Leaf) and future Mn accumulation rate (RAR Mn); and that under growth conditions where RGRPlant/Leaf exceeds RAR Mn, excess Mn can be managed by maximizing RGR Plant/Leaf and minimizing RAR Mn. The parameters RGR Plant/Leaf and RAR Mn were calculated using the conventional growth analysis techniques. The dynamics of Mn phytotoxicity was investigated by growing Mn-tolerant Lee and Mn-sensitive Forrest soybeans in the greenhouse using Wahiawa series, a manganiferous Oxisol in Hawaii. The soybeans were grown at soil pHs 4.78, 5.5, and 6.00 and five growth conditions (control, 80-90% field capacity, 40% shading, green manure and phosphorus at 150 mg kg-1). RAR Mn consistently exceeded RGR Leaf in most treatments. Over the range of soil pH and growth conditions, we found strong positive correlation between RGR Leaf and RAR Mn, this correlation mediated by a more fundamental correlation of both rate processes to plant water use. The dynamics of Mn phytotoxicity, referred to as the 'dual feedback effect' model described a continuous negative interaction between current RGR Leaf and future RAR Mn and between current RAR Mn and future RGR Leaf. Manganese accumulation rate exceeded plant growth rate, leaf Mn increased with time and growth treatments did not affect growth rate unless soil pH was increased to eliminate excessive Mn in the soil. Field experiments were conducted in Rugao series, an acid Alfisol in Northern Philippines. The soil is acid (pH 4.40) with abundant Fe-Mn concretions within the surface 20-cm. Preliminary field experiment showed Mn phytotoxicity in local soybeans cv. PSB Sy2 and PSB Sy6 as leaf symptoms in addition to low plant growth rates and grain yields associated with leaf Mn exceeding a critical value of 500 mg kg-1. Results of a second field experiment showed that cultivar, liming, and the management of phosphorus (P), manure and mulching modified plant growth rate and enhanced tolerance to excess soil Mn. Lime control (2 t ha-1) neutralized half of the exchangeable AI while keeping saturated paste Mn in excess. Mulching did not affect saturated paste-and increased RAR Mn without affecting RGR Leaf. Increases in RGR Leaf due to P and manure were accompanied by increases in RAR Mn. This increase in RGR Leaf translated to increased yields even when RAR Mn and soil solution Mn were increased as in the case of manure addition. Increases in grain yield due to manure exceeded the increases due to lime or P. Chicken manure was more effective than green manure in increasing grain yield. Plant growth rate exceeded Mn accumulation rate, leaf Mn decreased with time and manure treatments alleviated Mn phytotoxicity despite an increase in soil Mn.

Resumo: Estudou-se a seletividade do herbicida nicosulfuron, isolado e em mistura com atrazine, a trinta híbridos comerciais de milho, no ano agrícola 2006/2007, em área da UNESP, Campus de Jaboticabal (SP). O delineamento experimental foi o de blocos ao acaso, com quatro repetições, em esquema fatorial 5 x 30. Foram avaliados cinco herbicidas: nicosulfuron isolado (0, 50 e 60 g ha-1) e em mistura com atrazine (20 g ha-1 + 1,5 kg ha-1; 40 g ha-1 + 3,0 kg ha-1). O nicosulfuron isolado e em mistura com atrazine foi seletivo a 23 híbridos (A015, AG 2040, AG 8060, AGN 30A06, BM 1115, BRS 1035, BX 974, CDXS 012, CDXT 295, MAXIMUS, NB 3234, NB 4214, NB 8304, P 30K 73, P 30F36, P32R48, P30S40, SHS 5080, SHS 7070, SHS 7080, XB 6010, XB 6012, XB 7116), com base na produtividade de grãos. Dentre os trinta híbridos estudados, doze apresentaram efeito significativo de fitointoxicação, sendo eles: AG 2040, AG 8060, AGN 30A06, CDXS012, CDXT 295, NB 3234, NB 7324, SHS 5090, SHS 7070, XB 6010, XB 6012, XB 7116. A injúria visual causados pela aplicação de 50 e 60 g ha-1 nicosulfuron foi mais pronunciada do que as doses em mistura com atrazine. Os híbridos que sofreram perda na produção de grãos pela aplicação de nicosulfuron, isolado ou em mistura com atrazine, foram AGN 30A05, BRS 1015, BRS 1031, BX 981, NB7324, SHS 5090, P 30R32. / Abstract: Aiming selectivity studying the nicosulfuron herbicide, isolated and in mixture with atrazine, on thirty corn hybrids, in the agricultural year of 2006/2007, at UNESP, Campus of Jaboticabal, (São Paulo State). The experimental design was completely randomized blocks, four replications, in a factorial scheme 5 x 30. Five herbicides treatments were evaluated; isolated nicosulfuron (0, 50 and 60 g ha-1) and in mixture with atrazine (20 g ha-1 + 1.5 kg ha-1 and 40 g ha-1 + 3.0 kg ha-1). Nicosulfuron isolated and in mixtures with atrazine was selectivy to 23 hybrids (A015, AG 2040, AG 8060, AGN 30A06, BM 1115, BRS 1035, BX 974, CDXS 012, CDXT 295, MAXIMUS, NB 3234, NB 4214, NB 8304, P 30K 73, P 30F36, P32R48, P30S40, SHS 5080, SHS 7070, SHS 7080, XB 6010, XB 6012, XB 7116) based in grain yield. Among thirty hybrids studied, only twelve hybrids show significant effect of phytotoxicity, which were: AG 2040, AG 8060, AGN 30A06, CDXS012, CDXT 295, NB 3234, NB 7324, SHS 5090, SHS 7070, XB 6010, XB 6012, XB 7116. The visual damage caused by the application of 50 e 60 g ha-1 nicosulfuron were more pronounced than the nicosulfuron doses in combination with atrazine. The hybrids that suffered losses in its production by the application of nicosulfuron alone or in combination with atrazine were hybrids AGN 30A05, BRS 1015, BRS 1031, BX 981, NB7324, SHS 5090 and P30R32. / Orientador: Julio Cezar Durigan / Coorientadora: Núbia Maria Correia / Banca: Pedro Luis da Costa Aguiar Alves / Banca: Fernando Tadeu de Carvalho / Mestre

Use of Nano Zero Valent Iron (nZVI) for treatment of different halogenated hydrocarbons, arsenic and various other contaminants has been proved successful. However, with so much diversified use of nZVI in the field and heighted attention to engineered nanoparticles, the environmental fate and impact of the nZVI remains unknown. The goal of this project was to evaluate the effects of different types of nZVI on Typha latifolia, a common wetland plant and hybrid poplar (Populous deltoids x Populous nigra), a woody plant used in phytoremediation. Plants grown hydroponically in a green house were dosed with different concentration of bare or bimetallic nZVI (with 10% nickel coating) for one to four weeks. The results showed that bare nZVI had toxic effects to Typha in higher concentrations but enhanced growth of plants at lower concentrations. Bare nZVI did not significantly affect the growth of poplars but bimetallic nZVI did impede the growth. Bimetallic nano particles were significantly more toxic and resulted in death of Typha within a week of dosing. Scanning electron microscope (SEM) clearly showed the adsorption of the nZVI on the plant root surface, confirmed by Energy dispersive x-ray (EDX) analysis. Transmission electron microscope (TEM) and Scanning Transmission electron microscope (STEM) confirmed the uptake of nZVI by poplar plant, but such internalization was not observed in case of Typha. However, uptake of the nanoparticles was only limited to the root and the translocation of particles to the shoot was not observed.

Made available in DSpace on 2014-06-11T19:28:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-03Bitstream added on 2014-06-13T20:58:20Z : No. of bitstreams: 1 rosa_cs_me_jabo.pdf: 131509 bytes, checksum: bc16df4958bfbe25ec06eb32b88f84cd (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi estudar a veiculação do oxyfluorfen à palha de arroz e a seletividade de Salvia splendens ao herbicida. Para tal, um ensaio de campo foi instalado, no delinamento de blocos casualisados, no esquema fatorial 4 x 3, com quatro repetições. Os tratamentos experimentais constaram de quatro quantidades de palha de arroz (0, 4, 6 e 8 t/ha) e três doses do herbicida oxyfluorfen (0, 1 e 2 L/ha). Os parâmetros avaliados foram altura de plantas, número de inflorescências e fitoxicidade de sálvia e a densidade da comunidade infestante. Concluiu-se que os tratamentos que levaram a veiculação do herbicida (nas duas doses testadas e nas três quantidades de palha) apresentaram bom controle de plantas daninhas sem que efeitos fitotóxicos severos fossem observados nas plantas de sálvia. A pulverização direta do herbicida sobre o solo e as plantas de sálvia não se mostrou viável para esta ornamental, visto que foram observados sintomas severos de fitointoxicação. O tratamento que obteve os resultados mais satisfatórios e por isso pode ser recomendado foi o que recebeu o herbicida na dose de 2 L/ha veiculado à 4 t/ha de palha de arroz. / The objective of this work was to study the possibility of oxyfluorfen herbicide translocation the straw rice and the selectivity Salvia splendens for the product. The randomized block design was used, in the factorial scheme 4 x 3, with four repetitions. The main factor was corporate for four amount straw rice (0, 4, 6 and 8 t/ha) and three doses of the oxyfluorfen herbicide (0, 1 and 2 L/ha). The results showed that traits which the herbicide was used with straw rice, showed great results to weeds control, with out occurrence of high phytotoxicity in the salvia plants.

Made available in DSpace on 2014-06-11T19:28:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-29Bitstream added on 2014-06-13T20:18:18Z : No. of bitstreams: 1 takahashi_en_me_jabo.pdf: 374500 bytes, checksum: 91c4b9c66141fafc6fde0277d2b00c0b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Votorantim de Celulose e Papel Vcp / Este trabalho teve como objetivo estudar os efeitos de deriva dos herbicidas clomazone e sulfentrazone em dois clones comerciais de E. grandis x E. urophylla da Votorantim Celulose e Papel, Unidade Florestal. A pesquisa foi realizada em duas etapas. O Ensaio 1 foi o exploratório, para determinação da dose crítica dos herbicidas clomazone e sulfentrazone e, o Ensaio 2, o efeito das aplicações de subdoses destes herbicidas em plantas de eucalipto, determinadas previamente no Ensaio 1. A metodologia de plantio e condução do experimento foram semelhantes para os dois ensaios, sendo as mudas previamente selecionadas de dois clones (VCP1 e VCP2) e plantadas em vasos com capacidade para 5,0 L, preenchidos com Neossolo Quartzarênico. Ao redor de 80 dias após o plantio foi realizada a aplicação dos herbicidas. O delineamento experimental do Ensaio 1 utilizado para cada herbicida foi o de blocos casualizados com os tratamentos dispostos em esquema fatorial 2x9, com três repetições, onde constituíram como fatores principais dois clones de eucalipto expostos a oito doses do herbicida para o Ensaio 1. No caso do Ensaio 2 o delineamento experimental foi o mesmo, no entanto, no esquema fatorial de 2x8. A avaliação de ambos ensaios foram realizados 30 dias após a aplicação, e no caso do Ensaio 2 fez uma avaliação dos sintomas da aplicação dos herbicidas ao longo do experimento. O Ensaio 1 indicou como sendo as doses críticas entre 18 a 180 mL ha-1 e 22 a 220 mLha-1, para clomazone e sulfentrazone, respectivamente. Em função disso foi estabelecido as doses para o Ensaio 2, sendo para o herbicida clomazone de 0 a 2000 mL ha-1 e para o sulfentrazone de 0 a 1500 mL ha-1. No Ensaio 2 observou-se que a aplicação do clomazone resultou em folhas novas rosadas, amareladas e em alguns casos esbranquiçadas como um todo ou parte dela, e as nervuras mantiveram-se verdes... / This research aimed to develop accurate information about effects of unintentional drift of two herbicides drift (clomazone and sulfentrazone) on growth of two Votorantim Celulose e Papel Eucalyptus grandis x E. urophylla commercial clones. The first step of the project this research were carried out on two steps, being first the exploitore trial (Trial 1) reaching determined the critical doses of clomazone e sulfentrazone application under Eucalyptus. The second step (Trial 2) as being trial to evaluated the herbicides’ subdoses effects on Eucalyptus plants. Application rates of Trial 1 indicated doses ranging between 18 and 180 mL ha-1 to clomazone and 22 and 220 mL ha-1 to sulfentrazone, so we tested the sensitivity of Eucalyputs clonelets to critical, as being the critica. Through these results second research imposed to doses to clomazone ranging between 0 and 2000 mL ha-1 for clomazone, and 0 and 1500 mL ha-1 for sulfentrazone. One cutting of each clone were planted in 5.0 liter plastic pots filled with sandy soil. 80 days after planting the herbicides application were carried out. The treatments were applied to plots with a completely randomized blocks with 2x8 factorial design, replicated three times, using two hybrid Eucalyptus grandis x E. urophylla clones and eight herbicides doses. xi Visual herbicide injury evaluation and growth measurements were made 30 days after application. Clomazone drift application led to changes in Eucalyptus leaf color, typically exhibit in younger leaves yellowing, pinking and some cases whitening between leaves veins and older leaves turned strongly green and thicker. Growth parameters reduced between 13 and 57% when clomazone were applied. Critical doses to clomazone were 800 to 1200 mL ha-1, to clone VCP1 e VCP2, respectively. The symptoms of sulfentrazone treatment included speckling and spotting to younger and older leaves, usually there with were...(Complete abstract, click electronic access below)

Resumo: Este trabalho teve como objetivo estudar os efeitos de deriva dos herbicidas clomazone e sulfentrazone em dois clones comerciais de E. grandis x E. urophylla da Votorantim Celulose e Papel, Unidade Florestal. A pesquisa foi realizada em duas etapas. O Ensaio 1 foi o exploratório, para determinação da dose crítica dos herbicidas clomazone e sulfentrazone e, o Ensaio 2, o efeito das aplicações de subdoses destes herbicidas em plantas de eucalipto, determinadas previamente no Ensaio 1. A metodologia de plantio e condução do experimento foram semelhantes para os dois ensaios, sendo as mudas previamente selecionadas de dois clones (VCP1 e VCP2) e plantadas em vasos com capacidade para 5,0 L, preenchidos com Neossolo Quartzarênico. Ao redor de 80 dias após o plantio foi realizada a aplicação dos herbicidas. O delineamento experimental do Ensaio 1 utilizado para cada herbicida foi o de blocos casualizados com os tratamentos dispostos em esquema fatorial 2x9, com três repetições, onde constituíram como fatores principais dois clones de eucalipto expostos a oito doses do herbicida para o Ensaio 1. No caso do Ensaio 2 o delineamento experimental foi o mesmo, no entanto, no esquema fatorial de 2x8. A avaliação de ambos ensaios foram realizados 30 dias após a aplicação, e no caso do Ensaio 2 fez uma avaliação dos sintomas da aplicação dos herbicidas ao longo do experimento. O Ensaio 1 indicou como sendo as doses críticas entre 18 a 180 mL ha-1 e 22 a 220 mLha-1, para clomazone e sulfentrazone, respectivamente. Em função disso foi estabelecido as doses para o Ensaio 2, sendo para o herbicida clomazone de 0 a 2000 mL ha-1 e para o sulfentrazone de 0 a 1500 mL ha-1. No Ensaio 2 observou-se que a aplicação do clomazone resultou em folhas novas rosadas, amareladas e em alguns casos esbranquiçadas como um todo ou parte dela, e as nervuras mantiveram-se verdes...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This research aimed to develop accurate information about effects of unintentional drift of two herbicides drift (clomazone and sulfentrazone) on growth of two Votorantim Celulose e Papel Eucalyptus grandis x E. urophylla commercial clones. The first step of the project this research were carried out on two steps, being first the exploitore trial (Trial 1) reaching determined the critical doses of clomazone e sulfentrazone application under Eucalyptus. The second step (Trial 2) as being trial to evaluated the herbicides' subdoses effects on Eucalyptus plants. Application rates of Trial 1 indicated doses ranging between 18 and 180 mL ha-1 to clomazone and 22 and 220 mL ha-1 to sulfentrazone, so we tested the sensitivity of Eucalyputs clonelets to critical, as being the critica. Through these results second research imposed to doses to clomazone ranging between 0 and 2000 mL ha-1 for clomazone, and 0 and 1500 mL ha-1 for sulfentrazone. One cutting of each clone were planted in 5.0 liter plastic pots filled with sandy soil. 80 days after planting the herbicides application were carried out. The treatments were applied to plots with a completely randomized blocks with 2x8 factorial design, replicated three times, using two hybrid Eucalyptus grandis x E. urophylla clones and eight herbicides doses. xi Visual herbicide injury evaluation and growth measurements were made 30 days after application. Clomazone drift application led to changes in Eucalyptus leaf color, typically exhibit in younger leaves yellowing, pinking and some cases whitening between leaves veins and older leaves turned strongly green and thicker. Growth parameters reduced between 13 and 57% when clomazone were applied. Critical doses to clomazone were 800 to 1200 mL ha-1, to clone VCP1 e VCP2, respectively. The symptoms of sulfentrazone treatment included speckling and spotting to younger and older leaves, usually there with were...(Complete abstract, click electronic access below) / Orientador: Pedro Luís da Costa Aguiar Alves / Coorientador: Ken McNabb / Banca: Rinaldo Cesar de Paula / Banca: Edivaldo Domingues Velini / Mestre

O herbicida deve ter a capacidade de controlar as plantas daninhas sem reduzir a produtividade e a qualidade da matéria-prima. Todavia, a tolerância da cana-de-açúcar pode variar com o herbicida, a dose desse produto, o genótipo da variedade, a época de aplicação (semi-seca, seca, semi-úmida e úmida), ambientes de produção, o estádio fenológico da cultura, dentre outros fatores. Visando o melhor entendimento do comportamento da cana-de-açúcar a aplicações do herbicida diuron+hexazinone+sulfometuron-methyl, avaliou-se a seletividade em diferentes estádios de desenvolvimento, em condições de campo, em casa de vegetação, e em laboratório. No campo, com início em setembro de 2013, as aplicações deste herbicida foram feitas em pré-emergência, esporão, 2 a 3 folhas e 5 a 6 folhas, comparando com o desempenho do herbicida amicarbazone, nas mesmas épocas, em canavial de segundo corte, onde avaliou-se fitotoxicidade, os parâmetros tecnológicos (fibra, pol, brix e ATR) e a produtividade. Constatou-se que mesmo com índices de fitotoxicidade altos nos diferentes estádios de desenvolvimento até 90 DAA, a produtividade não foi prejudicada a níveis significativos, bem como os parâmetros tecnológicos, quando comparados a testemunha. Na casa de vegetação, foi avaliado a seletividade do herbicida diuron+hexazinone+sulfometuron-methyl nos mesmos estádios de desenvolvimento avaliados em campo, nas variedades CTC 15, B86-7515, BR85-5536 e RB92-579. Observou-se diferenças significativas entre as variedades na variável altura em uma mesma época de aplicação, porém não refletiu na massa de matéria seca da parte aérea, a qual manteve-se semelhante entre os tratamentos. Para entendimento da fisiologia deste herbicida em cana-de-açúcar, avaliou-se a absorção e translocação ao longo do tempo, após sua aplicação nas fases de 2 a 3 e 5 a 6 folhas, onde apesar de serem detectadas diferenças significativas no quesito fitotoxicidade em ensaio de campo preliminar, tal acontecimento não pode ser justificado por diferenças no parâmetro absorção, conforme resultados do estudo. / The herbicide should be capable of controlling weeds without reducing productivity and quality of the raw material. However, the tolerance of sugarcane can vary with the herbicide, the dose of this product, the variety genotype, timing of application (semi-dry, dry, semi-wet and wet), production environments, the stadium phenological culture, among other factors. Aimed at better understanding the behavior of sugarcane to the herbicide diuron + hexazinone applications + sulfometuron-methyl, evaluated the selectivity at different stages of development in field conditions in the greenhouse and in the laboratory. In the field, starting in September 2013, the applications of this herbicide were made in pre-emergence, spur, 2-3 leaves and 5-6 leaves, compared to the performance of amicarbazone herbicide, at the same times, in the second cut cane field where phytotoxicity was evaluated, the technological parameters (fiber, pol, Brix and ATR) and productivity. It was found that with high phytotoxicity rates in different stages of development up to 90 DAA, productivity was not affected at significant levels, as well as technological parameters compared the witness. In the greenhouse, the selectivity of the herbicide diuron + hexazinone was rated + sulfometuron-methyl the same developmental stages evaluated in the field, in varieties CTC 15, RB86-7515, BR85-5536 and RB92-579. There were statistically significant differences between varieties in the variable height in the same time of application, but not reflected in the dry matter of the shoot, which remained similar between treatments. In order to understand the physiology of this herbicide in sugarcane, studies wih absorption and translocation was carried out over time, after application in the stages of 2 to 3 and 5 to 6 leaves, which despite being detected significant differences in field test for phytotoxicity such an event can not be justified by differences in absorption parameter, according to study results.

The increasing applications of different nanomaterials in the myriad of nano-enabled products and their potential for leaching have raised considerable environmental, health and safety (EHS) concerns. As systematic studies investigating potential anomalies in the morphology and anatomy of crop plants are scarce, herein we report on the developmental responses of two agriculturally significant crop plants, maize (Zea mays L.) and cabbage (Brassica oleracea var. capitata L.), upon in vitro exposure to nanoparticles of citrate-coated silver (Citrate-nAg) and zinc oxide (nZnO). Analyses involve histology of the primary root morphology and anatomy using light microscopy, metal biouptake, moisture content, rate of germination, and root elongation. Comparative toxicity profiles of the ionic salts (AgNO3 and ZnSO4) are developed. Notably, we uncover structural changes in maize primary root cells upon exposure to Citrate-nAg, nZnO, AgNO3, and ZnSO4, possibly due to metal biouptake, suggesting potential for functional impairments in the plant growth and development. Citrate-nAg exposure results in lower Ag biouptake compared to AgNO3 treatment in maize. Microscopic evidence reveals 'tunneling-like effect' with nZnO treatment, while exposure to AgNO3 leads to cell erosion in maize root apical meristem. In maize, a significant change in metaxylem count is evident with Citrate-nAg, AgNO3, and ZnSO4 treatment, but not with nZnO treatment (p>0.1). In both maize and cabbage, measures of germination and root elongation reveal lower nanoparticle toxicity compared to free ions. As moisture data do not support osmotically-induced water stress hypothesis for explaining toxicity, we discuss other proximate mechanisms including the potential role of growth hormones and transcription factors. These findings highlight previously overlooked, anatomically significant effects of metal nanoparticles, and recommend considering detailed anatomical investigations in tandem with the standard developmental phytotoxicity assays (germination and root elongation) as the latter ones appear less sensitive for screening plant responses to nanomaterial insults.

The increasing applications of different nanomaterials in the myriad of nano-enabled products and their potential for leaching have raised considerable environmental, health and safety (EHS) concerns. As systematic studies investigating potential anomalies in the morphology and anatomy of crop plants are scarce, herein we report on the developmental responses of two agriculturally significant crop plants, maize (Zea mays L.) and cabbage (Brassica oleracea var. capitata L.), upon in vitro exposure to nanoparticles of citrate-coated silver (Citrate-nAg) and zinc oxide (nZnO). Analyses involve histology of the primary root morphology and anatomy using light microscopy, metal biouptake, moisture content, rate of germination, and root elongation. Comparative toxicity profiles of the ionic salts (AgNO3 and ZnSO4) are developed. Notably, we uncover structural changes in maize primary root cells upon exposure to Citrate-nAg, nZnO, AgNO3, and ZnSO4, possibly due to metal biouptake, suggesting potential for functional impairments in the plant growth and development. Citrate-nAg exposure results in lower Ag biouptake compared to AgNO3 treatment in maize. Microscopic evidence reveals 'tunneling-like effect' with nZnO treatment, while exposure to AgNO3 leads to cell erosion in maize root apical meristem. In maize, a significant change in metaxylem count is evident with Citrate-nAg, AgNO3, and ZnSO4 treatment, but not with nZnO treatment (p>0.1). In both maize and cabbage, measures of germination and root elongation reveal lower nanoparticle toxicity compared to free ions. As moisture data do not support osmotically-induced water stress hypothesis for explaining toxicity, we discuss other proximate mechanisms including the potential role of growth hormones and transcription factors. These findings highlight previously overlooked, anatomically significant effects of metal nanoparticles, and recommend considering detailed anatomical investigations in tandem with the standard developmental phytotoxicity assays (germination and root elongation) as the latter ones appear less sensitive for screening plant responses to nanomaterial insults.