ABSTRACT The present work explores a practical strategy for real-time assessment of foliar-based mineral fertilizers diffusion. Thereby, a dialysis tubing membrane was employed as a leaf cell-proxy for tracing the release of three commercial foliar fertilizer formulations and their correspondent primary compounds, MnCO3, Mg(OH)2, and Cu2O at the field-recommended concentration, by simply measuring changes on conductivity and pH during 96 h. It enabled either modulating fertilizer diffusion kinetics, as well as comparing the commercial formulations to its primary compound ones. Hence, the proposed approach stands out as a fast and effective tool for addressing relevant information about the performance of foliar fertilizer formulation, one of the bottlenecks of programs developing new fertilizer formulations.

ABSTRACT Seed treatment is an interesting alternative to deliver micronutrients to field crops. The aim of this study was to investigate the uptake of Cu and Zn by maize seedlings, with the application of the water-insoluble sources copper carbonate and zinc oxide as seed treatment. Treatments were composed of a control (untreated seeds), five doses of copper (0.14, 0.28, 0.56, 1.12 and 2.24 mg Cu∙seed–1) and zinc (0.55, 1.10, 2.20, 4.40 and 8.80 mg Zn∙seed–1) as well as five doses of copper and zinc combined (0.14, 0.28, 0.56, 1.12 and 2.24 mg Cu∙seed–1; 0.55, 1.10, 2.20, 4.40 and 8.80 mg Zn∙seed–1). Plants were cultivated in sand, under greenhouse conditions and, at the two-leaf stage (15 days), the root and shoot tissues dry mass and concentration of Cu and Zn were determined, which allowed to calculate accumulation and uptake efficiency of these micronutrients by maize plants. Seed treatment with copper carbonate and zinc oxide increased both root and shoot concentration and accumulation of Cu and Zn in maize seedlings, with two fully expanded leaves. Cu tended to accumulate in roots, while Zn was more evenly distributed among roots and shoots. Combined application of copper carbonate and zinc oxide resulted in lower uptake of both Cu and Zn by maize if compared to individual applications, with Cu uptake reduced in a higher extent.

Seed treatment is a low-cost and efficacious method to deliver a diversity of compounds to field crops. This study evaluated the uptake of seed-applied Cu by maize and the effect on seed vigor. The treatments were composed of a control (untreated seeds) and five dosages of Cu: 0.11, 0.22, 0.44, 0.88 and 1.76 mg Cu seed–1, applied as cuprous oxide and copper oxychloride formulations. Seedling emergence and the speed of seedling emergence were determined in three periods: 1, 60 and 120 days after Cu application. Evaluations of root and shoot dry mass, Cu tissue concentration and efficiencies of Cu uptake and incorporation were conducted with two-leaf stage maize plants. Seed-applied Cu reduces the speed of maize seedling emergence, while the final emergence percentage is not affected. Shoot dry mass tends to increase with the application of Cu, while there is no interference on root dry mass within the dosages tested. Cu tissue concentration of both roots and shoots increases as higher dosages of Cu are applied to seeds, with higher accumulation in roots. Cuprous oxide promotes higher uptake of Cu by maize roots compared to copper oxychloride.

The occurrence of weed species with different levels of resistance to glyphosate has increasingly spread in agricultural areas. In Brazil, sourgrass is among the main species presenting issues in this regard. Thus, fast and reliable methods to detect glyphosate resistance are of special interest for this specie, either for research or rational management purposes. This study was carried out to verify the feasibility of using the germination test to detect glyphosate resistance in sourgrass. The experiment was conducted with two sourgrass biotypes, with different levels of susceptibility to glyphosate. The seeds were previously imbibed in solutions composed of 0, 0.1875%, 0.25%, 0.75%, 1.5%, 3% and 6% of glyphosate during two periods, five and ten minutes, and submitted to germination tests. The results indicate the germination test as a feasible and time-saving approach to evaluate glyphosate-resistant sourgrass, with results available in seven days.

RESUMO: O experimento teve como objetivo associar conceitos para avaliação do vigor de sementes, o envelhecimento acelerado e crescimento de plântulas medido por meio da análise de imagens. Para tanto, cinco lotes de sementes com diferentes níveis de vigor de dois híbridos simples foram utilizados. As sementes foram caracterizadas pelo teor de água, germinação, porcentagem e índice de velocidade de emergência de plântulas, envelhecimento acelerado e teste de frio. Os tratamentos foram constituídos por diferentes períodos de envelhecimento acelerado (0, 24, 48, 72 e 96h) e de crescimento de plântulas (48 e 72h) e, em seguida, as plântulas, submetidas à análise de imagens para mensuração do comprimento de raízes. A adaptação do teste de envelhecimento acelerado, reduzindo a duração do envelhecimento de 96h para 48h e a substituição do teste de germinação pela mensuração do comprimento de raízes das plântulas por meio da análise de imagens, comprovou-se um método potencial para avaliação da qualidade de sementes de milho. Assim, os tratamentos compostos por 48h de envelhecimento, seguido pela mensuração do comprimento de raízes utilizando a análise de imagens, forneceram dados confiáveis em comparação aos testes de vigor tradicionais e podem ser considerados uma nova abordagem para a análise de vigor de sementes.

ABSTRACT: This study aimed to associate two concepts of seed vigor testing, the aging and seedling growth using image analysis, providing a feasible and time-saving way to evaluate maize seed vigor in large scale. For this purpose, five seed lots with different vigor levels from two single hybrids were used. The seeds were characterized by moisture content, germination, seedling emergence, seedling emergence speed index, accelerated aging and cold tests. The treatments were composed by varying the accelerated aging periods (0, 24, 48, 72 and 96h) and seedling growth periods (48 and 72h), before submitting the seedlings to image analysis for seedling root length measurement. Considering the results obtained, the adaptation of accelerated aging test by reducing the aging duration from 96h to 48h, and the replacement of the germination test by seedling root length measurement using image analysis could be considered a potential tool for maize seed vigor assessment. The treatments composed of 48h of seed aging followed by seedlings root length measurements using image analysis provided reliable data, compared to traditional vigor tests and it could be considered an efficient and time-saving approach, associating two different concepts of seed vigor analysis.

Para a avaliação do vigor de sementes podem ser utilizados uma série de testes fisiológicos, os quais, baseados em diferentes conceitos, podem resultar em diferentes interpretações dos resultados obtidos, especialmente quando há comparações de lotes com diferentes níveis de vigor. O objetivo desse trabalho foi comparar diferentes abordagens para avaliação do vigor de sementes de pimentão e verificação da aplicabilidade do programa computacional 'Seed Vigour Imaging System' (SVIS) para este propósito. Dessa forma, em dois períodos de avaliação, avaliou-se quatro lotes de sementes de pimentão por meio dos testes de germinação, emergência de plântulas, envelhecimento acelerado e análise de imagens. O uso do SVIS pode ser considerado uma nova abordagem para avaliação do vigor de sementes de pimentão. Tanto o programa computacional como os testes tradicionais forneceram informação suficiente para a análise de vigor de sementes, permitindo igualmente a segregação dos lotes analisados e, ainda, preenchem requisitos importantes para um teste laboratorial, como padronização, eficiência, rapidez e baixo-custo. Assim, permitem a comparação entre laboratórios e diminuem os riscos da influência humana na interpretação de resultados, podendo ser considerado uma possível opção para ser incluída em programas de controle de qualidade na produção de sementes de pimentão.

Seed vigor is a major attribute in the determination of whether a seed lot can be commercialized. Different physiological tests are used to assess seed vigor and are generally based on different concepts, which could lead to variable interpretations, particularly when comparing lots presenting different vigor levels. This study was conducted to compare the different approaches used to evaluate bell pepper seed vigor and verify the applicability of the Seed Vigor Imaging System (SVIS) for this purpose. The experiment was performed using four seed lots of bell pepper hybrids in two periods, and the evaluations involved germination, seedling emergence, seedling emergence speed index, saturated salt accelerated aging and image analysis. The use of seedling imaging analysis by SVIS is a new approach for bell pepper seed vigor evaluation. Both the software and traditional tests provided sufficient information for seed vigor analysis, enabling the segregation of the analyzed seed lots. Thus, the new method fulfills the requirement for an efficient, rapid, cost-effective and standardized method that allows comparisons among laboratories and avoids human influence on the interpretation of the results. SVIS can be considered a feasible option to be included in quality assurance programs of the bell pepper seed industry.

Vigor é a característica que determina o potencial para rápida e uniforme emergência de plântulas e estabelecimento das culturas. Essa característica define crescimento inicial, o qual pode ter efeitos diretos e indiretos na capacidade da planta em capturar recursos naturais e intervir na sua competição intra e interespecífica. Objetivando identificar e entender os possíveis efeitos do vigor de sementes de milho no crescimento inicial da cultura, um experimento foi conduzido, por dois anos, na Universidade de São Paulo, Piracicaba, SP, Brasil; utilizando dois lotes de sementes a cada ano, os quais foram previamente caracterizados por testes de potencial fisiológico, como alto e baixo vigor. Assim, foram utilizados cinco diferentes proporções (100:0, 75:25, 50:50, 25:75 e 0:100) de sementes de lotes com maior ou menor vigor. As avaliações foram realizadas nos estádios fenológicos de quatro e oito folhas para altura de planta, diâmetro de colmo e índice de área foliar. Foi observado que os valores médios para todas as variáveis analisadas aumentaram de acordo com aumento de sementes com alto vigor na linha de semeadura. Assim, concluiu-se que o aumento da porcentagem de sementes com alto vigor resulta em maior crescimento inicial da cultura até o estádio fenológico de oito folhas.

Seed vigor is a characteristic that determines potential for fast and uniform seedling emergence and establishment of crops. Such characteristic defines crop initial growth what could have direct and indirect effects on capacity of plants in capturing natural nutritive resources and intervene in their competition intra- and interspecific. Aiming at identifying and understanding the possible effects of seed vigor on crop initial growth a field experiment was performed during two years at University of São Paulo, Piracicaba, SP, Brazil; using two seed lots at each year, which were previously characterized by tests of physiological potential as high and low vigor. Thus, five different ratios (100:0, 75:25, 50:50, 25:75, and 0:100) of seeds originating from seed lots with higher or lower vigor were used. Assessments were performed at the phenological stages of four and eight leaves by assessing plant height, stem diameter, and leaf area index. It was also observed that mean values for all variables assessed have increased according to increase of seeds with high vigor at planting row. Therefore, it is concluded that increased percentage of seeds with high vigor results in greater initial growth of cron crop until phenological stage of eight leaves.

Estudou-se os efeitos da utilização de lotes constituídos por sementes de milho de alto ou de baixo vigor, bem como a mistura desses em diferentes proporções, simulando-se o uso de lotes de sementes homogêneos e heterogêneos quanto ao vigor das sementes, sobre o crescimento inicial e produtividade das plantas. Observou-se que plantas originadas de sementes menos vigorosas foram inferiores às originadas de sementes mais vigorosas quanto ao crescimento inicial e, para os componentes de produção, as provenientes de sementes menos vigorosas não foram inferiores nas distribuições onde houve 100% de um tipo de semente, porém, foram inferiores quanto acúmulo de massa de matéria seca, número de grãos por fileira e produtividade de grãos nas demais distribuições. Assim, vigor de sementes está diretamente relacionado ao crescimento inicial das plantas; porém, seus efeitos não persistem até o final do ciclo da cultura quando há o uso de lotes homogêneos quanto ao vigor das sementes. O uso de lotes heterogêneos resulta em maior competição intraespecífica proporcionando menor capacidade competitiva às plantas provenientes de sementes de menos vigorosas, sendo estas dominadas pelas provenientes de sementes de alto vigor, refletindo negativamente em produção por planta.

The objective of this study was to evaluate the effects of using maize seed lots constitued of high and low vigor seeds, as well as mixtures of different proportions, on plant growth and yield. Plants from high vigor seeds showed higher initial growth than those from low vigor seeds, independently of seed distribution and position in the seeding row. Comparing the yield components between plants arising from high and low vigor seeds, when the percentages of one type of seed were 100% (homogeneous lots), results were similar, but plants from low vigor seeds had inferior results on other seed distributions (heterogeneous lots). Seed vigor is directly related to initial plant growth in maize but the effects do not continue until harvest when using seed lots with homogeneous vigor. However, the use of seed lots with heterogeneous vigor results in more intra-specific competition and a lower competitive capacity for plants originating from low vigor seeds, resulting in dominated plants which grow and yield less.

O vigor das sementes é um fator que determina a velocidade e uniformidade de emergência de plântulas e o crescimento inicial das plantas, que consistem em aspectos cruciais na competição com plantas daninhas. Assim, os objetivos neste estudo foram verificar os efeitos diretos do vigor de sementes de soja sobre a competição com plantas daninhas e rendimento de grãos. Um experimento de campo foi conduzido na Universidade de São Paulo, Piracicaba, Brasil, com três lotes de sementes do cultivar "Conquista", previamente caracterizados por meio de testes fisiológicos como de alto, intermediário e baixo vigor. O experimento foi dividido em parcelas com e sem controle de plantas daninhas, compondo seis tratamentos. Os dados de altura das plantas de soja, acúmulo de massa de matéria seca de plantas daninhas e de produtividade de grãos foram obtidos. O vigor das sementes não afetou a altura das plantas e o rendimento de grãos de soja neste estudo. As plantas desenvolvidas a partir de sementes de alto e médio vigor apresentaram os melhores resultados na competição com plantas daninhas, proporcionando redução do acúmulo de massa de matéria seca destas. Plantas provenientes do lote de sementes de alto vigor apresentam maior rendimento de grãos, tanto em parcelas com controle, como nas sem controle de plantas daninhas.

Seed vigor is one of the factors that determines the speed and uniformity of seedling emergence and initial plant growth, which are crucial aspects in the competition against weeds. The objective of this study was to verify the direct effects of soybean seed vigor on weed competition and grain yield. A field experiment was conducted with three seed lots of the "Conquista" cultivar, previously characterized by physiological tests as having high, intermediate and low vigor. The experiment was divided into weeded and unweeded plots with six treatments. Crop plant height, weed dry mass accumulation and crop grain yield data were recorded. Seed vigor did not affect plant height and grain yield. Plants which developed from seeds with high and intermediate vigor showed the best results for competition against weeds, reducing weed dry mass accumulation. Plants which developed from high vigor seeds give the best results for grain yield for both weeded and unweeded treatments.

O vigor de sementes está relacionado diretamente com a emergência rápida e uniforme de plântulas e crescimento inicial das plantas, fator que pode auxiliar significativamente na habilidade competitiva por recursos como água, luz e nutrientes. Dessa forma, objetivou-se neste trabalho avaliar o efeito do vigor de sementes de milho sobre o crescimento inicial das populações de plantas, produtividade final e competição com plantas daninhas. A pesquisa foi conduzida em área experimental da Universidade de São Paulo, Piracicaba, SP, no ano agrícola de 2007/2008. Foram utilizados quatro lotes de sementes certificadas do milho híbrido DOW8480, com diferentes níveis de vigor, compondo oito tratamentos, com controle e sem controle de plantas daninhas. As análises de campo ocorreram nos estádios fenológicos de 2, 4, 6 e 8 folhas, mensurando-se as plantas quanto altura, diâmetro de colmo e índice de área foliar. Avaliou-se, também, a radiação solar incidente na entrelinha da cultura no estádio fenológico de 4 folhas. No pendoamento, foram realizadas coletas de plantas daninhas presentes nas parcelas, as quais foram avaliadas quanto ao acúmulo de massa de matéria seca e, na colheita, foi avaliada a produtividade de grãos. Os resultados indicaram que vigor das sementes tem efeitos diretos no crescimento inicial da cultura, o que reflete na habilidade competitiva das plantas de milho com plantas daninhas, as quais têm menor crescimento. Além disso, quando em competição maximizada por recursos, o vigor das sementes influencia diretamente na produtividade de grãos.

Seed vigor is directly related to rapid and uniform seedling emergence and to crop initial development, factor which should have significant effects on the ability of plants to compete for the uptake of resources such as water, light and soil nutrients. It was investigated the effects of maize seed vigor on crop initial growth, yield and weed competition. The experiment was conducted in an experimental area at the University of Sao Paulo, Piracicaba, SP, Brazil during the 2007/2008 growing season and used four lots of maize seed hybrid DOW8480, previously characterized with different vigor levels, grown on plots with and without weed control to give a total of eight treatments. Field analysis were made at the 2, 4, 6 and 8 leaves development stages when plants were evaluated by height, stem diameter and leaf area index. The solar radiation incident on intercrop lines was also measured at the 4 leaf development stage. Weed samples were collected during the maize-tasseling stage and evaluated by dry mass accumulation and maize yield was evaluated at harvest. The results showed that seed vigor is directly related to initial crop growth and that this affects maize plant competitive ability with regard to weeds with inferior growth rates. Furthermore, seed vigor has direct effects on maize yield during maximized competition for the uptake of resources.