Crop yield can be raised by establishment of adequate plant stand using seeds with high germination ratio and vigor. Various pre-sowing treatments are adopted to achieve this objective. One of these ...approaches is the exposure of seeds to a low-to-medium level magnetic field (MF), in pulsed and continuous modes, as they have shown positive results in a number of crop seeds. On the basis of the sensitivity of plants to MF, different types of MF have been used for magnetopriming studies, such as weak static homogeneous magnetic fields (0–100 μT, including GMF), strong homogeneous magnetic fields (milliTesla to Tesla), and extremely low frequency (ELF) magnetic fields of low-to-moderate (several hundred μT) magnetic flux densities. The agronomic application of MFs in plants has shown potential in altering conventional plant production systems; increasing mean germination rates, and root and shoot growth; having high productivity; increasing photosynthetic pigment content; and intensifying cell division, as well as water and nutrient uptake. Furthermore, different studies suggest that MFs prevent the large injuries produced/inflicted by diseases and pests on agricultural crops and other economically important plants and assist in reducing the oxidative damage in plants caused by stress situations. An improved understanding of the interactions between the MF and the plant responses could revolutionize crop production through increased resistance to disease and stress conditions, as well as the superiority of nutrient and water utilization, resulting in the improvement of crop yield. In this review, we summarize the potential applications of MF and the key processes involved in agronomic applications. Furthermore, in order to ensure both the safe usage and acceptance of this new opportunity, the adverse effects are also discussed.
ABSTRACT Mimosa scabrella Bentham (bracatinga) is a prominent forest species in the south of the country, due mainly to the high rate of increase, rapid development cycle, and to enable multiple uses ...of wood production, both for firewood and for more noble purposes. The aim of this work was to estimate the physiological variation among 40 mother trees, based on germinative and biometric characterization of seeds and seedlings. Biometric traits were determined for the size and the fresh mass of 100 seeds, percentage of germination and normal seedlings, germination velocity index, daily mean germination, length, and dry mass of seedlings. Means were compared by the Scott-Knott test at 1% probability and estimates of Pearson correlation coefficients were obtained between all traits. The results indicate the existence of significant variation between arrays of same or different origin for both the biometric features as those from the germination test. The physiological quality of the seeds showed no direct relation to its size.
Abstract The objective of this work was to evaluate the effect of chemical thinning with metamitron on fruit of the Maciel and Sensação peach (Prunus persica) tree cultivars, as well as to identify ...its relation to the carbohydrate content in their branches. The experimental design was randomized complete blocks, and the treatments were trees with no thinning, manual fruit thinning, and chemical thinning with 200 mg L-1 metamitron applied at 20, 40, and 60 days after full blooming. The evaluated variables were: abscission percentage, yield per plant, number of fruit, presence of lignin in fruit, and carbohydrate content in the branches. The carbohydrate content was evaluated in trees with and without chemical thinning seven days after the application of the product. The use of metamitron promotes fruit thinning in the ‘Maciel’ and ‘Sensação’ peach trees, with a decrease in the carbohydrate content in their branches. Metamitron application 20 and 40 days after full blooming favors fruit abscission in both studied cultivars.
Resumo O objetivo deste trabalho foi avaliar o efeito do raleio químico com metamitron em frutos de pessegueiro (Prunus persica) das cultivares Maciel e Sensação, bem como a sua relação com o teor de carboidratos nos seus ramos. O delineamento experimental foi de blocos ao acaso, e os tratamentos foram plantas sem raleio, raleio manual de frutos e raleio químico com 200 mg L-1de metamitron aos 20, 40 e 60 dias após a plena floração. As variáveis analisadas foram: percentagem de abscisão, produção por planta, número de frutos, presença de lignina nos frutos e teores de carboidratos nos ramos. O teor de carboidratos foi avaliado em plantas com e sem raleio químico, sete dias após a aplicação do produto. O uso de metamitron promove raleamento dos frutos dos pessegueiros ‘Maciel’ e 'Sensação', com redução no conteúdo de carboidratos nos seus ramos. A aplicação de metamitron aos 20 e 40 dias após a plena floração favorece a abscisão dos frutos de ambas as cultivares estudadas.
Abstract The aim of this study was to evaluate the initial growth of Agonandra brasiliensis Miers ex Benth. & Hook. F. in response to different levels of shading and doses of controlled-release ...fertiliser (CRF). The experiment was conducted at Embrapa Roraima in Boa Vista, in a completely randomised experimental design and a 2 x 5 factorial scheme, of two luminosity levels (50 and 30%) and five doses of CRF (formulation 18-05-09, NPK) (0, 0.5, 1, 2 and 3 g L-1 substrate), with five replications, each consisting of five plants. At 240 days after transplanting, the growth characteristics were evaluated, and the influence of the light levels and the CRF dose was recorded on these characteristics, either individually or interactively. It is suggested that plants of Agonandra brasiliensis be fertilised with a dose of 2 g L-1 CRF and grown in an environment with 50% of luminosity to maximize growth and efficiency in the production of high-quality seedlings.
Objetivou-se com este trabalho estimar parâmetros e valores genéticos para os caracteres diâmetro do coleto e altura de progênies de bracatinga em fase inicial de desenvolvimento. As sementes foram ...coletadas de 40 matrizes nativas nos municípios de Abelardo Luz, Chapadão do Lageado, Lages e Três Barras, SC. O teste de progênie foi conduzido na Fazenda Experimental do Centro de Ciências Agroveterinárias da Universidade do Estado de Santa Catarina, em Lages, visando à seleção de materiais genéticos adaptados ao local. O delineamento utilizado foi o de blocos ao acaso, com quarenta tratamentos (progênies), 30 repetições e dez plantas por parcela em linhas simples. Aos 12 meses de idade, foram avaliados os caracteres: diâmetro do coleto e altura total dos indivíduos. Diferenças significativas foram observadas entre procedências e progênies. Os coeficientes de herdabilidade em nível de indivíduo e de média de progênies, assim como os coeficientes de variação genética foram altos, para os dois caracteres avaliados, e os maiores valores foram encontrados para as procedências de Abelardo Luz e Chapadão do Lageado, indicando um forte controle genético na herança destes caracteres e possibilidade de encontrar indivíduos superiores.
The aim of this study was to evaluate the effect of pre-germination treatments (magneto-priming and immersion of seeds in gibberellic acid solution) on variables associated with germination, ...emergence and vigor of Passiflora edulis seeds ‘BRS Gigante Amarelo’ cultivar. Seeds were extracted from fruits, washed, immersed for 6 hours in solutions with different GA3 concentrations and later arranged in a circular form in Petri dishes at temperature of 25°C, with and without exposure to magnetic field. Subsequently, analyses associated with the germination and emergency test were carried out. The experimental design was completely randomized design, with 3x2 factorial, three GA3 concentrations (0, 50 and 100 mg L-1) and presence/absence of magnetic field (MF), with four replicates of 20 seeds each. Variables germination percentage, germination speed index, mean germination time, percentage of emerged seedlings, emergence speed index, shoot length and root length and seedling dry weight were evaluated. Results indicate that the exposure of passion fruit seeds to MF in an isolated way stimulates seed germination, emergence and vigor, being an alternative to conventional treatments based on chemical substances.
Improvements in the traditional production system of peach seedlings, with a focus on the use of selected rootstocks, tend to minimize some of the problems experienced with this crop in the south of ...Brazil, such as the scarcity of vigorous nursery plants and the lack of a genetic identity for commercial rootstocks. The aim of this study was to investigate the different patterns of nutrient absorption and allocation related to the rootstock in ‘BRS Rubimel’ peach plants by analyzing growth variables during the post-graft period. The experimental design consisted of randomized blocks in a 3 × 3 factorial scheme, with three peach rootstock varieties (i.e., ‘Flordaguard’, ‘Capdeboscq’, and ‘Okinawa Roxo’) and three post-graft evaluation periods (i.e., 30, 60, and 90 days after the start of budding), corresponding to a total of nine treatments, with three replications, each including five plants. During the three evaluation periods, morphological growth characteristics were measured, and the macronutrient content was determined in the different plant organs (i.e., leaf, stem, and roots). The nutrient content in plants of the ‘BRS Rubimel’ peach plants was influenced by the rootstock. Despite showing greater N use efficiency, ‘Capdeboscq’ accumulated a large part of this nutrient in the roots, using it for root growth, which resulted in a smaller scion diameter compared to that of ‘Flordaguard’. Comparing the three rootstocks and the evaluated variables, it seems that ‘Flordaguard’ can be used as a rootstock for the ‘BRS Rubimel’ peach plants, as it induces a greater scion diameter as well as the uniform allocation of dry matter between organs during the post-graft period, hence ensuring greater initial plant vigor.
Objetivou-se com este estudo avaliar os efeitos da aplicação de solução nutritiva com concentrações crescentes de zinco (Zn) no desenvolvimento inicial e no teor de pigmentos de plantas de feijão ...cultivadas em condições de casa de vegetação. O experimento foi desenvolvido no Laboratório de Nutrição de Plantas (LNP) e em casa de vegetação pertencentes ao Departamento de Botânica da Universidade Federal de Pelotas (UFPel). A semeadura foi realizada em vasos preenchidos com areia média lavada. Sete dias após a emergência das plântulas foi aplicada, com intervalos de dois dias, solução nutritiva com quatro concentrações crescentes de Zn (2, 50, 75 e 100 µM), dispostas em um delineamento experimental inteiramente casualizado com quatro repetições, sendo cada uma delas composta por seis plantas. Aos 45 dias após a emergência das plântulas, avaliaram-se as seguintes variáveis: altura das plantas, diâmetro do caule, número de folhas, área foliar e comprimento de raiz, além do índice de pigmentos fotossintéticos. Com o aumento das concentrações de Zn verificou-se decréscimo significativo para as variáveis diâmetro do caule e comprimento de raiz, sugerindo que maiores concentrações de Zn podem influenciar negativamente no desenvolvimento das plantas de feijão. Os índices de clorofila e flavonoides apresentaram elevação com o aumento das doses de Zn. Esse efeito possivelmente está relacionado a uma reação estratégica da espécie, que visa minimizar o efeito tóxico das concentrações crescentes de Zn no desenvolvimento das plantas.Palavras-chave: Feijão. Micronutriente. Pigmentos foliares. Toxicidade.
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