In recent years, the application of natural substances on crops has been intensified in order to increase the resistance and yield of the soybean crop. Among these products are included plant biostimulants that may contain algae extracts, amino acids, and plant regulators in their composition. However, there is little information on the isolated effect of each of these constituents. The objective of this research was to evaluate the effect of the application of isolated amino acids on the antioxidant metabolism of the soybean crop. Experiments were carried out in a greenhouse and in the field with the application of the amino acids glutamate, phenylalanine, cysteine, glycine in seed treatment, and foliar application at V4 growth stage. Antioxidant metabolism constituents evaluated were superoxide dismutase, catalase, peroxidase, hydrogen peroxide content, proline, and lipid peroxidation. In addition, resistance enzymes as polyphenol oxidase and phenylalanine ammonia-lyase (PAL) were evaluated. In both experiments, the use of cysteine, only in seed treatment and in both seed treatment and foliar application increased the activity of the enzyme PAL and catalase. Also in both experiments, the use of phenylalanine increased the activity of the enzyme PAL when the application was carried out as foliar application or both in seed treatment and foliar application. In the field experiment, the application of glutamate led to an increase in the activity of the catalase and PAL enzymes for seed treatment and foliar application. The use of the set of amino acids was only efficient in foliar application, which led to a greater activity of the enzymes peroxidase, PAL, and polyphenol oxidase. The other enzymes as well as lipid peroxidation and hydrogen peroxide presented different results according to the experiment. Therefore, glutamate, cysteine, phenylalanine, and glycine can act as signaling amino acids in soybean plants, since small doses are enough to increase the activity of the antioxidant enzymes.

A batata (Solanum tuberosum) ocupa a quarta posição mundial como fonte de alimento vegetal, sendo superada apenas pelo milho, arroz e trigo. O país maior produtor é a China, seguido da Rússia, Índia, Ucrânia e Estados Unidos; o Brasil ocupa a décima nona colocação, com produção de 3,5 milhões de t, cultivadas em aproximadamente 139 mil ha, e produtividade média de 25 t ha -1 (FAO, 2011). O estado do Paraná, na safra de 2010, apresentou área de plantio de 30.000 ha com produtividade média de 24 t ha -1 , sendo que na região de Guarapuava foram cultivados 2.995 ha com produtividade média de 28 t ha -1 (IBGE, 2011).A cultura da batata demanda alto investimento, sendo que atualmente a lavoura custa cerca de R$ 20.000,00 por ha (insumos, operações mecânicas, RESUMOA cultura da batata demanda alto investimento para a sua implantação. Dentre os insumos responsáveis pelo alto custo da lavoura, destacam-se os fertilizantes e a semente. O objetivo deste trabalho foi identificar o efeito de doses de fertilizantes e tamanhos de batata-sementes no crescimento, produtividade e rentabilidade da cultura da batata. O experimento foi conduzido em uma lavoura comercial de batata em Guarapuava-PR, a partir de dezembro de 2010. Os tratamentos foram constituídos de 0, 2, 4 e 6 t ha -1 do fertilizante mineral 4-14-08 (parcela) e batatas-semente do tipo I e III (subparcela), arranjados em esquema de parcela subdividida, em blocos ao acaso, com três repetições. Foram avaliados o comprimento da haste principal, número de hastes, índice de área foliar, massa fresca e número de tubérculos, aos 24, 41 e 57 dias após a emergên-cia, além de quantificar a produtividade comercial e o número de tubérculos no período da colheita. Calculou-se também a máxima eficiência técnica e econômica das doses de fertilizantes. Não houve interação significativa entre doses de fertilizantes e tamanhos de batata-semente em nenhuma característica analisada. As doses de fertilizantes influenciaram todas as características analisadas, sendo que, de modo geral, as maiores doses resultaram em maiores valores das características. Entretanto, as doses de fertilizantes influenciaram com menor intensidade o número de hastes, que foi a característica mais influenciada pelo tamanho da batata-semente, sendo maior em plantas oriundas de sementes do tipo I. O tamanho da batata-semente não influenciou a produtividade de tubérculos. Observou-se aumento da produtividade de tubérculos com o aumento da dose de fertilizante até 4,2 t ha -1 , porém a máxima eficiência econômica foi atingida com 3,5 t ha -1 de fertilizante. Conclui-se, portanto, que a utilização da dose de 3,5 t ha -1 e batatas-semente do tipo III resultaram na melhor opção econômica para o produtor. Palavras-chave:Solanum tuberosum, adubação, índice de área foliar, produção, tubérculo. ABSTRACT NPK fertilization and potato tuber seed size on growth, yield and profitability of potato plantsPotato crops need high investment for its establishment. Among the inputs responsible for the high crop cost, fertilizers and s...

Gypsum is used in agriculture as calcium (Ca 2+) and sulfur (S) source, and to mitigate native toxic levels of aluminum (Al 3+). However, the effects on soil chemical attributes, corn leaf nutritional status, grain yield, and profitability should be better understood. Gypsum rates (0, 3, 6, 9, and 12 Mg ha −1) were applied at once (2009) or split in two (2009-2010) or three (2009-2010-2011) annual applications, to a Typic Hapludox under no-till from Southern Brazil. The use of gypsum increased Ca 2+ and S-SO 4 2− and reduced Al 3+ levels in the soil up to 0.8 m depth. Increasing gypsum rates reduced Mg 2+ levels up to 0.6 m. Corn leaf concentrations of Ca and S were increased, while Mg concentration was decreased by gypsum use. The maximum technical efficiency (MTE) rate of gypsum for corn (2013/2014) grain yield was 6.34 Mg ha −1. The most profitable rate for the period 2009-2014 growing seasons was achieved with 4.60, 5.63, and 6.08 Mg ha −1 of gypsum applied at once or split in two and three annual applications, respectively. The use of gypsum within the MTE interval improves chemical attributes in the soil profile, corn leaf nutritional status, corn grain yield, and land use profitability. The use of gypsum causes soil Mg 2+ leaching. Split application reduces leaching process for S-SO 4 2− , but not for Mg 2+ .

The residual effects of gypsum rates and the interaction with N-fertilization on soil fertility, black oat root growth and aboveground biomass yield under no till lacks information. This study evaluated soil chemical attributes up to 0.8 m depth and aboveground biomass of black oat in a continuous no-till area as affected by gypsum rates (0, 3, 6, 9 and 12 Mg ha −1) and topdressing N-fertilization (0, 50 and 100 kg ha −1) to a Typic Hapludox in Southern Brazil. Black oat root growth was also evaluated for two gypsum rates (0 and 6 Mg ha −1) and all N treatments. Gypsum application increased Ca 2+ and SO 4 2 −-S fraction and reduced Mg 2+ levels in all soil layers, and N-fertilization increased NO 3 − and NH 4 + levels in the soil. Gypsum increased root length, superficial area and volume up to 0.8 m depth, while N-fertilization reduced root growth attributes in soil layers between 0.4 and 0.8 m depth. Gypsum increased (quadratically) the aboveground biomass yield of black oats in the two growing seasons, as did N-fertilization, but no interaction between gypsum and N-fertilization was observed. Gypsum can be used to improve soil fertility attributes, black oat biomass and root growth under no till. The higher N-fertilization (100 kg ha −1) increased black oat yield and reduced root growth in depth. In the average of the growing seasons, the gypsum rate of 7.36 Mg ha −1 applied 54 months earlier, associated with a rate of at least 50 kg ha −1 of N (urea) applied at the beginning of black oat tillering achieved the higher aboveground biomass yield.

On-farm soybean yield has increased considerably in the last 50 years in southern Brazil, but there is still little information about how selection and breeding for yield increase has changed the agronomic attributes of cultivars. The objectives of this study were to evaluate the changes in soybean yield, seed oil and protein concentration, and changes in plant attributes that might be associated with yield improvement of 26 soybean cultivars released over the past 50 years in southern Brazil, sown simultaneously in a common field environment for two growing seasons. The average rate of yield gain was 45.9 kg ha−1 yr−1 (2.1% ha−1 yr−1), mainly due increased seed number per area and harvest index. Over year of cultivar release, cultivars became less susceptible to lodging, as well as plant mortality reduced. Meanwhile, the seed oil concentration increased, and seed protein concentration decreased, which could have negative consequences for soybeans use and requires further attention for breeding of future cultivars. Breeders have successfully contributed to the annual rate of soybean yield increase in southern Brazil. By our results, as well as the official on-farm production data, there is no evidence of soybean yield reaching a plateau in the near future in southern Brazil.

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Harvest-aid herbicides are used to anticipate soybean harvest and make the field available for next crop during the growing season. However, this anticipation can interrupt the transport of photoassimilates and reduce seed yield, as well as affect the seed quality. It is also not well known if cultivars with earlier growth cycle are more sensitive to harvest-aid herbicides. This work evaluated how different moments of harvest-aid herbicides application affect soybean yield, seed physiological quality, and oxidative metabolism. Two cultivars were used, one early and another medium growth cycle. The herbicide used was paraquat. Experiments were carried out in the field to evaluate yield attributes, and from the seeds harvested, seed quality attributes were evaluated in controlled environment. Early application of harvest-aid herbicides reduced seed yield and 1000-seed mass in both evaluated cultivars, being more expressive for early growth cycle cultivar. Seeds from plants submitted to early application of harvestaid herbicides had higher enzymatic activity related to oxidative metabolism. The early growth cycle cultivar (maturity group -MG 6.2) produced more than the medium growth cycle cultivar (MG 7.7), however, had greater sensitivity to the early application of harvest-aid herbicide.