RESUMO:O objetivo deste trabalho foi avaliar o desenvolvimento inicial da guavira (Campomanesia adamantium) cultivada sob diferentes doses de fósforo e nitrogênio. O experimento foi realizado em casa de vegetação, da Universidade Federal da Grande Dourados, em Dourados-MS. Foram estudadas cinco doses de fósforo (20, 120, 200, 280 e 380 kg ha -1 ), na forma de superfosfato simples e cinco doses de nitrogênio (6, 36, 60, 84 e 114 kg ha -1 ), na forma de sulfato de amônio. Os tratamentos foram definidos utilizando-se a matriz experimental Plan Puebla III, dando origem a nove combinações, respectivamente, de doses de fósforo e de nitrogênio (kg ha -1 ): 280 e 84; 280 e 36; 120 e 6; 120 e 36; 120 e 84; 200 e 60; 380 e 84, 20 e 36 e 280 e 114. O delineamento experimental utilizado foi blocos casualizados, com quatro repetições. A unidade experimental foi composta por cinco vasos, com uma planta por vaso. A colheita das plantas foi feita aos 270 dias após o transplante (DAT). Sob as maiores doses de P e N utilizadas observaram-se as maiores alturas de plantas (38,12 cm), aos 261 DAT; o maior número de folhas por planta (54), aos 186 DAT; a maior massa seca de folhas (5,68 g planta -1 ), a maior área foliar (610 cm 2 planta -1 ), a maior massa seca de raiz (6,2 g planta -1 ) e o maior número de ramos (3 planta -1 ) aos 270 DAT. O teor de clorofila foi em média de 36 ICF. Recomenda-se o uso de 380 kg ha -1 de fósforo e de 114 kg ha -1 de nitrogênio para o melhor desenvolvimento inicial da guavira. Palavras-chave:Campomanesia adamantium, planta medicinal, adubação nitrogenada, adubação fosfatada ABSTRACT: Effect of nitrogen and phosphorus supply on initial development of guavira [Campomanesia adamantium (Cambess.) O. Berg] cultivated in pots. The aim of this trial was to evaluate the initial development of Campomanesia adamantium grown under different phosphorus and nitrogen rates. The experiment was conducted in a greenhouse at the Universidade Federal da Grande Dourados, Dourados-MS. It was studied five phosphorus rates (20, 120, 200, 280 and 380 kg ha -1 ) in the form of superphosphate and five nitrogen rates (6, 36, 60, 84 and 114 kg ha -1 ) in the form of ammonium sulfate. Treatments were defined using the Plan Puebla experimental matrix, resulting in nine combinations, respectively, of phosphorus and nitrogen (kg ha -1 ): 280 and 84, 280 and 36, 120 and 6, 120 and 36, 120 and 84, 200 and 60, 380 and 84, 20 and 36 and 280 and 114. The experimental design was randomized block with four replications. Experimental unit consisted of five vessels, with one plant per pot. The trial harvest was carried out 270 days after transplanting (DAT). Highest rates of N and P resulted on the greatest plant height (38.12 cm) reached after 261 DAT, maximum number of leaves per plant (54) at 186 DAT, highest dry weight of leaves (13.99 and 5.68 g plant -1 ) and root (15.9 and 6.2 g plant -1 ), greatest leaf area (610 cm 2 plant -1 ) and number of branches (3 planta -1 ), all at 270 DAT. The average of Chlorophyll levels was 36 ICF. T...

This study aimed to test the hypothesis that increases in leaf nitrogen concentration would reduce the sensitivity of sugarcane photosynthesis to low temperature. IACSP95-5000 plants were grown inside a growth chamber at 30/20 o C (day/night) and we evaluated the effects of leaf nitrogen spraying (2.5% urea) on plants facing low temperature (22/12°C) for eight days. The leaf nitrogen supply increased leaf nitrogen concentration and plants exhibited higher leaf gas exchange as compared to nonsprayed ones. We also found higher activity of the carboxylation enzymes, Rubisco and phosphoenolpyruvate carboxylase, as well as a higher chlorophyll content in plants sprayed with nitrogen. Such enhancement of photosynthetic performance was associated with an increase in number of leaves and in total leaf area. Our results suggest that the effects of low temperature on photosynthesis of field-grown sugarcane plants could be alleviated by leaf nitrogen supply, with likely consequences for biomass production and crop yield.

<p>A nutrição mineral do cafeeiro é de vital importância para a produtividade do mesmo e diversos locais que, anteriormente, eram considerados inaptos ao cultivo da cultura, hoje em dia, apresentam lavouras altamente produtivas, onde a correção da fertilidade do solo, ao longo do tempo, aliada com uma nutrição mineral adequada, são um dos principais pilares para esse sucesso. Observa-se que diferentes cultivares de diversas espécies exigem níveis de nutrição diferenciados, para expressarem seu máximo potencial produtivo sob determinadas condições de cultivo. Objetivou-se, neste trabalho, avaliar quatro novas cultivares de cafeeiro quanto ao seu crescimento inicial, sob diferentes doses de nitrogênio, fósforo e potássio. O experimento foi instalado na Fazenda Experimental da EPAMIG, em São Sebastião do Paraíso – MG, em fevereiro de 2012. Foram utilizados quatro cultivares de cafeeiro que foram submetidos a doze tratamentos (esquema fatorial, sendo quatro cultivares, três nutrientes e quatro doses), contendo três repetições, sob delineamento em blocos casualizados. Foi feita uma análise conjunta dos dados. As características avaliadas foram: altura, diâmetro do colo, crescimento do primeiro ramo plagiotrópico, número de ramos plagiotrópicos, índice de clorofila e foram feitas análises de solo e foliares. Concluiu-se que nas condições químicas iniciais do solo utilizado no experimento podem-se reduzir em até 50% as adubações com N, P e K, tanto em adubação de cobertura como para adubação de primeiro ano, em lavouras cafeeiras plantadas com as cultivares Pau Brasil MG1, Paraíso MG H419-1 e Topázio MG 1190.</p>

Background: The study of cold tolerance in maize seeds and seedlings through physiological quality assessments, as well as the genetic control associated with this trait, allows an early characterization of genotypes. Here we studied the genetic control for cold tolerance during the germination process in maize seeds and genes influenced by this stress. Results: Six maize lines were used, three classified as tolerant and three as susceptible to low germination temperature. A field was developed to produce the hybrid seeds, in a partial diallel scheme including the reciprocal crosses. For the expression analysis, seeds from two contrasting lines were used, as well as their hybrid combination and their reciprocal crosses, on dried and moistened seeds at 10°C for 4 and 7 days. It was evaluated the catalase (CAT) and esterase (EST) enzymes, heat-resistant proteins and the genes Putative stearoyl-ACP desaturase (SAD), Ascorbate Peroxidase (APX), Superoxide Dismutase (SOD) and Mitogen Activated Protein Kinase (ZmMPK5). The estimated values for heterosis, general and specific combining abilities and reciprocal maternal and non-maternal effects were carried out and it showed that there is heterosis for germination at low temperatures, also the nonadditive genes were more important and there was a reciprocal effect. Conclusions: There is a greater expression of the CAT and EST enzymes in moistened seeds at seven days and there is less expression of heat-resistant proteins and the SAD gene at seven days of moistening. Also, there are variations in the expression of the APX, SOD and ZmMPK5 genes in dried and moistened seeds, as well as among the genotypes studied.

This study aimed to evaluate the effect of genetic composition and arrangement between female and male parents on tolerance to delayed drying of maize seeds, evaluating the physiological quality and enzyme expression. Ears were harvested close to the stage of physiological maturity (around 35% moisture) and the genotypes were identified as line 1 (L1), line 2 (L2), the hybrid (HB - ♀L1 and ♂L2), and the reciprocal hybrid (HR - ♀L2 and ♂L1). For assessment of physiological quality, CDR (4x6x2) was used, consisting of four genotypes, six times of delay before artificial drying (10, 18, 24, 28, 32, and 40 hours), and two drying delay temperatures (42 and 48 °C). DIC (4x3) was used for enzymatic expression, consisting of four genotypes and three delay times before artificial drying (10, 24 and 40 hours) at 48 °C. Analysis of variance F (p < 0.05), Tukey’s test (p < 0.05), and analysis of polynomial regressions were performed on the data. Lineage arrangement affects seed tolerance to drying delay. Therefore, susceptible lines should not be used as female parents. The seeds of the line most susceptible (L2) to delay in drying exhibit less expression of α-amylase (α-AM).