Concentra����es e composi����es qu��micas do meio nutritivo para o cultivo in vitro de orqu��dea

Pl��ntulas de orqu��deas cultivadas in vitro respondem de forma distinta aos v��rios meios de cultura empregados nessa t��cnica. Este trabalho comparou o meio nutritivo Knudson C, utilizado no cultivo de orqu��deas, com o denominado MN e outros dois meios preparados com fertilizantes Peters��: NPK 10-30-20 + micronutrientes e NPK 30-10-10 + micronutrientes para o cultivo in vitro de pl��ntulas do h��brido Etibaia (Cattleya walkeriana x C. loddigesii), com seis meses de idade, germinadas sobre o meio Knudson C. Os tr��s ��ltimos meios foram testados com as seguintes doses de sais: 0,25; 0,50; 1,00; 1,75; e 2,25 g L-1, e o meio Knudson C, 2,0 g L-1. A todos os meios adicionaram-se 20 g L-1 de sacarose, solidificado com 10 g L-1 de ��gar, e o pH foi ajustado a 5,7. Aos meios MN e Peters�� foram acrescentados 2 g L-1 de carv��o ativado e 200 ml L-1 de ��gua de coco. Foram utilizados frascos de vidro de 320 mL contendo 35 mL de meio nutritivo, e o experimento foi mantido em sala de crescimento a 27 �� 2 ��C, 16/8 h luz/escuro e irrdi��ncia de 48 ��mol m-2s-1. Melhores respostas para produ����o de mat��ria fresca foram obtidas com os fertilizantes NPK, em compara����o com os meios Knudson C e MN. A produ����o de mat��ria fresca aumentou linearmente com o aumento da dose de nutrientes nos meios MN e nos dois NPK. As pl��ntulas de orqu��dea cultivadas em meio Knudson C apresentaram os menores valores para as vari��veis avaliadas.

Cultivo in vitro de pl��ntulas de orqu��dea em meios com diferentes concentra����es de fertilizante mineral

Existem diversos meios nutritivos utilizados no cultivo in vitro de orqu��deas, com diferentes composi����es e concentra����es de sais, resultando em respostas distintas entre eles. O objetivo deste trabalho foi avaliar o crescimento in vitro de pl��ntulas de orqu��dea (Cattleya walkeriana Gardner) sob diferentes doses de fertilizante NPK, adicionado ao meio de cultivo, como fonte de nutrientes. Foi utilizado o fertilizante Peters�� na formula����o NPK 10-30-20 + Mg + micronutrientes, nas doses de: 0,0; 1,0; 2,0; 3,0; 4,0; 5,0 e 10,0 g L-1 de meio, acrescido de ��gua de coco (150 mL L-1), sacarose (20 g L-1), carv��o ativado (2 g L-1) e pH corrigido para 5,6. Foram utilizados frascos de vidro de 320 mL de capacidade, contendo 35 mL de meio onde foram inoculadas dez pl��ntulas com seis meses de idade, previamente germinadas em meio Knudson C. O experimento foi mantido em sala de crescimento a 27 �� 2 ��C, 16/8 h luz/escuro e irradi��ncia de 48 ��mol m-2 s-1. A produ����o m��xima de mat��ria seca da parte a��rea das plantas, aos seis meses de idade, foi estimada em 0,255 g/frasco com uso de 5,22 g L-1 do fertilizante adicionado ao meio de cultura. Considerando a possibilidade de salinidade elevada do meio, para algumas esp��cies de orqu��dea, estimou-se a dose de fertilizante (3,55 g L-1) necess��ria para obten����o de 90% da produ����o m��xima. As ra��zes apresentaram dr��stica redu����o do crescimento (menor n��mero e curtas) em condi����es de alta concentra����o de fertilizante.

Produ����o de mudas de pimenteira-do-reino em substrato comercial fertilizado com adubo de libera����o lenta

As doen��as provocadas por pat��genos de solo v��m causando s��rios preju��zos pipericultura nacional, em consequ��ncia da morte prematura das plantas. Em raz��o disso, o objetivo deste trabalho foi avaliar a produ����o de mudas de tr��s gen��tipos de pimenteira-do-reino, em substrato comercial isento de solo, e determinar as doses adequadas de adubo de libera����o lenta, para cada gen��tipo, nesse substrato. Foram produzidas mudas clonais dos gen��tipos 'Guajarina', 'Ia��ar��' e 'Cingapura', em substrato comercial composto por casca de p��nus e vermiculita. Ao substrato, foram misturadas cinco doses de adubo de libera����o lenta, f��rmula NPK 15-09-12: 0,0; 2,5; 5,0; 7,5 e 10 kg m-3. Aos 120 dias ap��s a repicagem, os resultados mostraram que houve diferen��as de crescimento entre os gen��tipos para todas as caracter��sticas avaliadas, com exce����o de altura de plantas. Houve efeito das doses do adubo para todas as caracter��sticas avaliadas, por��m a intera����o entre gen��tipos e doses do adubo foi constatada somente para o n��mero de folhas e massas de mat��rias secas do sistema radicular e total. As mudas de 'Guajarina' foram as que obtiveram maior massa de mat��ria seca total, enquanto as de 'Cingapura' obtiveram o menor valor. As doses do adubo que proporcionaram os valores m��ximos de massa de mat��ria seca total das mudas foram 4,4 kg m-3 para 'Guajarina'; 6,4 kg m-3 para 'Ia��ar��' e 5,3 kg m-3 para 'Cingapura'.

Production of cabbage grown in pots containing legumes' root and shoot

Roots effect is not generally considered in studies assessing the performance of crops in response to green manuring. However, such effect can contribute to a better understanding of crop rotation. The aim of this study was to assess the effect of root and shoot of two legumes on the production of cabbage. The experiment was conducted in pots of 10 liters containing substrate of 2:1 soil/sand. The experiment was arranged in a factorial scheme (2x3 + 2) in a randomized block design with five replicates using two legume species (Crotalaria juncea L. and Canavalia ensiformis L), three plant parts (root, shoot, or whole plant), and two additional treatments (mineral fertilization with 100% and 50% of the recommended dose of N for growing cabbage). Pots with legume treatments received mineral fertilizer with 50% of the recommended dose of N for growing cabbage. The experimental plot consisted of a pot containing one plant of cabbage. Legumes were grown in pots and harvested at 78 days. The root biomass was determined in extra pots. Production was assessed using head fresh and dry weight. The application of the whole plant of both legume species reduced cabbage production. However, root or shoot of both legume species was equivalent to 50% of mineral N fertilization required for the cultivation of cabbage.

Composi����o qu��mica dos gr��os de milho em resposta �� aduba����o mineral e inocula����o com rizobact��rias

Para o aumento da produtividade agr��cola no Pa��s, s��o necess��rios estudos para melhor aproveitamento da aduba����o mineral, a fim de uma produ����o de gr��os com melhor qualidade nutricional. Este trabalho teve como objetivo avaliar o teor e o ac��mulo de prote��na, de cinzas e de nutrientes em gr��os de milho provenientes de plantas submetidas �� inocula����o com Pseudomonas fluorescens e cultivadas em diferentes n��veis de aduba����o NPK no solo. Foram testados seis tratamentos, em delineamento experimental de blocos casualizados, no esquema fatorial 3 x 2, sendo tr��s n��veis de aduba����o qu��mica com NPK (0,125 e 250 kg ha-1) e dois n��veis de inoculante �� base de P. fluorescens (com e sem), com quatro repeti����es, sendo instalado em Latossolo Vermelho eutrof��rrico, utilizando o cultivar de milho h��brido 30F35. Determinaram-se os teores e ac��mulo de N, P, K, Ca, Mg, Zn, Cu, Fe, Mn, prote��na e cinzas dos gr��os. Os dados foram submetidos �� an��lise de vari��ncia e as m��dias, comparadas pelo teste de Tukey (p < 0,05). A aplica����o de P. fluorescens via inocula����o incrementou os teores de P e K dos gr��os de milho, independentemente dos n��veis de aduba����o. Os teores dos nutrientes, de prote��na e de cinzas dos gr��os de milho n��o foram influenciados pelos n��veis de aduba����o mineral, com exce����o do Cu, que aumentou com a eleva����o dos n��veis de aduba����o.

Effect of cattle manure on sunflower production and water use in two types of soil

The aim of the present study was to evaluate water consumption, use efficiency and yield components of sunflower variety Embrapa 122 V/2000 cultivated in two types of soil (Fluvissol and Haplic Luvisol) subjected to increasing doses of cattle manure. The experiment was carried out in a greenhouse at Universidade Estadual da Para��ba. The experimental design was completely randomized in a factorial scheme. The irrigation was performed every other day, replacing the water absorbed by the plants. The water consumption and the use efficiency were evaluated, being the use efficiency determined by the ratio of the total dry mass of sunflower and the amount of water used to produce it in each treatment. Plants were harvested at 95 days after sowing when the following parameters were evaluated: number of seeds per plant, weight of seeds per plant, weight of 1000 seeds and the outer diameter of the capitulum (head). The results showed that the sunflower was positively affected by cattle manure application, increasing the production components and the water use efficiency, regardless of the type of soil. Excepting for the 1000 seeds weight and the water use efficiency, the type of soil affected significantly the water use, the number and weight of seeds per plant. The plants cultivated in Haplic Luvisol had a better performance.

Yield and nutrition of sunflower fertilized with sewage sludge stabilized by different processes

The different methods of sewage sludge stabilization modify their physical chemical and biological properties, altering its efficiency when applied in agriculture. The objective of this study was to evaluate the nutrient levels in soil and the yield of sunflower fertilized with sewage sludge stabilized by different processes. The experiment was conducted in Cambisol, with the treatments: control (without fertilization), fertilization with sewage sludge solarized, composted, vermicomposted, limed and chemical fertilizer recommended for sunflower crop. The experimental design a randomized block with four replications. The different methods of sewage sludge treatment did not affect the yield; however, the application of sewage sludge, regardless the stabilization process adopted, was more effective than chemical fertilizer and the control treatment. Overall, fertilization with limed sewage sludge provided higher soil nutrients concentrations, while treatments with composted and vermicomposted sewage sludge showed higher levels of nutrients in the plant.

Molybdenum mixed with glyphosate and alone via foliar spray in no-tillage common bean grown on corn stover

The effect of molybdenum (Mo) on common bean grown in desiccated corn stover in a no-tillage system was evaluated under two application modes: Mo mixed with the desiccant glyphosate and Mo direct spray to the bean leaves. The treatments (four replicates) were assigned to a completely randomized block design in a split-plot arrangement with the application of Mo (0, 100, 200, 400 and 800 g ha-1) mixed with glyphosate in the main plots and Mo foliar spray (0 and 100 g ha-1) in the sub-plots. The field experiments were carried out in 2009 and 2010 in the municipality of Coimbra, Minas Gerais State, with the common bean cultivar Ouro Vermelho. Mo mixed with glyphosate had neither an effect on common bean yield nor on the Mo and N contents in leaves, however it increased the Mo and N contents in seeds. Application of Mo via foliar spray increased Mo content in leaves and Mo and N contents in seeds. The reapplication of molybdenum with glyphosate for desiccation in subsequent crops caused a cumulative effect of Mo content in bean seeds.

Urease inhibitor (NBPT) and efficiency of single or split application of urea in wheat crop

NBPT (N-(n-butyl) thiophosphoric triamide), a urease inhibitor, has been reported as one of the most promising compounds to maximize urea nitrogen use in agricultural systems. The objective of this study was to evaluate the performance of irrigated wheat fertilized with urea or urea + NBPT as single or split application. The experiment was conducted from June to October 2006 in Vi��osa, MG, Brazil. The experimental design followed a 2��2 factorial scheme, in which urea or urea + NBPT were combined with two modes of application: full dose at sowing (60kg ha-1) or split (20kg ha-1 at sowing + 40kg ha-1 as topdressing at tillering), in randomized blocks with ten replications. The split application of nitrogen fertilization does not improve the yield wheat under used conditions. The use of urease inhibitor improves the grain yield of wheat crop when urea is applied in topdressing at tillering, but its use does not promote difference when urea is applied in the furrow at planting.

Abortamento de frutos da nogueira macad��mia sob influ��ncia da aduba����o mineral

A nogueira macad��mia (Macadamia integrifolia) apresenta elevada taxa de abortamento de frutos. A nutri����o desequilibrada pode ser um dos fatores que contribui para isso. Objetivou-se, com esta pesquisa, avaliar a influ��ncia de doses de N e do parcelamento da aduba����o NPK, de cobertura, na redu����o do abortamento de frutos da nogueira macad��mia. Foram desenvolvidos dois experimentos, durante tr��s anos agr��colas, num Latossolo Vermelho, em Jaboticabal, Estado de S��o Paulo. O primeiro experimento foi constitu��do por cinco doses de N (0, 50, 100, 150 e 200 kg ha-1 ano-1) e quatro repeti����es. O segundo experimento foi constitu��do por quatro formas de parcelamento da aduba����o NPK (T1: outubro T2: outubro + dezembro, T3: outubro + dezembro + fevereiro e T4: outubro+dezembro + fevereiro + abril) e cinco repeti����es. A maior parte dos frutos (77,7 %) foi abortada no in��cio de seu desenvolvimento. A aplica����o de N, bem como o parcelamento da aduba����o NPK de cobertura, pelo menos em duas vezes (outubro e dezembro), n��o alteraram o n��mero de frutos abortados por planta de macad��mia, mas, por aumentarem o n��mero total de frutos emitidos e reduzirem a percentagem de abortamento, proporcionaram maior produtividade de nozes.

Effects of levels of potassium and nitrogen on yields and post-harvest conservation of onions in winter

Potassium and nitrogen are the elements present in the highest percentage in the onion dry matter. The objective of this experiment was to evaluate yield and post-harvest conservation of Vale Ouro IPA-11 onion cultivar regarding to nitrogen and potassium levels. The experiment was carried out in Petrolina-PE, Brazil, from June to September 2009. The experimental design was a completely randomized block in a 4 x 3 factorial design, composed of four nitrogen levels (0, 60, 120 and 180 kg ha-1) and three potassium levels (0, 90 and 180 kg ha-1) with three replications. The highest yield of commercial bulbs was achieved at an estimated N level of 172.6 kg ha-1. The lowest yield of noncommercial bulbs was estimated at N level of 147.0 kg ha-1. Lower percentage of smaller bulbs (class 2) were obtained by increasing levels of N x K, with a quadratic effect at the dose of 90 kg ha-1 K2O and minimum production point with 127.6 kg N ha-1 (20.3%). Regarding larger caliber bulbs (class 4), linear effects were found both in the absence and for the level of 90 kg ha-1 of K2O as levels of N were increased. When the highest level of 180 kg ha-1 K2O was applied, the level of 92.8 kg ha-1 of N was estimated as the one that would promote the highest bulb yield of this class (35.4%), and 5.3% was found in the lack of potassium fertilization.

Fitossociologia de plantas daninhas em monocultivo de milho e em cons��rcio com diferentes Fabaceae

O milho est�� entre os cereais mais cultivados e utilizados pela popula����o mundial. Com o objetivo de efetuar o levantamento da comunidade de plantas daninhas no cultivo de milho em monocultivo e em cons��rcio, com diferentes Fabaceae, cultivado sob diferentes manejos, este trabalho foi realizado durante o per��odo da primavera/ver��o de 2011/2012. Avaliaram-se os tratamentos: milho em monocultivo com aduba����o NPK na semeadura e com capina, milho em monocultivo sem aduba����o NPK na semeadura e com capina, milho em monocultivo com aduba����o NPK na semeadura sem capina, milho + mucu-preta, milho + crotal��ria e milho + feij��o-de-porco. A capina aumenta o ��ndice de Valor de Import��ncia (IVI) do falso massambar�� (Sorghum arundinaceum) no monocultivo, enquanto para o apaga-fogo (Alternanthera tenella colla) a aduba����o promove controle eficiente. O cons��rcio com a mucuna preta favorece o aumento do IVI do camalote (Rottboelia exaltata), j�� o cons��rcio com a crotal��ria favorece o falso massambar�� (Sorghum arundinaceum). As plantas de milho em monocultivo apresentaram maior altura (ALM) e peso de mat��ria seca (PMSM). Contudo, o monocultivo proporcionou plantas daninhas mais altas (ALPD), al��m de maiores no peso da mat��ria seca de plantas daninhas de folhas estreitas (PMSPDE). A capina no monocultivo elevou a ALM e o PMSM, apesar de elevar tamb��m a ALPD e o PMSPDE. O monocultivo com aduba����o com NPK na semeadura apresenta ALPD menor que o sem aduba����o completa; entretanto, o PMSPDE aumentou com a aduba����o. A aduba����o com NPK na semeadura no monocultivo eleva o PMSM. O cons��rcio do milho com a mucuna preta apresenta efeito semelhante sobre as vari��veis analisadas em compara����o aos outros cons��rcios avaliados, assim como os cons��rcios do milho com a crotal��ria e do milho com o feij��o-de-porco apresentam efeitos semelhantes sobre as vari��veis analisadas.

Phytomass production and nutrient accumulation by green manure species

Green manuring is recognized as a viable alternative to improve nutrient cycling in soils. The aim of this study was to evaluate the phytomass production and nutrient accumulation in shoots of the summer green manures jack bean &#91;Canavalia ensiformis (L.) DC.&#93;, dwarf pigeon pea (Cajanus cajanvar var. Flavus DC.), dwarf mucuna &#91;Mucuna deeringiana (Bort) Merr&#93; and sunn hemp (Crotalaria juncea L.), under nitrogen fertilization and/or inoculation with N-fixing bacteria. A split plot design was arranged with the four Fabaceae species as main plots and nitrogen fertilization (with and without) and inoculation with diazotrophic bacteria (with and without) as the subplots, in a 2�� factorial. The experiment was arranged as a randomized complete block design with four replications. In the conditions of this trial, the sunn hemp had the highest production of shoot phytomass (12.4 Mg ha-1) and nutrient accumulation, while the dwarf mucuna had the lowest production of shoot phytomass (3.9 Mg ha-1) and nutrient accumulation. The results showed no effect of nitrogen fertilization or inoculation with N-fixing bacteria on the production of shoot phytomass and nutrient accumulation, except for inoculation without nitrogen fertilization, resulting in greater P accumulation (p <0.05) in the sunn hemp and greater Zn and Mn accumulation in the dwarf mucuna. These findings indicate that N fertilization or inoculation with N2-fixing bacteria for Fabaceae are low efficiency practices in the edaphoclimatic conditions of this study.

Crescimento, ��ndices fisiol��gicos e produtividade de cultivares de feijoeiro sob diferentes n��veis de aduba����o

Conhecimentos sobre o ac&#250;mulo e a distribui&#231;&#227;o da fitomassa do feijoeiro comum, sob diferentes n&#237;veis de aduba&#231;&#227;o, podem auxiliar no manejo da cultura. Este trabalho objetivou avaliar o crescimento, os &#237;ndices fisiol&#243;gicos e a produtividade de cultivares de feij&#227;o, sob diferentes n&#237;veis de aduba&#231;&#227;o NPK. O experimento foi conduzido em um Nitossolo Vermelho distrof&#233;rrico, no munic&#237;pio de Botucatu, SP, no delineamento experimental de blocos casualizados, em parcelas subdivididas, com quatro repeti&#231;&#245;es. As parcelas foram constitu&#237;das por seis tratamentos ('P&#233;rola', sem aduba&#231;&#227;o; 'P&#233;rola', com 50% da aduba&#231;&#227;o recomendada; 'P&#233;rola', com 100% da aduba&#231;&#227;o recomendada; 'IAC Alvorada', sem aduba&#231;&#227;o; 'IAC Alvorada', com 50% da aduba&#231;&#227;o recomendada e 'IAC Alvorada', com 100% da aduba&#231;&#227;o recomendada) e, as subparcelas, por sete &#233;pocas de coletas no decorrer do ciclo. A aduba&#231;&#227;o NPK aumentou os ac&#250;mulos de mat&#233;ria seca, os componentes da produ&#231;&#227;o e a produtividade de gr&#227;os dos cultivares P&#233;rola e IAC Alvorada de forma semelhante. O cultivar IAC Alvorada apresentou maiores &#237;ndices de &#225;rea foliar e mat&#233;ria seca de folhas, quando comparados com os de P&#233;rola, sob aduba&#231;&#227;o NPK recomendada, por&#233;m, sem esses &#237;ndices refletirem-se em maior produtividade de gr&#227;os. O m&#225;ximo ac&#250;mulo de mat&#233;ria seca foi alcan&#231;ado aos 80 DAE e a maior taxa de crescimento da cultura ocorreu aos 55 DAE, independentemente do tratamento.

Juvenile tree growth correlates with photosynthesis and leaf phosphorus content in central Amazonia

Light and soil water availability may limit carbon uptake of trees in tropical rainforests. The objective of this work was to determine how photosynthetic traits of juvenile trees respond to variations in rainfall seasonality, leaf nutrient content, and opening of the forest canopy. The correlation between leaf nutrient content and annual growth rate of saplings was also assessed. In a terra firme rainforest of the central Amazon, leaf nutrient content and gas exchange parameters were measured in five sapling tree species in the dry and rainy season of 2008. Sapling growth was measured in 2008 and 2009. Rainfall seasonality led to variations in soil water content, but it did not affect leaf gas exchange parameters. Subtle changes in the canopy opening affected CO2 saturated photosynthesis (A pot, p = 0.04). Although A pot was affected by leaf nutrient content (as follows: P > Mg > Ca > N > K), the relative growth rate of saplings correlated solely with leaf P content (r = 0.52, p = 0.003). At present, reduction in soil water content during the dry season does not seem to be strong enough to cause any effect on photosynthesis of saplings in central Amazonia. This study shows that leaf P content is positively correlated with sapling growth in the central Amazon. Therefore, the positive effect of atmospheric CO2 fertilization on long-term tree growth will depend on the ability of trees to absorb additional amount of P