Days After Plant Emergence Research Articles

Nitrogen Availability and Physiological Response of Corn After 12 Years with Organic and Mineral Fertilization

The study aimed to evaluate the effects of long-term organic and mineral fertilization on soil solution dynamics of nitrogen (N), as well as to understand its relationship with corn plant growth, plant N uptake, and grain yield. The study was conducted in Santa Maria, State of Rio Grande do Sul, Brazil, for 12 years. The treatments consisted of pig slurry (PS); cattle slurry (CS); pig deep-litter (PL); mineral fertilizer (NPK); and no fertilization (control). We determined concentrations of dissolved inorganic N (DIN) and dissolved organic N (DON) in soil solution in situ, prior to sowing and during the growing cycle of corn. In plants, we determined the gaseous exchange, shoot N content, grain yield, and indices of recovery and efficiency of N. DIN in soil solution was the predominant N form in all treatments, ranging from 53 to 80% of total dissolved nitrogen (TDN). NPK was the only treatment that maintained high NO3-concentration in the soil solution up to 35 days after plant emergence (DAE) and this resulted in higher grain yield. The plants fertilized with CS obtained a recovery of 80% of the N, and promoted improvements in crop growth. The results of this study showed the importance of combining the application of organic fertilizers (before sowing) with mineral sources of N (topdressing), allowing the maintenance of N availability in the soil solution during periods of demand of organic fertilizer.

INTERAÇÃO ENTRE TAMANHOS DE VASO E DOSES DE GLYPHOSATE NO CONTROLE DE BRAQUIÁRIA

RESUMO Objetivou-se com este trabalho avaliar a interação entre o tamanho do vaso de cultivo e doses de glyphosate no crescimento, na fisiologia e na eficácia de controle de Brachiaria decumbens. A semeadura foi feita em vasos contendo 2, 5, 10 e 20 L de substrato, mantidos em casa de vegetação. Entre os 41 e 63 dias após a emergência (DAE), avaliou-se o crescimento deB. decumbens. Aos 64 DAE, fez-se a aplicação do glyphosate nas doses de 0,0, 0,8, 1,6 e 3,2 kg ha-1 de equivalente ácido. Foram avaliadas as trocas gasosas e a fluorescência da clorofila a, aos dois dias após a aplicação (DAA), bem como a eficácia de controle, aos 7, 14, 21 e 28 DAA, sendo nesta última avaliação determinada ainda a matéria seca da parte aérea. Por fim, aferiu-se ainda a capacidade de rebrota de B. decunbens aos 28 dias após o corte. O crescimento de B. decumbens aumentou linearmente com o aumento do tamanho do vaso. As trocas gasosas e os parâmetros de fluorescência foram afetados pelas doses de glyphosate, mas não pela variação do tamanho do vaso. Não houve interação significativa entre doses e tamanhos de vasos sobre a eficácia de controle, porém essa variável aumentou consideravelmente com o aumento da dose e, discretamente, com o aumento do tamanho de vaso, sobretudo nas avaliações até os 14 DAA. A matéria seca da parte área aos 28 DAA e de rebrota foi dependente da interação entre tamanho do vaso e dose de glyphosate. O tamanho do vaso deve ser escolhido com critério para ensaios de eficácia de controle de B. decumbens com herbicida sistêmico.

Infestation of Caliothrips phaseoli (Thysanoptera: Thripidae) on Bean Cultivars Grown in the Winter, Rainy, and Dry Seasons in Brazil.

The present study aimed to identify common bean (Phaseolus vulgaris L.) cultivars less susceptible to Caliothrips phaseoli (Hood) in different growing seasons, to evaluate whether climatic conditions influence plant resistance to C. phaseoli infestation, and to investigate the preferred plant part for insect feeding. Eighteen common bean cultivars were evaluated in the winter season, and 19 cultivars were assessed in the rainy and dry seasons, under field conditions in the municipality of Jaboticabal, state of São Paulo, Brazil. Infestation of C. phaseoli nymphs in the upper and lower parts of the beans plants was recorded at weekly intervals from 25 days after plant emergence (DAE) to 60 DAE. In the winter season, the cultivars 'IAC Galante,' 'IAC Centauro,' 'IAC Carioca Eté,' and 'IAC Formoso' had significantly lower number of thrips than the cultivar 'IAC Diplomata.' In the rainy season, the cultivars 'IAC Harmonia' and 'IPR Siriri' had the lowest thrips infestation, differing from the cultivars 'BRS Pontal' and 'IAC Una.' The bean cultivars were equally susceptible to C. phaseoli in the dry season. The results suggest that C. phaseoli nymphs prefer to infest leaves of the lower part of bean plants, like most generalist herbivorous insects. In the winter and dry seasons, the highest thrips infestation was observed at 60 DAE, while in the rainy season, it was recorded from 32 to 46 DAE. Overall, C. phaseoli infestation on bean cultivars was not influenced by either temperature, relative humidity, or rainfall.

Mini-tubérculos de batata semente básica produzidos sob parcelamento e doses de nitrogênio em substrato

Objetivou-se com este trabalho determinar a produção de mini-tubérculos de batata semente básica em função da dose e do parcelamento do nitrogênio (N) aplicado ao substrato. Os tratamentos foram constituídos por quatro doses de N (0, 115, 230, 460 mg L-1 de substrato) e por cinco modos de parcelamento das doses (M): M1 [10% no plantio + 90% aos 21 dias após a emergência (DAE)]; M2 [10% no plantio + 3% diariamente (21 a 51 DAE)]; M3 [50% no plantio + 50% aos 21 DAE]; M4 [50% no plantio + 1,6% diariamente (21 a 51 DAE)]; M5 (100% no plantio). O experimento foi instalado no delineamento em blocos casualizados, em esquema fatorial 4x5 (doses x modos), com três repetições, na Universidade Federal de Viçosa. As cultivares plantadas foram Atlantic e Opaline, utilizando-se mini-tubérculos da categoria básica. As plantas foram cultivadas em vasos de 3 L, contendo substrato comercial. Aos 25, 35 e 56 DAE foram avaliados o teor (TN) e quantidade de N na folha (QNA). Na colheita, aos 86 DAE, foram avaliados número e massas fresca e seca de tubérculos. Em ambas as cultivares, na fase inicial de crescimento da planta, nenhuma combinação de tratamentos (dose e modo) influenciou TN. Nas avaliações posteriores, TN aumentou com aumento da dose de N. Nas duas cultivares, QNA não foi afetado pela aplicação diluída das doses de N. Nenhuma combinação de dose e modo de aplicação do fertilizante nitrogenado influenciou o número de tubérculos. Quando houve efeito de dose de N sobre a massa de tubérculos, a dose zero proporcionou o maior valor da massa. A aplicação concentrada de N no momento da tuberização é prejudicial para a planta, pois reduz a massa seca e fresca de tubérculos.

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The objective of this study was to evaluate the efficacy of several soil systemic insecticides applied as bed-top banded spray applications against sweetpotato whitefly. Broccoli ‘Emerald Crown’ was direct seeded into double row beds on 42 inch centers on 25 Aug, 2011. Plots were one bed wide by 35 ft long and bordered by one untreated bed. Stand establishment was achieved using overhead sprinkler irrigation, and irrigated with furrow irrigation thereafter. Four replications of each treatment were arranged in a RCB design. Product formulations and rates for each spray program are provided in the table. The soil insecticides were applied as a surface-band treatment using a single-row boom equipped with 1 flat fan nozzle (8004VS) oriented parallel with the seed line and calibrated to deliver 25 gallons of spray per acre at 40 psi. A 2-3 inch spray band was placed directly over each seed line immediately following planting. The insecticides were incorporated into the soil using sprinkler irrigation that is commonly employed for seed germination during stand establishment. Evaluations of SWF control was estimated by counting the number of total nymphs on two, 2-cm disk sections taken from 2 consecutive basal leaves collected from each of 5 plants per replicate at various days after plant emergence (DAPE). SWF nymph densities on each leaf disk were estimated under magnification in the laboratory. Because of heterogeneity of mean variances, data were log transform (mean+0.5) and subjected to ANOVA; means were separated using Fprotected LSD (P ≤ 0.05). Actual non-transformed means are presented in the table.

Determinação do nível de controle econômico de Enneothrips flavens Moulton, 1941 (Thysanoptera: Thripidae) em cultivar de amendoim de porte ereto

O objetivo do presente trabalho foi avaliar diferentes níveis de controle econômico de Enneothrips flavens, na cultura do amendoim ereto, nas épocas de cultivo "das águas" e "da seca ". O estudo foi realizado na área experimental do Departamento de Fitossanidade da FCAV/UNESP - Campus de Jaboticabal, SP, em 2007/2008. Para a avaliação, foram realizadas amostragens a partir dos 17 dias após a emergência das plantas (DAE), coletando-se dez folíolos fechados por parcela. Determinaram-se a produção de grãos em casca e a massa seca de 100 sementes. Determinadas a produção e o número de aplicações de thiametoxam + lambda-cialotrina, foram obtidos o ganho de produção e a variação no rendimento líquido. Concluiu-se no estudo que as plantas de amendoim foram mais infestadas dos 17 aos 30 e dos 47 aos 74 (DAE) para o plantio na época "da seca" e dos 32 aos 53 (DAE) na época "das águas"; o tratamento controle total obteve as maiores produções e variação no rendimento líquido em relação à testemunha com 26,43 sacas. ha-1 e R$ 585,66 para o plantio realizado na época "da seca", e com 53,88 sacas. ha-1 e R$ 1354,26 para o plantio realizado na época "das águas". O controle de E. flavens com 20% dos folíolos atacados para os cultivos rea-lizados foi o mais próximo do controle total na produção (sacas.ha-1) e variação do rendimento líquido; o inseticida thiametoxam + lambda-cialotrina mostrou-se eficiente no controle da praga resultando em acréscimo na produção de amendoim nas duas épocas de cultivo.

Competition of soybean with blackjack (<i>Bidens pilosa L.</i>)and pigweed(<i>Amaranthus hybridus L.</i>)

Field studies were conducted to evaluate competitiveness between blackjack or pigweed and soybean using replacement series. Plant height of the three species was not affected by interspecific competition. Branching was reduced in soybean at 75 days after plant emergence (DPE), but increased in the weed species. Soybean, blackjack and pigweed shoot dry weight was reduced in most mixtures. The weed species had higher relative growth rate (RGR) and leaf area index (LAI) than soybean. The highest LAI occurred in monoculture pigweed. Competitive ration (CR) values showed that pigweed was the most competitive of the three species. Soybean pod number per plant, 1000 seed weight and grain yield per plant were significantly less in mixtures with the two weed species. Pigweed caused more reduction in soybean yield components than blackjacks. The number of blackjack seeds per head, seed heads per branch and seeds per plant were significantly reduced in mixtures while seed production by pigweed in mixture increased by 30 to 253%. It is concluded that both weed species reduce soybean vegetative growth except for height and components of yield.

INOCULAÇÃO E ADUBAÇÃO MINERAL EM FEIJÃO-CAUPI: EFEITOS NA NODULAÇÃO, CRESCIMENTO E PRODUTIVIDADE

A nodulação e o crescimento das leguminosas têm influência dos nutrientes contidos no solo, principalmente P, K e Mo. O presente trabalho objetivou avaliar em campo o efeito da inoculação com Bradyrhizobium elkanii e da adubação com P, K e Mo sobre a nodulação, crescimento e produtividade de feijão-caupi (cultivar BRS Guariba). O estudo foi conduzido em uma área experimental, utilizando-se um Neossolo Flúvico, em Teresina, PI. Os tratamentos foram dispostos em um delineamento em blocos casualizados com seis tratamentos e quatro repetições. Os tratamentos consistiram de aplicação ou não de P, K e Mo no solo e de inoculante rizobiano nas sementes. No tratamento com inoculação foi utilizado um inoculante a base de turfa contendo Bradyrhizobium elkanii, estirpe BR 3262. A semeadura foi realizada em parcela experimental de 3,2 m x 5,0 m e procederam-se as coletas dos dados aos 35 e 50 dias após a emergência (DAE) para a determinação do número e massa seca dos nódulos e das massas secas da parte aérea e raiz e acúmulo de N na parte aérea. A produtividade de grãos foi determinada aos 58 DAE. Não se verificou diferença entre os tratamentos para massa seca das raízes, parte aérea e acúmulo de N aos 35 DAE, para massa seca das raízes aos 50 DAE e para a produtividade de grãos. Em solo com adequado conteúdo de P e K a inoculação com Bradyrhizobium elkanii associada à adubação fosfatada, potássica e molíbidica não contribuiu para o aumento do número e massa dos nódulos e nem tampouco da produtividade de grãos de feijão-caupi.

Exportação de nutrientes nos tubérculos de batata em função de doses de sulfato de potássio

A batata, importante olerícola no Brasil e no mundo, recebe altas doses de fertilizantes, especialmente potássicos. Dentre estes, o sulfato de potássio destaca-se devido ao conceito de que sua utilização melhora a qualidade dos tubérculos. Os fertilizantes representam um significativo percentual dos custos de produção desta cultura. Logo, o uso eficiente dos adubos deve ser alcançado para garantir competitividade do bataticultor no mercado. A avaliação das quantidades de nutrientes extraídas e exportadas pelos tubérculos durante o ciclo de desenvolvimento é uma ferramenta útil para otimizar o uso de fertilizantes. Para avaliar a extração e exportação de nutrientes nos tubérculos de batata, em função de doses de sulfato de potássio, foram aplicados 0; 125; 250; 500; 1000 e 2000 kg ha-1 de K2SO4 no sulco de plantio, em Viçosa (MG). Para avaliar os teores e as exportações de N, P, K, Ca, Mg, S, Cl, Mn e Zn nos tubérculos, duas plantas/parcela foram amostradas aos 20 dias após a emergência das plantas (DAE), aos 48 DAE e na colheita. O experimento foi analisado como fatorial 6x3, com seis doses de K2SO4 e três épocas de amostragem, delineado em blocos ao acaso, com quatro repetições. A adubação com sulfato de potássio promoveu acréscimos nos teores de Cl, Mn e Zn nos tubérculos. As exportações de K, Ca, Mg, S, Mn e Cl aumentaram em resposta às doses de sulfato de potássio, somente na colheita. Na máxima produtividade de tubérculos (30,5 Mg ha-1, com 736 kg ha-1 de K2SO4), foram estimadas as seguintes exportações, em kg ha-1: N (99,1); P (14,2); K (118,5); Ca (2,10); Mg (6,50); S (9,28); Cl (8,18); Mn (0,048) e Zn (0,102). A exportação de nutrientes nos tubérculos representa importante perda de nutrientes do solo e sua avaliação, a princípio, deve ser utilizada para calibrar a recomendação de fertilizantes.

Total soil electrical conductivity and critical soil K+ to Ca2+ and Mg2+ ratio for potato crops

Soil K+ to Ca2+ and Mg2+ ratio as well as the total salinity were evaluated in response to potassium fertilizer application onto potato. Potassium was applied at six different rates (0, 60, 120, 240, 480 and 960 kg ha-1 of K2O), as K2SO4, and was placed during planting time in the furrow. Soil from the 0-200 mm layer was collected in the furrow, 20 and 48 days after plant emergence (DAE) to evaluate soil pH, K+, Ca2+ and Mg2+ contents and the total electrical conductivity (EC). A factorial design (6x2), with six K rates and two sampling times was set up in a randomized block design with four replications. The application of K fertilizer increased exchangeable K, did not affect pH and exchangeable Ca and Mg contents, but caused a linear increase of the soil K+/(Ca2++Mg2+)1/2 ratio as well as EC. At 20 DAE, the critical soil K+/(Ca2++Mg2+)1/2ratio and the EC associated with maximum tuber yield (30.5 Mg.ha-1, with 353.4 kg ha-1 of K2O) were 1.79 and 1.6 dS m-1, respectively. The highest soil K+/(Ca2++Mg2+)1/2 ratio and EC were obtained with the highest application of K fertilizer, which led to a reduction in the potato tuber yield.

Effects of zinc fungicides and different zinc fertilizer application methods on soluble and total zinc in potato plant shoots

The experiment was carried out to evaluate the effects of fungicides [with or without zinc (Zn)] and different Zn fertilizer application methods (no fertilizer; soil application; shoot application; soil plus shoot application) on the soluble and total Zn in the dry matter of potato shoots. Zinc fertilizer was applied to the shoots at 20 and 45 days after plant emergence (DAE), immediately before plant sampling. At 25 DAE, Zn fungicide increased soluble and total Zn in the fourth leaf. The same occurred, at 45 DAE, with the Zn fertilizer applied to the shoots. It were not observed significant increases on both soluble and total Zn contents in the fourth leaf of plants that received soil Zn fertilization. Even in the leaves with 262 mg Zn kg‐1, there was no phytotoxicity symptoms. The total Zn concentration at 20 DAE was the best index correlated to potato tuber yield reaching 50.9 mg Zn kg‐1 in the fourth leaf of plants at the highest marketable tuber yield treatment. Plant nutrient element contents [phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), and manganese (Mn)] were not affected by the treatments.

Critical phosphorus concentrations in potato plant parts at two growth stages

Adequately evaluating the phosphorus (P) nutritional status of a potato crop is dependent upon sampling the appropriate plant part at a defined growth stage. To establish P critical concentration levels in various potato plant parts (leaves, stems, tubers, leaflets, and petioles) at two growth stages [20 and 50 days after plant emergence (DAE)], an experiment under Brazilian climatic and soil conditions was conducted using seven P treatment levels (0, 40, 80, 160, 320, 640, and 1,280 kg P2O5 ha‐1) applied in a randomized complete block design with four replications. ‘Baraka’ potato tubers were seeded at a spacing of 0.80 x 0.30 m following agronomic cultural practices recommended for this crop. Phosphorus concentrations in all the potato plant parts were significantly affected by the P fertilizer rates applied. The highest correlation between the P concentration in the various plant parts and marketable yield and optimum profit yield was obtained for the petiole taken 20 days DAE. Critical P levels associated with optimum profit yield were lower than those for maximum marketable tuber yield, and they were, 0.41, 0.39,0.39,0.57, and 0.57 g P 100 mg‐1 DM in the leaf, stem, tuber, petiole, and leaflet, respectively.

Gaucho as an Aphicide in Winter Wheat,1996B

Abstract Plots were seeded by farm 30 ft drill on 5 Sep (37.5 lb/acre) at the Dye Farm near Pomeroy, WA. Gaucho 480 was applied at 3 rates as seed treatment: 0.5, 0.75, and 1.0 oz (AI)/cwt. An untreated plot served as the check. Plots were 30 X 600 ft replicated 4 times in a RCB design. The experiment was designed to measure: 1) the impact of aphids on winter wheat yields; and 2) the value of Gaucho as an aphicide in winter wheat. Treatments were evaluated at 30, 50, and 65 days after plant emergence (DAE) by visual examination for aphid species per tiller plus number of aphids per tiller. At maturity, crop was harvested by cutting 24 X 600 ft strips from each replicate with a combine. Mean grain yields and test weight (tw) were calculated per acre for each replicate.

Control of Hessian Fly and Russian Wheat Aphid in Spring Wheat, 1996B

Abstract Plots were seeded 14 Apr (60 lb/acre) at the Dye Farm near Pomeroy, WA. Two rates of Gaucho 480 (0.5, and 1.0 oz(AI)/cwt) were applied as seed treatments, and an untreated check was set up. Plots were arranged in a RCB design with 4 replicates of 36 X 400 ft each. Numbers of heads and tillers per 10 plants, % HF-infested tillers, and % RWA-infested tillers were recorded at 85 days after plant emergence (DAE) (Feeks scale 10.5). Harvest data were collected on 21 Aug by cutting 24 ft strips per replicate and weighing the grain in a weigh wagon. Yield per acre was calculated for each treatment.

Source and mode of sulphur application on groundnut productivity

Abstract The effectiveness of 20 kg/ha sulphur (S) of the S‐containing compounds iron sulphate (FeSO4), gypsum, phosphogypsum, elemental S, and pyrite on groundnut (Arachis hypogaea L.) productivity was determined for plants grown on calcareous soil in the field. Plants grown with S compared to those without S had increased plant height, number of flowers, nodule numbers and weight, higher dry matter, seed, haulm (leaves and stems), and oil yields; higher tissue concentrations of nitrogen (N), phosphorus (P), S, iron (Fe), and zinc (Zn); and higher total uptake of mineral nutrients. Elemental S, pyrite, and FeSO4 were more effective than gypsum and phosphogypsum, with FeSO4 being the most effective source of S for improving plant growth traits, yield, and nutrient uptake. The most effective method of FeSO4 application was half to the soil at planting time (basal) followed by the remainder in three equal foliar sprays at 30,50, and 70 days after plant emergence (DAE). Pyrite and elemental S were most effec...