Hydrogen peroxide in the mitigation of salt stress in bell pepper / Peróxido de hidrogênio na mitigação do estresse salino em pimentão

Bell pepper is a vegetable of great socioeconomic importance in the Brazilian market. However, in the semi-arid region of northeast Brazil, its cultivation is limited by the high concentrations of salts in water sources. On this basis, this study was developed to determine the effect of foliar application of hydrogen peroxide in mitigating salt stress by evaluating gas exchange, photosynthetic pigments, and growth in 'All Big' bell pepper plants. The experiment was conducted in greenhouse conditions in Campina Grande - PB, Brazil. Treatments were distributed in a randomized block design with a 5 × 5 factorial arrangement corresponding to five levels of irrigation-water electrical conductivity (ECw: 0.8, 1.2, 2.0, 2.6, and 3.2 dS m-1) and five concentrations of hydrogen peroxide (H2O2: 0, 15, 30, 45, and 60 µM), with three replicates and one plant per plot. Foliar application of hydrogen peroxide at the concentration of 15 µM attenuated the effects of salt stress in 'All Big' bell pepper plants irrigated with saline water at ECw of up to 1.4 dS m-1. Hydrogen peroxide at a concentration of 15 µM associated with water salinity of 0.8 dS m-1 increased stomatal conductance, CO2 assimilation rate, instantaneous carboxylation efficiency, and the growth of the bell pepper plants. Application of hydrogen peroxide at concentrations greater than 15 µM intensified the deleterious effects of salt stress in 'All big' bell pepper at 90 days after sowing.

O pimentão é uma hortícola de grande importância socioeconômica no mercado brasileiro. Contudo, no semiárido do Nordeste brasileiro seu cultivo é limitado devido a ocorrência de fontes hídricas com elevadas concentrações de sais. Deste modo, objetivou-se com o presente estudo, avaliar o efeito da aplicação foliar de peróxido de hidrogênio na mitigação do estresse salino nas trocas gasosas, nos pigmentos fotossintéticos e no crescimento das plantas de pimentão 'All Big'. O experimento foi conduzido em condições de casa de vegetação, em Campina Grande-PB. Os tratamentos foram distribuídos no delineamento de blocos casualizados, em esquema fatorial 5 × 5, correspondendo a cinco níveis de condutividade elétrica da água de irrigação ­ CEa (0,8; 1,2; 2,0; 2,6 e 3,2 dS m-1) e cinco concentrações de peróxido de hidrogênio ­ H2O2 (0, 15, 30, 45 e 60 µM), com três repetições e uma planta por parcela. A aplicação foliar de peróxido de hidrogênio na concentração de 15 µM atenuou os efeitos do estresse salino em plantas de pimentão 'All Big' irrigadas com águas salinas em CEa de até 1,4 dS m-1. O peróxido de hidrogênio na concentração de 15 µM associado à salinidade da água de 0,8 dS m-1 proporcionou aumento na condutância estomática, na taxa de assimilação de CO2, na eficiência instantânea de carboxilação e no crescimento das plantas de pimentão. Aplicação de peróxido de hidrogênio em concentrações maiores que 15 µM, intensificou os efeitos deletérios do estresse salino em pimentão 'All big', aos 90 dias após o semeio.

Twenty-five-centimeter pre-grazing canopy height in palisade grass and forage peanut

Short-term grazing behavior variables are sensitive to the canopy structure and have an impact on daily forage intake. This study evaluated the effect of pre- and post-grazing canopy heights on the forage harvesting process at a patch scale in a mixture of Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. syn. Urochloa brizantha R.D. Webster cv. Marandu (palisade grass) and Arachis pintoi Krapov. & W.C. Greg. cv. Belomonte (forage peanut). Treatments were allocated to a split-plot arrangement in a completely randomized design. The plots, in their entirety, consisted of two pre-grazing canopy heights: 25 cm (CH25) and 35 cm (CH35); subplots consisted of three levels of defoliation severity: no defoliation (DS0); 20% depletion of pre-grazing canopy height (DS20); and 40% depletion of pre-grazing canopy height (DS40), with eight replications. Heifers were allowed to graze the patches (0.7 × 0.7 m) and their grazing behavior was recorded. Canopy structure measurements were taken both before and after grazing. Patches from CH35 presented greater stem mass for grass (p = 0.001) and legume (p = 0.002) than did patches from CH25. Bite rate, bite mass and instantaneous intake rate were greater for CH25 than for CH35 (p < 0.001, p = 0.068, and p = 0.074), and bite mass and instantaneous intake rate were lower for DS20 compared to DS0 (p = 0.032 and p = 0.016). Greater stem mass in the grazing strata negatively influenced the instantaneous intake rate.

Ecophysiology of Mesosphaerum suaveolens (L) Kuntze (Lamiaceae) under saline stress and salicylic acid / Ecofisiologia de Mesosphaerum suaveolens (L) Kuntze (Lamiaceae) sob estresse salino e ácido salicílico

Mesosphaerum suaveolens (L.) Kuntze is a species widely used in folk medicine and has a high aromatic and therapeutic potential. However, its cultivation in semi-arid regions can be limited by salts in the irrigation water. The objective of this study was to evaluate the effect of salicylic acid (SA) as a mitigator of saline stress on the growth and gas exchange of M. suaveolens. The experimental design used was the randomized blocks in an incomplete factorial scheme (Central Composite Design), with five electrical conductivities water (ECw = 0.5, 1.45, 5.0, 8.55, and 10.0 dS m-¹) and five SA doses (0.0, 0.29, 1.0, 1.71, and 2.0 mM). Plant height, number of leaves, stem diameter, leaf area, root length, and height/diameter ratio, and gas exchange (stomatal conductance, net CO2 assimilation rate, transpiration rate, instantaneous, and intrinsic water use efficiency, instantaneous carboxylation efficiency, and leaf temperature) were evaluated. The application of 0.9 mM SA attenuates the negative effect of saline stress on the number of leaves and leaf area of M. suaveolens. The application of SA stimulates the number of leaves, plant height, and root growth, but does not affect the gas exchange of M. suaveolens. ECw reduces the growth and gas exchange of M. suaveolens plants.

Mesosphaerum suaveolens (L.) Kuntze é uma espécie muito utilizada na medicina popular e que possui um elevado potencial aromático e terapêutico. No entanto, sua exploração em regiões semiáridas pode ser limitada em função do teor de sais na água de irrigação. O objetivo deste estudo foi avaliar o efeito do ácido salicílico (AS) como mitigador do estresse salino sobre o crescimento e trocas gasosas de M. suaveolens. O delineamento estatístico utilizado foi o de blocos casualizados, em esquema fatorial incompleto (Delineamento Composto Central), com cinco condutividades elétricas de água (CEa = 0,5, 1,45, 5,0, 8,55 e 10,0 dS m-¹) e cinco doses de AS (0,0, 0,29, 1,0, 1,71 e 2,0 mM). Foram avaliados a altura de plantas, número de folhas, diâmetro do caule, área foliar, comprimento de raiz e relação altura/diâmetro do caule e trocas gasosas (condutância estomática, taxa de assimilação líquida de CO2, transpiração, eficiência instantânea e eficiência intrínseca no uso da água e de carboxilação e a temperatura foliar). A aplicação do AS na dose de 0,9 mM atenua o efeito do estresse salino sobre o número de folhas e área foliar. A aplicação de AS estimula o número de folhas e o crescimento em altura e da raiz, mas não afeta as trocas gasosas. A CEa reduz o crescimento e as trocas gasosas das plantas de M. suaveolens.

Growth analysis, photosynthate partition and nodulation in bean and soybean / Análise de crescimento, partição de fotoassimilados e nodulação em feijão e soja

Photoassimilate partition and allocation among plant organs varies throughout their development and is also influenced by factors inherent to the genotype and the environment. Nodulation in the soybean-diazotrophic bacteria interaction is more effective than in the bean-diazotrophic bacteria interaction. This investigation studied growth and photoassimilate partitioning throughout the bean and soybean cycles and inferred how much it could affect the nodulation of the roots. For this purpose, an experiment with two treatments was carried out, soybean (cultivar BRS GO - 7760 - RR) and bean (cultivar BRS Estilo), with four replications, conducted in pots and entirely randomized. The seeds were inoculated with commercial rhizobia specific for bean and soybean LeguMax® (Novozymes-Turfal). Plants were analyzed throughout their cycles based on leaf area and dry mass of all organs, including nodules. Mathematical models were fitted to the data and based on them, the instantaneous physiological indicators of growth were estimated, and the percentages of photoassimilate partition among organs were evaluated. Crop growth rate, relative growth rates, net assimilation rate as well as net photosynthesis rate had higher values in soybean compared to bean, following the pattern of leaf area and total dry mass. For both species, the highest rates occurred at the beginning of the cycle, decreasing with age. Unlike the bean, soybean has a high capacity to supply photosynthates to all of its organs throughout its entire cycle, favoring the maintenance of nodule growth and explaining its greater capacity for nitrogen assimilation.

Durante o desenvolvimento das plantas a partição e alocação de fotoassimilados variam entre os seus órgãos, e dependem de fatores inerentes ao genótipo e ao meio ambiente. A nodulação é mais efetiva na interação soja-bactéria diazotrófica do que na interação feijão-bactéria diazotrófica. Esta pesquisa tem como objetivo estudar o crescimento e a partição de fotoassimilados ao longo dos ciclos do feijão e da soja e inferir o quanto isso pode afetar a nodulação das raízes. Para tanto, foi instalado um experimento com dois tratamentos, soja (cultivar BRS GO - 7760 - RR) e feijão comum (cultivar BRS Estilo), com quatro repetições, conduzido em vasos e inteiramente ao acaso. As sementes foram inoculadas com inoculantes comerciais específicos para feijão e soja LeguMax® (Novozymes-Turfal). Plantas foram coletadas ao longo de seus ciclos e medidas as áreas foliares e as massas secas de todos os órgãos, incluindo nódulos. Modelos matemáticos foram ajustados aos dados e, com base neles, foram estimados os indicadores fisiológicos instantâneos do crescimento e, também, foram avaliadas as porcentagens de partição de fotoassimilados entre os órgãos. A taxa de crescimento das culturas (CGR), as taxas de crescimento relativo (RGR), a taxa líquida de assimilação (NAR) e a taxa líquida de fotossíntese (Pn) apresentaram maiores valores na soja em relação ao feijoeiro. Para ambas as culturas as maiores taxas ocorreram no início do ciclo, decrescendo ao longo do ciclo cultural. Diferentemente do feijoeiro a soja tem alta capacidade de suprir de fotoassimilados a todos os seus órgãos ao longo de todo o seu ciclo, o que favorece o maior crescimento dos seus nódulos, justificando a sua maior capacidade na captura do N2 atmosférico.

Análises fisiológicas e de crescimento e produtividade da mandioca sob níveis de irrigação / Physiological and growth analysis and productivity of cassava under irrigation levels

O objetivo dessa pesquisa foi avaliaro crescimento,produtividade easrespostas fisiológicas da mandioca sob níveis de irrigação na Zona da Mata de Alagoas. O delineamento estatístico utilizado foi blocos casualizados, em esquema de parcelas subdivididas, com quatro repetições. Os tratamentos foram seis níveis de irrigação, em função da evapotranspiração da cultura ­ETC(L0= 0% (sequeiro), L1= 40%, L2= 80%, L3= 120%, L4= 160% e L5= 200% da ETC). As variáveis foram divididas em grupos: crescimento e produção (avaliadas em seis períodosbimestrais ­1 ano) e as fisiológicas (taxa fotossintética líquida e transpiratória, temperatura foliar, condutância estomática, eficiência instantânea do uso de água, rendimento quântico potencial, eficiência quântica efetiva do fotossistema II (ΦPSII) eíndice SPADforam avaliadas em cinco períodos bimestrais ­10 meses).Obalanço hídrico dos níveis de irrigação, foi realizado em escala decendial. A evapotranspiração anual da cultura da mandiocaestimada foi1.030 mm, e nas áreas de sequeiro, a chuva efetiva somouapenas 522 mm, o que geroudéficit hídrico de 508 mm, e isso torna evidente a importância de utilização da irrigação em cultivos na região. De maneira geral, crescimento, produtividade e as respostas fisiológicas da mandioca são superiores em áreas irrigadas quando comparadas com cultivos de sequeiro e a irrigação proporciona as produtividades de raízes e biomassa total de 97 e 155 t ha-1, sob os níveis de irrigação de 129 e 136% da ETC, respectivamente, na região estudada.(AU)

The objective of this research was to evaluate the growth, productivity and the physiological responses of cassava under irrigation levels in the Alagoas Forest Zone. The statistical design used was randomized blocks, in a split-plot scheme, with four replications. The treatments were six levels of irrigation, depending on the evapotranspiration of the crop ­ETC(L0=0% (Rainfed), L1= 40%, L2= 80%, L3= 120%, L4= 160% and L5= 200% of the ETC). The variables were divided into groups: growth and production (evaluated in six bimonthly periods -1 year) and the physiological (net photosynthetic rate and transpiratory,leaf temperature, stomatal conductance, instantaneous water use efficiency, potential quantum yield, effective quantum efficiency of photosystem II and SPAD indexwere evaluated in five bimonthly periods ­10 months). The water balance of the irrigation levels was carried out, on a decendial scale. The annual evapotranspiration of cassava addedaround 1,030 mm, and in dryland areas, the effective rainfall is only 522 mm, which generates a water deficit of 508 mm, and this makes the importance evident of use of irrigation in crops in the region. In general, cassava growth, yield andthephysiological responses are superior in irrigated areas when compared with therainfed crops, and irrigation providestheroot and total biomass yields of 97 and 155 Mg ha-1,under the irrigation levels of 129 and 136% of the ETC, respectively, in the studied region.(AU)

Population growth of Tetranychus urticae Koch (Acari: Tetranychidae) and predation rate of the pest mite by Neoseiulus idaeus Denmark & Muma (Acari: Phytoseiidae) in two grape cultivars

ABSTRACT The two-spotted spider mite, Tetranychus urticae Koch, has caused significant damage to vineyards in the valley of the São Francisco River in Brazil. Neoseiulus idaeus Denmark & Muma is one of the most abundant species of predatory mites on vines in this region. This study evaluated the population growth rates of T. urticae on leaves of two grape (Vitis vinifera L.) cultivars (Italia and Superior Seedless) and jack bean [Canavalia ensiformis (L.) DC.] and, also, to estimate the predation rates of the pest mite by N. idaeus on leaves of both grape cultivars and jack bean. A higher oviposition rate of T. urticae was observed on Superior Seedless than on Italia grape leaves; however, there was no significant difference in the instantaneous growth rates of T. urticae for these grape cultivars. For Superior Seedless, the spider mite egg viability was significantly lower than on Italia grape, indicating a resistance factor in this grape cultivar. The phytoseiid N. idaeus preyed higher number of T. urticae females on Superior Seedless leaves than on Italia grape and jack bean leaves for the densities of 10 and 20 pest mites per leaf arena (9 cm2). Evaluations of leaf trichomes in both grape cultivars indicated the occurrence of longer trichomes on the basal portion of the main veins of Superior Seedless leaves. The presence of these longer trichomes may be associated with the better performance of N. idaeus on Superior Seedless leaves.

Foliar application of H2O2 as salt stress attenuator in 'BRS Rubi do Cerrado' sour passion fruit / Aplicação foliar de H2O2 como atenuante do estresse salino em maracujazeiro-azedo 'BRS Rubi do Cerrado'

Irrigation with saline water causes a reduction in yield, especially in semi-arid regions. Cultivation strategies have been developed to mitigate salt stress on plants, such as the use of hydrogen peroxide. The objective of this study was to evaluate the attenuating effect of hydrogen peroxide on the gas exchange and growth of 'BRS Rubi do Cerrado' sour passion fruit cultivated under irrigation with saline water. The design was completely randomized in split-plot plots, with water salinity levels ECw (0.6, 1.2, 1.8, 2.4, and 3.0 dS m-1) considered the plots and the concentrations of hydrogen peroxide H2O2 (0, 15, 30, and 45 µM) considered the subplots, with three replicates. Gas exchange (stomatal conductance, transpiration, CO2 assimilation rate, intercellular CO2 concentration, instantaneous water use efficiency, and instantaneous carboxylation efficiency), and absolute and relative growth rates in stem diameter were evaluated. An increase in irrigation water salinity from 0.6 dS m-1 reduced gas exchange, and exogenous application of hydrogen peroxide did not promote a significant effect on gas exchange. However, foliar application of hydrogen peroxide at 15 µM increased the growth of 'BRS Rubi do Cerrado' sour passion fruit.(AU)

A irrigação com águas salinas causa redução na produtividade, principalmente nas regiões semiáridas. Estratégias de cultivo vêm sendo desenvolvidas, a exemplo uso de peróxido de hidrogênio para mitigar o estresse salino sobre as plantas. Objetivou-se avaliar o efeito atenuante do peróxido de hidrogênio sobre as trocas gasosas e o crescimento do maracujazeiro-azedo 'BRS Rubi do Cerrado' cultivado sob irrigação com águas salinas. O delineamento foi inteiramente casualizados em parcelas subdivididas, sendo os níveis de salinidade da água - CEa (0,6, 1,2, 1,8, 2,4 e 3,0 dS m-1) consideradas as parcelas, e as concentrações de peróxido de hidrogênio ­ H2O2 (0, 15, 30 e 45 µM) as subparcelas, com três repetições. Foram avaliadas as trocas gasosas (condutância estomática, transpiração, taxa de assimilação de CO2, concentração intercelular de CO2, eficiência instantânea no uso da água e eficiência instantânea de carboxilação), e a taxa de crescimento absoluto e relativo do caule. O aumento na salinidade da água de irrigação a partir da salinidade de 0,6 dS m-1 reduziu as trocas gasosas; a aplicação exógena de peróxido de hidrogênio não promoveu efeito significativos sob as trocas gasosas. A aplicação foliar de 15 µM de peróxido de hidrogênio aumentou o crescimento do maracujazeiro-azedo 'BRS Rubi do Cerrado'.(AU)

Population growth of Tetranychus urticae Koch (Acari: Tetranychidae) and predation rate of the pest mite by Neoseiulusidaeus Denmark & Muma (Acari: Phytoseiidae) in two grape cultivars

The two-spotted spider mite, Tetranychus urticae Koch, has caused significant damage to vineyards in the valley of the São Francisco River in Brazil. Neoseiulus idaeus Denmark & Muma is one of the most abundant species of predatory mites on vines in this region. This study evaluated the population growth rates of T. urticae on leaves of two grape (Vitis vinifera L.) cultivars ('Italia' and 'Superior Seedless') and jack bean [Canavalia ensiformis (L.) DC.] and, also, to estimate the predation rates of the pest mite by N. idaeus on leaves of both grape cultivars and jack bean. A higher oviposition rate of T. urticae was observed on 'Superior Seedless' than on 'Italia' grape leaves; however, there was no significant difference in the instantaneous growth rates of T. urticae for these grape cultivars. For 'Superior Seedless', the spider mite egg viability was significantly lower than on 'Italia' grape, indicating a resistance factor in this grape cultivar. The phytoseiid N. idaeus preyed higher number of T. urticae females on 'Superior Seedless' leaves than on 'Italia' grape and jack bean leaves for the densities of 10 and 20 pest mites per leaf arena (9 cm2). Evaluations of leaf trichomes in both grape cultivars indicated the occurrence of longer trichomes on the basal portion of the main veins of 'Superior Seedless' leaves. The presence of these longer trichomes may be associated with the better performance of N. idaeus on 'Superior Seedless' leaves.

Defoliation intensity and leaf area index recovery in defoliated swards: implications for forage accumulation

This study evaluated the leaf area index (LAI) recovery mechanisms and forage accumulation rates on the regrowth of different grass species subjected to different defoliation intensities. For that purpose, plots of Pennisetum clandestinum (kikuyugrass), Lolium multiflorum (annual ryegrass), and Avena strigosa (black oats) were defoliated from 20 to 80 % of their initial heights (25, 20, and 25 cm, respectively). At different increments in height, forage samples were collected to ground level and used to estimate tiller population density (TPD), leaf area per tiller (LA), and forage mass. From these data, we calculated the leaf area index (LAI), average leaf area index (aLAI), and average and instantaneous forage accumulation rate (FAR and IFAR, respectively). Data were plotted over time (days) to describe LAI recovery and forage accumulation rates. As the defoliation intensity increased, greater canopy heights were needed for pastures to achieve their maximum forage accumulation rates, which required longer regrowth intervals. The need for high tiller recruitment after defoliation, which delayed canopy LAI recovery, seemed to be one of the main cause. Thus, grazing management strategies that involve costly tiller recruitment could decrease both overall forage production and sward persistence over time. However, the plant ability to recover LAI after successive intense defoliations seems to be species-dependent and related to their phenotypic plasticity.

Defoliation intensity and leaf area index recovery in defoliated swards: implications for forage accumulation

This study evaluated the leaf area index (LAI) recovery mechanisms and forage accumulation rates on the regrowth of different grass species subjected to different defoliation intensities. For that purpose, plots of Pennisetum clandestinum (kikuyugrass), Lolium multiflorum (annual ryegrass), and Avena strigosa (black oats) were defoliated from 20 to 80 % of their initial heights (25, 20, and 25 cm, respectively). At different increments in height, forage samples were collected to ground level and used to estimate tiller population density (TPD), leaf area per tiller (LA), and forage mass. From these data, we calculated the leaf area index (LAI), average leaf area index (aLAI), and average and instantaneous forage accumulation rate (FAR and IFAR, respectively). Data were plotted over time (days) to describe LAI recovery and forage accumulation rates. As the defoliation intensity increased, greater canopy heights were needed for pastures to achieve their maximum forage accumulation rates, which required longer regrowth intervals. The need for high tiller recruitment after defoliation, which delayed canopy LAI recovery, seemed to be one of the main cause. Thus, grazing management strategies that involve costly tiller recruitment could decrease both overall forage production and sward persistence over time. However, the plant ability to recover LAI after successive intense defoliations seems to be species-dependent and related to their phenotypic plasticity.(AU)

Cell damage, gas exchange, and growth of Annona squamosa L. under saline water irrigation and potassium fertilization / Dano celular, trocas gasosas e crescimento da Annona squamosa L. irrigada com águas salinas e fertilização potássica

The semi-arid region of Northeastern Brazil has water limitations in terms of both quantity and quality, with salt stress as a limiting factor for increasing yield in most crops. In this context, the present study aimed to evaluate cell damage, gas exchange, and growth of custard apple under salt stress and potassium fertilization. The research was carried out at the Experimental Farm of CCTA/UFCG, in São Domingos-PB, Brazil. A randomized block design was arranged in a 2 × 5 factorial scheme, with two levels of electrical conductivity of irrigation water (ECw; 1.3 and 4.0 dS m-1) and five potassium doses (10, 15, 20, 25, and 30 g of K2O per plant per year). Water salinity of 4.0 dS m-1 negatively affected the stem diameter and number of leaves in custard apple at 179 and 210 days after transplanting (DAT). The highest relative growth in stem diameter in the period of 179-245 DAT was obtained in plants irrigated with 4.0 dS m-1 water and fertilized with 20 g of K2O per plant. Potassium doses of up to 30 g of K2O resulted in a higher percentage of cell damage and relative water content in custard apple leaf tissue. Water saturation deficit decreased with the increase in K2O doses in plants irrigated with water of 1.3 dS m-1. Irrigation with 1.3 dS m-1 water and estimated K2O doses ranging from 16 to 22 g per plant resulted in an increase in stomatal conductance, transpiration, CO2 assimilation rate, and instantaneous carboxylation efficiency in custard apple plants at 210 DAT.(AU)

A região semiárida do Nordeste brasileiro apresenta limitações hídricas em termos quantitativos e qualitativos, tendo o estresse salino como um fator limitante para o aumento da produtividade na maioria das culturas. Neste contexto, o presente estudo teve como objetivo, avaliar o dano celular, as trocas gasosas e o crescimento da pinheira sob estresse salino e adubação potássica. A pesquisa foi realizada na Fazenda Experimental do CCTA/UFCG, em São Domingos-PB, Brasil. Foi utilizado o delineamento em blocos casualizados, arranjados em esquema fatorial 2 × 5 sendo dois níveis de condutividade elétrica da água de irrigação - CEa (1,3 e 4,0 dS m-1) e cinco doses de potássio (10, 15, 20, 25 e 30 g de K2O por planta por ano). A salinidade da água de 4,0 dS m-1 afetou de forma negativa o diâmetro de caule e o número de folhas da pinheira, aos 179 e 210 dias após o transplantio (DAT). O maior crescimento relativo em diâmetro de caule no período de 179-245 DAT foi obtido nas plantas irrigadas com água de 4,0 dS m-1 e adubação com 20 g de K2O por planta. Doses de potássio de até 30 g de K2O resultaram em maior percentual de dano celular e conteúdo relativo de água nos tecidos foliares da pinheira. O déficit de saturação hídrica diminuiu com o aumento nas doses de K2O nas plantas irrigadas com água de 1,3 dS m-1. Irrigação com água de 1,3 dS m-1 e doses estimadas de K2O variando de 16 a 22 g por planta resultaram em incremento na condutância estomática, transpiração, taxa de assimilação de CO2 e eficiência instantânea de carboxilação das plantas de pinheira, aos 210 DAT.(AU)

Animal performance and welfare of giant freshwater prawn (Macrobrachium rosenbergii) subjected to feed restriction

Behavior activities of giant freshwater prawn Macrobrachium rosenbergii juvenile, their performance, and acquired lesions when under temporary feed restrictions were analyzed. Five animals/experimental units (10 prawns/m2 ) were employed for treatments DFL ­ daily feed supply in the light phase; DFD ­ daily feed supply in the dark phase; AFL ­ alternating feed supply in the light phase; and AFD ­ alternating feed supply in the dark phase, for a 24-hour period, with four replications each. Prawns were fed a pellet diet, twice a day, with 10% of their biomass/day. Specimens were monitored during 60 consecutive days, with behavior recording daily and weighed every 10 days, with assessment of lesions and/or amputated limbs at the end of the experimental period. Types of behavior comprised exploring, grooming, inactivity, crawling, swimming, excavation, burrowing, agonism, and feed ingestion by scan sampling, with instantaneous registration every 60 s, in 15-min windows, before and after feed, in light and dark phases. Feed restricted in alternate days during light and dark phases did not interfere in growth or survival of the specimens, with increase in apparent feed intake and less feed conversion ratio and specific growth rate. Agonistic behavior was higher in specimens with feed restrictions, with an increase in the number of lesions and amputations. The above demonstrates welfare decrease in farmed M. rosenbergii and depreciation in the quality of the final product.(AU)

Gas exchanges, growth and production of okra cultivated with saline water and silicon fertilization / Trocas gasosas, crescimento e produção de quiabeiro cultivado com águas salinas e adubação silicatada

Excess salts in water and/or soil are a critical factor that adversely affects the physiology and growth, besides limiting the production of crops in the semiarid region of Northeast Brazil. One way to reduce the effect of salt stress on plants is by using silicon (Si) fertilization. In this context, the objective of this study was to evaluate the gas exchange, growth, and production of okra cv. Valença as a function of irrigation with saline water and Si doses. The experiment was conducted in a greenhouse in the municipality of Pombal - PB, Brazil. The experimental design adopted was randomized blocks in a 5 × 2 factorial scheme corresponding to five levels of electrical conductivity of water ECw (0.3, 1.0, 1.7,2.4, and 3.1 dS m-¹) and two doses of Si fertilization (100 and 200 g of Si per plant), with four replicates. Salt stress increased the intercellular concentration of CO2 in the substomatal chamber and reduced the CO2 assimilation rate, instantaneous carboxylation efficiency, growth, and production of okra plants. Intrinsic water use efficiency and average weights of okra fruits were not influenced by irrigation with saline water and Si doses. The supply of 200 g Si per plant reduced the deleterious effect of salt stress on stomatal conductance and leaf area of okra, at 45 days after sowing but did not increase production.

O excesso de sais na água e/ou no solo é um fator crítico que afeta adversamente a fisiologia, o crescimento e limita a produção dos cultivos no semiárido do Nordeste brasileiro. Uma forma de reduzir o efeito do estresse salino sobre as plantas é o uso da adubação com silício. Neste contexto, objetivou-se avaliar as trocas gasosas, o crescimento e a produção do quiabeiro cv. Valença em função da irrigação com águas salinas e doses de silício. O experimento foi conduzido em casa-de-vegetação no município de Pombal-PB. Adotou-se o delineamento experimental de blocos casualizados, em esquema fatorial 5 x 2, sendo cinco níveis de condutividade elétrica da água – CEa (0,3; 1,0; 1,7; 2,4 e 3,1 dS m-¹) e duas doses de adubação silicatada (100 e 200 g de Si planta-¹) com quatro repetições. O estresse salino aumentou a concentração intercelular de CO2 na câmera subestomática e reduziu a taxa de assimilação de CO2, a eficiência instantânea de carboxilação, o crescimento e a produção das plantas de quiabeiro.A eficiência intrínseca no uso da água e o peso médio de frutos do quiabeiro não foram influenciados pela irrigação com águas salinas e doses de silício. O fornecimento de 200 g planta-¹ de silício diminuiu o efeito deletério do estresse salino sobre a condutância estomática e a área foliar de quiabeiro, aos 45 dias após a semeadura, no entanto, não aumentou produção da cultura.

Gas exchanges, growth and production of okra cultivated with saline water and silicon fertilization / Trocas gasosas, crescimento e produção de quiabeiro cultivado com águas salinas e adubação silicatada

Excess salts in water and/or soil are a critical factor that adversely affects the physiology and growth, besides limiting the production of crops in the semiarid region of Northeast Brazil. One way to reduce the effect of salt stress on plants is by using silicon (Si) fertilization. In this context, the objective of this study was to evaluate the gas exchange, growth, and production of okra cv. Valença as a function of irrigation with saline water and Si doses. The experiment was conducted in a greenhouse in the municipality of Pombal - PB, Brazil. The experimental design adopted was randomized blocks in a 5 × 2 factorial scheme corresponding to five levels of electrical conductivity of water ECw (0.3, 1.0, 1.7,2.4, and 3.1 dS m-¹) and two doses of Si fertilization (100 and 200 g of Si per plant), with four replicates. Salt stress increased the intercellular concentration of CO2 in the substomatal chamber and reduced the CO2 assimilation rate, instantaneous carboxylation efficiency, growth, and production of okra plants. Intrinsic water use efficiency and average weights of okra fruits were not influenced by irrigation with saline water and Si doses. The supply of 200 g Si per plant reduced the deleterious effect of salt stress on stomatal conductance and leaf area of okra, at 45 days after sowing but did not increase production.(AU)

O excesso de sais na água e/ou no solo é um fator crítico que afeta adversamente a fisiologia, o crescimento e limita a produção dos cultivos no semiárido do Nordeste brasileiro. Uma forma de reduzir o efeito do estresse salino sobre as plantas é o uso da adubação com silício. Neste contexto, objetivou-se avaliar as trocas gasosas, o crescimento e a produção do quiabeiro cv. Valença em função da irrigação com águas salinas e doses de silício. O experimento foi conduzido em casa-de-vegetação no município de Pombal-PB. Adotou-se o delineamento experimental de blocos casualizados, em esquema fatorial 5 x 2, sendo cinco níveis de condutividade elétrica da água CEa (0,3; 1,0; 1,7; 2,4 e 3,1 dS m-¹) e duas doses de adubação silicatada (100 e 200 g de Si planta-¹) com quatro repetições. O estresse salino aumentou a concentração intercelular de CO2 na câmera subestomática e reduziu a taxa de assimilação de CO2, a eficiência instantânea de carboxilação, o crescimento e a produção das plantas de quiabeiro.A eficiência intrínseca no uso da água e o peso médio de frutos do quiabeiro não foram influenciados pela irrigação com águas salinas e doses de silício. O fornecimento de 200 g planta-¹ de silício diminuiu o efeito deletério do estresse salino sobre a condutância estomática e a área foliar de quiabeiro, aos 45 dias após a semeadura, no entanto, não aumentou produção da cultura.(AU)

Length-based estimates of growth parameters and mortality rates of fish populations from a coastal zone in the Southeastern Brazil

Small-scale fisheries in Brazil contribute to a significant share of total fish production, accessing a large variety of species. Life history parameters from these resources are important for their management and conservation, based on primary data. The objective of this article is to generate growth parameters and mortality rates of ten fish populations from a coastal zone in Southeastern Brazil. Monthly samples were taken between January 2011 and November 2014 from landings of the beach-seine fishery in an area adjacent to the entrance of the Guanabara Bay. All fishes were measured (total length) and weighed. The length-weight relationships (LWR) were estimated by linear regression analysis on log-transformed data of the equation: W = aL b . The Von Bertalanffy Growth Function (VBGF) was fitted to size-at-age data to obtain growth parameters (K, L ∞ ). The length-converted catch curve was used for estimating the instantaneous total mortality (Z). Taylor’s equations provided an independent estimate of the natural mortality (M) and longevity. The difference between Z and M derived Fishing mortality (F). A total of 2,938 individuals from ten fish species were used to determine the length-weight relationships. Harengula clupeola (Cuvier, 1829) has a new maximum length record for the FishBase LWR database. Sardinella brasiliensis (Steindachner, 1879) presented the smallest and largest size recorded for LWR observed in the literature and FishBase database. Upeneus parvus showed the greatest total length, while Trichiurus lepturus Linnaeus, 1758, Orthopristis ruber (Cuvier, 1830) and Dactylopterus volitans (Linnaeus, 1758) presented the smallest sizes for LWR in FishBase. The other species showed parameters within the expected values for each group. The performance index combining information from Kand L ∞ presented values between 2.32 and 3.76 and were considered appropriate for the populations evaluated.

Length-based estimates of growth parameters and mortality rates of fish populations from a coastal zone in the Southeastern Brazil

Small-scale fisheries in Brazil contribute to a significant share of total fish production, accessing a large variety of species. Life history parameters from these resources are important for their management and conservation, based on primary data. The objective of this article is to generate growth parameters and mortality rates of ten fish populations from a coastal zone in Southeastern Brazil. Monthly samples were taken between January 2011 and November 2014 from landings of the beach-seine fishery in an area adjacent to the entrance of the Guanabara Bay. All fishes were measured (total length) and weighed. The length-weight relationships (LWR) were estimated by linear regression analysis on log-transformed data of the equation: W = aL b . The Von Bertalanffy Growth Function (VBGF) was fitted to size-at-age data to obtain growth parameters (K, L ∞ ). The length-converted catch curve was used for estimating the instantaneous total mortality (Z). Taylors equations provided an independent estimate of the natural mortality (M) and longevity. The difference between Z and M derived Fishing mortality (F). A total of 2,938 individuals from ten fish species were used to determine the length-weight relationships. Harengula clupeola (Cuvier, 1829) has a new maximum length record for the FishBase LWR database. Sardinella brasiliensis (Steindachner, 1879) presented the smallest and largest size recorded for LWR observed in the literature and FishBase database. Upeneus parvus showed the greatest total length, while Trichiurus lepturus Linnaeus, 1758, Orthopristis ruber (Cuvier, 1830) and Dactylopterus volitans (Linnaeus, 1758) presented the smallest sizes for LWR in FishBase. The other species showed parameters within the expected values for each group. The performance index combining information from Kand L ∞ presented values between 2.32 and 3.76 and were considered appropriate for the populations evaluated.(AU)

Phytophagous mites on genetically modified maize with Bacillus thuringiensis genes / Ácaros fitófagos em milho geneticamente modificado com genes de Bacillus thuringiensis

The study of non-target organisms such as mites, can provide information about the possible effects of transgenic maize cultivars on the arthropod community. This study aimed to evaluate the abundance of phytophagous mites in the area of Bt maize and evaluate the instantaneous population growth rate, and food preference of phytophagous mites on Bt maize. We registered the species occurrence and the number of adult mite individuals on four maize cultivars, one non-Bt 30F35, and three containing the proteins Cry1Ab (30F35 Yg), Cry1F (30F35 Hx) and Vip3a (Impacto Viptera). Cry proteins disrupt the midgut epithelium of insect pests. The food preference and instantaneous population growth rate (ri) were evaluated using the two-spotted spider mite Tetranychus urticae as model. The species Catarhinus tricholaenae and Aceria zeala were recorded. The Bt maize cultivars did not significantly affect the average number of C. tricholaenae and A. zeala mites compared to conventional cultivar. The population growth rates of T. urticae were similar for the different maize cultivars. T. urticae showed no preference between the leaf of Bt or conventional cultivars. Bt maize did not affect the abundance of species in phytophagous mite.

O estudo de organismos não-alvo, tais como ácaros, pode fornecer informações sobre os possíveis efeitos de cultivares de milho transgênico na comunidade de artrópodos. Este estudo teve como objetivo avaliar a abundância de ácaros fitófagos na área de milho Bt e avaliar a taxa de crescimento populacional instantânea e preferência alimentar de ácaros fitófagos em milho Bt. Registramos a ocorrência de espécies e número de indivíduos adultos de ácaros em quatro cultivares de milho, um não-Bt 30F35, e três contendo a proteína Cry1Ab (30F35 Yg), Cry1F (30F35 Hx) e VIP3A (Impacto Viptera). A preferência alimentar e taxa instantânea de crescimento populacional foram avaliadas utilizando fêmeas adultas do ácaro-rajado Tetranychus urticae. As espécies Catarhinus tricholaenae e Aceria zeala foram registradas. As cultivares de milho Bt não afetaram significativamente o número médio de ácaros C. tricholaenae e A. zeala em relação ao cultivar convencional. As taxas de crescimento populacional de T. urticae foram similares para os diferentes cultivares. T. urticae não mostrou preferência entre a folha de milho Bt ou cultivares convencionais. Sugere-se, então, que o milho Bt não afeta a abundância de espécies, preferência alimentar e taxa de crescimento de ácaros fitófagos.

Phytophagous mites on genetically modified maize with Bacillus thuringiensis genes / Ácaros fitófagos em milho geneticamente modificado com genes de Bacillus thuringiensis

The study of non-target organisms such as mites, can provide information about the possible effects of transgenic maize cultivars on the arthropod community. This study aimed to evaluate the abundance of phytophagous mites in the area of Bt maize and evaluate the instantaneous population growth rate, and food preference of phytophagous mites on Bt maize. We registered the species occurrence and the number of adult mite individuals on four maize cultivars, one non-Bt 30F35, and three containing the proteins Cry1Ab (30F35 Yg), Cry1F (30F35 Hx) and Vip3a (Impacto Viptera). Cry proteins disrupt the midgut epithelium of insect pests. The food preference and instantaneous population growth rate (ri) were evaluated using the two-spotted spider mite Tetranychus urticae as model. The species Catarhinus tricholaenae and Aceria zeala were recorded. The Bt maize cultivars did not significantly affect the average number of C. tricholaenae and A. zeala mites compared to conventional cultivar. The population growth rates of T. urticae were similar for the different maize cultivars. T. urticae showed no preference between the leaf of Bt or conventional cultivars. Bt maize did not affect the abundance of species in phytophagous mite.(AU)

O estudo de organismos não-alvo, tais como ácaros, pode fornecer informações sobre os possíveis efeitos de cultivares de milho transgênico na comunidade de artrópodos. Este estudo teve como objetivo avaliar a abundância de ácaros fitófagos na área de milho Bt e avaliar a taxa de crescimento populacional instantânea e preferência alimentar de ácaros fitófagos em milho Bt. Registramos a ocorrência de espécies e número de indivíduos adultos de ácaros em quatro cultivares de milho, um não-Bt 30F35, e três contendo a proteína Cry1Ab (30F35 Yg), Cry1F (30F35 Hx) e VIP3A (Impacto Viptera). A preferência alimentar e taxa instantânea de crescimento populacional foram avaliadas utilizando fêmeas adultas do ácaro-rajado Tetranychus urticae. As espécies Catarhinus tricholaenae e Aceria zeala foram registradas. As cultivares de milho Bt não afetaram significativamente o número médio de ácaros C. tricholaenae e A. zeala em relação ao cultivar convencional. As taxas de crescimento populacional de T. urticae foram similares para os diferentes cultivares. T. urticae não mostrou preferência entre a folha de milho Bt ou cultivares convencionais. Sugere-se, então, que o milho Bt não afeta a abundância de espécies, preferência alimentar e taxa de crescimento de ácaros fitófagos.(AU)

Comparação de modelos não lineares para descrever o crescimento de fêmeas leiteiras mestiças taurino x zebu no nordeste do Brasi / Comparison of nonlinear models to describe the growth of crossbred taurine x zebu dairy cows in northeastern Brazil

Objetivou-se comparar as funções matemáticas de Brody (BD), Von Bertalanffy (VB), Logístico (LG) e Gompertz (GP), identificar a que melhor descreve o crescimento, estimar componentes da curva (peso assintótico: a; índice de maturidade: k) e caracterizar o formato (ponto de inflexão: PI; taxa de crescimento instantâneo: TCI) da curva média de crescimento de fêmeas mestiças (Bos taurus x Bos indicus) em sistema de produção semi-extensivo. Foram utilizados 537 registros de pesagens realizadas em intervalos de 30 dias durante o período de 2010 a 2012, pertencentes a três propriedades. Os valores de a e k foram, respectivamente, 1.982 kg e 0,000286 kg/dia para BD; 550,50 kg e 0,00232 kg/dia para VB; 405,20 kg e 0,006374 kg/dia para LG e 479,70 kg e 0,00353 kg/dia para GP. Baseado nos critérios estatísticos observou-se que os modelos VB, BD e LG apresentaram os maiores (>0,74) coeficientes de determinação ajustados (Ra²), e menor valor do resíduo foi encontrado no modelo GP (4.918,38), indicando que todos os modelos se adequaram estatisticamente aos dados observados. Para os critérios de interpretação biológica, os modelos VB (8,48 meses) e LG (9,4 meses) apresentaram PI mais próximos do observado, o modelo VB (12,04-0,535 kg/mês) foi o único capaz de descrever a TCI, e os demais modelos subestimaram o incremento de peso corporal. O modelo de VB apresentou o melhor ajuste aos dados de crescimento de fêmeas mestiças com alta variabilidade genética em sistema semi-extensivo...

The objectives of this study were to compare different mathematical functions [Brody (BD), Von Bertalanffy (VB), logistic (LG) and Gompertz (GP)], to identify the model that best describes growth, to estimate curve components (asymptotic weight: a; maturation rate: k), and to characterize the shape (point of inflection: PI; instantaneous growth rate: IGR) of the average growth curve of crossbred cows (Bos taurus x Bos indicus) raised in a semi-extensive production system. This study used 537 weight records from three farms obtained at intervals of 30 days over the period from 2010 to 2012. The values of a and k were, respectively, 1,982 kg and 0.000286 kg/day for BD; 550.50 kg and 0.00232 kg/day for VB; 405.20 kg and 0.006374 kg/day for LG, and 479.70 kg and 0.00353 kg/day for GP. According to the statistical criteria, models VB, BD and LG exhibited the highest (>0.74) adjusted coefficient of determination (Ra²), while the lowest residual value was observed for GP (4,918.38), indicating that all models accurately fit the data observed. Regarding the criteria of biological interpretation, models VB (8.48 months) and LG (9.4 months) provided a PI close to the observed, VB (12.04-0.535 kg/month) was the only model able to describe IGR, and the remaining models underestimated the increase in body weight. Model VB provided the best fit to the growth data of crossbred cows with high genetic variability raised in a semi-extensive system...

Comparação de modelos não lineares para descrever o crescimento de fêmeas leiteiras mestiças taurino x zebu no nordeste do Brasi / Comparison of nonlinear models to describe the growth of crossbred taurine x zebu dairy cows in northeastern Brazil

Objetivou-se comparar as funções matemáticas de Brody (BD), Von Bertalanffy (VB), Logístico (LG) e Gompertz (GP), identificar a que melhor descreve o crescimento, estimar componentes da curva (peso assintótico: a; índice de maturidade: k) e caracterizar o formato (ponto de inflexão: PI; taxa de crescimento instantâneo: TCI) da curva média de crescimento de fêmeas mestiças (Bos taurus x Bos indicus) em sistema de produção semi-extensivo. Foram utilizados 537 registros de pesagens realizadas em intervalos de 30 dias durante o período de 2010 a 2012, pertencentes a três propriedades. Os valores de a e k foram, respectivamente, 1.982 kg e 0,000286 kg/dia para BD; 550,50 kg e 0,00232 kg/dia para VB; 405,20 kg e 0,006374 kg/dia para LG e 479,70 kg e 0,00353 kg/dia para GP. Baseado nos critérios estatísticos observou-se que os modelos VB, BD e LG apresentaram os maiores (>0,74) coeficientes de determinação ajustados (Ra²), e menor valor do resíduo foi encontrado no modelo GP (4.918,38), indicando que todos os modelos se adequaram estatisticamente aos dados observados. Para os critérios de interpretação biológica, os modelos VB (8,48 meses) e LG (9,4 meses) apresentaram PI mais próximos do observado, o modelo VB (12,04-0,535 kg/mês) foi o único capaz de descrever a TCI, e os demais modelos subestimaram o incremento de peso corporal. O modelo de VB apresentou o melhor ajuste aos dados de crescimento de fêmeas mestiças com alta variabilidade genética em sistema semi-extensivo...(AU)

The objectives of this study were to compare different mathematical functions [Brody (BD), Von Bertalanffy (VB), logistic (LG) and Gompertz (GP)], to identify the model that best describes growth, to estimate curve components (asymptotic weight: a; maturation rate: k), and to characterize the shape (point of inflection: PI; instantaneous growth rate: IGR) of the average growth curve of crossbred cows (Bos taurus x Bos indicus) raised in a semi-extensive production system. This study used 537 weight records from three farms obtained at intervals of 30 days over the period from 2010 to 2012. The values of a and k were, respectively, 1,982 kg and 0.000286 kg/day for BD; 550.50 kg and 0.00232 kg/day for VB; 405.20 kg and 0.006374 kg/day for LG, and 479.70 kg and 0.00353 kg/day for GP. According to the statistical criteria, models VB, BD and LG exhibited the highest (>0.74) adjusted coefficient of determination (Ra²), while the lowest residual value was observed for GP (4,918.38), indicating that all models accurately fit the data observed. Regarding the criteria of biological interpretation, models VB (8.48 months) and LG (9.4 months) provided a PI close to the observed, VB (12.04-0.535 kg/month) was the only model able to describe IGR, and the remaining models underestimated the increase in body weight. Model VB provided the best fit to the growth data of crossbred cows with high genetic variability raised in a semi-extensive system...(AU)