Responses of three invasive alien aquatic plant species to climate warming and plant density.

Climate warming may impact plant invasion success directly, as well as indirectly through changes among interactions within plant communities. However, the responses of invasive alien aquatic species to plant density and rising temperatures remain largely unknown. We tested the effects of plant density and neighbour plant identity at different temperatures to better understand the performance of a community of invasive species exposed to climate warming. A microcosm experiment was conducted with three invasive aquatic plants species-Elodea canadensis, Egeria densa and Lagarosiphon major-, at mono and polycultures with low and high plant density, at 16 °C, 19 °C and 23 °C. The results clearly demonstrated that rising temperature influenced, either as a single parameter or as a combined factor, at least one of the measured traits of the three invasive species. Leaf area of E. densa, root number of L. major and growth of E. densa and L. major were influenced by temperature, plant density and neighbour identity. Plant density influenced all traits with the exception of leaf area of E. canadensis and lateral branch production of E. densa. Neighbour identity had no effect on growth rate and leaf area of E. canadensis, on lateral branch and roots production of E. densa and on leaf area of L. major. These findings establish that rising temperature could enhance competition or facilitation among E. canadensis, L. major and E. densa and could cancel the beneficial effects of the presence of a neighbour species; however, the magnitude of this effect was strongly dependent on plant density. Rising temperature due to climate change will likely play a crucial role in interactions between invasive species within plant communities and in the further spread of these invasive aquatic plants.

Influence of management practices on water-related grain yield determinants.

Adequate management of N supply, plant density, row spacing, and soil cover has proved useful for increasing grain yields and/or grain yield stability of rainfed crops over the years. We review the impact of these management practices on grain yield water-related determinants: seasonal crop evapotranspiration (ET) and water use efficiency for grain production per unit of evapotranspired water during the growing season (WUEG,ET,s). We highlight a large number of conflicting results for the impact of management on ET and expose the complexity of the ET response to environmental factors. We analyse the influence of management practices on WUEG,ET,s in terms of the three main processes controlling it: (i) the proportion of transpiration in ET (T/ET), (ii) transpiration efficiency for shoot biomass production (TEB), and (iii) the harvest index. We directly relate the impact of management practices on T/ET to their effect on crop light interception and provide evidence that management practices significantly influence TEB. To optimize WUEG,ET,s, management practices should favor soil water availability during critical periods for seed set, thereby improving the harvest index. The need to improve the performance of existing crop growth models for the prediction of water-related grain yield determinants under different management practices is also discussed.

Desempenho agronômico de variedades de girassol em função de populações de plantas / Agronomic performance of sunflower varieties as a function of plant populations

O girassol é uma planta que se adapta em diversas condições edafoclimáticas, sendo utilizada para alimentação humana e animal, bem como para fins ornamentais. Objetivou-se neste trabalho avaliar o desempenho agronômico de variedades de girassol cultivadas em diferentes densidades de plantas. Utilizou-se o delineamento experimental de blocos completos casualizados, em esquema fatorial 3x4, envolvendo 3 variedades de girassol (Embrapa 122, IAC Iarama, IAC Uruguai) e 4 populações de plantas (30, 45, 60 e 75 mil plantas por hectare), com 4 repetições. Cada parcela foi composta por 4 fileiras de plantas com 5 metros de comprimento e espaçamento de 0,70 m entre fileiras de plantas. Na colheita foram avaliados: altura de plantas; diâmetro do caule; diâmetro do capítulo; peso de 1000 aquênios; número de capítulos. Verificou-se efeito significativo das diferentes variedades de girassol na altura de plantas, diâmetro de capítulo, número de capítulos pequenos, número de capítulos normais, e número total de capítulos. Também foi verificado efeito significativo da população de plantas sobre o diâmetro do capítulo, altura de plantas, número total de capítulos e número de capítulos pequenos. A interação entre variedades e população foi significativa apenas para o número de capítulos normais e produtividade. A densidade de plantas ideal para o desempenho agronômico da cultura do girassol depende da variedade utilizada. A maior densidade de plantas possibilita maior produtividade da variedade Embrapa 122.(AU)

Sunflower is a plant that adapts to different soil and climatic conditions, being used for human and animal food, and ornamental purposes. The objective of this work was to evaluate the agronomic performance of sunflower varieties grown in different plant densities. A randomized complete block experimental design was used, in a 3x4 factorial, with 3 sunflower varieties (Embrapa 122, IAC Iarama, IAC Uruguay) and 4 plant populations (30, 45, 60 and 75 thousand plants per hectare), with 4 repetitions. Each plot consisted of 4 rows of plants with 5 meters in length and spacing of 0.70 m between rows of plants. At harvest were evaluated: plant height; stem diameter; capitulum size; one thousand achenes weight; number of capitulum. There was a significant effect of different sunflower varieties on plant height, capitulum diameter, number of small capitulum, number of normal capitulum, and total number of capitulum. There was also a significant effect of plant population on capitulum diameter, plant height, total number of capitulum and number of small capitulum. The interaction between varieties and population was significant only for the number of normal capitula and productivity. The ideal plant density for the agronomic performance of the sunflower crop depends on the variety used. The higher density of plants allows for greater productivity of the variety Embrapa 122.(AU)

Efectos de espaciamientos sobre el crecimiento y rendimiento del fríjol caupí cultivar Caupicor 50 / Effects of spacings on the growth and yield of cowpea beans cultivar Caupicor 50

RESUMEN El fríjol caupí es una leguminosa importante en la región Caribe de Colombia, por su contribución a la dieta de sus pobladores y por ser una alternativa de ingresos para pequeños productores; sin embargo, los rendimientos obtenidos no superan los 600 kg ha-1, debido al desconocimiento del efecto de las prácticas culturales en la especie, como en los diversos cultivares. El objetivo del estudio fue evaluar el efecto de diferentes espaciamientos e hidrogel sobre características vegetativas y reproductivas del fríjol caupí cultivar Caupicor 50, en el departamento de Sucre, del Caribe colombiano. Se utilizó el diseño experimental parcelas sub-subdivididas, con tres repeticiones (bloques). Se combinaron dos distancias entre hileras: 60 y 80 cm en la parcela principal, tres distancias entre plantas: 20, 30 y 40 cm en la subparcela e hidrogel: 0 y 5 g/planta en la sub-subparcela. Las variables evaluadas fueron: altura de planta, área foliar, índice de área foliar, tasa de crecimiento del cultivo, número de vainas/planta, longitud de vaina, número de semillas/vaina, peso de cien semillas y rendimiento de semillas/ha. El mayor rendimiento, se estimó con 20 cm entre plantas y 60 cm entre hileras (83.333 plantas ha-1), con un rendimiento de 2.027 kg ha-1, asociado a mayor área foliar, índice de área foliar y tasa de crecimiento del cultivo y, a menor número de vainas por planta, longitud de vaina y peso de cien semillas.

ABSTRACT Cowpea bean is an important legume in the Caribbean region of Colombia, for its contribution to the diet of its habitants and being an alternative income for small producers. Nevertheless, the yields obtained do not exceed 600 kg ha-1, due to the unknown of the effect of cultural methods on the species, as in the different cultivars. The purpose of the study was to evaluate the effect of different spacing and hydrogel on vegetative and reproductive characteristics of cowpea beans, cultivar Caupicor 50 in the department of Sucre of the Caribbean region of Colombia. A split-plot design was used, with three replications (blocks). Two distances between rows: 60 and 80 cm in the main plot, three spaces between plants: 20, 30, and 40 cm in the subplot, and hydrogel: 0 and 5 g / plant in the sub-sub plot were combined. The variables evaluated were: plant height, leaf area, leaf area index, crop growth rate, number of pods per plant, pod length, number of seeds per pod, the weight of one hundred seed, and seed yield/ha. The highest yield, 2,027 kg ha-1, was estimated with 20 cm between plants and 60 cm between rows (83,333 plants ha-1) and was associated with greater leaf area, leaf area index and crop growth rate, and a lower number of pods per plant, pod length and weight of one hundred seeds.

Unraveling the impact on agronomic traits of the genetic architecture underlying plant-density responses in canola.

Plant density defines vegetative architecture and the competition for light between individuals. Brassica napus (canola, rapeseed) presents a radically different plant architecture compared to traditional crops commonly cultivated at high density, and can act as a model system of indeterminate growth. Using a panel of 152 spring-type accessions and a double-haploid population of 99 lines from a cross between the cultivars Lynx and Monty, we performed genome-wide association studies (GWAS) and quantitative trait locus (QTL) mapping for 12 growth and yield traits at two contrasting plant densities of 15 and 60 plants m-2. The most significant associations were found for time to flowering, biomass at harvest, plant height, silique and seed numbers, and seed yield. These were generally independent of plant density, but some density-dependent associations were found in low-density populations. RNA-seq transcriptomic analysis revealed distinctive latent gene-regulatory responses to simulated shade between Lynx and Monty. Having identified candidate genes within the canola QTLs, we further examined their influence on density responses in Arabidopsis lines mutated in certain homologous genes. The results suggested that TCP1 might promote growth independently of plant density, while HY5 could increase biomass and seed yield specifically at high plant density. For flowering time, the results suggested that PIN genes might accelerate flowering in plant a density-dependent manner whilst FT, HY5, and TCP1 might accelerate it in a density-independent. This work highlights the advantages of using agronomic field experiments together with genetic and transcriptomic approaches to decipher quantitative complex traits that potentially mediate improved crop productivity.

Phytochrome B enhances plant growth, biomass and grain yield in field-grown maize.

BACKGROUND AND AIMS: Phytochrome B (phyB) is a photosensory receptor important for the control of plant plasticity and resource partitioning. Whether phyB is required to optimize plant biomass accumulation in agricultural crops exposed to full sunlight is unknown. Here we investigated the impact of mutations in the genes that encode either phyB1 or phyB2 on plant growth and grain yield in field crops of Zea mays sown at contrasting population densities. METHODS: Plants of maize inbred line France 2 wild type (WT) and the isogenic mutants lacking either phyB1 or phyB2 (phyB1 and phyB2) were cultivated in the field during two seasons. Plants were grown at two densities (9 and 30 plants m-2), irrigated and without restrictions of nutrients. Leaf and stem growth, leaf anatomy, light interception, above-ground biomass accumulation and grain yield were recorded. KEY RESULTS: At high plant density, all the lines showed similar kinetics of biomass accumulation. However, compared with the WT, the phyB1 and phyB2 mutations impaired the ability to enhance plant growth in response to the additional resources available at low plant density. This effect was largely due to a reduced leaf area (fewer cells per leaf), which compromised light interception capacity. Grain yield was reduced in phyB1 plants. CONCLUSIONS: Maize plants grown in the field at relatively low densities require phyB1 and phyB2 to sense the light environment and optimize the use of the available resources. In the absence of either of these two light receptors, leaf expansion is compromised, imposing a limitation to the interception of photosynthetic radiation and growth. These observations suggest that genetic variability at the locus encoding phyB could offer a breeding target to improve crop growth capacity in the field.

Yield performance of soybean cultivars with indeterminate growth habits in response to plant spatial arrangement / Desempenho produtivo de cultivares de soja de crescimento indeterminado em resposta a arranjos espaciais de plantas

Modifications in plant spatial arrangements, such as the use of narrow rows, twin rows, and crossed rows, may favor the development and productivity of soybeans due to the morphophysiological changes occurring in the plants. The aim of this research was to assess yield components, mortality rate, harvest index, and the yield, of two soybean cultivars, with indeterminate growth habits, in response to alternative plant spatial arrangements. The experiment was conducted in Londrina, Paraná State, Brazil, in the 2013/14 and 2014/15 growing seasons, with randomized complete block design, in a 4 × 3 × 2 factorial scheme, with three replications. The treatments were composed of four row spacings, at 0.2 m (narrow rows); 0.2/0.8 m (twin rows); 0.5 m (traditional); and 0.5 m (crossed rows); at three seeding rates (150, 300, and 450 thousand viable seeds ha-1) in two cultivars (BMX Potência RR and BRS 359 RR). In both growing seasons, there was a water deficit, and climatic conditions that would restrict soybean growth and development. The narrow rows, twin rows, and crossed rows did not favor yield performance compared to traditional spacing in either cultivar. The tested cultivars showed high phenotypic plasticity, allowing large changes in row spacing and seeding rate without major changes in the yield. The narrow rows, when associated with a high seeding rate, favored plant mortality. Grains per pod and harvest index were not influenced by the plant spatial arrangement.(AU)

Modificações no arranjo espacial de plantas, como o uso de espaçamento reduzido, de fileiras duplas e semeadura cruzada podem favorecer o crescimento e o rendimento de grãos da soja em virtude das alterações morfofisiológicas ocorridas nas plantas. O objetivo do trabalho foi avaliar os componentes de rendimento, a taxa de mortalidade, o índice de colheita e o rendimento de grãos de duas cultivares de soja com tipo de crescimento indeterminado em resposta a arranjos espaciais de plantas alternativos. O experiment foi conduzido em Londrina-PR, nas safras 2013/14 e 2014/15, sob o delineamento experimental de blocos completes casualizados, em esquema fatorial 4 x 3 x 2, com 3 repetições. Os tratamentos foram constituídos de quatro espaçamentos entre fileiras, sendo 0,2 m (reduzido); 0,2/0,8 m (fileirasduplas); 0,5 m (cruzado) e 0,5 m (tradicional); três densidades de semeadura (150, 300 e 450 mil sementes viáveis ha-1) e duas cultivares (BMX Potência RR e BRS 359 RR). Em ambas as safras houve deficit hídrico e condições climáticas restritivas ao crescimento e desenvolvimento da soja. Os arranjos em espaçamento reduzido, fileiras duplas e cruzado não favorecem o desempenho produtivo em relação ao espaçamento tradicional, para ambas as cultivares. As cultivares testadas apresentam alta plasticidade fenotípica, permitindo modificações no espaçamento e na densidade sem alterações expressivas no rendimento de grãos. O espaçamento reduzido, quando associado à alta densidade, aumenta a mortalidade de plantas. O número de grãos por vagem e o índice de colheita não são influenciados pelo arranjo espacial de plantas.(AU)

Yield performance of soybean cultivars with indeterminate growth habits in response to plant spatial arrangement / Desempenho produtivo de cultivares de soja de crescimento indeterminado em resposta a arranjos espaciais de plantas

Modifications in plant spatial arrangements, such as the use of narrow rows, twin rows, and crossed rows, may favor the development and productivity of soybeans due to the morphophysiological changes occurring in the plants. The aim of this research was to assess yield components, mortality rate, harvest index, and the yield, of two soybean cultivars, with indeterminate growth habits, in response to alternative plant spatial arrangements. The experiment was conducted in Londrina, Paraná State, Brazil, in the 2013/14 and 2014/15 growing seasons, with randomized complete block design, in a 4 × 3 × 2 factorial scheme, with three replications. The treatments were composed of four row spacings, at 0.2 m (narrow rows); 0.2/0.8 m (twin rows); 0.5 m (traditional); and 0.5 m (crossed rows); at three seeding rates (150, 300, and 450 thousand viable seeds ha-1) in two cultivars (BMX Potência RR and BRS 359 RR). In both growing seasons, there was a water deficit, and climatic conditions that would restrict soybean growth and development. The narrow rows, twin rows, and crossed rows did not favor yield performance compared to traditional spacing in either cultivar. The tested cultivars showed high phenotypic plasticity, allowing large changes in row spacing and seeding rate without major changes in the yield. The narrow rows, when associated with a high seeding rate, favored plant mortality. Grains per pod and harvest index were not influenced by the plant spatial arrangement.

Modificações no arranjo espacial de plantas, como o uso de espaçamento reduzido, de fileiras duplas e semeadura cruzada podem favorecer o crescimento e o rendimento de grãos da soja em virtude das alterações morfofisiológicas ocorridas nas plantas. O objetivo do trabalho foi avaliar os componentes de rendimento, a taxa de mortalidade, o índice de colheita e o rendimento de grãos de duas cultivares de soja com tipo de crescimento indeterminado em resposta a arranjos espaciais de plantas alternativos. O experiment foi conduzido em Londrina-PR, nas safras 2013/14 e 2014/15, sob o delineamento experimental de blocos completes casualizados, em esquema fatorial 4 x 3 x 2, com 3 repetições. Os tratamentos foram constituídos de quatro espaçamentos entre fileiras, sendo 0,2 m (reduzido); 0,2/0,8 m (fileirasduplas); 0,5 m (cruzado) e 0,5 m (tradicional); três densidades de semeadura (150, 300 e 450 mil sementes viáveis ha-1) e duas cultivares (BMX Potência RR e BRS 359 RR). Em ambas as safras houve deficit hídrico e condições climáticas restritivas ao crescimento e desenvolvimento da soja. Os arranjos em espaçamento reduzido, fileiras duplas e cruzado não favorecem o desempenho produtivo em relação ao espaçamento tradicional, para ambas as cultivares. As cultivares testadas apresentam alta plasticidade fenotípica, permitindo modificações no espaçamento e na densidade sem alterações expressivas no rendimento de grãos. O espaçamento reduzido, quando associado à alta densidade, aumenta a mortalidade de plantas. O número de grãos por vagem e o índice de colheita não são influenciados pelo arranjo espacial de plantas.

Sprout density for the production of organic mini-cabbage from mother plant regrowth / Densidade de brotos para a produção de mini-repolho orgânico do rebrota da planta mãe

The method of producing organic mini-cabbages from regrowth of mother-plant was initiated at the Unidade de Referência em Agroecologia of the Incaper in 2013, possibly acting as an efficient alternative for the obtainment of cabbages with a more adequate average weight for the desires of the modern consumer. The aim of this study was to define sprout density in the mother plant, which allows better productivity and commercial standards for organic mini-cabbages. The experiment was developed during the period from September to November 2015, using the F1 Shinsei hybrid, in a design with randomized blocks, with five replications. Sprout density was determined following thinning, constituting the following treatments: two, three, four, five and six sprouts per plant. Best management of sprouts was the technique with four sprouts per plant, since it allowed greater productivity (52,997kg ha-1) and a greater number of commercial heads, together with a commercial standard of heads with average weight (414g) and median diameter (8.8cm) adequate for the standards demanded by the consumer.(AU)

A técnica de produção de mini-repolhos orgânicos por rebrota da planta-mãe foi iniciada na Unidade de Referência em Agroecologia do Incaper, no ano de 2013, podendo ser uma alternativa eficiente para obtenção de repolhos com peso médio mais apropriado ao desejo do consumidor moderno. O objetivo deste trabalho foi definir a densidade de brotos da planta-mãe, que permita melhor produtividade e padrão comercial de mini-repolhos orgânicos. O experimento foi desenvolvido no período de setembro a novembro de 2015, utilizando-se o híbrido F1 Shinsei, no delineamento de blocos casualizados, com cinco repetições. As densidades de brotos foram estabelecidas após desbastes, constituindo os seguintes tratamentos: dois, três, quatro, cinco e seis brotos por planta. O melhor manejo de rebrotas foi a condução com quatro brotos por planta, pois permitiu maior produtividade (52.997kg ha-1) e maior número de cabeças comerciais, aliados a um padrão comercial de cabeças com peso médio (414g) e diâmetro médio (8,8cm) adequados aos padrões exigidos pelo consumidor.(AU)

Partial correlation analysis in the study of morphogenesis and herbage accumulation in Panicum maximum cv. Tanzânia / Análise de correlação parcial no estudo da morfogênese e do acúmulo de forragem de Panicum maximum cv. ‘Tanzânia

The objective of this study was to evaluate, through partial correlation analysis, the degree of association between herbage accumulation and morphogenetic traits of Tanzania grass (Panicum maximum Jacq.) defoliated with 95% of light interception and fertilized with nitrogen, under different planting densities. The experiment was carried out in a randomized complete design with 12 treatments and two replicates, in a 4 × 3 factorial arrangement consisting of four nitrogen rates (0, 80, 160, and 320kg ha-1 Yr-1) and three planting densities (9, 25, and 49 plants m-2). Harvests were performed at 25cm above the soil, when the plots intercepted 95% of the incident light. The simple correlation coefficients between herbage accumulation and leaf and stem elongation rates and leaf appearance rate were high and positive. Correlation between herbage accumulation and leaf lifespan; however, was high and negative. The study of partial correlation coefficients revealed considerable changes in the correlation structure, whereby the association with stem elongation had a negative value statistically equal to zero, indicating no relationship between these variables. A similar result was observed for the correlations between herbage accumulation and leaf appearance and leaf lifespan. The partial correlation between accumulation and leaf elongation was different from zero and positive indicating a strong association. In Guinea grass cv. Tanzania canopies defoliated at 95% light interception, leaf elongation is the morphogenetic variable with the highest strength of association with herbage accumulation.(AU)

Objetivou-se avaliar, por meio de correlação parcial, o grau de associação entre o acúmulo de forragem e as características morfogênicas do capim-tanzânia (Panicum maximum Jacq.) desfolhado com 95% de interceptação luminosa e adubado com nitrogênio em diferentes densidades de planta. O delineamento foi em blocos completos casualizados, com 12 tratamentos e duas repetições em esquema fatorial 4 × 3, constituído por 4 doses de nitrogênio (0, 80, 160 e 320kg ha-1 ano-1) e três densidades de plantas (9, 25 e 49 plantas m-2). As colheitas foram realizadas a 25cm do nível do solo quando as parcelas interceptavam 95% da luz incidente. Os coeficientes de correlação simples foram altos e positivos, entre o acúmulo de forragem e as taxas de alongamento de folha e de colmo e aparecimento de folha. Já a associação do acúmulo com a duração da vida das folhas foi alta e negativa. O estudo dos coeficientes de correlação parcial implicou em mudanças consideráveis na estrutura da correlação, onde a associação com o alongamento de colmos assumiu valor negativo e estatisticamente igual a zero, indicando não haver relação de causa e efeito entre estas variáveis. Resultado semelhante foi observado para a associação entre o acúmulo de forragem e o aparecimento de folhas e a duração da vida da folha. á a correlação parcial entre o acúmulo e o alongamento de folhas foi diferente de zero e positiva. Nesse contexto, em dosséis forrageiros de capim-tanzânia desfolhados com 95% de interceptação de luz, a taxa de alongamento foliar é a variável morfogênica que apresenta maior grau de associação com o acúmulo de forragem.(AU)

Plant-plant interactions influence developmental phase transitions, grain productivity and root system architecture in Arabidopsis via auxin and PFT1/MED25 signalling.

Transcriptional regulation of gene expression influences plant growth, environmental interactions and plant-plant communication. Here, we report that population density is a key factor for plant productivity and a major root architectural determinant in Arabidopsis thaliana. When grown in soil at varied densities from 1 to 32 plants, high number of individuals decreased stem growth and accelerated senescence, which negatively correlated with total plant biomass and seed production at the completion of the life cycle. Root morphogenesis was also a major trait modulated by plant density, because an increasing number of individuals grown in vitro showed repression of primary root growth, lateral root formation and root hair development while affecting auxin-regulated gene expression and the levels of auxin transporters PIN1 and PIN2. We also found that mutation of the Mediator complex subunit PFT1/MED25 renders plants insensitive to high density-modulated root traits. Our results suggest that plant density is critical for phase transitions, productivity and root system architecture and reveal a role of Mediator in self-plant recognition.

Size, physiological quality, and green seed occurrence influenced by seeding rate in soybeans / Tamanho, qualidade fisiológica e ocorrência de sementes verdes de soja influenciados pela densidade de semeadura

The seeding rate influences the intraspecific competition, which might affect the development and quality of seeds in soybean. However, the impact of seeding rate on the physical and physiological qualities of soybean seeds needs to be better elucidated. This study aimed to evaluate the effects of soybean plant density on the seed size as well as the effects of the interaction between the plant density and seed size on the seed mass, green seed occurence, and physiological seed quality. The experiments were carried out in the growing seasons of the years 2013/14 and 2014/15 in a Latossolo Vermelho distroférrico, under a randomized complete block design, using the NK 7059 RR cultivar with six replications. Four plant densities (150, 300, 440, and 560 thousand viable seeds ha–1) were evaluated. After the classification of seeds into four sizes, using a set of sieves, a 4 ×4 factorial scheme was used for the statistical analysis of the four plant densities and four seed sizes. The seed samples were evaluated for the seed mass, green seed percentage, germination, and vigor. Under thermal and water stress during seed development, an increase in the seeding rate led to a reduction in the green seed occurrence and an increase in the seed size and mass. However, in the absence of thermal and water stress, the seed size and mass were not altered by the seeding rate and, there was no occurrence of green seeds.(AU)

A densidade de semeadura, por influenciar na competição intraespecífica, pode afetar o desenvolvimento e a qualidade das sementes de soja produzidas. Entretanto, o impacto da densidade de semeadura sobre a qualidade física e fisiológica das sementes de soja precisa ser melhor elucidado. Objetivou-se avaliar os efeitos da densidade de semeadura sobre o tamanho das sementes produzidas e a interação entre a densidade de semeadura e o tamanho das sementes sobre a massa, a ocorrência de sementes verdes e a qualidade fisiológica das mesmas. O experimento foi conduzido nas safras 2013/14 e 2014/15, em um Latossolo Vermelho distroférrico, sob o delineamento de blocos casualizados, utilizando-se a cultivar NK7059 RR, com seis repetições. Os tratamentos consistiram de quatro densidades de semeadura (150, 300, 440 e 560 mil sementes viáveis ha-1). Após a classificação em peneiras das sementes produzidas, adotou-se o esquema fatorial 4 x 4, com 4 densidades e 4 tamanhos de sementes. Avaliaram-se a massa de mil sementes, porcentagem de sementes verdes, germinação e vigor. O aumento na densidade de semeadura reduz a porcentagem de sementes verdes e incrementa o tamanho e a massa de sementes, em condições de estresse térmico e hídrico durante a fase de formação das mesmas. O tamanho e massa de sementes não são alterados pela densidade de semeadura na ausência de estresse térmico e hídrico e, nesses casos, não há ocorrência de sementes verdes de soja.(AU)

Ecological and evolutionary consequences of tri-trophic interactions: Spatial variation and effects of plant density.

PREMISE OF STUDY: The factors driving variation in species interactions are often unknown, and few studies have made a link between changes in interactions and the strength of selection. METHODS: We report on spatial variation in functional responses by a seed predator (SP) and its parasitic wasps associated with the herb Ruellia nudiflora. We assessed the influence of plant density on consumer responses and determined whether density effects and spatial variation in functional responses altered natural selection by these consumers on the plant. We established common gardens at two sites in Yucatan, Mexico, and planted R. nudiflora at two densities in each garden. We recorded fruit output and SP and parasitoid attack; calculated relative fitness (seed number) under scenarios of three trophic levels (accounting for SP and parasitoid effects), two trophic levels (accounting for SP but not parasitoid effects), and one trophic level (no consumer effects); and compared selection strength on fruit number under these scenarios across sites and densities. KEY RESULTS: There was spatial variation in SP recruitment, whereby the SP functional response was negatively density-dependent at one site but density-independent at the other; parasitoid responses were density-independent and invariant across sites. Site variation in SP attack led, in turn, to differences in SP selection on fruit output, and parasitoids did not alter SP selection. There were no significant effects of density at either site. CONCLUSIONS: Our results provide a link between consumer functional responses and consumer selection on plants, which deepens our understanding of geographic variation in the evolutionary outcomes of multitrophic interactions.

Sprout density for the production of organic mini-cabbage from mother plant regrowth / Densidade de brotos para a produção de mini-repolho orgânico do rebrota da planta mãe

ABSTRACT: The method of producing organic mini-cabbages from regrowth of mother-plant was initiated at the Unidade de Referência em Agroecologia of the Incaper in 2013, possibly acting as an efficient alternative for the obtainment of cabbages with a more adequate average weight for the desires of the modern consumer. The aim of this study was to define sprout density in the mother plant, which allows better productivity and commercial standards for organic mini-cabbages. The experiment was developed during the period from September to November 2015, using the F1 Shinsei hybrid, in a design with randomized blocks, with five replications. Sprout density was determined following thinning, constituting the following treatments: two, three, four, five and six sprouts per plant. Best management of sprouts was the technique with four sprouts per plant, since it allowed greater productivity (52,997kg ha-1) and a greater number of commercial heads, together with a commercial standard of heads with average weight (414g) and median diameter (8.8cm) adequate for the standards demanded by the consumer.

RESUMO: A técnica de produção de mini-repolhos orgânicos por rebrota da planta-mãe foi iniciada na Unidade de Referência em Agroecologia do Incaper, no ano de 2013, podendo ser uma alternativa eficiente para obtenção de repolhos com peso médio mais apropriado ao desejo do consumidor moderno. O objetivo deste trabalho foi definir a densidade de brotos da planta-mãe, que permita melhor produtividade e padrão comercial de mini-repolhos orgânicos. O experimento foi desenvolvido no período de setembro a novembro de 2015, utilizando-se o híbrido F1 Shinsei, no delineamento de blocos casualizados, com cinco repetições. As densidades de brotos foram estabelecidas após desbastes, constituindo os seguintes tratamentos: dois, três, quatro, cinco e seis brotos por planta. O melhor manejo de rebrotas foi a condução com quatro brotos por planta, pois permitiu maior produtividade (52.997kg ha-1) e maior número de cabeças comerciais, aliados a um padrão comercial de cabeças com peso médio (414g) e diâmetro médio (8,8cm) adequados aos padrões exigidos pelo consumidor.

Partial correlation analysis in the study of morphogenesis and herbage accumulation in Panicum maximum cv. 'Tanzânia' / Análise de correlação parcial no estudo da morfogênese e do acúmulo de forragem de Panicum maximum cv. 'Tanzânia'

ABSTRACT: The objective of this study was to evaluate, through partial correlation analysis, the degree of association between herbage accumulation and morphogenetic traits of 'Tanzania' grass (Panicum maximum Jacq.) defoliated with 95% of light interception and fertilized with nitrogen, under different planting densities. The experiment was carried out in a randomized complete design with 12 treatments and two replicates, in a 4 × 3 factorial arrangement consisting of four nitrogen rates (0, 80, 160, and 320kg ha-1 Yr-1) and three planting densities (9, 25, and 49 plants m-2). Harvests were performed at 25cm above the soil, when the plots intercepted 95% of the incident light. The simple correlation coefficients between herbage accumulation and leaf and stem elongation rates and leaf appearance rate were high and positive. Correlation between herbage accumulation and leaf lifespan; however, was high and negative. The study of partial correlation coefficients revealed considerable changes in the correlation structure, whereby the association with stem elongation had a negative value statistically equal to zero, indicating no relationship between these variables. A similar result was observed for the correlations between herbage accumulation and leaf appearance and leaf lifespan. The partial correlation between accumulation and leaf elongation was different from zero and positive indicating a strong association. In Guinea grass cv. 'Tanzania' canopies defoliated at 95% light interception, leaf elongation is the morphogenetic variable with the highest strength of association with herbage accumulation.

RESUMO: Objetivou-se avaliar, por meio de correlação parcial, o grau de associação entre o acúmulo de forragem e as características morfogênicas do capim-tanzânia (Panicum maximum Jacq.) desfolhado com 95% de interceptação luminosa e adubado com nitrogênio em diferentes densidades de planta. O delineamento foi em blocos completos casualizados, com 12 tratamentos e duas repetições em esquema fatorial 4 × 3, constituído por 4 doses de nitrogênio (0, 80, 160 e 320kg ha-1 ano-1) e três densidades de plantas (9, 25 e 49 plantas m-2). As colheitas foram realizadas a 25cm do nível do solo quando as parcelas interceptavam 95% da luz incidente. Os coeficientes de correlação simples foram altos e positivos, entre o acúmulo de forragem e as taxas de alongamento de folha e de colmo e aparecimento de folha. Já a associação do acúmulo com a duração da vida das folhas foi alta e negativa. O estudo dos coeficientes de correlação parcial implicou em mudanças consideráveis na estrutura da correlação, onde a associação com o alongamento de colmos assumiu valor negativo e estatisticamente igual a zero, indicando não haver relação de causa e efeito entre estas variáveis. Resultado semelhante foi observado para a associação entre o acúmulo de forragem e o aparecimento de folhas e a duração da vida da folha. á a correlação parcial entre o acúmulo e o alongamento de folhas foi diferente de zero e positiva. Nesse contexto, em dosséis forrageiros de capim-tanzânia desfolhados com 95% de interceptação de luz, a taxa de alongamento foliar é a variável morfogênica que apresenta maior grau de associação com o acúmulo de forragem.

Size, physiological quality, and green seed occurrence influenced by seeding rate in soybeans / Tamanho, qualidade fisiológica e ocorrência de sementes verdes de soja influenciados pela densidade de semeadura

The seeding rate influences the intraspecific competition, which might affect the development and quality of seeds in soybean. However, the impact of seeding rate on the physical and physiological qualities of soybean seeds needs to be better elucidated. This study aimed to evaluate the effects of soybean plant density on the seed size as well as the effects of the interaction between the plant density and seed size on the seed mass, green seed occurence, and physiological seed quality. The experiments were carried out in the growing seasons of the years 2013/14 and 2014/15 in a Latossolo Vermelho distroférrico, under a randomized complete block design, using the NK 7059 RR cultivar with six replications. Four plant densities (150, 300, 440, and 560 thousand viable seeds ha–1) were evaluated. After the classification of seeds into four sizes, using a set of sieves, a 4 ×4 factorial scheme was used for the statistical analysis of the four plant densities and four seed sizes. The seed samples were evaluated for the seed mass, green seed percentage, germination, and vigor. Under thermal and water stress during seed development, an increase in the seeding rate led to a reduction in the green seed occurrence and an increase in the seed size and mass. However, in the absence of thermal and water stress, the seed size and mass were not altered by the seeding rate and, there was no occurrence of green seeds.

A densidade de semeadura, por influenciar na competição intraespecífica, pode afetar o desenvolvimento e a qualidade das sementes de soja produzidas. Entretanto, o impacto da densidade de semeadura sobre a qualidade física e fisiológica das sementes de soja precisa ser melhor elucidado. Objetivou-se avaliar os efeitos da densidade de semeadura sobre o tamanho das sementes produzidas e a interação entre a densidade de semeadura e o tamanho das sementes sobre a massa, a ocorrência de sementes verdes e a qualidade fisiológica das mesmas. O experimento foi conduzido nas safras 2013/14 e 2014/15, em um Latossolo Vermelho distroférrico, sob o delineamento de blocos casualizados, utilizando-se a cultivar NK7059 RR, com seis repetições. Os tratamentos consistiram de quatro densidades de semeadura (150, 300, 440 e 560 mil sementes viáveis ha-1). Após a classificação em peneiras das sementes produzidas, adotou-se o esquema fatorial 4 x 4, com 4 densidades e 4 tamanhos de sementes. Avaliaram-se a massa de mil sementes, porcentagem de sementes verdes, germinação e vigor. O aumento na densidade de semeadura reduz a porcentagem de sementes verdes e incrementa o tamanho e a massa de sementes, em condições de estresse térmico e hídrico durante a fase de formação das mesmas. O tamanho e massa de sementes não são alterados pela densidade de semeadura na ausência de estresse térmico e hídrico e, nesses casos, não há ocorrência de sementes verdes de soja.

Partial correlation analysis in the study of morphogenesis and herbage accumulation in Panicum maximum cv. Tanzânia / Análise de correlação parcial no estudo da morfogênese e do acúmulo de forragem de Panicum maximum cv. ‘Tanzânia’

The objective of this study was to evaluate, through partial correlation analysis, the degree of association between herbage accumulation and morphogenetic traits of Tanzania grass (Panicum maximum Jacq.) defoliated with 95% of light interception and fertilized with nitrogen, under different planting densities. The experiment was carried out in a randomized complete design with 12 treatments and two replicates, in a 4 × 3 factorial arrangement consisting of four nitrogen rates (0, 80, 160, and 320kg ha-1 Yr-1) and three planting densities (9, 25, and 49 plants m-2). Harvests were performed at 25cm above the soil, when the plots intercepted 95% of the incident light. The simple correlation coefficients between herbage accumulation and leaf and stem elongation rates and leaf appearance rate were high and positive. Correlation between herbage accumulation and leaf lifespan; however, was high and negative. The study of partial correlation coefficients revealed considerable changes in the correlation structure, whereby the association with stem elongation had a negative value statistically equal to zero, indicating no relationship between these variables. A similar result was observed for the correlations between herbage accumulation and leaf appearance and leaf lifespan. The partial correlation between accumulation and leaf elongation was different from zero and positive indicating a strong association. In Guinea grass cv. Tanzania canopies defoliated at 95% light interception, leaf elongation is the morphogenetic variable with the highest strength of association with herbage accumulation.

Objetivou-se avaliar, por meio de correlação parcial, o grau de associação entre o acúmulo de forragem e as características morfogênicas do capim-tanzânia (Panicum maximum Jacq.) desfolhado com 95% de interceptação luminosa e adubado com nitrogênio em diferentes densidades de planta. O delineamento foi em blocos completos casualizados, com 12 tratamentos e duas repetições em esquema fatorial 4 × 3, constituído por 4 doses de nitrogênio (0, 80, 160 e 320kg ha-1 ano-1) e três densidades de plantas (9, 25 e 49 plantas m-2). As colheitas foram realizadas a 25cm do nível do solo quando as parcelas interceptavam 95% da luz incidente. Os coeficientes de correlação simples foram altos e positivos, entre o acúmulo de forragem e as taxas de alongamento de folha e de colmo e aparecimento de folha. Já a associação do acúmulo com a duração da vida das folhas foi alta e negativa. O estudo dos coeficientes de correlação parcial implicou em mudanças consideráveis na estrutura da correlação, onde a associação com o alongamento de colmos assumiu valor negativo e estatisticamente igual a zero, indicando não haver relação de causa e efeito entre estas variáveis. Resultado semelhante foi observado para a associação entre o acúmulo de forragem e o aparecimento de folhas e a duração da vida da folha. á a correlação parcial entre o acúmulo e o alongamento de folhas foi diferente de zero e positiva. Nesse contexto, em dosséis forrageiros de capim-tanzânia desfolhados com 95% de interceptação de luz, a taxa de alongamento foliar é a variável morfogênica que apresenta maior grau de associação com o acúmulo de forragem.

Sprout density for the production of organic mini-cabbage from mother plant regrowth / Densidade de brotos para a produção de mini-repolho orgânico do rebrota da planta mãe

The method of producing organic mini-cabbages from regrowth of mother-plant was initiated at the Unidade de Referência em Agroecologia of the Incaper in 2013, possibly acting as an efficient alternative for the obtainment of cabbages with a more adequate average weight for the desires of the modern consumer. The aim of this study was to define sprout density in the mother plant, which allows better productivity and commercial standards for organic mini-cabbages. The experiment was developed during the period from September to November 2015, using the F1 Shinsei hybrid, in a design with randomized blocks, with five replications. Sprout density was determined following thinning, constituting the following treatments: two, three, four, five and six sprouts per plant. Best management of sprouts was the technique with four sprouts per plant, since it allowed greater productivity (52,997kg ha-1) and a greater number of commercial heads, together with a commercial standard of heads with average weight (414g) and median diameter (8.8cm) adequate for the standards demanded by the consumer.

A técnica de produção de mini-repolhos orgânicos por rebrota da planta-mãe foi iniciada na Unidade de Referência em Agroecologia do Incaper, no ano de 2013, podendo ser uma alternativa eficiente para obtenção de repolhos com peso médio mais apropriado ao desejo do consumidor moderno. O objetivo deste trabalho foi definir a densidade de brotos da planta-mãe, que permita melhor produtividade e padrão comercial de mini-repolhos orgânicos. O experimento foi desenvolvido no período de setembro a novembro de 2015, utilizando-se o híbrido F1 Shinsei, no delineamento de blocos casualizados, com cinco repetições. As densidades de brotos foram estabelecidas após desbastes, constituindo os seguintes tratamentos: dois, três, quatro, cinco e seis brotos por planta. O melhor manejo de rebrotas foi a condução com quatro brotos por planta, pois permitiu maior produtividade (52.997kg ha-1) e maior número de cabeças comerciais, aliados a um padrão comercial de cabeças com peso médio (414g) e diâmetro médio (8,8cm) adequados aos padrões exigidos pelo consumidor.

Semeadura cruzada em cultivares de soja com tipo de crescimento determinado / Sowing in crossed rows in soybean cultivars with determinate growth habit

Alterações no arranjo espacial de plantas podem aumentar a produtividade de grãos de soja sem aumentos expressivos no custo de produção. A técnica denominada semeadura cruzada vem despertando interesse no setor produtivo por ter sido utilizada por alguns recordistas de produtividade de soja no Brasil. O objetivo desse trabalho foi avaliar o desempenho agronômico de cultivares de soja com tipo de crescimento determinado, em diferentes arranjos de plantas. Os experimentos foram conduzidos em Londrina, PR, nas safras 2011/12 e 2012/13, sob o delineamento de blocos completos ao acaso, em esquema fatorial 2x2x2, com três repetições. Os tratamentos foram formados pela combinação de dois espaçamentos entre fileiras (0,4 e 0,6 m), duas densidades de semeadura (375.000 e 562.500 sementes ha-1) e de dois sistemas de semeadura (semeadura cruzada e não cruzada). Na safra 2010/11, utilizou-se a cultivar BRS 294 RR e na safra 2011/12 a cultivar BRS 295 RR. Nas duas safras, a produtividade de grãos não foi influenciada pelo sistema de semeadura, pela densidade de plantas e pela interação entre esses fatores, o que demonstra a alta plasticidade fenotípica das cultivares utilizadas. Para a cultivar BRS 294 RR, o espaçamento de 0,6 m entre fileiras conferiu maior produtividade de grãos em relação ao espaçamento de 0,4 m, principalmente porque proporcionou aumento da produção de grãos oriunda dos ramos.(AU)

Increases in the soybean grain yield without significant alterations in the production cost can be achieved with variations in the spatial plant arrangement. The sowing in crossed rows has aroused the interest of Brazilian soybean producers once this practice was used in some areas with record-breaking soybean yield in Brazil in 2010/11 and 2011/12 growing seasons. This study aimed to evaluate the agronomic performance of soybean cultivars with determinate growth habit managed under different spatial plant arrangements, including crossed rows. The experiments were carried out in Londrina, PR, at 2011/12 and 2012/13 growing seasons. A randomized complete block experimental design in a 2x2x2 factorial scheme was used, with three replications. The treatments were formed by combining two row spacing (0.4 and 0.6 m), two seeding rates (375,000 and 562,500 seeds ha-1) and two sowing systems (crossed or parallel rows).The cultivar BRS 294 RR was used in 2011/12 and BRS 295 RR in 2012/13 growing season. In both cultivars and years the grain yield was not affected by the sowing system, seeding rate, or by the interactions among factors, showing the high soybean phenotypic plasticity. Row spacing of 0.6 m showed the highest soybean grain yield in BRS 294 RR, mainly due to a higher grain production in the branches.(AU)

Semeadura cruzada em cultivares de soja com tipo de crescimento determinado / Sowing in crossed rows in soybean cultivars with determinate growth habit

Alterações no arranjo espacial de plantas podem aumentar a produtividade de grãos de soja sem aumentos expressivos no custo de produção. A técnica denominada semeadura cruzada vem despertando interesse no setor produtivo por ter sido utilizada por alguns recordistas de produtividade de soja no Brasil. O objetivo desse trabalho foi avaliar o desempenho agronômico de cultivares de soja com tipo de crescimento determinado, em diferentes arranjos de plantas. Os experimentos foram conduzidos em Londrina, PR, nas safras 2011/12 e 2012/13, sob o delineamento de blocos completos ao acaso, em esquema fatorial 2x2x2, com três repetições. Os tratamentos foram formados pela combinação de dois espaçamentos entre fileiras (0,4 e 0,6 m), duas densidades de semeadura (375.000 e 562.500 sementes ha-1) e de dois sistemas de semeadura (semeadura cruzada e não cruzada). Na safra 2010/11, utilizou-se a cultivar BRS 294 RR e na safra 2011/12 a cultivar BRS 295 RR. Nas duas safras, a produtividade de grãos não foi influenciada pelo sistema de semeadura, pela densidade de plantas e pela interação entre esses fatores, o que demonstra a alta plasticidade fenotípica das cultivares utilizadas. Para a cultivar BRS 294 RR, o espaçamento de 0,6 m entre fileiras conferiu maior produtividade de grãos em relação ao espaçamento de 0,4 m, principalmente porque proporcionou aumento da produção de grãos oriunda dos ramos.

Increases in the soybean grain yield without significant alterations in the production cost can be achieved with variations in the spatial plant arrangement. The sowing in crossed rows has aroused the interest of Brazilian soybean producers once this practice was used in some areas with record-breaking soybean yield in Brazil in 2010/11 and 2011/12 growing seasons. This study aimed to evaluate the agronomic performance of soybean cultivars with determinate growth habit managed under different spatial plant arrangements, including crossed rows. The experiments were carried out in Londrina, PR, at 2011/12 and 2012/13 growing seasons. A randomized complete block experimental design in a 2x2x2 factorial scheme was used, with three replications. The treatments were formed by combining two row spacing (0.4 and 0.6 m), two seeding rates (375,000 and 562,500 seeds ha-1) and two sowing systems (crossed or parallel rows).The cultivar BRS 294 RR was used in 2011/12 and BRS 295 RR in 2012/13 growing season. In both cultivars and years the grain yield was not affected by the sowing system, seeding rate, or by the interactions among factors, showing the high soybean phenotypic plasticity. Row spacing of 0.6 m showed the highest soybean grain yield in BRS 294 RR, mainly due to a higher grain production in the branches.