Seed inoculation with Azospirillum brasilense in corn plants submitted to water limitation

The objective of this work was to evaluate the seed inoculation with Azospirilum brasilense in corn plants under limitation of the water supply. Two assays were carried out in greenhouse conditions, using low nitrogen substrate pots. At first one, corn seeds were inoculated or not with A. brasilense and treated or not with a biostimulant (IBA+GA+KT). At the second experiment, two corn genotypes were inoculated or not with A. brasilense. In both assays, plants were submitted to limited condition of water supply at initial vegetative growth. During this period gas exchange parameters were determined at the plants. After stress period, dry matter and nitrogen content were determined in roots and above ground parts of the plants. In addition, substrate nitrogen content was determined. It was observed effects of water restriction supply for gas exchange parameters and dry matter accumulation. Corn seed inoculation with A. brasilense did not affect plant responses to water limitation; neither improves the nitrogen content on substrate or plants.The objective of this work was to evaluate the seed inoculation with Azospirilum brasilense in corn plants under limitation of the water supply. Two assays were carried out in greenhouse conditions, using low nitrogen substrate pots. To the first assay, corn seeds were inoculated or not with A. brasilense and treated or not with a biostimulant (IBA + KT + GA). At the second assay, two corn genotypes were inoculated or not with A. brasilense. In both assays, plants were submitted to limited condition of water supply at initial vegetative growth. During this period, gas exchange parameters were determined at the plants. After stress period, dry matter and nitrogen content were determined in roots and above ground parts of the plants. In addition, substrate nitrogen content was determined. It was observed effects of water restriction supply for gas exchange parameters and dry matter accumulation. Corn seed inoculation with A. brasilense did not affect plant responses to water limitation; neither improves the nitrogen content on substrate or plants

Consumo de água e eficiência produtiva de plantas de trigo tratadas com Etil-trinexapac

Efficient use of the resources of the growing environment, which is affected by plant traits, is very important for crop adaptation on production system. This work aimed to study the water consumption and yield efficiency of wheat plants treated with Trinexapac-ethyl. Two experiments were carried out, in greenhouse conditions, between 2014 and 2015. Experiments were arranged in randomized blocks design in a factorial 2x3, with four replicates. Two wheat cultivars were sprayed with three Trinexapac-ethyl doses (0, 125 and 188 g a.i. ha-1), at main culm elongation stage. The water consumption, plant height, source-sink distance and the morphological parameters of the flag leaf were evaluated. At the end of the growing cycle, yield and yield components were determined, as well as harvest index. Trinexapac-ethyl reduced plant growth, without affecting grain production. Plant growth regulator application does not reduce either water consumption or wheat crop harvest index.O uso eficiente de recursos do ambiente de cultivo, o qual é influenciado por características da planta, é de grande importância para a adaptação de culturas em sistemas de produção. O presente trabalho teve como objetivo estudar o consumo de água e a eficiência produtiva de plantas de trigo tratadas com Etil-trinexapac. Foram conduzidos dois experimentos, em cultivo protegido, entre 2014 e 2015. Utilizou-se o delineamento experimental de blocos casualizados, em esquema fatorial 2x3, com quatro repetições. Dois cultivares de trigo, foram submetidos à aplicação de três doses de Etil-trinexapac (0, 125 e 188 g ha-1 de i.a.) na fase de alongamento do colmo principal. Foram avaliados: consumo de água, altura da planta e distância fonte e dreno, e os parâmetros morfológicos da folha bandeira. Ao final do ciclo da cultura, foram avaliados componentes de produção, produção de grãos e índice de colheita da cultura. A aplicação de Etil-trinexapac reduziu o crescimento de plantas de trigo, sem afetar a produção de grãos. A aplicação do regulador não reduz o consumo de água, tampouco o índice de colheita da cultura do trigo

Componentes produtivos do trigo em função da temperatura no período de diferenciação de espiguetas

A limiting factor for wheat crop expansion or off-season crop in the Brazilian Cerrado is the occurrence of elevated temperatures during cropping cycle. This study aimed to evaluate the effects of temperature during the spikelet differentiation stage on biometric and productive parameters of wheat cultivars. A greenhouse experiment was carried out under a randomized blocks design, organized in a 2 x 4 factorial scheme, with four replicates. Two day/night thermo periods (16/9 ˚C and 25/16 ˚C) were applied in four wheat cultivars (BRS 394, BRS 331, BRS Parrudo and BRS Guamirim) during the spikelet differentiation stage. Yield components were determined for individual tillers and for the whole plant. Both thermo periods do not affect yield components of wheat, either morphological and productive uniformity of tillers, which show large variation among wheat cultivars.Um fator limitante para a expansão tritícola no Cerrado brasileiro ou para o cultivo em safrinha é a ocorrência de altas temperaturas no decorrer do ciclo da cultura. O presente trabalho teve como objetivo avaliar o efeito da temperatura durante o estádio de diferenciação de espiguetas sobre parâmetros biométricos e componentes produtivos de cultivares de trigo. O experimento foi conduzido em cultivo protegido com delineamento experimental de blocos casualizados, em esquema fatorial 2 x 4, com quatro repetições. Dois regimes de temperatura diurna e noturna (16/9 ˚C e 25/16 ˚C) foram utilizados em quatro cultivares de trigo (BRS 394, BRS 331, BRS Parrudo e BRS Guamirim) durante o período de diferenciação das espiguetas. Os componentes de produção foram avaliados em perfilhos individuais e na planta inteira. Os regimes de temperatura testados não afetam os componentes de rendimento da cultura, tampouco a uniformidade morfológica e produtiva dos perfilhos, parâmetros que apresentaram grande variação entre as cultivares testadas

Épocas e densidades de semeadura sobre o desempenho agronômico do arroz irrigado no sistema pré-germinado

In recent years, paddy rice growers from the south of Santa Catarina, Brazil, have anticipated the sowing date to the beginning of September, aiming to harvest the crop ratoon. In addition to that, they have increased the sowing density to mitigate the smaller plant growth. The objective of this work was to analyze the effects of sowing time and density on the agronomic performance of pregerminated rice. The experiment was set in the city of Praia Grande, SC, Brazil, during the 2018/2019 growing season.  A randomized block design was used, with treatments arranged in split plots. Three sowing dates were tested in the main plots: September 10 (early sowing), October 15 (preferential sowing), and November 20 (late sowing). Four sowing densities were evaluated in the split plots: 80 kg, 120 kg, 160 kg, and 200 kg of seeds per hectare. Morphological characteristics and the yield and components of grains were assessed. Grain yield ranged from 6,277 kg ha-1 to 9,605 kg ha-1 and was affected by the interaction between sowing date and density. The highest yield was achieved when rice was sowed on October 15 at the density of 120 kg ha-1. On the earliest sowing date, grain yield increased linearly by 12.54 kg ha-1 for each kg of added seed above the lowest density evaluated in the trial. The highest grain productivity achieved on this sowing date was 7,858 kg ha-1. Plant density had a small impact on rice yield at the latest sowing date. The highest yield at this planting time (8,546 kg ha-1) was gathered at the density of 120 kg ha-1.  The optimum seed density to maximize pregerminated rice yield in the south of Santa Catarina depends on the sowing date and is higher when the crop is sowed early.Nos últimos anos, os produtores de arroz irrigado do Litoral Sul de Santa Catarina têm antecipado a semeadura da cultura para o início do mês de setembro, visando viabilizar o cultivo do rebrote. Paralelamente a isto, eles têm aumentado a densidade de semeadura para compensar o menor crescimento da cultura. Este trabalho foi conduzido com o objetivo de analisar os efeitos da época e densidade de semeadura sobre o desempenho agronômico do arroz no sistema pré-germinado. O experimento foi implantado no município de Praia Grande, SC, na safra 2018/2019. O trabalho foi conduzido no delineamento experimental de blocos ao acaso, arranjados em parcelas subdivididas. Na parcela principal testaram-se três épocas de semeadura: 10/09 (semeadura antecipada), 15/10 (semeadura preferencial) e 20/11 (semeadura tardia). Nas subparcelas avaliaram-se quatro densidades de semeadura: 80, 120, 160 e 200 kg de sementes ha-1. Foram avaliados caracteres morfológicos, o rendimento de grãos e seus componentes. O rendimento de grãos variou de 6.277 a 9.605 kg ha-1 e foi afetado pela interação entre época e densidade de semeadura. A máxima produtividade foi obtida com a semeadura feita na época preferencial, com densidade de 120 kg ha-1. Na semeadura antecipada, o rendimento aumentou linearmente 12,54 kg ha-1 para cada kg de sementes adicionado à menor densidade. A máxima produtividade obtida nesta época de semeadura foi de 7.858 kg ha-1 com 200 kg  ha-1 de sementes. A densidade de semeadura teve pouco impacto sobre a produtividade na semeadura tardia. Nesta época de semeadura, o maior rendimento (8.546 kg ha-1) foi registrado na densidade de 120 kg ha-1. A densidade ótima para maximizar a produtividade do arroz pré-germinado no Litoral Sul de Santa Catarina depende da época de semeadura, sendo mais alta quando a cultura é semeada antecipadamente

Source-sink relationship of soybean accessed by increasing in solar radiation through the plant canopy

ABSTRACT The photosynthetic metabolism is a key point to improve soybean yield. In this work, we demonstrated that radiation use by soybean plants can be improved, aiming to improve the grain yield in the lower canopy. The objective of this study was to observe whether the increase in solar radiation input in the canopy of soybean plants improves their yield performance. Three experiments were carried out during the 2017/2018 season. For each experiment, treatments consisted in the opening of one or two side rows of cultivation at the R2 and R5 stage of soybean plants (NA5909RR) until maturity, plus a control. Increase on solar radiation provided by the oppening of rows enhanced the yield potential in the nodes of the lower canopy, mainly when two rows were opened. The main benefits of increasing the radiation available throughout the canopy of soybean plants are observed in the number of pods and thousand-grain weight, demonstrating the importance of increasing the availability of assimilates in lower leaves. Interestingly, the benefits of the increase in solar interceptation were observed regardless of the yield potential of the area, which varied between 4.9 and 6.7 ton ha-1

Tolerancia a la defoliación de cultivares de soya liberados para su comercialización en diferentes décadas

Breeding programs have increased the precocity and yield potential of modern soybean cultivars. Such changes may have altered the crop tolerance to defoliation due to the smaller leaf area of modern cultivars. The objective of this study was to determine the tolerance to defoliation of soybean cultivars commercialized in Brazil in different decades, their photosynthetic efficiency and the relationship between photosynthetic efficiency and tolerance to defoliation in the reproductive phase. The experiment was set in a greenhouse with controlled humidity and temperature, in the municipality of Lages, Santa Catarina State, South of Brazil, during the growing season of 2018/2019. A randomized block design was used, with treatments arranged in a 5×5 factorial scheme. The first factor was composed of five soybean cultivars released in different years: Davis (1968), Paraná (1974), BR-16 (1985), FT Abyara (1991), and Brasmax Elite IPRO (2014). The second factor consisted of five levels of defoliation applied in stage R3: 0, 16.6, 33.3, 50.0, and 66.6%. Leaf area, photosynthetic activity parameters, grain yield and its components were determined. Brasmax Elite IPRO had the lowest grain yield per plant and did not increase yield compared to older cultivars, regardless of defoliation level. There were no significant differences in photosynthetic efficiency or defoliation tolerance between the modern cultivar Brasmax Elite IPRO and the old cultivars Davis, Paraná, BR-16, and FT Abyara.Los programas de mejoramiento han aumentado la precocidad y el potencial de rendimiento de los cultivares de soya modernos. Dichos cambios pueden haber alterado la tolerancia del cultivo a la defoliación, siendo la pérdida de área foliar un factor agravante de la pérdida de productividad. El objetivo de este estudio fue determinar la tolerancia a la defoliación de cultivares de soya comercializados en Brasil en diferentes décadas, su eficiencia fotosintética y la relación entre la eficiencia fotosintética y la tolerancia a la defoliación en la fase reproductiva. El experimento se realizó en un invernadero con humedad y temperatura controladas, en el municipio de Lages en el estado de Santa Catarina, Sur de Brasil, en la temporada de crecimiento 2018/2019. Se utilizó un diseño de bloques al azar, con tratamientos en esquema factorial 5×5. El primer factor estuvo compuesto por cinco cultivares de soya comercializados en diferentes años: Davis (1968), Paraná  1974), BR-16 (1985), FT Abyara (1991) y Brasmax Elite IPRO (2014). El segundo factor consistió en cinco niveles de defoliación aplicados en la etapa R3: 0, 16.6, 33.3, 50.0 y 66.6%. Se determinó área foliar, parámetros de actividad fotosintética, rendimiento de grano y sus componentes. Brasmax Elite IPRO mostró el rendimiento de grano más bajo por planta y no aumentó el rendimiento en comparación con los cultivares más antiguos, independientemente del nivel de defoliación. No hubo diferencias significativas en la eficiencia fotosintética ni en la tolerancia a la defoliación entre el cultivar moderno Brasmax Elite IPRO y los antiguos cultivares Davis, Paraná, BR-16 y FT Abyara

Defoliation tolerance of soybean cultivars commercially released in different decades

Breeding programs have increased the precocity and yield potential of modern soybean cultivars. Such changes may have altered the crop tolerance to defoliation due to the smaller leaf area of modern cultivars. The objective of this study was to determine the tolerance to defoliation of soybean cultivars commercialized in Brazil in different decades, their photosynthetic efficiency and the relationship between photosynthetic efficiency and tolerance to defoliation in the reproductive phase. The experiment was set in a greenhouse with controlled humidity and temperature, in the municipality of Lages, Santa Catarina State, South of Brazil, during the growing season of 2018/2019. A randomized block design was used, with treatments arranged in a 5×5 factorial scheme. The first factor was composed of five soybean cultivars released in different years: Davis (1968), Paraná (1974), BR-16 (1985), FT Abyara (1991), and Brasmax Elite IPRO (2014). The second factor consisted of five levels of defoliation applied in stage R3: 0, 16.6, 33.3, 50.0, and 66.6%. Leaf area, photosynthetic activity parameters, grain yield and its components were determined. Brasmax Elite IPRO had the lowest grain yield per plant and did not increase yield compared to older cultivars, regardless of defoliation level. There were no significant differences in photosynthetic efficiency or defoliation tolerance between the modern cultivar Brasmax Elite IPRO and the old cultivars Davis, Paraná, BR-16, and FT Abyara