RESUMO

Corn is the second most cultivated crop in Brazil, the number-one country in pesticide consumption. Chemical control of weeds is performed using herbicides such as S-metolachlor with pre- and post-emergence action and thus the toxicity of herbicides constitutes a matter of great concern. The present investigation aimed to examine the effects of an S-metolachlor-based herbicide on Lactuca sativa L. (lettuce) and Zea mays L. (maize) utilizing various bioassays. The test solutions were prepared from commercial products containing the active ingredient. Seeds from the plant models were exposed in petri dishes and maintained under biochemical oxygen demand (BOD) at 24°C. Distilled water was negative and aluminium positive control. Macroscopic analyses (germination and growth) were conducted for both plant species, and microscopic analysis (cell cycle and chromosomal alterations) were performed for L. sativa root tip cells. Detrimental interference of S-metolachlor-based herbicide was noted with lettuce for all parameters tested reducing plant germination by over 50% and the germination speed by over 45% and showing a significant decrease in mitotic index, from 16.25% to 9,28% even on the lowest concentration tested. In maize, there was no significant interference in plant germination; however, speed of germination was significantly hampered, reaching a 51.22% reduction for the highest concentration tested. Data demonstrated that the herbicide was toxic as evidenced by its phyto- and cytotoxicity in L. sativa L. and Z. mays L.

Assuntos

RESUMO

Lettuce is an important cool-temperature crop, and its principal abiotic stress is low heat tolerance. Lettuce production has become more challenging in the context of global warming changes. Hence, the main objective of this research was to investigate the relationship between stability and lettuce heat tolerance. Field and greenhouse trials were run in 2015 (summer) and 2016 (fall and spring). The environments were composed of a combination of season and place (field, glass, and plastic greenhouse), and the assessed genotypes were BRS Leila and Mediterrânea, Elisa, Everglades, Simpson, and Vanda. Statistical analysis showed a significant effect (p < 0.05) of environments (E), genotypes (G), and the GEI. BRS Leila, Elisa, and BRS Mediterrânea showed the greatest means to the first anthesis in suitable environments (milder temperatures). Among these cultivars, BRS Mediterrânea was the most stable and adapted to hot environments. The environmental conditions studied in this research, mainly high temperatures, could become a reality in many lettuce-producing areas. Therefore, the results can help indicate and develop lettuce varieties with greater heat tolerance.

RESUMO

In regions where water is a limited resource, lettuce production can be challenging. To address this, water management strategies like deficit irrigation are used to improve water-use efficiency in agriculture. Associating this strategy with silicon (Si) application could help maintain adequate levels of agricultural production even with limited water availability. Two lettuce crop cycles were conducted in a completely randomized design, with a factorial scheme (2 × 3), with three irrigation levels (60%, 80% and 100%) of crop evapotranspiration (ETc), and with and without Si application. To explore their combined effects, morphological, productive, physiological and nutritional parameters were evaluated in the crops. The results showed that deficit irrigation and Si application had a positive interaction: lettuce yield of the treatment with 80% ETc + Si was statistically similar to 100% ETc without Si in the first cycle, and the treatment with 60% ETc + Si was similar to 100% ETc without Si in the second cycle. Photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate and total chlorophyll content increased under water-stress conditions with Si application; in the first cycle, the treatment with 80% ETc + Si increased by 30.1%, 31.3%, 7.8%, 28.46% and 50.3% compared to the same treatment without Si, respectively. Si application in conditions of water deficit was also beneficial to obtain a cooler canopy temperature and leaves with higher relative water content. In conclusion, we found that Si applications attenuate water deficit effects and provide a strategy to ameliorate the yield and water productivity in lettuce crops, contributing to more sustainable practices in agriculture.

RESUMO

Inoculation with Bacillus subtilis is a promising approach to increase plant yield and nutrient acquisition. In this context, this study aimed to estimate the B. subtilis concentration that increases yield, gas exchange, and nutrition of lettuce plants in a hydroponic system. The research was carried out in a greenhouse in Ilha Solteira, Brazil. A randomized block design with five replications was adopted. The treatments consisted of B. subtilis concentrations in nutrient solution [0 mL "non-inoculated", 7.8 × 103, 15.6 × 103, 31.2 × 103, and 62.4 × 103 colony forming units (CFU) mL-1 of nutrient solution]. There was an increase of 20% and 19% in number of leaves and 22% and 25% in shoot fresh mass with B. subtilis concentrations of 15.6 × 103 and 31.2 × 103 CFU mL-1 as compared to the non-inoculated plants, respectively. Also, B. subtilis concentration at 31.2 × 103 CFU mL-1 increased net photosynthesis rate by 95%, intercellular CO2 concentration by 30%, and water use efficiency by 67% as compared to the non-inoculated treatments. The concentration of 7.8 × 103 CFU mL-1 improved shoot accumulation of Ca, Mg, and S by 109%, 74%, and 69%, when compared with non-inoculated plants, respectively. Inoculation with B. subtilis at 15.6 × 103 CFU mL-1 provided the highest fresh leaves yield while inoculation at 15.6 × 103 and 31.2 × 103 CFU mL-1 increased shoot fresh mass and number of leaves. Concentrations of 7.8 × 103 and 15.6 × 103 increased shoot K accumulation. The concentrations of 7.8 × 103, 15.6 × 103, and 31.2 × 103 CFU mL-1 increased shoot N accumulation in hydroponic lettuce plants.

RESUMO

The application of metallic nanoparticles improves the yield and content of bioactive compounds in plants. The aim of the present study was to determine the effects of the foliar application of copper nanoparticles (CuO-NPs) in the yield and content of bioactive compounds in lettuce. Different concentrations of CuO-NPs (0, 0.5, 1, 2, 4, and 6 mg mL-1) were applied in lettuce. The yield, nutraceutical quality, and enzymatic activity were determined. Foliar spraying of CuO-NPs induced an increase in the biosynthesis of bioactive compounds. In addition to an increase in the activity of the enzymes superoxide dismutase (SOD) and catalase (CAT) in lettuce plants, there were no negative effects on yield. Therefore, with the application of CuO-NPs, better quality lettuces are produced for the human diet due to the higher production of bioactive compounds.

RESUMO

One of the main challenges faced bylettuce producers is the interference of weeds whichaffectscrop development and productivity.The aim of this study was to evaluate the occurrence of programmed weeding on the growth and production of Lucy Brown American lettuce.The experiment was carried out between March and May 2017 at the Federal University of Roraima Cauamé campus, in Boa Vista, Roraima, Brazil. The experimental design used was randomized blocks with six treatments, four replications and four lettuce plants per experimental unit. The treatments tested were as follows: 100% weed control (100% WC); weed control 5 days after transplanting (WC 5 DAT); weed control 10 days after transplanting (WC 10 DAT); weed control 15 days after transplanting (WC 15 DAT); weed control 20 days after transplanting (WC 20 DAT) and 100% without weed control (100% WWC). The following variables were evaluated: shootheight, stem height, stem diameter, number of leaves, leaf length, leaf width, root length, shoot freshweight, total fresh weight, shoot dry weightand productivity. The ‘Lucy Brown’lettuce crop must be weed-freeafter 5 days of transplanting the seedlings to avoid productivitylosses. The lack of weed control in the cultivation of ‘Lucy Brown’ lettuce causes a 71.88% decrease in its productivity.

Um dos principais desafios enfrentados pelos produtores dealface é a interferência das plantas daninhas que afetam o desenvolvimento e produtividadedas culturas. Objetivou-se com este trabalho avaliar a ocorrência de capinas programadas de plantas daninhas sobre o crescimento e a produção da cultura da alface americana Lucy Brown. O experimento foi desenvolvido entre os meses de março e maio de 2017, no Campus do Cauamé, da Universidade Federal de Roraima, Boa Vista, Roraima, Brasil. O delineamento experimental foi blocos casualizados, com seis tratamentos e quatro repetições com quatro plantas de alface por unidade experimental. Foram testados os tratamentos: 100% controle de plantas daninhas (100% CPD), controle de plantas daninhas 5 dias após transplantio (CPD 5 DAT), controle de plantas daninhas 10 dias após transplantio (CPD10 DAT), controle de plantas daninhas 15 dias após transplantio (CPD 15 DAT), controle de plantas daninhas 20 dias após transplantio (CPD 20 DAT) e 100% sem controle de plantas daninhas (100% SCPD); sobre as variáveis: altura de planta, altura do caule, diâmetro do caule, número de folhas, comprimento da folha, largura da folha, comprimento da raiz, massa fresca da parte área, massa fresca total da planta, massa seca da parte aérea e produtividade. A alface americana “Lucy Brown” deve estar sem convivênciadas plantas daninhas a partir dos 5 dias do transplantio das mudas para evitar perdas de rendimento. No cultivo da alface americana “Lucy Brown”, a ausência de controle das plantas daninhas causa decréscimo de 71,88% na sua produtividade.

Assuntos

RESUMO

One of the main challenges faced bylettuce producers is the interference of weeds whichaffectscrop development and productivity.The aim of this study was to evaluate the occurrence of programmed weeding on the growth and production of Lucy Brown American lettuce.The experiment was carried out between March and May 2017 at the Federal University of Roraima Cauamé campus, in Boa Vista, Roraima, Brazil. The experimental design used was randomized blocks with six treatments, four replications and four lettuce plants per experimental unit. The treatments tested were as follows: 100% weed control (100% WC); weed control 5 days after transplanting (WC 5 DAT); weed control 10 days after transplanting (WC 10 DAT); weed control 15 days after transplanting (WC 15 DAT); weed control 20 days after transplanting (WC 20 DAT) and 100% without weed control (100% WWC). The following variables were evaluated: shootheight, stem height, stem diameter, number of leaves, leaf length, leaf width, root length, shoot freshweight, total fresh weight, shoot dry weightand productivity. The ‘Lucy Brownlettuce crop must be weed-freeafter 5 days of transplanting the seedlings to avoid productivitylosses. The lack of weed control in the cultivation of ‘Lucy Brown lettuce causes a 71.88% decrease in its productivity.(AU)

Um dos principais desafios enfrentados pelos produtores dealface é a interferência das plantas daninhas que afetam o desenvolvimento e produtividadedas culturas. Objetivou-se com este trabalho avaliar a ocorrência de capinas programadas de plantas daninhas sobre o crescimento e a produção da cultura da alface americana Lucy Brown. O experimento foi desenvolvido entre os meses de março e maio de 2017, no Campus do Cauamé, da Universidade Federal de Roraima, Boa Vista, Roraima, Brasil. O delineamento experimental foi blocos casualizados, com seis tratamentos e quatro repetições com quatro plantas de alface por unidade experimental. Foram testados os tratamentos: 100% controle de plantas daninhas (100% CPD), controle de plantas daninhas 5 dias após transplantio (CPD 5 DAT), controle de plantas daninhas 10 dias após transplantio (CPD10 DAT), controle de plantas daninhas 15 dias após transplantio (CPD 15 DAT), controle de plantas daninhas 20 dias após transplantio (CPD 20 DAT) e 100% sem controle de plantas daninhas (100% SCPD); sobre as variáveis: altura de planta, altura do caule, diâmetro do caule, número de folhas, comprimento da folha, largura da folha, comprimento da raiz, massa fresca da parte área, massa fresca total da planta, massa seca da parte aérea e produtividade. A alface americana “Lucy Brown” deve estar sem convivênciadas plantas daninhas a partir dos 5 dias do transplantio das mudas para evitar perdas de rendimento. No cultivo da alface americana “Lucy Brown”, a ausência de controle das plantas daninhas causa decréscimo de 71,88% na sua produtividade.(AU)

Assuntos

RESUMO

The purpose of this study was to evaluate doses of sulfur applied at topdressing, with and without organic compost supply at planting, in the production, physiological quality and content of macronutrients in lettuce seeds. Ten treatments were evaluated in a 5x2 factorial scheme (five sulfur doses at topdressing x with and without application of organic compost at planting). The experimental design was a randomized block design, with four replicates. The sulfur doses applied at topdressing fertilization were 50, 100, 150 and 200 kg ha-1 of S, in addition to the control treatment (dose zero). Regarding the treatments with organic compost, the dose of 70 t ha-1 of compost (wet basis) was supplied at planting. The following characteristics were evaluated: seed production (mass and number of seeds per plant), seed quality (mass of one thousand seeds, first count of the standard germination test, germination percentage, and germination speed index) and content of macronutrients and mineral accumulation. The organic compost supply at planting increased seed production by 43% compared to the treatment without the application of organic compost, while the doses of sulfur did not affect the production of lettuce seeds. The supply of organic compost increased the accumulation of a great part of the macronutrients, except for the accumulation of calcium. The lettuce seeds quality was not affected by both the main treatments, the sulfur doses at topdressing and the organic compost supply at planting. The descending order of nutrients accumulated in the lettuce seeds was nitrogen> potassium> phosphorus> magnesium> calcium> sulfur.

Assuntos

RESUMO

Lettuce is the main leafy vegetable commercialized in Brazil and it is cultivated in many different environment conditions and regions. But, under high temperature and high light intensity lettuce plants tend to early flowering, making it difficult to obtain high-quality lettuce harvest. Thus, this study was aimed to evaluate the productive performance of lettuce cultivars in a greenhouse in the municipality of Humaitá, Amazonas state (AM). The cultivars used were Rafaela and Hanson, Veneranda, Mônica SF 31, Simpson, Solaris, Elba, Quatro Estações and Babá de Verão. The lettuce seedlings were transplanted 24 days after sowing into a greenhouse covered by 100 micra polyethylene transparent agrofilm. It was used bed with 33-m-long and 1-m-wide, using 30 cm x 30 cm spacing between plants. The experimental design was randomized complete block with four replications. The parameters evaluated 32 days after transplanting were plant diameter, number of leaves, stem length and shoot dry mass. Cultivars Babá de Verão and Elba presented a better agronomic performance for cultivation in greenhouse in municipality of Humaitá, Amazonas state.

A alface é a principal folhosa comercializada no Brasil, sendo cultivada em muitas regiões e ambientais diferentes. Entretanto, sob altas temperaturas e elevada intensidade luminosa as plantas de alface tendem ao florescimento precoce, dificultando a obtenção de uma colheita de alface de alta qualidade. Assim, no presente estudo objetivou-se avaliar o desempenho produtivo de cultivares de alface em ambiente protegido no município de Humaitá, estado do Amazonas (AM). As cultivares usadas foram Rafaela e Hanson, Veneranda, Mônica SF 31, Simpson, Solaris, Elba, Quatro estações e Baba de Verão. As mudas de alface foram transplantadas 24 dias após a semeadura para casa de vegetação coberta com agrofilme de polietileno transparente de 100 micra. Foi utilizado canteiro com 33 m de comprimento e 1 m de largura, utilizando-se espaçamento de 30 cm x 30 cm entre plantas. O experimento foi conduzido utilizando-se delineamento em blocos completos casualizados com 4 repetições. Os parâmetros avaliados 32 dias após o transplantio foram o diâmetro da planta, número de folhas, comprimento do caule e massa seca da parte aérea. As cultivares Baba de Verão e Elba apresentaram melhor desempenho agronômico para o cultivo protegido no município de Humaitá, estado do Amazonas.

RESUMO

Lettuce is the main leafy vegetable commercialized in Brazil and it is cultivated in many different environment conditions and regions. But, under high temperature and high light intensity lettuce plants tend to early flowering, making it difficult to obtain high-quality lettuce harvest. Thus, this study was aimed to evaluate the productive performance of lettuce cultivars in a greenhouse in the municipality of Humaitá, Amazonas state (AM). The cultivars used were Rafaela and Hanson, Veneranda, Mônica SF 31, Simpson, Solaris, Elba, Quatro Estações and Babá de Verão. The lettuce seedlings were transplanted 24 days after sowing into a greenhouse covered by 100 micra polyethylene transparent agrofilm. It was used bed with 33-m-long and 1-m-wide, using 30 cm x 30cm spacing between plants. The experimental design was randomized complete block with four replications. The parameters evaluated 32 days after transplanting were plant diameter, number of leaves, stem length and shoot dry mass. Cultivars Babá de Verão and Elba presented a better agronomic performance for cultivation in greenhouse in municipality of Humaitá, Amazonas state.

A alface é a principal folhosa comercializada no Brasil, sendo cultivada em muitas regiões e ambientais diferentes. Entretanto, sob altas temperaturas e elevada intensidade luminosa as plantas de alface tendem ao florescimento precoce, dificultando a obtenção de uma colheita de alface de alta qualidade. Assim, no presente estudo objetivou-se avaliar o desempenho produtivo de cultivares de alface em ambiente protegido no município de Humaitá, estado do Amazonas (AM). As cultivares usadas foram Rafaela e Hanson, Veneranda, Mônica SF 31, Simpson, Solaris, Elba, Quatro estações e Baba de Verão. As mudas de alface foram transplantadas 24 dias após a semeadura para casa de vegetação coberta com agrofilme de polietileno transparente de 100 micra. Foi utilizado canteiro com 33 m de comprimento e 1 m de largura, utilizando-se espaçamento de 30 cm x 30 cm entre plantas. O experimento foi conduzido utilizando-se delineamento em blocos completos casualizados com 4 repetições. Os parâmetros avaliados 32 dias após o transplantio foram o diâmetro da planta, número de folhas, comprimento do caule e massa seca da parte aérea. As cultivares Baba de Verão e Elba apresentaram melhor desempenho agronômico para o cultivo protegido no município de Humaitá, estado do Amazonas.

Assuntos