Corn productivity and topdressing application cost of nitrogen fertilizers / Produtividade de milho e custo da aplicação em cobertura de fertilizantes nitrogenados

Nitrogen(N) is the most required nutrient in the cultivation of corn (Zea maysL.), also representing a significantshare in the production costs. The objective was to evaluate the efficiency for one experimental year of different sourcesof nitrogen fertilizers applied in topdressing on the corn grain yield and their respective fertilization costs. The experiment was carried out under field conditions and without irrigation under no-tillage system, in a Red Oxissol. For sowing, 280 kg ha-1of NPK fertilizer 12-30-20 was used for all treatments. In addition to the control treatment (NPK), four nitrogen formulations wereapplied in topdressing: Urea, Super N, Nitromag, and Sulfammo, both formulations applied 50% in the V3/V4 and 50% V7/V8 stages, in four replicates.Grain yield was determined at the physiological maturation. The type of nitrogen fertilizer did not influence corn grain yield, an average of 9016 kg ha-1. The largest profits were achieved with the application of Super N, Urea and Nitromag. Nitrogen fertilizers with slow and controlled N release does not promote an increase in corn grain yield in relation to Urea. The use of Super N in topdressing has the highest profitability in corn cultivation.(AU)

O nitrogênio (N) é o nutriente mais requerido no cultivo do milho (Zea maysL.), ainda representa significativa participação no custo de produção. O objetivo foi avaliar a eficiência em um ano experimental de diferentes fontes de fertilizantes nitrogenados aplicados em cobertura na produtividade de grãos demilho e os seus respectivos custos da adubação. O experimento foi realizado em condições de campo e sem irrigação sob sistema plantio direto, em Latossolovermelho. Na semeadura foi utilizado 280 kgha-1de adubo NPK 12-30-20 para todos os tratamentos. Além do tratamento testemunha (NPK), quatro formulações nitrogenadas foram aplicadas em cobertura: Ureia, Super N, Nitromag, e Sulfammo, ambas as formulaçõesaplicadas 50% no estádioV3/V4 e 50% V7/V8,em quatro repetições. Na maturação fisiológica foi determinada a produtividade de grãos.O tipo de fertilizante nitrogenado não influenciou na produtividade de grãos de milho, média de 9016 kg ha-1. Os maiores lucros foram com a aplicação de Super N, Ureia e Nitromag. O uso em cobertura de fertilizantes nitrogenados de lenta e controlada liberação de N não promovem aumento na produtividade de grãos de milho em relação a Ureia. O uso de Super N em cobertura apresenta a maior lucratividadeno cultivo do milho.(AU)

Respostas fisiológicas e enzimáticas no milho sob diferentes concentrações de nitrogênio / Physiological and enzymatic responses in maize under different nitrogen concentrations

O estudo de aspectos químicos e bioquímicos associados ao desenvolvimento das diferentes partesdas plantas permite a observação e o entendimento de uma série de reações que levam à produção de fitomassa e grãos pela cultura de milho. Assim, objetivou-se estudar a diferença na eficiência de uso do nitrogênio nas raízes e parte aérea em dois genótipos de milho, na fase inicial de crescimento das plantas e avaliar as respostas bioquímico-fisiológicas desses órgãos quando as plantas são submetidas a distintas doses de N em condições hidropônicas. O experimento foi realizado em casa de vegetação, em solução nutritiva por20 dias, com dois genótipos (AS1522 e AS1596) submetidos a quatro concentrações de N (zero; 112; 224 e 448 mg dm-3). O delineamento utilizado foi em inteiramente casualizado com trêsrepetições. Houve diferença entre os genótipos estudados para as variáveis biométricas, massa de matéria seca, acúmulo de N e aminoácidos livres totais na parte aérea das plantas. Na raiz, a atividade da redutase do nitrato foi a variável que diferenciou a eficiência no uso do nitrogênio entre os genótipos. O genótipo AS1596 é mais eficiente no uso do nitrogênio.(AU)

The study of chemical and biochemical aspects associated with the development of different plant parts enables the assessment of a series of reactions leading to the production of biomass and grain culture. Thus, the objective of was to study the difference in nitrogen efficiency in roots and shoots of two corn genotypes in the initial stages of plants growth, and evaluate the biochemical and physiological responses of these organs, when plants are subjected to different doses of N, under hydroponic conditions. The experiment was conducted in a greenhouse in nutrient solution for 20 days, with two genotypes(AS1522 and AS1596) subjected to four N concentrations (zero, 112, 224 and 448 mg dm-3). Completely randomized desing with three replications das apply. The major differences among genotypes for biometric variables, dry matter, Nac cumulation and free amino acids were observed in the shoots. At root, the activity of nitrate reductase activity was the variable that stood out and provided the largest differences between genotypes. The genotype AS1596 is more efficient in N utilization.(AU)

Fermentation dynamics and quality of maize silage with Pigeon pea / Dinâmica da fermentação e qualidade da silagem de milho com feijão guandu

Tropical legumes are used to prepare mixed silages to enrich the crude protein (CP) content. In This context, objective of this study was to evaluate the dynamics of fermentation and quality of maize silage with different levels of Pigeon pea. The experimental design was entirely randomized, with four repetitions. The treatments comprised maize silages with six levels of added Pigeon pea (0, 20, 40, 60, 80, and 100%), calculated based on natural matter. The maize hybrid and Pigeon pea varieties used were B 2800 PWU and Cajanus cajan cv. BRS Mandarin, respectively. For the silage, the maize and Pigeon pea were harvested when they reached 335.7 g kg-1 dry matter (DM) and 281.3 g kg-1 DM, respectively. The results revealed that the added of up to 40% Pigeon pea in maize silages promote nutritive increment without compromising their fermentative profile of the silage. Exclusive Pigeon pea silage (100%) undergoes fermentative losses that compromise the silage quality. Therefore, mixed silages of maize with Pigeon pea, with appropriate levels of addition, are a viable alternative to increase the nutritive value of silages, mainly the CP content, contributing to reducing the cost of acquisition of protein salts.(AU)

As leguminosas tropicais têm sido utilizadas para a confecção de silagens mistas para enriquecer os teores de proteína bruta (PB). Neste contexto, o objetivo deste estudo foi avaliar a dinâmica da fermentação e qualidade da silagem de milho com níveis de feijão guandu. O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repetições. Os tratamentos foram constituídos da silagem de milho com seis níveis de feijão guandu (0; 20; 40; 60, 80 e 100%), calculado com base na matéria natural. O híbrido de milho e a variedade de feijão guandu utilizados foram o B 2800 PWU e o Cajanus cajan cv. BRS Mandarim, respectivamente. Para a ensilagem, o milho e o feijão guandu foram colhidos quando atingiram 335,7 g kg-1 de MS (matéria seca) e 281,3 g kg-1 MS, respectivamente. Os resultados mostraram que a adição de até 40% de feijão guandu na ensilagens de milho promove incremento nutritivo sem comprometer o seu perfil fermentativo da silagem. Silagem exclusiva de feijão guandu apresenta perdas fermentativas que compromete a qualidade da silagem. Portanto, silagens mistas de milho com feijão guandu, combinadas com níveis adequados de adição, torna-se alternativa viável para incrementar o valor nutritivo da silagem, principalmente os teores de PB, contribuindo com redução do custo com aquisição de sais proteínados.(AU)

Creole corn seed promotes increase in production and nutritional aspects in hydroponic forage / Semente de milho crioula promove incremento nos aspectos produtivos e nutricionais da forragem hidropônica

The aimed of this study to assess the productivity and nutritional characteristics of hydroponic corn forage derived from bico de ouro creole seeds and AL-Bandeirante. Two treatments (T), each representing a corn seed variety, were randomly allocated to beds filled with a wood sawdust substrate: T1 (n=5) - bico de ouro creole seed variety, and T2 (n=5) - AL-Bandeirante hybrid seed variety. On the 13th day, forage was collected to assess seedling biometry, green and dry mass production, and bromatological analyses. The data were subjected to statistical analysis, with a 5% significance level. The creole seed variety yielded higher seedling height (17.53 cm), root length (10.19 cm), stem (5.37 cm), leaf (12.17 cm), and greater production of green mass (7.22 kg/m²) and dry matter (2.05kg/m²) (P<0.05). The AL-Bandeirante corn forage had higher dry matter content (39.18%), mineral matter (2.33%), non-fiber carbohydrate (31.88%), and estimated total digestible nutrients (68.14%) (P<0.05), while the creole corn forage had higher organic matter content (99.45%), ethereal extract (19.53%), neutral detergent fiber (45.56%), and cellulose (15.46%) (P<0.05). Crude protein, acid detergent fiber, and lignin were similar between the treatments (P>0.05). Despite the AL-Bandeirante variety yielding a higher concentration of certain nutrients, its forage productivity was significantly low. Therefore, under the conditions of this study, the use of the creole seed variety is recommended.(AU)

O objetivo com este estudo foi avaliar a produtividade e as características nutricionais da forragem hidropônica de milho derivada de sementes de crioulo bico de ouro e AL-Bandeirante. Dois tratamentos (T), cada um representando uma variedade de semente de milho, foram distribuídos aleatoriamente em canteiros preenchidos com substrato de serragem de madeira: T1 (n=5) - variedade de semente crioula bico de ouro e T2 (n=5) - AL-Bandeirante variedade de semente híbrida. No 13º dia foi coletada forragem para avaliação da biometria das plântulas, produção de massa verde e seca e análises bromatológicas. Os dados foram submetidos à análise estatística, com nível de significância de 5%. A variedade de semente crioula proporcionou maior altura de plântula (17,53 cm), comprimento de raiz (10,19 cm), caule (5,37 cm), folha (12,17 cm) e maior produção de massa verde (7,22 kg/m²) e matéria seca (2,05kg /m²) (P<0,05). A forragem de milho AL-Bandeirante apresentou maior teor de matéria seca (39,18%), matéria mineral (2,33%), carboidrato não fibroso (31,88%) e nutrientes digestíveis totais estimados (68,14%) (P<0,05), enquanto a forragem de milho crioulo apresentou maior teor de matéria orgânica (99,45%), extrato etéreo (19,53%), fibra em detergente neutro (45,56%) e celulose (15,46%) (P<0,05). Proteína bruta, fibra em detergente ácido e lignina foram semelhantes entre os tratamentos (P>0,05). Apesar da variedade AL-Bandeirante apresentar maior concentração de alguns nutrientes, a produtividade de forragem foi significativamente baixa. Portanto, nas condições deste estudo, recomenda-se o uso da variedade crioula de sementes.(AU)

Replacing corn silage with extruded forage in sheep feeding

The objective was to evaluate levels of replacement of corn silage with extruded forage (Foragge®) in sheep feeding. Twenty adult Santa Inês ewes in maintenance, and 55.8 kg average weight were housed in metabolic cages, and the treatments consisted of 20, 40, 60 and 80% replacement of corn silage with Foragge®extruded forage with 60% Uruchloa brizanthain the diet. The design was completely randomized, with regression analysis and non-parametric analysis at 5% probability. The supply of up to 80% extruded roughage to replace corn silage increased dry matter intake and digestibility, and fecal output in dry matter (p < 0.05). Also, it increased the efficiency of ingestion, rumination and chewing activities of sheep, but did not alter urinary parameters and energy metabolites (p > 0.05). However, it reduced the concentration of uric acid (p < 0.05). Foragge®extruded roughage can replace corn silage by up to 80% with changes in intake, digestibility, fecal parameters, ingestive behavior and concentration of uric acid and urea, with no modifications in urinary parameters and energy metabolites.(AU)

Grãos secos de destilaria de milho na dieta de codornas japonesas na fase de cria / Dried corn distillery grains in the diet of japanese quailsin the brooding phase / Granos secos de destilería de maíz en la dieta de las codornices japonesas en fase de cría

Objetivou-se avaliar o desempenho de codornas japonesas na fase de cria emfunçãodosníveis de inclusão de grãos secos de destilaria (DDG) de milho na dieta. Foramutilizadas 720 codornas poedeiras (Coturnix coturnix japonica) com 1 dia de vida até 21 dias de idade, distribuídas em delineamento inteiramente casualizado com cinco tratamentos eseisrepetições, com 24 codornas por unidade experimental. Os tratamentos utilizados foram: dietacontrole com 0% de DDG, dieta com 5% de inclusão de DDG, dieta com10%de inclusãodeDDG, dieta com 15% de inclusão de DDG e dieta com 20% de inclusão de DDG. Foi avaliado o consumo de ração (g/ave/dia), o ganho de peso (g/ave/dia), conversão alimentar(kg/kg) e a viabilidade das aves. Os dados foram submetidos a análise de regressão a 5%deprobabilidade e pelo teste de Dunnet. Foi observado efeito (P<0,05) para ganho empeso, maspara o consumo de ração e conversão alimentar não houve diferença entre as dietas (P>0,05). Conclui-se que a inclusão de 14,8% de DDG de milho na dieta de codornas japonesas maximizou o ganho de peso e não prejudicou o consumo de ração e conversão alimentar dasaves.(AU)

The objective was to evaluate the performance of Japanese quails in the brooding phaseasafunction of the levels of inclusion of corn distillers dried grains (DDG) in the diet. Weused720 laying quail (Coturnix coturnix japonica) with 1 day of life and 21 days of age, distributed in internally randomized delineation with five treatments and six repetitions, with24 quails per experimental unit. The treatments used were control diet with 0%DDG, diet with 5% inclusion of DDG, diet with 10% inclusion of DDG, diet with 15% inclusion of DDG and diet with 20% inclusion of DDG. feed intake (g / bird / day), weight gain (g/ bird/ day), feed conversion (kg / kg) and bird viability were evaluated. The data were submittedtoregression analysis at 5% probability and by the Dunnet test. There was an effect (P<0.05) forweight gain, but for feed intake and feed conversion there was no difference between the diets (P>0.05). It was concluded that the inclusion of 14.8% corn DDG in the diet of Japanesequails maximized weight gain and did not affect feed intake and feed conversion of the birds.(AU)

El objetivo fue evaluar el desempeño zootécnico de las codornices japonesas en la etapadecrianza en función de los niveles de inclusión de grano seco de destilería (DDG) de maízenladieta. Se utilizaron 720 codornices ponedoras (Coturnix coturnix japonica) de 1 día a 21díasde edad, distribuidas en un diseño completamente al azar con cinco tratamientos yseisrepeticiones, con 24 codornices por unidad experimental. Los tratamientos utilizados fueron: dieta control con 0% de DDG, dieta con 5% de inclusión de DDG, dieta con 10%de inclusiónde DDG, dieta con 15% de inclusión de DDG y dieta con 20% de inclusión de DDG. Seevaluó el consumo de alimento (g/ave/día), la ganancia de peso (g/ave/día), la conversiónalimenticia (kg/kg) y la viabilidad del ave. Los datos fueron sometidos a análisis de regresiónal 5% de probabilidad y mediante la prueba de Dunnet. Hubo un efecto (P<0,05) paralaganancia de peso, pero para el consumo de alimento y la conversión alimenticia nohubodiferencia entre las dietas (P>0,05). Se concluyó que la inclusión de 14,8%de DDGdemaízen la dieta de las codornices japonesas maximizó la ganancia de peso y no afectó el consumode alimento ni la conversión alimenticia de las aves.(AU)

Does the use of corn and soybean hulls affect calf performance in the preweaning period?

The objective of this study was to assess the effects of two levels of soybean hulls (0 and 400.1 g/kg) and whole or ground corn in the diet of newborn crossbred dairy male calves on intake, performance, blood indicators, and feeding cost. Twenty-eight calves with an average weight of 33.0±6.2 kg and four days of age were distributed into four treatment groups in a completely randomized design (n = 7) for 56 days. Weekly samples of feed, diets, and leftovers were collected to determine dry matter and nutrient intakes. To evaluate apparent digestibility, samples were taken using titanium dioxide as a maker. Blood samples were also collected to evaluate blood indicators. The inclusion of soybean hulls resulted in greater neutral detergent fiber intake by the calves, but reduced their non-fibrous carbohydrates intake, which was also reduced by the use of whole corn in the diet. Although the total digestible nutrients content of diets decreased with the use of whole corn and inclusion of soybean hulls, its intake did not vary (0.75 kg/d), regardless of the factors analyzed. The apparent digestibilities of dry matter (0.87 kg/kg) and crude protein (0.89 kg/kg) were similar, resulting in similar performance between the animals, regardless of the factors analyzed. In the quantities evaluated, the use of soybean hulls or whole corn did not affect blood indicators and was insufficient to reduce feed costs; the cost of daily feed was $2.06, while the cost per kilogram of gain was $3.74. The inclusion of up to 400.1 g/kg of soybean hulls or the replacement of ground corn with whole corn does not affect the performance of crossbred dairy calves during the preweaning period, demonstrating that both can be used in animal feed during this phase of production.(AU)

Productivity and nutrient export in a maize and forage grasses intercropping under semiarid conditions / Produtividade e exportação de nutrientes em um consórcio de milho e gramíneas forrageiras nas condições do semiárido

The aim was to evaluate the productive performance and nutrient export of maize intercropped with drought-tolerant forage grasses. The experimental design was a randomized blocks in a 2x2x2+1 factorial scheme (two forage grasses species ­ Massai and Buffel; two forage sowing methods - in the furrow and broadcast; and two forage sowing times - anticipated and simultaneous; and monoculture maize as an additional control), with three replicates. The maize+forage intercropping promoted greater competition for resources, especially water, limiting N uptake, chlorophyll synthesis, and biomass production by maize under semiarid conditions. Early sowing gave forage plants a competitive advantage, favoring forage establishment before or immediately after the sowing of maize. Thus, the simultaneous sowing of forage grasses in a semiarid environment is a more appropriate option considering the importance of high levels of chlorophyll to ensure high photosynthetic activity in maize plants and greater capacity of biomass synthesis. Massai intercropped with maize exhibits a greaterpotential for biomass production than Buffel under semiarid conditions. Maize+Buffel result in highest macronutrient export by maize, while maize+Massai result in highest macronutrient exports by total forage biomass under a semiarid environment. The choice of the forage species and its sowing time in relation to maize are the main determinants of successful intercropping systems under semiarid conditions.(AU)

O objetivo foi avaliar o desempenho produtivo e a exportação de nutrientes do consórcio de milho com gramíneas forrageiras tolerantes ao estresse hídrico. O experimento foi delineado em blocos casualizados em esquema fatorial 2x2x2+1 (duas espécies de gramíneas forrageiras ­ Massai e Buffel; dois métodos de semeadura ­ no sulco e a lanço; e duas épocas de semeadura ­ antecipada e simultânea; e monocultivo de milho como um controle adicional), com três repetições. O consórcio milho+forragem promoveu maior competição por recursos, principalmente água, limitando a absorção de N, síntese de clorofila e produção de biomassa pelo milho para condições semiáridas. A semeadura precoce deu vantagem competitiva às plantas forrageiras, favorecendo seu estabelecimento antes ou imediatamente após a semeadura do milho. Assim, a semeadura simultânea de gramíneas forrageiras em ambiente semiárido é uma opção mais adequada, considerando a importância de garantir altos teores de clorofila e, consequentemente, alta atividade fotossintética nas plantas de milho para garantir a capacidade de síntese de biomassa.Massai consorciado com milho apresenta maior potencial para produção de biomassa do que Buffel em condições semiáridas.Milho+Buffel resulta em maior exportação de macronutrientes pelo milho, enquanto milho+Massai resulta em maior exportação de macronutrientes pela biomassa forrageira total em ambiente semiárido.A escolha da espécie forrageira e sua época de semeadura em relação ao milho são os principais determinantes do sucesso do consórcio no semiárido.(AU)

Sealing strategies in corn silage and sheep performance in feedlots / Estratégias de vedação na ensilagem de milho e desempenho de ovinos em confinamento

The objective of this study was to evaluate the effects of different sealing strategies on aerobic stability and feed value of corn silage supplied to finishing lambs. The treatments were set up according to the silo sealing strategy: BP (black polyethylene film), BP + Bagasse (black polyethylene film + sugarcane bagasse) and BP + Silostop (Silostop® Orange oxygen barrier film + black polyethylene film). Six lambs per treatment were used, totaling 18 animals in an experimental period of 63 days. The silage from LP treatment presented the highest aerobic stability, however with lower dry matter digestibility coefficients. No significant differences were detected among treatments for intake and performance of lambs. But for final body weight, weight gain, daily average gain, feed efficiency and dry matter intake, the best results, in absolute value, were found for lambs fed with silage from LP + Bagasse treatment. The silage sealed exclusively with black polyethylene film showed greater aerobic stability. The different sealing strategies used in this experiment did not influence the performance of finishing Dorper x Santa Inês lambs.(AU)

Objetivou-se avaliar os efeitos de differentes estratégias de vedação sobre a estabilidade aeróbia e o valor alimentício da silagem de milho fornecida para cordeiros em terminação. Os tratamentos foram definidos de acordo com a estratégia de vedação do silo: LP (lona preta de polietileno), LP + Bagaço (lona preta de polietileno + bagaço de cana) e LP + Silostop (lona preta de polietileno + filme de barreira de oxigênio Silostop® Orange). Foram utilizados seis cordeiros por tratamento, totalizando 18 animais, em um período experimental de 63 dias. A silagem do tratamento LP apresentou maior estabilidade aeróbia, porém proporcionou menor coeficiente de digestibilidade da matéria seca. Não foi observada diferença significativa entre os tratamentos para o consumo e desempenho dos cordeiros. Todavia, para o peso corporal final, ganho de peso, ganho médio diário, eficiência alimentar e consumo de matéria seca, os melhores resultados, em valor absoluto, foram encontrados para os cordeiros alimentados com dieta à base da silagem coberta com LP + Bagaço. A silagem vedada exclusivamente com a lona preta de polietileno apresentou maior estabilidade aeróbia. As diferentes estratégias de vedação utilizadas nesse experimento não influenciaram o desempenho de cordeiros Dorper x Santa Inês em terminação.(AU)

Performance of maize cultivars for the production of sweet corn, baby corn, and fodder / Desempenho de cultivares de milho para produção de milho verde, minimilho e forragem

Maize has multiple functions and can be used for human consumption, animal feed, or in industrial processes. Grain production has made Brazil a world reference. However, few cultivars are available despite the relevance of sweet corn, especially for family farmers. This is similar to baby corn, in which sweet corn or popcorn is used for its production. In the Brazilian semi-arid region, plant and animal production are limited by water deficit in the dry season. Therefore, the production of sweet and baby corn generates income from the commercialization of the ears and roughage production with the whole-plant harvest. This research has aimed to assess the agronomic performance of five cultivars for sweet corn, baby corn, and fodder production in Agreste Meridional, a semi-arid region of Pernambuco, Brazil. Two experiments were carried out in a randomized block design with five treatments (AG 1051, Alagoano, Branquinha, São Luiz, and PV2 Viçosense) and four blocks. The 1st experiment assessed the performance of the cultivars for sweet corn and fodder yield, in which the cultivars AG 1051 and Branquinha had higher yields for ears (21.9 and 20.3 Mg ha-1) and fodder (10.7 and 10.9 Mg DM ha-1), respectively. The 2nd experiment assessed the performance of the cultivars for baby corn and fodder yield, in which the cultivars AG 1051 and PV2 Viçosense obtained the highest yield for ears (3.1 and 2.9 Mg ha-1, respectively); Branquinha had a higher yield for fodder (8.9 Mg DM ha-1). Therefore, these cultivars have desirable characteristics and can be used in intensive or extensive production.(AU)

O milho apresenta múltiplas funções, podendo ser utilizado no consumo humano, alimentação animal ou em processos industriais. A produção de grãos tornou o Brasil uma referência mundial. Porém, apesar da relevância do milho verde, principalmente para agricultores familiares, são poucos os cultivares disponíveis. Do mesmo modo, para o minimilho, em que são utilizados milho doce ou pipoca para sua obtenção. Na região semiárida, as produções vegetal e animal são limitadas pelo déficit hídrico na época seca. Portanto, com a produção de milho verde e minimilho é possível obter renda com a comercialização das espigas e produzir volumoso com a colheita da planta inteira. O objetivo dessa pesquisa foi avaliar o desempenho agronômico de cinco cultivares para produção de milho verde e minimilho e produção de forragem no Agreste Meridional, região semiárida de Pernambuco. Foram realizados dois experimentos no delineamento em blocos casualizados, com cinco tratamentos (AG 1051, Alagoano, Branquinha, São Luiz e PV2 Viçosense) e quatro blocos. No primeiro experimento avaliou-se o desempenho dos cultivares para produção de milho verde e forragem, em que os cultivares AG 1051 e Branquinha tiveram, respectivamente, maiores produtividades de espigas comerciais (21,9 e 20,3 Mg ha-1) e de forragem (10,7 e 10,9 Mg MS ha-1). No segundo experimento, avaliou-se o desempenho dos cultivares para a produção de minimilho e forragem, em que os cultivares AG 1051 e PV2 Viçosense obtiveram a maior produtividade de espiguetas comerciais (3,1 e 2,9 Mg ha-1, respetivamente); Branquinha, maior produtividade de forragem (8,9 Mg MS ha-1). Portanto, esses cultivares reúnem características desejáveis, podendo ser utilizados em sistemas intensivos ou extensivos de produção.(AU)

Maize Lethal Necrosis disease: review of molecular and genetic resistance mechanisms, socio-economic impacts, and mitigation strategies in sub-Saharan Africa.

BACKGROUND: Maize lethal necrosis (MLN) disease is a significant constraint for maize producers in sub-Saharan Africa (SSA). The disease decimates the maize crop, in some cases, causing total crop failure with far-reaching impacts on regional food security. RESULTS: In this review, we analyze the impacts of MLN in Africa, finding that resource-poor farmers and consumers are the most vulnerable populations. We examine the molecular mechanism of MLN virus transmission, role of vectors and host plant resistance identifying a range of potential opportunities for genetic and phytosanitary interventions to control MLN. We discuss the likely exacerbating effects of climate change on the MLN menace and describe a sobering example of negative genetic association between tolerance to heat/drought and susceptibility to viral infection. We also review role of microRNAs in host plant response to MLN causing viruses as well as heat/drought stress that can be carefully engineered to develop resistant varieties using novel molecular techniques. CONCLUSIONS: With the dual drivers of increased crop loss due to MLN and increased demand of maize for food, the development and deployment of simple and safe technologies, like resistant cultivars developed through accelerated breeding or emerging gene editing technologies, will have substantial positive impact on livelihoods in the region. We have summarized the available genetic resources and identified a few large-effect QTLs that can be further exploited to accelerate conversion of existing farmer-preferred varieties into resistant cultivars.

Produtividade de híbridos de milho pipoca submetidos a diferentes populações na semeadura / Productivity of poppy corn hybrids submitted to different populations in seeding / Productividad de híbridos de maíz poppy presentados a poblaciones diferentes en la sembrada

Quando se trata de milho pipoca o Brasil é o segundo maior produtor, mas necessitando ainda de importações para suprir a demanda interna do país, visto a importância de estudos que melhor explorem as recomendações agronômicas para a cultura do milho pipoca. Assim, o presente estudo objetivou avaliar o impacto da população de plantas sobre algumas variáveis morfológicas e na produtividade final de grãos de dois híbridos de milho pipoca (8203 e 4512). Foram estudadas as populações de 60.000, 65.000, 70.000, 75.000 e 80.000 plantas por ha-1 no espaçamento de 0,45cm entre linha de semeadura. O experimento foi conduzido no ano agrícola 2018/2019, na área experimental do Departamento de Ciências Agronômicas e Ambientais da Universidade Federal de Santa Maria, campus Frederico Westphalen ­ RS, em um delineamento de blocos casualizados em um esquema fatorial (2x5). O diâmetro de colmo, comprimento da espiga e peso de mil sementes diminuíram à medida que se aumentou a população de plantas. Para ambos os híbridos, e para a maioria das variáveis analisadas as densidades populacionais não interferiram de forma significativa na produtividade final de grãos do milho pipoca. Entretanto quando se trabalha a média das populações se observa uma superioridade do híbrido 8203 para as variáveis, altura de planta, altura de inserção da espiga, prolificidade, empalhamento, diâmetro de espiga, número de grãos por espiga, peso de mil sementes e produtividade final de grãos.(AU)

When it comes to popcorn, Brazil is the second largest producer, but still needing imports to supply the country's domestic demand, given the importance of studies that better explore agronomic recommendations for popcorn culture. Thus, the aim of the present study was to evaluate the impact of the plant population on some morphological variables and the final consumption of two hybrid popcorn kernels (8203 and 4512). The populations of 60.000, 65.000, 70.000, 75.000 and 80.000 plants per ha-1 were studied in the 0.45cm spacing between sowing lines. The experiment was carried out in the agricultural year 2018/2019, in the experimental area of the Department of Agricultural and Environmental Sciences of the Federal University of Santa Maria, Frederico Westphalen campus - RS, in a randomized block design in a factorial scheme (2x5). The stem diameter, ear length and weight of a thousand seeds decreased as the plant population increased. For both hybrids, and for most of the variables analyzed, population densities did not significantly affect the final grain yield of popcorn. However, when working with the average population, a superiority of the 8203 hybrid is observed for the variables, plant height, height of ear insertion, prolificacy, stuffing, ear diameter, number of grains per ear, weight of a thousand seeds and final productivity of grain.(AU)

En lo que respecta a las palomitas de maíz, Brasil es el segundo mayor productor, pero aún necesita importaciones para satisfacer la demanda interna del país, dada la importancia de los estudios que exploran mejor las recomendaciones agronómicas para el cultivo de palomitas de maíz. Por lo tanto, el objetivo del presente estudio fue evaluar el impacto de la población de plantas en algunas variables morfológicas y en el rendimiento final de grano de dos híbridos de palomitas de maíz (8203 y 4512). Se estudiaron las poblaciones de 60.000, 65.000, 70.000, 75.000 y 80.000 plantas por ha-1 en el espacio de 0.45cm entre líneas de siembra. El experimento se realizó en el año agrícola 2018/2019, en el área experimental del Departamento de Ciencias Agronómicas y Ambientales de la Universidad Federal de Santa María, campus Frederico Westphalen - RS, en un diseño de bloques al azar en un esquema factorial (2x5). El diámetro del tallo, la longitud de la mazorca y el peso de mil semillas disminuyeron à medida que aumentó la población de plantas. Para ambos híbridos, y para la mayoría de las variables analizadas, las densidades de población no afectaron significativamente el rendimiento final de grano de las palomitas de maíz. Sin embargo, cuando se trabaja con la población promedio, se observa una superioridad del híbrido 8203 para las variables, altura de la planta, altura de inserción de la mazorca, prolificidad, relleno, diámetro de la mazorca, número de granos por mazorca, peso de mil semillas y productividad final de grano.(AU)

Symptoms of deficiency and initial growth of maize cultivated with biochar under nutrient omission / Sintomas de deficiência e crescimento inicial do milho cultivado com biocarvão sob omissão de nutrientes

Maize is the second largest agricultural crop in Brazil. It reaches high yields as supported by the intensive use of technologies, particularly mineral fertilization, which is normally costly. To lower production costs and improve crop productivity on small farms, the present study tested the efficiency of poultry litter biochar as a source of nutrients in the initial growth of BRS 2022 maize by the 'diagnosis by subtraction' method. The study was carried out in a greenhouse, using a completely randomized experimental design with a factorial arrangement (7×3). The following treatments were tested: complete nutrient solution (N, P, K, Ca, Mg, S, B, Cl, Cu, Fe, Mn, and Zn); complete nutrient solutions with omission of only nitrogen (-N), phosphorus (-P), potassium (-K), calcium (-Ca), and magnesium (-Mg); and complete absence of nutrients and three increasing rates of biochar (0, 5, and 10 t ha-1). Absence of nutrients with biochar rates significantly influenced the growth and dry biomass production variables of the maize plants. Except for stem diameter and the ratio between shoot and root dry biomass, all variables were influenced by the interaction between nutrients and biochar rates. Nutrient omission limited maize growth; however, the application of biochar reduced these limitations and significantly improved all analyzed variables. In the treatments without fertilizer, maize growth was very low, with generalized symptoms of deficiency that would decrease with the application of biochar. Even in the treatment with complete fertilization, which showed some slight visual symptoms, these decreased with the application of biochar.(AU)

A cultura do milho é a segunda maior produção agrícola do Brasil. Alcança altos rendimentos, apoiada no uso intensivo de tecnologias, em particular, a adubação mineral, normalmente onerosa. Na visão de baixar custos de produção e melhorar a produtividade da cultura na pequena propriedade rural, neste trabalho foi testado pelo método diagnose por subtração a eficiência do biocarvão da cama de frango como fonte de nutrientes ao crescimento inicial do milho BRS 2022. O estudo foi realizado em casa de vegetação, utilizando delineamento experimental inteiramente casualizado, em esquema fatorial (7x3), com os seguintes tratamentos: solução nutritiva completa (N, P, K, Ca, Mg, S, B, Cl, Cu, Fe, Mn, Zn); soluções nutricionais completas com a omissão de apenas nitrogênio (-N), fósforo (-P), potássio (-K), cálcio (-Ca) e magnésio (-Mg); com ausência completa de nutrientes e três doses crescentes de biochar (0, 5 e 10 t ha-1). As variáveis de crescimento e produção de biomassa seca de plantas de milho foram significativamente influenciadas pela ausência de nutrientes e pelo efeito das doses de biocarvão. Com exceção do diâmetro do caule e da relação entre a parte aérea e a biomassa da raiz seca as interações também foram significativamente afetadas pelos tratamentos. A omissão de nutrientes limitou o crescimento do milho, no entanto, a aplicação do biocarvão diminuiu essas limitações e melhorou significativamente todas as variáveis analisadas. Nos tratamentos sem adubação, o crescimento do milho foi muito baixo, com sintomas generalizados de deficiência que diminuiriam com a aplicação do biocarvão. Até mesmo o tratamento com adubação completa que apresentou alguns leves sintomas visuais, houve redução a aplicação do biocarvão.(AU)

Quality of sweet corn seeds treated before and after storage / Qualidade de sementes de milho doce tratadas antes e após armazenamento

This work aims to evaluate the effect of industrial treatment with different chemicals and also seed sizes on the physiological behavior of sweet corn in addition to evaluating the content of active ingredients of insecticides before and three months after storage. Four lots of a single sweet corn cross hybrid (L1, L2, L3 and L4) and different sieves (S1, S2 and S3) were carried out in two experiments. Experiment 1: industrial seed treatment, T1 = untreated seeds (control), T2 = Maxim Advanced®, T3 = CruiserⓇ 350 FS and T4 = PonchoⓇ. Experiment 2: quantification of the content of active ingredients, commercial products Cruiser® 350 FS and Poncho and the distribution efficiency was measured by HPLC-UV. The results showed that industrial seed treatment with Maxim Advanced®, CruiserⓇ 350 FS and PonchoⓇ can be carried out three months before sowing without damaging sweet corn seeds. HPLC is efficient to quantify the content of active ingredients in sweet corn seeds treated with Cruiser 350 FS and PonchoⓇ. The industrial seed treatment was calibrated for each batch, which is justified by the different amounts of active ingredient between batches and seed sizes.

Este trabalho tem por objetivo avaliar efeito do tratamento industrial com diferentes produtos químicos e também tamanhos de sementes sobre o comportamento fisiológico do milho doce além de avaliar o teor de ingredientes ativos dos inseticidas antes e três meses após o armazenamento. Quatro lotes de um único híbrido cruzado de milho doce (L1, L2, L3 e L4) e diferentes peneiras (S1, S2 e $3) foram realizados dois experimentos. Experimento 1: tratamento industrial de sementes, T1 = sementes não tratadas (controle), T2 = Maxim Advanced®, T3 = Cruiser 350 FS e T4 = Poncho®. Experimento 2: quantificação do teor de princípios ativos, produtos comerciais CruiserⓇ 350 FS e Poncho e a eficiência de distribuição foi medida por HPLC-UV. Os resultados mostraram que o tratamento de sementes industriais com Maxim Advanced®, CruiserⓇ 350 FS e Poncho® pode ser realizado três meses antes da semeadura sem danificar as sementes de milho doce. A HPLC é eficiente para quantificar o conteúdo de ingredientes ativos em sementes de milho doce tratadas com CruiserⓇ 350 FS e Poncho®. O tratamento industrial de sementes foi calibrado para cada lote, o que se justifica pelas diferentes quantidades de ingrediente ativo entre os lotes e os tamanhos das sementes.

A stomata classification and detection system in microscope images of maize cultivars.

Plant stomata are essential structures (pores) that control the exchange of gases between plant leaves and the atmosphere, and also they influence plant adaptation to climate through photosynthesis and transpiration stream. Many works in literature aim for a better understanding of these structures and their role in the evolution process and the behavior of plants. Although stomata studies in dicots species have advanced considerably in the past years, even there is not much knowledge about the stomata of cereal grasses. Due to the high morphological variation of stomata traits intra- and inter-species, detecting and classifying stomata automatically becomes challenging. For this reason, in this work, we propose a new system for automatic stomata classification and detection in microscope images for maize cultivars based on transfer learning strategy of different deep convolution neural netwoks (DCNN). Our performed experiments show that our system achieves an approximated accuracy of 97.1% in identifying stomata regions using classifiers based on deep learning features, which figures out as a nearly perfect classification system. As the stomata are responsible for several plant functionalities, this work represents an important advance for maize research, providing an accurate system in replacing the current manual task of categorizing these pores on microscope images. Furthermore, this system can also be a reference for studies using images from different cereal grasses.

H2O2 priming induces proteomic responses to defense against salt stress in maize.

KEY MESSAGE: H2O2 priming reprograms essential proteins' expression to help plants survive, promoting responsive and unresponsive proteins adjustment to salt stress. ABSTACRT: Priming is a powerful strategy to enhance abiotic stress tolerance in plants. Despite this, there is scarce information about the mechanisms induced by H2O2 priming for salt stress tolerance, particularly on proteome modulation. Improving maize cultivation in areas subjected to salinity is imperative for the local economy and food security. Thereby, this study aimed to investigate physiological changes linked with post-translational protein events induced by foliar H2O2 priming of Zea mays plants under salt stress. As expected, salt treatment promoted a considerable accumulation of Na+ ions, a 12-fold increase. It drastically affected growth parameters and relative water content, as well as promoted adverse alteration in the proteome profile, when compared to the absence of salt conditions. Conversely, H2O2 priming was beneficial via specific proteome reprogramming, which promoted better response to salinity by 16% reduction in Na+ content and shoots growth improvement, increasing 61% in dry mass. The identified proteins were associated with photosynthesis and redox homeostasis, critical metabolic pathways for helping plants survive in saline stress by the protection of chloroplasts organization and carbon fixation, as well as state redox. This research provides new proteomic data to improve understanding and forward identifying biotechnological strategies to promote salt stress tolerance.

A 3D ecotoxi-topological profile: Using concentration-time-response surfaces to show peroxidase activity in Zea mays (L.) exposed to aluminium or arsenic in hydroponic conditions.

This study sought to use concentration-time-response surfaces to show the effects of exposure to toxic (semi-)metals on peroxidase activity in higher plants as a function of exposure-concentration and exposure-time. Maize (Zea mays L.) seedlings (i.e., leaves and roots) were exposed to arsenic (as As3+) or aluminium (as Al3+) under hydroponic conditions, and their biomass and peroxidase enzyme responses were assessed at different concentration-time-exposures. The 3D ecotoxi-profile generated with these data showed two distinct regions: the first region is formed by exposures (i.e., points for time-concentration pairings) that were not statistically different from the results of the control points (i.e., zero toxicant concentration and all exposure-times), whereas the second region is formed by exposure pairings with results that were statistically different to those obtained from control pairings. Overall, the data show that enzyme activity increased over a shorter exposure-time when there was an increase in the exposure-concentration of the toxicant, which can be seen on a 3-D toxicity profile. We propose that quantitative relationship ratios from different assessed endpoints (e.g., biomass and enzyme activity) and enzymatic concentration-time-response surfaces could be helpful in the field of environmental-policy management.

Supplemental irrigation using brackish water on maize in tropical semi-arid regions of Brazil: yield and economic analysis

Supplemental irrigation during dry spells could reduce maize yield losses in tropical semi-arid regions, notably in small farms. However, good quality water reserves are not sufficient to meet the demands of farming communities. Consequently, our objective was to evaluate the productivity and profitability of maize under different simulated rainfall scenarios, with and without supplemental irrigation (SI) with brackish water. The field experiments were carried out during the cropping seasons of 2018 and 2019 on Ultisol. The experiment followed a randomized block design in the split-plot scheme with four replicates. The plots were formed by simulating the water supply in the soil corresponding to four water scenarios (rainy, normal, drought and severe drought), and the sub-plots with or without SI with brackish water (Electrical conductivity of 4.5 dS m−1). Mean yields of green maize ears were 13,083, 11,532, 10,358 and 9,609 kg ha−1 for rainy, normal, drought and severe drought scenarios, as supplemented with brackish water. For the same treatments without SI the values were 11,394, 7,896, 3,913 and 1,374 kg ha−1, respectively. Data on farmer's income showed that under normal, drought and severe drought supplementation with brackish water becomes economically advantageous from 0.9, 1.0 and 2.4 ha, respectively, while maize cultivation without SI is not advantageous under the last two scenarios. For severe drought conditions, however, SI using brackish water reduced commercial yield by 27 % with negative effects on the farmers’ profitability. In this case, it is necessary to use water with either lower salinity or select salt tolerant crops.

Supplemental irrigation using brackish water on maize in tropical semi-arid regions of Brazil: yield and economic analysis

Supplemental irrigation during dry spells could reduce maize yield losses in tropical semi-arid regions, notably in small farms. However, good quality water reserves are not sufficient to meet the demands of farming communities. Consequently, our objective was to evaluate the productivity and profitability of maize under different simulated rainfall scenarios, with and without supplemental irrigation (SI) with brackish water. The field experiments were carried out during the cropping seasons of 2018 and 2019 on Ultisol. The experiment followed a randomized block design in the split-plot scheme with four replicates. The plots were formed by simulating the water supply in the soil corresponding to four water scenarios (rainy, normal, drought and severe drought), and the sub-plots with or without SI with brackish water (Electrical conductivity of 4.5 dS m−1). Mean yields of green maize ears were 13,083, 11,532, 10,358 and 9,609 kg ha−1 for rainy, normal, drought and severe drought scenarios, as supplemented with brackish water. For the same treatments without SI the values were 11,394, 7,896, 3,913 and 1,374 kg ha−1, respectively. Data on farmer's income showed that under normal, drought and severe drought supplementation with brackish water becomes economically advantageous from 0.9, 1.0 and 2.4 ha, respectively, while maize cultivation without SI is not advantageous under the last two scenarios. For severe drought conditions, however, SI using brackish water reduced commercial yield by 27 % with negative effects on the farmers profitability. In this case, it is necessary to use water with either lower salinity or select salt tolerant crops.(AU)