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In the present study, we aimed to assess the in vitro viability of pollen grains from maize cultivars collected at different times and days in the field. Four cultivars (Sol da Manhã, XB 6012, XB 8010, and BRS 2020) were evaluated from the second to fifth day of anthesis in three times. Pollen samples were evaluated for their in vitro viability through standard germination test in liquid and solid media and tetrazolium staining. The experimental design was completely randomized, in 4x4x3 split-split plots with four replicates. Data were subjected to analysis of variance followed by a means clustering test and linear regression analysis. The average percentage of viable pollen varied according to the day, collection time, and cultivar. In general, XB 8010 and BRS 2020 had the highest frequency of viable pollen. The highest percentages of viable pollen were observed on the second day of anthesis at 10:00h.

ResumoOs objetivos deste trabalho foram avaliar cultivares de milho quanto à eficiência na absorção e uso de nitrogênio (N) através de índices de eficiência de utilização de nitrogênio, em níveis contrastantes desse nutriente em ambiente de casa de vegetação. O experimento foi conduzido em casa de vegetação e o delineamento experimental utilizado foi o de blocos casualizados, com 20 tratamentos e quatro repetições, dispostos em um esquema fatorial de 10 x 2. As 10 cultivares de milho foram representadas por variedades locais e híbridos comerciais e as doses de N aplicadas foram de 100 e 400 mg dm -3 . As parcelas foram representadas por vasos de 8 L, os quais continham 4 plantas por vaso, sendo colhidas no estádio fenológico V8. As características avaliadas foram o peso de matéria seca e teor de N da parte aérea e raízes. Também foi avaliada a eficiência nutricional das cultivares. As cultivares estudadas apresentaram características distintas quanto à eficiência no uso e absorção de N nos ambientes com alto e baixo nível de nitrogênio. Os níveis contrastantes de N utilizados permitiram que ocorressem diferenças necessárias para distinguir as cultivares mais eficientes. Genótipos eficientes para uso de N e responsivos a sua aplicação podem ser selecionados pelos índices utilizados nesse trabalho. Palavras-chave: Zea mays, casa de vegetação, doses de nitrogênio AbstractThe objectives of this study were to evaluate corn cultivars for efficiency in the absorption and use of nitrogen (N) levels of efficiency through the use of nitrogen in contrasting levels of this nutrient in the greenhouse. The experiment was carried out in a greenhouse and the experimental design was in randomized blocks, with 20 treatments and four replicates, in a 10 x 2 factorial arrangement. All 10 maize cultivars were represented by local varieties and commercial hybrids, and the applied N levels were 100 and 400 mg dm -3 . Plots were represented by 8L pots containing 4 plants each, which were harvested in phenological stage V8. The evaluated characteristics were dry matter weight and N level of shoot and roots. The nutritional efficiency of cultivars was also evaluated. The studied cultivars had distinct characteristics concerning N use and absorption efficiency in environments of high and low nitrogen levels. The contrasting N levels allowed the occurrence of differences needed to distinguish the most efficient cultivars. Genotypes efficient for N use and responsive to its application can be selected based on the indexes used in this work.

Abstract

O objetivo desse trabalho foi avaliar características morfofisiológicas entre diferentes procedências de canafístula (<em>Peltophorum dubium</em>) submetidas a ambientes distintos quanto à disponibilidade de água e nutrientes no solo. O experimento foi conduzido em casa de vegetação, em delineamento experimental inteiramente casualizado, com 12 tratamentos e quatro repetições, dispostos em esquema fatorial 3 (procedências) x 2 (adubações) x 2 (irrigações). Foram coletados dados de altura de plantas, diâmetro do colo e índice SPAD (<em>soil plant analysis development</em>) ao longo do experimento em intervalos de 15 dias. Ao final do experimento foi aferido o peso da matéria seca da parte aérea, de raízes e total, quociente entre matéria seca de parte aérea e matéria seca de raízes, potencial hídrico foliar e índice de qualidade de Dickson. As progênies oriundas da Serra da Bodoquena e Serra de Maracaju demonstraram maior capacidade de resistir ao estresse hídrico e nutricional em relação às progênies da região de Ivinhema, MS. As diferenças entre procedências são intensificadas em ambientes que não proporcionam déficit hídrico para as mudas de canafístula. O estresse hídrico imposto às plantas de canafístula causa mais danos morfofisiológicos do que o estresse por falta de nutrientes.

Peltophorum dubium can be an alternative of forestry species to be included in integrated croplivestock-forestry systems in tropical region. The aim of this research was to evaluate the performance of P. dubium under intraspecific tree competition and cardinal directions to measure the possibility of introduction in integrated livestock-forestry systems. The experiment was performed in a Nelder Wheel competition, which is used in forestry research to test tree competition. The experimental design was factorial (10×2×5) with 12 replicates. The treatments were accomplished by ten tree competitions (159, 201, 255, 322, 408, 516, 653, 827, 1,046 and 1,324 trees ha -1 ), two cardinal directions (North-South and East-West) and five times after planting (12, 18, 24, 30 and 36 months). The highest tree competition (1,342 trees ha -1 ) in 36 months after planting, promoted increase in the cylindrical volume of the tree in both North-South and East-West cardinal directions. Nevertheless, the cardinal direction East-West was profitable to increase tree height, diameter at breast height (DBH), cylindrical volume per tree and cylindrical volume per hectare. The DBH measured in 24 months after planting was 5.0 cm, which is considered the minimum DBH to introduce livestock into the integrated system without significant damage on trees. Regarding these preliminary results in the first three years, P. dubium was promising as Brazilian native species to be inserted in integrated livestock-forestry system or single forestry as an option for Eucalyptus spp.

The orientation of tree-rows in a silvopastoral system associated with different seasons of the year allows more or less sunlight penetration, resulting in deliberate modification of the microclimate composition and thermal conditions provided to animals. In this sense, the aims of this study were to evaluate microclimatic variables and thermal comfort indices for east-west and north-south oriented silvopastoral systems, compared to unshaded systems during summer and winter. The study was conducted at the Modelo II Farm (21° 08’ S 53° 17’ W) at an altitude of 354 m. A randomized block design in scheme of split-split plots with five repetitions was adopted. Two planting directions and a control treatment (unshaded) were evaluated in the plots. Collection times were evaluated in sub-plots, and the distance from eucalyptus trees was evaluated in sub-sub-plots. Changes in the east-west and north-south planting directions did not promote changes in climate variables, nor did they change the thermal comfort indices during summer. There were differences, however, in temperature and relative humidity of the air, black globe temperature, and radiant heat load during winter. Silvopastoral systems provide improvements in the environment and, concomitantly, to the thermal comfort of animals, when compared to unshaded systems. However, thermal stress situations occur despite the presence of trees, depending on the time of the day and the distance from the rows of eucalyptus trees.

A blood meal is a by-product of the meat processing industry and can be used as nitrogen fertilizer due to its minimum content of 10 % Nitrogen. The objective of this work was to evaluate the effect of doses of blood meal, such as nitrogen fertilizer in topdressing, on the production components and the severity of diseases in sweet corn. The experiment was developed at the Federal Institute of Education, Science and Technology of Mato Grosso do Sul (IFMS), Ponta Porã campus, in a Quartzarenic Neosol. The experimental design used was randomized blocks with five treatments of blood meal doses of (0 kg ha-1; 48 kg ha-1; 96 kg ha-1; 120 kg ha-1 and 144 kg ha-1) and one treatment using urea for topdressing fertilization with 120 kg ha -1 of N. The experiment analyzed the severity of white spot on the tasseling and milk grain stages and also the production components: plant height, insertion height of the first ear, stalk diameter, length of the unhusked commercial ears, diameter of unhusked commercial ears, number of grain row, weight of husked commercial ears, weight of unhusked commercial ears and productivity in kg ha-1. The use of blood meal was as efficient as the use of urea as a nitrogen fertilizer for doses starting from 48 kg ha-1, the maximum productivity was obtained when the dose of 112 kg ha-1 of N blood meal was used. The severity of the white spot did not progress in treatments containing nitrogen fertilization in topdressing.