João Carlos Cardoso Galvão

Estoques totais de carbono orgânico e seus compartimentos em argissolo sob floresta e sob milho cultivado com adubação mineral e orgânica

Soil organic matter and its different pools have key importance in nutrient availability, soil aggregation, and in the greenhouse gas fluxes between the earth surface and the atmosphere. The objectives of this study were: a) to evaluate the effect of maize production systems under organic and mineral fertilization on total organic carbon (TOC) and total nitrogen (TN) stocks and on organic carbon pools (C) in an Acrisol; and b) to estimate the contribution of these systems in the atmospheric CO2 sequestration or emission. The production systems included two levels of organic compost: level 0 (control) and levelxa01 (40xa0m3xa0ha-1); and three levels of mineral fertilizer (0, 1 and 2), which correspond to 0,250 (AM1), and 500xa0kgxa0ha-1 (AM2) of the 4-14-8 formula. Organic and mineral fertilizer were combined and applied during 16 years. As a reference of the steady state, soil samples were collected from an adjacent area of the same soil type, under secondary Atlantic Forest (AF). Where organic compost was added, the production systems presented higher organic C and N soil storage, light fraction carbon (CLF) and labile carbon (CL) than production systems without fertilization or with mineral fertilizer only. This confirms the importance of organic fertilizer utilization as a management strategy to improve soil quality. However, the soil under AF showed higher values of organic C and N storage and carbon pools than soils under production systems. Due to their higher sensitivity, the stocks of the CLF and CL were more severely decreased than the TOC stocks and thus, may be used as indicators of the anthropogenic impact or the influence of management alterations on the soil organic matter.

Efeito da aplicação de águas residuárias de suinocultura sobre a produção do milho para silagem

This work was carried out with the objective of evaluating the effect of four depths of water and swine wastewater-gross and after sieving, on production of corn (Zea mays, L.) for silage. Water was applied in eight lysimeters, in other eight gross swine wastewater (ARB) was applied and the sieved pig wastewater (ARP) on the other eight. The depths applied corresponded to 0.5, 1.0, 1.5 and 2.0 times of the reference evapotranspiration. The production components, height of the plants, height of spikes, spike index, productivity of spikes and productivity of green matter were evaluated 140 days after sowing. The mean productivities of green matter in the treatments with ARB and ARP were equivalent to 45 and 46 t ha-1, corresponding to, respectively, 51 and 52% higher than the productivity in the water treatment. The application of swine wastewater increased the height of plants, spike index, height of spikes and weight of spikes. In general, the sieving of swine wastewater and the water depth did not affect the production components of the silage corn.

Características da porosidade de um Argissolo Vermelho-Amarelo submetido a diferentes sistemas de preparo de solo

The porosity characteristics of a Red-Yellow Podzolic was evaluated after 10 years of cultivation, under the following soil management treatments: no-tillage, moldboard plowing + disking, disk plowing + disking, off-set disk harrowing followed by moldboard plowing + disking, off-set disk harrowing followed by disk plowing + disking and off-set disk harrowing followed by disking. Undisturbed 15 cm high and 15 cm deep soil blocks, were sampled for morphometric analysis of the soil porosity. Results indicated the presence of surface sealing and discontinuity between top and subsurface in treatments where offset disk harrowing was employed. The no-tillage system showed higher connection between macropores, without discontinuities between the topsoil and deeper layers.

Formas de fósforo no solo em sistemas de milho exclusivo e consorciado com feijão sob adubação orgânica e mineral

Soil management systems affect the P dynamics in content and forms. The aim of this work was to measure the effect of several cultivations systems in the long term (16 years) on the different soil P forms. The treatments consisted of combinations of the two cultivation systems: sole corn (C) and corn-bean intercrop (CB), with two levels (0 and 1) of organic fertilizer (OF), at rates of 0 and 40xa0m3xa0ha-1xa0year-1 and three levels (0, 1, 2) of mineral fertilizer (MF) N-P-K, in the doses 0, 250 and 500xa0kgxa0ha-1 of the formula 4-14-8. An area under Atlantic Forest was used as reference of a balanced state. The values of total organic P (Pto) changed from 184.2 to 280.2 and from 184.4 to 282.9xa0mgxa0kg-1 in 0-10 and 10-20xa0cm deep soil, respectively. The highest values were observed for 500xa0kgxa0ha-1 of mineral fertilizer + organic fertilizer, corresponding on average to 26.4xa0% P in the soil. The C/Pto ratio of the treatments tended to be constant. An increase of the Pto values with the increase of the soil organic carbon content was observed. The mineral fertilizer promoted P increment in the microbial biomass (Pmb) in the sole corn crop system. The increase of Pmb was 262 and 164xa0% of the system that received the organic compost in the sole corn crop and corn-bean intercrop, respectively. On average, the fraction of organic soluble P corresponded to 90xa0% Pto, prevailing over the basic soluble fraction. The 500xa0kgxa0ha-1 of mineral fertilizer and 500xa0kgxa0ha-1 of mineral fertilizer + organic fertilizer treatments in the intercrop system caused increases in the total labile P (Plt) values of 53 and 157xa0%, respectively, compared to the reference. The labile organic P fraction (Plo) corresponded to 3.7xa0% of Pto for the cultivation systems; for the Atlantic Forest soil this relationship was 10.7xa0% at both depths. The increments in the contents of most labile P forms, owing to the organic manure, demonstrate the importance of this management system for an improvement of the P cycle.

Alteração de atributos químicos do solo e estado nutricional e características agronômicas de plantas de milho, considerando as modalidades de calagem em plantio direto

Lime application on the soil surface in no-tillage systems, without incorporation, has not been effective in certain edaphic and climatic conditions for the correction of acidity or for calcium and magnesium supply to plants. Searching alternatives for limestone application without the conventional tilling and harrowing operations, this study tried to evaluate the efficiency of different lime application forms for the chemical soil attributes, nutritional state, and agronomic characteristics of corn crop. A randomized block design with split-plots and three replications was used. The treatments applied on the plots were: double hybrid corn Z 8447; corn variety AL 25; and double hybrid AG 122; and on the split-plots: control without liming; lime applied along the soil profile in the planting furrow; lime applied by spreading on soil surface; lime applied along the soil profile into the planting furrow plus more lime spread on the soil surface. Where lime was applied in the furrows, maize was sown in the furrows that had received lime. Soils were sampled 30 and 150 days after liming, from the sowing line to a distance of 25 cm from the sowing line, and at five depths. The pH was determined in the water and exchangeable Ca, Mg and Al in the samples. The nutritional state of foliar tissue was evaluated for the three cultivars, as well as some agronomic crop characteristics. Results showed that the lime applied into the planting furrow was distributed efficiently along the soil profile down to a depth of 20 cm, in a 10 cm wide strip. Surface lime application only had an effect on the chemical soil characteristics down to a depth of 5 cm. The concurrent application along the soil profile into the planting furrow plus more lime on the surface was the most efficient, with higher values of pH, exchangeable Ca and Mg, and lower levels of exchangeable Al. No effect of the lime application mode was observed on the nutritional state of the tested cultivars or the agronomic characteristics of the corn crop.

Controle genético da resistência aos enfezamentos do milho

The objective of this work was to identify the genetic control of the resistance to corn (Zea mays L.) stunt. Two experiments were set up at March 2001, in Coimbra and Sete Lagoas, Minas Gerais State, Brazil. Each experiment consisted of 25 treatments, five of them were represented by maize hybrids. Other treatments were the hybrid combinations and their reciprocal ones. The randomized blocks design with three replicates was used. The experimental plot was integrally used and consisted of two 5xa0m rows at a 0.9xa0m spacing from each other, with 25xa0plants per row, representing a population around 55,000xa0plantsxa0ha-1. At the time of kernel fulfilling, the evaluations were performed for incidence and severity of the corn stunt. The disease index was also used. In both places, the productivity of the maize kernels were evaluated for each plot. Therefore, since this method presents high heritability itxa0was possible to confirm its efficiency. The genetic control of the resistance to corn stunt is mainly controlled by the alleles with predominant addictive effects; the parents differed in relation to the frequency of the addictive and nonaddictive alleles for resistance to corn stunt.

Superação da dureza de sementes e frutos de Stylosanthes scabra J. Vogel e seu efeito na germinação

This study was carried out to evaluate methods of breaking Stylosanthes scabra seed and fruit hardness, separately. The methods evaluated were: control dry heat at 85°C for 10, 12, and 14 hours, immersion in concentrated sulphuric acid for five and 10 minutes, and immersion in boiling water for one minute. The germination test consisted of evaluating normal seedlings (germination percentage), abnormal seedlings, hard seeds and dead seeds. It was concluded that the best treatment was seed scarification with concentrated sulfuric acid for five and 10 minutes. In relation to fruit scarification, an immersion time longer than 10 minutes deserves further study. The dry heat treatment did not overcome the impermeabily of the seed covering layers. Boiling water led to the death of more than 90% of the seeds.This study aimed to evaluate the efficiency of the accelerated aging test at different periods and exposure temperatures in evaluation of the physiological seed quality of sweet corn lots. The assays were carried out from February to June 2000 at the Laboratorio de Sementes of the Phytotechny Department in the Universidade Federal de Vicosa - MG. Corn seeds of the cultivar BR 400 (Super-Doce) were used into four lots obtained from a drying process at 30, 40, 50 and 60oC and an environmental relative humidity of 60%. Initially the moisture content of the seeds was determined and then the seed physiologic quality were evaluated by the germination, first germination count and cold tests. The entirely randomized experimental design was used for these tests. Two experiments were carried out in evaluating the methodology of the accelerated aging test. The first experiment was carried out at 42oC temperature on an entirely randomized design and a factorial scheme 4x4 (four aging periods: zero, 48, 72 and 96 hours and four seed lots) arranged on a split-plot design over time. The second experiment was carried out at 45oC temperature by using the same design and a factorial scheme 4x4 (four aging periods: zero, 24, 48 and 72 hours and four seed lots). In both experiments, the 45oC temperature and the 24hour-exposure to the accelerated aging provided a better differentiation among lots with different quality levels. The 42oC temperature over a 72 hour-period allowed a better differentiation between seed lots as to their physiologic quality.

Intensidades de perdas, ataque de insetos-praga e incidência de inimigos naturais em cultivares de milho em cultivo de safrinha

Conduziu-se este trabalho visando a estudar as intensidades de perdas, densidades de insetos-praga e inimigos naturais em 49 cultivares de milho (Zea mays L.) em cultivo de safrinha em Coimbra, MG, Brasil. A produtividade media das cultivares foi de 3438,74 kg/ha, sendo as cultivares Traktor, CDX98D06, CO9621, OC705 e 97TR61 as mais produtivas. Ocorreram 29,62% de perdas na produtividade das cultivares, devido principalmente ao ataque de Sitophilus zeamais (Motsch., 1865) (Coleoptera: Curculionidae) aos graos. O inseto-praga mais abundante foi Dalbulus maidis (DeLong & Wolcott, 1923) (Homoptera: Cicadellidae), seguido por adultos de Diabrotica speciosa (Germ., 1824) (Coleoptera: Chrysomelidae) e lagartas de Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae). O inimigo natural mais abundante foi o predador Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae). As densidades desses insetos foram semelhantes nas cultivares, com excecao de D. maidis. As cultivares menos atacadas por D. maidis foram: SHS5060, COE9994, HT8A97, NB6077, Z8550, CD3351, Maister, AG122, HS12L1133, HT47C, 97TR61, CDX98D04 e A975.

Incidência de insetos fitófagos e de predadores no milho e no feijão cultivados em sistema exclusivo e consorciado

This work was carried out in Coimbra, MG,Brazil, during the agricultural year of 1996/97 and it had the objective of evaluating the phytophagous insects and predators occurrence in maize and bean cultivated in exclusive and policultive systems. One cultivation of maize (from 10/25/1996 to 03/24/1997) and two cultivation of bean were conducted [the first one from 10/25/1996 to 01/20/1997 (rainy period cultivation) and the second one from 03/25/1997 a 07/21/1997 (drought period cultivation)]. The population of phytophagous insects and predators incident in the cultures were counted directly. Lower herbivores population density, which attacks preferentially maize [Dalbulus maidis (Delong & Wolcott) (Homoptera: Cicadellidae) and Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae)] and bean [Diabrotica speciosa (Germ.), Cerotoma arcuata (Oliv.) (Coleoptera: Chrysomelidae) and Empoasca kraemeri (Ross & Moore) (Homoptera: Cicadellidae)] were associated to the intercropped system. The generalists-insect densities as Thrips tabaci Lind. (Thysanoptera: Thripidae) and Pseudoplusia includens (Walk.) (Lepidoptera: Noctuidae) were higher in the bean intercropped with maize. The phytophagous-insect total number was higher in the bean intercropped with maize in the rainy period cultivation than in the bean cultivated exclusively. The opposite happened in the drought period cultivation. The predators Anthicus sp. (Coleoptera: Anthicidae) and Hymenoptera: Formicidae were more abundant in the maize and bean cultivated exclusively than when the cultures were cultivated intercropped.

Qualidade dos grãos de milho em função da umidade de colheita e da temperatura de secagem

Com este trabalho, objetivou-se avaliar o efeito imediato e latente de quatro teores de umidade de colheita, associados a quatro niveis de temperatura do ar de secagem sobre a qualidade do milho, colhido com 25, 22, 16,5 e 15% b.u. e secado nas temperaturas de 40, 60, 80 e 100 oC, ate a umidade final de 13% b.u. Os graos foram submetidos as analises de teor de impureza e materia estranha, massa especifica aparente, indice de danos, indice de trincas e susceptibilidade a quebra. De modo geral, pode-se inferir que os graos colhidos com os teores de umidade de 15 e 16,5% e secos nas temperaturas do ar de secagem de 40 e 60 oC, foram os tratamentos que menos afetaram a qualidade do milho.