Denise Garcia de Santana

Influência da cultura antecessora e da adubação nitrogenada na produtividade de milho em sistema plantio direto e solo preparado

In the Cerrado region a proportion of the top dressed N for corn might be applied to the previous cover crop. This could accelerate the decomposition rate and increase overall N availability to corn. Therefore, the objectives of this experiment were: a) to evaluate maize productivity after oil radish and millet grown in winter with and without nitrogen applied and b) to determine the efficiency of recovery of N fertilizer by corn and quantify the losses by volatilization of ammonia of N fertilizers in no-tillage (NT) and conventional tillage (CT). The experimental design was a randomized complete block in strips with four replications. At flowering, the dry matter production and N accumulation of the oil radish were, respectively, 2,274 and 53.0kg ha-1 under NT, and 2,546 and 61.6kg ha-1 under CT. For millet the results obtained were 5,202 and 107.8kg ha-1 under NT, and 5,101 and 104.1kg ha-1 under CT. Until the seeding of the maize under NT, after desiccation by knife rolling the winter crops, 77.3 and 130.7kg N ha-1 were released in the sequences of oil radish - maize and of millet - maize, respectively. Under CT the winter crops were incorporated into the soil before the seeding of the maize. In the growth cycle of corn the losses of N via ammonia volatilization were less than 2.0% of the N applied at pre-seeding (71.3kg N ha-1 in a mixture urea:ammonium sulphate of 4:1) and 14% of the N at the 6-leaf stage (35.7kg N ha-1 of ammonium sulphate), evaluated in NT and CT in the sequence oil radish - corn. Under NT the fertilizer-N-use-efficiency was 57.1 and 42.1% of the N applied in the sequence millet - corn and oil radish-maize, respectively. Under CT these values were 46.8 and 46.3%, respectively. The application of N fertilizer caused a mean yield increase of 2,396kg grain ha-1 in the sequence millet-corn under NT compared to the non-fertilized control. These increase under CT was 895kg grain ha-1 in the sequence oil radish-corn under NT, and 1,166 and 166kg grain ha-1 in the sequences millet-corn and oil radish-corn, respectively.

Silicon accumulation and water deficit tolerance in Brachiaria grasses

The beneficial effects of silicon (Si) fertilization have been observed for several plant species, especially when submitted to stress, either biotic or abiotic. Among the possible reasons for the greater adaptability and resistance of brachiaria grass in areas of low fertility soils in Brazilian savanna, stands its capacity of absorbing and accumulating Si in aerial parts. To evaluate the effect of Si on dry matter yield of Brachiaria decumbens Stapf and Brachiaria brizantha Hochst, grown under two soil moisture regimes, a trial was set up in a completely randomized design factorial scheme (5 × 2 × 2), with five Si rates: (0; 242; 484; 968 and 1,452 kg ha-1), two soil water tensions (60% and 80% of field capacity) and the two brachiaria species. The experiment was installed in a greenhouse, using one of the most representative soils in the region under cerrado, Typic Haplustox. Both brachiaria species can be considered Si-accumulating plants, since they present high Si contents in their aerial parts. Application of Si to the soil increased the contents of this element in both grass species but did not change their tolerance to water deficit, and did not affect dry matter yield.

Calculating germination measurements and organizing spreadsheets

Com o objetivo de minimizar as dificuldades dos iniciantes, estamos propondo o uso de planilhas eletronicas convencionais para o calculo das principais medidas de germinacao (ou emergencia), a organizacao dos dados finais para a analise estatistica e alguns comandos eletronicos envolvidos nesses passos.

Produtividade e rendimento industrial de híbridos de milho doce em função de espaçamentos e populações de plantas

In the present study we analyzed two sweet corn hybrids, in four row spacing and five plant populations. A randomized block design was used, in a 2x4x5 factorial, corresponding to hybrid (MD2001 and MD2002), row spacing (60; 70; 80 and 90 cm) and plant populations (50; 55; 60; 65 and 70 thousand plants ha-1) with four replications. Aiming to obtain a minimum ear length of 150 mm, recommended row spacing and population were 60 cm and 67 thousand plants ha-1, respectively. Under these management conditions, hybrid MD2001 presented greater ear kernel productivity, while hybrid MD2002 presented better industrial yield. Ear length and diameter, and the number of kernel lines represented the major components in ear and kernel productivity. Kernel depth was the major component for improving the industrial yield.

Comportamento inicial de espécies na revegetação da mata de galeria na Fazenda Mandaguari, em Indianópolis, MG

Degraded areas demand priority regarding actions for revegetation and recovery . However, there is a scarcity of studies to effectively guide us in these recovery practices. The objective of this work was to verify the growth, development and survival capacity of the individuals of the species implanted in the area of permanent preservation around the water reservoir on Mandaguari Farm, in Indianopolis, Minas Gerais. The species observed in fragments of the natural vegetation in the areas of the farm were the basis for the selection and production of seedlings used in the replanting. The replanting was carried out between 2005 and 2006 in 2.34 ha, which was divided in 26 parcels, measuring 21 x 21 m (441 m2). The distribution of the species was randomly performed with some restrictions in the randomization, so as to allocate neutral or even resistant species to flooding close to the margin of the dam. The areas differed from each other as to the percentile composition of the ecological groups (succession) and spacing (3 x 3 and 3 x 6 m). In spite of their relatively high mortality rates, Guazuma ulmifolia and Aegiphila lhotzkiana (50 and 28.6%, respectively) aggregated important development characteristics, which are their covering capacity (increments in height of 160 and 155 cm, respectively) and establishment (increments in diameter of 40.6 and 36.3 mm, respectively). Therefore, they were qualified as edifying agents in the regeneration process. Chorisia speciosa, in spite of the little prominence in height increment (71 cm), invested more in the diametric growth (31.4 mm), which is a fundamental characteristic for the establishment of the species.

Fontes e proporção de material orgânico para a produção de mudas de cafeeiro em tubetes

Neste trabalho, objetivou-se avaliar a qualidade das mudas de cafeeiro (Coffea arabica L.) produzidas em tubetes com substrato artificial suplementado com fontes de material orgânico em diferentes proporcoes. O experimento foi conduzido sob delineamento experimental de blocos casualizados em esquema fatorial 3 x 6, com quatro repeticoes em parcelas formadas por seis tubetes. O primeiro fator correspondeu as fontes de material orgânico (esterco bovino, humus de minhoca e cama de peru) e o segundo, suas proporcoes (0, 20, 40, 60, 80 e 100%) no substrato artificial (BioPlant-cafe) fertilizado com osmocote® (NPK 15-09-12). As caracteristicas avaliadas foram: altura da muda, diâmetro de caule, numero de pares de folhas, area foliar e massa seca da parte aerea e do sistema radicular. Pode-se concluir que o humus de minhoca adicionado ao substrato artificial na proporcao de 80% ou em uso exclusivo (100%) aumentou a area foliar das mudas de cafeeiro e, como consequencia proporcionou um maior acumulo de massa seca da parte aerea. O uso de esterco bovino (acima de 30%) e a cama de peru nao alterou ou reduziu as caracteristicas vegetativas das mudas de cafeeiro (altura da muda, diâmetro de caule, numero de pares de folhas e area foliar) e diminuiu o acumulo de massa seca.

Germinação de diásporos recém-colhidos de Myracrodruon urundeuva Allemão (Anacardiaceae) ocorrente no cerrado do Brasil Central

Myracrodruon urundeuva occurs in Northeast, Southeast, and West Center Brazilian regions, being considered as a vulnerable species to extinction. Diaspores collected in the Araguari River valley, MG, were used in three experiments, in a completely randomized design, with five replications of 50 diaspores each one. In the first and second experiments, germination boxes with vermiculite moistened with distilled water, GA3 and cytokinin at 1, 10, 100 µg mL-1, and 0.2% KNO3 were used as treatments. The first experiment was conducted under continuous fluorescent white lamps and the second in darkness. In the third experiment the diaspores were moistened with distilled water and stratified during one to six days at 45 oC in darkness. Control treatment was constituted by diaspores moistened with water, without stratification. For the experiments conducted under light conditions, data were collected observing the embryo protrusion every 24 hours; in darkness conditions counting was processed after seven days from the beginning of the experiment. Under continuous light, diaspores treated with 1 µg.mL1 GA3 were more homogeneous (CVt = 17.13%) and synchronized (Z = 0.64) in relation to the other treatments. The germinability ranged from 52.8% to 60% and occurred between two and three days. In darkness condition, germinability ranged from 50.4% to 58.8% and under stratification, from 49.6% to 61.2%. For the experiment testing stratification, the lowest mean time, the highest rate and germination uniformity were registered for diaspores stratified during six days. Although the germination process had been fast, low germinability indicates that new investigations are necessary to the sustainable exploration of this species.

Multiple dormancy and maternal effect on Miconia ferruginata (Melastomataceae) seed germination, Serra de Caldas Novas, Goiás, Brazil

Species with mostly asexual reproduction are interesting subjects for germination studies since variation would be more easily linked to environmental factors. Miconia ferruginata DC. is an apomictic treelet in Brazilian cerrado areas on rocky outcrops. Germination of seeds collected from individuals occurring in the Serra de Caldas Novas State Park, Goias, was studied in three experiments under controlled conditions. Germination characteristics differed among individuals and were correlated with altitude and soil Al content. Seeds from plants growing at lower altitudes, with lower soil aluminium content, presented malformed seeds with absence of embryo which rendered lower, but better synchronized germination. The nested analysis showed that from the total variance, 78.14% for germinability, 54.56% for uncertainty of the germination process, and 68.30% for the quantity of seeds without embryo was attributed to the altitudinal effect. Individuals nested within altitude contributed up to 16.93% for the total variance. It means that there is low variability among individuals of the same altitude and high variability among individuals from different points of the slope, making clear that for the studied population the environmental effect is stronger than the genetic component to determine the seed quality. The testa of the seeds provides a mechanical dormancy which seems to be associated also with phenolic compounds, which help to disperse germination through time. Photoblastism was also registered for seeds of this species.

Emergência de plântulas oriundas de sementes recém colhidas e armazenadas de Copaifera langsdorffii Desf. (caesalpinioideae), triângulo mineiro, Brasil

Copaifera langsdorffii is a threatened species that presents seeds with multiple dormancy and low resistance to storage. Thus, it is interesting to know if the seeds lose viability from the physiological maturity point and if they resist to desiccation during the storage period. Four experiments were conducted using seeds from the Araguari River Valley, MG (matrix 1, July and matrix 2, August 2005). Two of them had newly-collected seeds and the other two used seeds stored in cold chamber. The loss of 31% of water from the seeds collected from the soil in relation to the seeds collected from the tree reduced the percentage of emergence in about 10%. The presence of aril increased the value of the coefficient of variation of the emergence, indicating the presence of germination inhibitors in this part of the seeds. The seeds had lost viability after storage, reducing significantly the percentages of emergence. This characteristic indicates that seeds of this species have some degree of recalcitrance. To obtain a high number of seedlings in short time, with high synchrony, seeds collected from newly-opened fruits, directly of the tree, without aril, and scarified are recommended.

Biometria de frutos e sementes e emergência de plântulas de duas espécies frutíferas do gênero Campomanesia

The species Campomanesia adamantium and Campomanesiapubescens are morphologically similar, occur in common areas in the Cerrado, so they are difficult to be separated and identified. The objectives were to analyze biometrics of fruits and seeds of C. adamantium and C. pubescens, and the process of emergence of seedlings, for comparisons between species. In November 2007, 50 fruits of each species were measured of the transversal length (mm) and longitudinal (mm) of the fruits and seeds, fresh weight of fruits (g), number of locules per fruit and number of loci seeds. For the emergence testing, two independent experiments, one for each species, were installed in a completely randomized design with six methods of fruit processing for removal, drying or washing the mucilage, and four replicates with 40 seeds per plot. With the fruits of greater volume, with accumulation of fresh and wider biometrics in relation to C. pubescens, C. adamantium has a potential for selection of promising materials for breeding purposes. Drying in the shade for 24 hours with seed mucilage reduces the percentage of emergence and normal seedlings of C. adamantium, besides the seedlings emergence rate, although this method is indifferent to seedlings of C. pubescens. Under the same experimental conditions, seedlings of C. pubescens have a higher capacity emergence and normal seedlings as well as higher daily frequencies of seedlings emerged and reducing the time of emergence in relation to the seedlings of C. adamantium.