Relações hídricas em cultivares de beterraba em diferentes níveis de salinidade do solo

The excess of salts in the soil can directly affect the development and yield of the plants, therefore, studies on water relationships of crops in such conditions are necessary to prevent or solve the problem. The study was conducted in a greenhouse at Universidade Estadual Paulista, Department of Agricultural Engineering, Botucatu, Brazil. The statistical design used was randomized blocks with four replications, consisting of five levels of soil salinity (1.0, 3.0, 6.0, 9.0, 12.0 dS m-1), two cultivars of sugar beet (Early Wonder and Itapuã) and two types of management of fertigation, totaling in all 80 plots. Measurements of water content of the leaves, diffuse resistance to water vapor, transpiration, leaf area and the water consumption of crop were determined. There was a decrease according to increasing salinity for the analysed physiological parameters in the Early Wonder variety while for the Itapuã variety a gradual increase was observed up to a salinity of 6 dS m-1. The water consumption by plants showed a reduction with increase of soil salinity for the two varieties.

Alternative substrates in the production of lettuce seedlings and their productivity in the field

Based on the hypothesis that alternative substrates should improve the yield of lettuce crops by producing better quality seedlings, the objective of this work was to evaluate the effect of different substrates on the production of seedlings of this species, and their growth in the field. The study was in two stages. The first consisted of the production of lettuce seedlings, and the second assessed their development in the field. Four alternative substrates were tested, obtained by mixing together a sieved vermicompost from which all clumps had been removed, sterilized sand, charred rice husks and basalt powder. The commercial substrate, Plantmax HA®, was also tested. In the first phase, which was conducted in a completely randomised design with four replications, the height, root length, number of leaves, leaf area and dry weight of the seedlings were all evaluated 28 days after sowing. In the second phase, which was carried out in the field in a randomised block design with four replications, the plants were harvested 50 days after transplanting and the head diameter, fresh weight, number of leaves and leaf and stem dry weight were evaluated. The alternative substrates produced larger seedlings in less time than the commercial substrate, resulting in a reduction of 10 days in the total crop cycle. The reduction in the time between sowing and harvesting, together with those aspects relating to sustainability, are the main advantages of the use of alternative substrates, since in the field crop production did not differ between treatments.

Comportamento de híbridos de milho transgênicos e respectivos híbridos isogênicos convencionais em relação à infestação de Spodoptera Frugiperda (j. E. Smith,1727) (Lepidoptera: Noctuidae) em duas localidades e épocas de semeadura

The fall armyworm Spodoptera frugiperda is one of the most important pests of maize. Various studies are conducted for their management, integrating chemical and biological control tactics as well as resistant plants. In order to offer alternatives for an efficient management of this pest with minimal use of pesticides, the technology of genetically modified plants resistant to insects has been widely studied. The aim of the present study was to evaluate the natural infestation of larvae of S. frugiperda and their injuries under field conditions in transgenic maize hybrids compared to their conventional isogenic counterparts at two sowing dates and two regions. The hybrids were planted in the off season of 2010 in Jaboticabal, SP, Brazil, and the summer of 2010/2011 in Jaboticabal, and Pindorama, SP, in a randomized block with seven treatments (hybrids) and four replications. Different levels of infestation of larvae occurred throughout the phenological development of plants in conventional and genetically modified hybrids with significant differences between the two groups in most evaluations. The hybrid 2B710HX was the least infested with caterpillars and had the least damaged leaf area. It follows that the Cry1F toxin was the most effective in protecting the plant in relation to other toxic proteins expressed by the other Bt hybrids against infestation and damage promoted by this pest, regardless of time of sowing.

Physiological indexese macro- and micronutrients in plant tissue and essential oil of Mentha piperita L. grown in nutrient solution with variation in N, P, K and Mg levels

Mentha piperita L. is an aromatic and medicinal species of the family Lamiaceae, known as mint or peppermint, and its leaves and branches produce essential oil rich in menthol. This study aimed to evaluate physiological indexes, macro- and micronutrients inthe shootsand essential oil of Mentha piperita L. grown in nutrient solution number 2 of Hoagland and Arnon (1950) with different N, P, K and Mg levels. Shoot length, dry mass of the different organs, total dry mass, leaf area, essential oil yield and composition, and macronutrient (N, P, K, Mg, Ca, S) and micronutrient (Mn, Cu, Fe, Zn) contents in the shoot were evaluated. Plants treated with 65%N/50%P/25%K/100%Mg had a tendency towards longer shoot, greaterroot and leaf blade dry masses, higher essential oil yield, higher menthol levels and lower menthone levels. The results showed that Mentha can be grown in nutrient solution by reducing 65% N, 50% P, 25% K and 100% Mg. This solution had better development compared to the other tested treatments. Therefore,we recommendMentha piperita L. to be grown with such nutrient levels.

Estimativa da área foliar de Euphorbia heterophylla

Leaf area estimate may contribute to understand the relationships of interference among weeds and crops. The objective of this research was to obtain a mathematical equation to estimate the leaf area of Euphorbia heterophylla based on linear measures of the leaf blade. Correlation studies were carried out using the real leaf area and leaf length (C) and the maximum leaf width (L) of 200 leaf blades which were collected from several agroecosystems at Universidade Estadual Paulista in Jaboticabal, SP, Brazil. The evaluated statistic models were: linear Y = a + bx; simple linear Y = bx; geometric Y = ax b; and exponential Y = ab x. All of the evaluated models can be used for E. heterophylla leaf area estimation. The simple linear regression model is suggested using C*L and taking the linear coefficient equal to zero. Thus, an estimate of the leaf area of E. heterophylla can be obtained using the equation Af' = 0.6816*(C*L).

Eficiência do silicato de potássio no controle do oídio e no desenvolvimento de abobrinha de moita

The most widely standard used for powdery mildew control on cucurbitaceas is the use of resistant cultivars and systemic fungicides, even though nutrition has been an option. The supply of silicon is benefic to many vegetable species, stimulating growth, yield, photosynthesis and regulation of transpiration; besides, its deposition in the epidermis avoids the invasion of fungus, bacteria and sucking insects. The aim of this experiment was to evaluate the influence of potassium silicate on powdery mildew control, development and yield of zucchini squash, cultivar Caserta. The experiment was conducted at Universidade Estadual Paulista, in greenhouse conditions and with a randomized design, divided in four replications, 11 plants per plot and five treatments: control (water), chemical treatment with fenarimol (2.4 g a.i. 100 L-1) and potassium silicate, in doses 1.5 L ha-1; 2.0 L ha-1 and 2.5 L ha-1. We evaluated the disease severity; gas exchange (net CO2 assimilation rates, transpiration, stomatal conductance and water use efficiency); growth (leaf area ratio, relative growth rate, absolute growth rate, net assimilation rate and specific leaf mass) and yield. The results showed that the foliar application of potassium silicate and fenarimol controlled powdery mildew and had no influence on plant growth. Therefore, the potassium silicate may be used as alternative for control of fungal pathogens and reduced application of chemical products, which provides a greater environmental sustainability. However, it is necessary to be careful with high doses because it was observed that 2.5 L h-1 was harmful to fruit production and gas exchange, despite being effective in controlling powdery mildew. According to this study it is recommended using 2.0 L ha-1 for control of powdery mildew to zucchini squash, and can replace the use of fenarimol, without affecting productivity and development of plants.

Adubação fosfatada no crescimento inicial e na nutrição de mudas de pinhão-manso

Physic nut (Jatropha curcas L.) is a perennial oilseed species that has aroused economic interest for biodiesel production. Among other factors, it is essential to determine the nutritional demands of this species to facilitate raising it as a crop. This study aimed to evaluate the early growth and mineral nutrition of physic nut, as well as soil fertility, as affected by phosphorus fertilization. The study was carried out in a plastic greenhouse in a completely randomized block experimental design with four replicates. The plants were grown in plastic pots filled with 50 dm³ of Latossolo Vermelho (Rhodic Hapludox). Application rates of 0, 50, 100, 150 and 200 mg dm-3 of P were tested, plus a control. Evaluations of plant height and root collar diameter were performed monthly. The experiment was ended 150 days after transplant of the seedlings, at which time leaf area, dry weight, leaf contents and total accumulation of macro- (N, P, K, Ca, Mg and S) and micronutrients (B, Cu, Fe, Mn and Zn) were performed, and soil chemical properties were analyzed. We concluded that absence of P fertilization alone is as limiting to early growth of physic nut as simultaneous absence of soil amendment and fertilization. The rate of 57 mg dm-3 of P may be recommended for initial growth of physic nut. The total accumulation of nutrients in physic nut seedlings exhibited the following order: K>N>Mg>Ca>P>S>Fe>Mn>B>Zn>Cu. Phosphorus fertilization resulted in increased soil cation exchange capacity (CEC).

Estimativa da área foliar de Panicum maximum usando dimensões lineares do limbo foliar

The objective of this study was to obtain a mathematical equation to estimate the leaf area of Panicum maximum using linear measures of leaf blade. Correlation studies were conducted involving the real leaf area (Sf), the main vein leaf length (C), and the maximum leaf width (L). The linear and geometric equations related to C provided good leaf area estimates. For practical reasons, the use of an equation involving only the C*L product is suggested. Thus, an estimate of P. maximum leaf area can be obtained by the equation Sf = 0.6058 (C*L), with the coefficient of determination R = 0.8586.

Categorias e mecanismos de resistência de genótipos de couve A Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae)

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

Increased carbon dioxide concentration in the air reduces the severity of Ceratocystis wilt in Eucalyptus clonal plantlets

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Phosphorus fertilization of 'Fuyutoyo' cabbages in phosphorus-rich Eutrustox soil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Functional traits of selected mangrove species in Brazil as biological indicators of different environmental conditions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Copper oxychloride fungicide and its effect on growth and oxidative stress of potato plants

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Carbohydrate production and transport in cotton cultivars grown under boron deficiency

An adequate supply of boron (B) is required for the optimal growth and development of cotton (Gossypium hirsutum L.) plants, but the low phloem mobility of B limits the possibilities of correcting B deficiency. There are indications that different cotton cultivars could have different responses to B deficiency. The differences in responses of cotton cultivars to B regarding photoassimilate production and transport were studied in a greenhouse experiment with nutrient solution. Treatments consisted of three cotton cultivars (FMT 701, DP 604BG and FMX 993) and five concentrations of B (0.0, 2.5, 5.0, 10.0 and 20.0 mu mol L-1). Sampling began at the phenological stage B1 (first square) and continued for four weeks. The leaf area and the number of reproductive branches and structures decreased due to B deficiency. A higher level of abortion of reproductive structures was observed under B deficiency. Boron deficiency increased the internal CO2 concentration but decreased the transpiration rate, stomatal conductance and photosynthesis. Despite the decrease in photosynthesis, nonstructural carbohydrates accumulated in the leaves due to decreased export to bolls in B-deficient plants. The response to B deficiency is similar among cotton cultivars, which shows that the variability for this trait is low even for cultivars with different genetic backgrounds.

Biomassa microbiana e degradação de serapilheira em pastos de tifton-85 manejados com índices de área foliar residual

Pós-graduação em Zootecnia - FCAV