Experimental observation of a complex periodic window

The existence of a special periodic window in the two-dimensional parameter space of an experimental Chua's circuit is reported. One of the main reasons that makes such a window special is that the observation of one implies that other similar periodic windows must exist for other parameter values. However, such a window has never been experimentally observed, since its size in parameter space decreases exponentially with the period of the periodic attractor. This property imposes clear limitations for its experimental detection.Comment: 4.2 pages, 4 figure

DRIS standards for nutritional evaluation of Phaseolus vulgaris in Cerrado, Goiás State, Brazil.

The knowledge of nutritional requirements of beans, the efficiency of soil acidity correction and the fertilization programs are essential to increase productivity. The Integrated Recommendation and Diagnosis System (DRIS) assists with nutritional diagnosis of cultivated plants based on existing interactions between nutrients and the hierarchizing of limitations. This study aimed at establishing standards using the DRIS method for areas of production of irrigated common beans and at determining the most limiting nutritional factors to production using leaf analyses interpreted by concentration ranges and DRIS. Eighteen different beanproducing areas were selected in a central pivot irrigation system, from which 82 sampling points were established to collect leaves of crop and determine their nutritional contents. The reference population had productivity of over 3,000 kg ha- 1. Using DRIS, we determined that phosphorus is the most limiting nutrient regarding its deficiency, with great sensitivity to diagnose nutritional problems of plants, especially micronutrients. Phosphorus (68.3%), molybdenum (65.9%), iron (64.6 %) and sodium (63.4%) and are nutrients with highest percentage of samples presenting levels below adequate according to sufficiency ranges for plants. Using DRIS, we can evaluate interactions among nutrients and determine of the magnitude of crop nutritional limitation whether due to deficiency or excess. These results may indicate which nutrients are limiting the crop productive capacity, allowing greater efficiency in its correction in soil

Índices de crescimento em capim-paraíso sob diferentes idades durante três ciclos de crescimento no litoral cearense.

Resumo: As forrageiras apresentam variação ao longo do seu crescimento, em razão de variação na idade fisiológica e das condições de meio e manejo. Objetivou-se avaliar os índices de crescimento em capim-paraíso em diferentes idades de crescimento (14; 21; 28; 35; 42; 49; 56; 63 e 70 dias) e durante três ciclos (chuvoso, seco 1 e seco 2), num delineamento inteiramente casualizado com medidas repetidas no tempo e duas repetições. Avaliaram-se a taxa de crescimento relativo (TCR), a razão de área foliar (RAF), a razão de peso foliar (RPF) e a área foliar específica (AFE). A interação entre idades de crescimento e ciclos foi significativa para todas as variáveis analisadas, exceto para a AFE. A TCR decresceu com as idades em ambos os ciclos, exceto no ciclo seco 2, com média de 0,0512 g?g-1?dia-1. A RAF e a RPF decresceram com o avanço nas idades. A AFE respondeu positivamente às idades. As idades de crescimento influenciam a dinâmica dos componentes morfofisiológicos do capim-paraíso. [Growth index in paraiso grass under different ages during three growth cycles in coastal Ceara]. Abstract: The forage plants show variation along their growth due to changes in physiological age, environment and management conditions. One aimed to analyze the growth index of paraiso grass, in different growth ages (14; 21; 28; 35; 42; 49; 56; 63 e 70 days) and cycles (rainy, dry 1 and dry 2). A completely randomized design in a split-plot layout with repeated measures and two replicates was adopetd. The relative growth rate (RGR), the leaf area ratio (LAR), the leaf weight ratio (LWR) and the specific leaf area (SLA) were evaluated. An interaction between growth ages and cycles was observed for all variable analyzed, except for SLA. The RGR showed a linear decreased effect in the cycles, except in dry 2 cycles, with an average of 0,0512 g?g-1?day-1. The LAR and LWR decreased along the ages. The SLA presented positive linear effect. The different growth ages influenced the morphofisiological components in paraiso grass

Accumulation and export of nutrients in cactus pear cladodes (Opuntia ficus-indica) under different managements in the Brazilian Semiarid.

Abstract: The present study evaluated the accumulation and export of nutrients in cactus pear (Opuntia ficus-indica) cv. Gigante, fertilized with combinations of nitrogen (10, 70, 100, 130, and 190 kg ha -1 year -1 N) and phosphorus (10, 70, 100, 130, and 190 kg ha -1 year -1 P2O5) under annual and biennial harvests, in Quixadá and Tejuçuoca, using a split-plot randomized block design with four replications. In Quixadá, under annual and biennial harvests, the following orders of accumulation of macronutrients (in kg ha -1 year -1) were found, respectively: K (98.8) > Ca (87.2) > N (46.7) > Mg (26.8) > S (18.4) > P (2.04) and Ca (33.5) > K (31.1) > S (18.6) > N (12.9) > Mg (10.5) > P (0.81). In Tejuçuoca, under annual and biennial harvests, the orders of accumulation of macronutrients were, respectively: K (146.5) > Ca (204.6) > N (128.1) > Mg (75.8) > S (50.3) > P (3.7) and K (397.2) > N (191.3) > S (241.2) > Ca (167.8) > Mg (131.0) > P (14.1). The maintenance/production fertilization in cactus pear should be planned according to productive potential, fertilization and harvest managements, and cultivation region, based on nutritional requirement and considering the nutrient recovery efficiency

Cactus Forage Productivity Modelling Using PHYGROW Software in a Semiarid Environment

Plant growth modeling has been shown an increasing strategy to cope with the high demand for food supply, mainly in climate vulnerable areas, providing them to be used in agriculture worldwide. Concerning semiarid regions, the PHYGROW software has been promising to model plant growth, as cactus forage (‘Opuntia stricta’ cv. “Mexican elephant ear”) which was used in this study. Production data from 2017 and 2018 in Petrolina, Permambuco state, Brazil, with 12 replicates each year were considered. This region shows a very hot and dry climate and has an erratic and seasonal rainfall, which varies a lot in quantity, frequency and intensity from one year to another. After the PHYGROW software parameterization, we performed the generation of the synthetic series and, afterwards, we add the field data to calibration and validation. The results showed a high prediction capacity of PHYGROW software, even in such an erratic climate as Brazilian Semiarid, considering the model performed as calibrated. In 2017 and 2018, the observed cactus forage biomass were 1745 ± 505.83 and 2016 ± 584.58 kg DM ha-1 and the estimated data were 1795 and 2314 kg DM ha-1, respectively. This relatively high deviation suggests an opportunity to add more data, in order to get the model more accurate. Although there was a high difference in precipitation from 2017 to 2018 (166 and 301 mm, respectively), cactus forage was capable to offset this fluctuation, which makes it a strategic resource to reduces the biomass variation and stockpiling necessity on the farm level. This study also demonstrated the importance of modelling to help the farmer to cope with the weather and feed variation in climate vulnerable areas, allowing them to anticipate and adopt strategies to cope with drought more efficiently

Densidade e estrutura do resíduo pós-pastejo em capim-massai adubado com nitrogênio e pastejado por ovinos.

Resumo: Somando-se ao suprimento nutricional, em especial a adubação nitrogenada, é imperativo o monitoramento rigoroso da condição residual do pasto. Objetivou-se avaliar a densidade e a estrutura do resíduo pós-pastejo em capim-massai adubado com N (0; 400; 800 e 1200 kg de N?ha-1?ano-1) e pastejado por ovinos num delineamento inteiramente casualizado com medidas repetidas no tempo. A elevação das doses de N influenciou as variáveis: densidade total de forragem residual, de forragem verde residual, de colmo verde residual, a relação lâmina foliar/colmo e o índice de qualidade da biomassa residual. Os ciclos de pastejo não exerceram alterações sobre a relação material vivo/material morto residual e densidade de forragem verde residual, sendo as demais variáveis modificadas pelos ciclos. A adubação nitrogenada proporciona respostas positivas sobre a densidade e estrutura do resíduo pós-pastejo do capim-massai. After grazing canopy structure and density of massai grass fertilized with nitrogen and grazed by sheep. Abstract: In addition to the nutrient supply, especially nitrogen, it is imperative to monitor carefully the residual condition of grass. To evaluate after grazing canopy structure and density of massai grass fertilized with nitrogen (0, 400, 800 and 1200 kg N?ha-1?year-1) and grazed by sheep in a completely randomized design with repeated measurements over time, this research was conducted. The nitrogen levels influenced the variables: residual total herbage density, residual green herbage density, residual green stem density, leaf/culm ratio and residual biomass quality index. The grazing cycles did not exert changes on the residual alive/senescent relation and residual green herbage density, being the others variables modified by the cycles. The nitrogen provides positive responses on after grazing canopy structure and density of massai grass

Dinâmica de perfilhamento em capim-massai adubado com nitrogênio e pastejado por ovinos.

Resumo: Avaliou-se a dinâmica de perfilhamento do capim-massai sob lotação rotativa com ovinos e adubado com nitrogênio (controle - 0; 400; 800 e 1200 kg N?ha-1?ano-1), num delineamento inteiramente casualizado com medidas repetidas no tempo. As taxa de aparecimento, sobrevivência e mortalidade perfilhos responderam crescentemente às doses de nitrogênio, com as duas primeiras taxas revelando ligeira variação entre os períodos de avaliação. Constatou-se resposta quadrática, alcançando valores máximos com o incremento das doses de nitrogênio para a taxa de florescimento de perfilhos, (0,051 perfilhos?100 perfilhos-1?dia-1, respectivamente) nas doses 613,5 kg de N?ha-1?ano-1, respectivamente. Para a taxa de florescimento, verificou-se oscilação entre os períodos de avaliação. A adubação nitrogenada proporciona mudanças positivas na dinâmica de perfilhamento do capim-massai. Tillering dynamics in massai grass fertilized with nitrogen and grazed by sheep. Abstract: The tillering dynamics in massai grass subjected to different nitrogen (N) fertilization levels (control - 0; 400; 800 and 1200 kg N?ha-1?year-1) and under rotational stocking with sheep was evaluated. A completely randomized design with measurements repeated in time was adopted. The tiller appearance, survival and mortality rates were increased with the nitrogen levels, with the two rate revealing slight variation between the periods of evaluation. There was showed quadratic response reaching maximum values with increasing levels of nitrogen for tillers flowering rate (0.051 tillers?100 tillers-1?day-1, respectively) for levels 613.5 kg of N?ha-1?year-1, respectively. For the flowering rate and reproductive basal tillers population density was differences observed between the evaluation periods. The nitrogen fertilization provide positive responses to the tillering dynamics of massai grass

Trocas gasosas em dois híbridos de sorgo para pastejo manejados em sequeiro.

Resumo: Em regiões semiáridas a sazonalidade da precipitação pluvial, impacta de forma negativa na produtividade e persistência de pastagens de sequeiro. Objetivou-se avaliar as trocas gasosas em dois híbridos de sorgo bicolor com sorgo sudão (BR007A x TX2785 e CMSX5157A x TX2785) para pastejo, cultivados em sequeiro, no litoral do Ceará. Adotou-se um delineamento em blocos casualizados com quatro repetições (parcelas de 100 m2). O pasto foi semeado com espaçamento de 30 cm entre linhas, perfazendo estande final médio de 700.000 plantas ha-1. Aos 35 dias de crescimento das plantas (período de estabelecimento), realizou-se o ensaio de trocas gasosas, com as avaliações sendo realizadas no horário de 9:00 às 12:00 horas da manhã, na lâmina foliar recém-expandida. Analisaram-se as seguintes variáveis: taxa de fotossíntese foliar, taxa de transpiração foliar, índice relativo de clorofila, taxa de transpiração foliar, temperatura da folha, concentração de dióxido de carbono na folha, condutância estomática, relação fotossíntese/transpiração e relação fotossíntese/condutância. Não se constatou diferença entre híbridos para as variáveis analisadas, todavia o presente estudo possibilitou a geração de conhecimentos no tocante as características fisiológicas dos híbridos BR007A x TX2785 e CMSX5157A x TX2785 em condições de sequeiro. Os híbridos de sorgo BR007A x TX2785 e CMSX5157A x TX2785 apresentam boas taxas fotossintéticas, mostrando-se como opção forrageira para os sistemas de produção de ruminantes em regiões litorâneas