Décio Eugênio Cruciani

Efeitos de inundações temporárias do solo em plantas de ervilha

Pea crop is a feasible option for agriculture in low lands during winter season. However, this crop is not adapted to extreme conditions of water deficit or excess. In hidromorfic soils, temporary waterlogging or flooding conditions often occur affecting directly plant growth. The effect of water level drawdown on the growth and yield of pea, cv Axe, and the most sensitive growing stage of the crop to soil water excess were estimated. The effects of waterlogging and water table drawdown were proportional to flooding time, especially when waterlogging occurred at the vegetative stage. The major susceptibility of the pea plants to waterlogging was in reproductive stage, with significant yield reduction in all treatments. On the other hand, we observed that drawdown velocity had no effect on results, but on vegetative stage when a water level lowering in depths of more than 20 cm per day caused crop yield reductions of nearly 20%.

Modelos da distribuição temporal de chuvas intensas em Piracicaba, SP

Time distribution models of intense and short rains are very important in hydrology and for extreme predictions in engineering projects. With this purpose, rain data of Piracicaba, SP, Brazil, from 1966 to 2000 were analyzed to establish time distribution models of 60 and 120 min intense rains, during the rainy season from October through March. Time distribution models were assessed by three intervals of twenty minutes duration, for 60 min rains and by four intervals of thirty minutes duration for 120 min rains. The prevailing precipitation model for both, 60 and 120 min rains was a negative exponential distribution, in 85.7 and 50.7% of cases, respectively. For 60 min rains fractions were distributed as 72.3, 21.4 and 6.2% of a total 20.7 mm precipitation. For 120 min rains, the result was 60.1, 25.2, 11.1 and 3.6% of a total 33.3 mm precipitation, in four successive intervals. Time distribution models for these rains were not affected by the amount of precipitation nor by their duration, in the intervals considered in this study.

Efeito de velocidades de rebaixamento do nível freático em diferentes períodos de desenvolvimento da cultura da alface

The work had the objectives of determining the effect of water table drawdown velocities on the growth and yield of lettuce crop in a flooded soil, identifying the stage of the crop cycle with the highest reduction in the productivity and obtaining a relation between the crop relative productivity and the daily stress index. The statistical experimental design was completely randomized in factorial scheme [(3 x 4) + 1], with three replications. The water table was lowered at 3 stages of the crop cycle (12, 22 and 32 days after the transplanting), four drawdown velocities (30 cm during 24, 48, 72 and 96 h) and a 13 treatment in which stress was not applied with the elevation of the water table. The lettuce presented as a sensible crop to the water-logging, although, it was not possible to define a value for the drainage coefficient because the highest drawdown velocity tested presented 50% of loss in the yield. Among the three crop stages in witch the stress caused by the water table elevation was applied, the first one caused the highest loss in the yield. The relative yield of lettuce plant had a negative linear relation with the daily stress index.

Effect of the water table management in the morpho-physiological adaptation of two wheat species to waterlogging

The effect of three different water table managements in the morpho-physiological adaptation to waterlogging of Triticum aestivum, L. and Triticum durum, L., and the relative influence of the main physical and biological interferance factors were studied. The trial was conducted at ESALQ/USP, Piracicaba, SP, under simulated conditions of a natural low land. After introduction of stress adaptation during the vegetative growth stage, while applying progressive times of hipoxics periods, there were observed different requirements and/or extraction capacities of nutrients between the two species; the fertilization on leaves was not enough to avoid nutritional deficiencies in wheat under hipoxia. The water table management used resulted in morpho-physiological adaptations, but not enough to reach adequate biometric parameters of productivity. The water table at a 15 cm depth throughout the crop cycle resulted in better performance.

Distribution of the potassium concentration in soil with lysimeters cultivated with peanut

A aplicacao de fertilizantes na agricultura pode provocar uma dinâmica de solutos no solo abaixo da zona radicular, podendo, alem de provocar prejuizos economicos, contaminar aguas subterrâneas. O presente trabalho teve como objetivo acompanhar o processo de deslocamento do ion potassio (K+) em lisimetros preenchidos com solo de textura arenosa e cultivado com amendoim (Arachis hypogaea L.), sob diferentes condicoes de atenuacao da densidade de fluxo radiante, como a utilizacao de filmes plasticos com diferentes espessuras (100 e 150 micras). O deslocamento do ion potassio (K+) foi monitorado por extratores de solucao instalados em diferentes profundidades (15 e 25 cm), e o manejo da fertirrigacao foi realizado com a utilizacao de tensiometros. Concluiu-se que a baixa radiacao solar incidente nos dois ambientes com coberturas plasticas afetou negativamente a produtividade do amendoim; o periodo em que o amendoim demanda maior quantidade de potassio ocorre dos 30 aos 55 dias apos a semeadura; as plantas de amendoim nao apresentaram deficiencia nutricional com menor lixiviacao de K+ para as camadas mais profundas do solo; nos lisimetros com cobertura plastica de 100 e 150 micras, ocorreu maior concentracao de K+ na superficie do solo.

ESTIMATIVA DE VARIAÇÕES NO COEFICIENTE RELATIVO DE DIFUSÃO DOS GASES NO SOLO COM BASE NA ANÁLISE DA CURVA DE RETENÇÃO DA ÁGUA

The aim of this study was to test the possibility of using water retention curves to assess increments in the relative coefficient of gas diffusion in the soil, Ds/Do, during the drainage process of Inceptisol soil samples. We first used a water retention curve to obtain data on increments of air-filled pore space during the drainage of soil samples. The greatest increments were found for the matric tension interval of 0 to 20kPa. Next, we studied Ds/Do increments during the drainage process, by measuring the diffusion coefficient of methane through the soil samples (Ds) within a two-chamber diffusion cell. The Ds values were measured from soil samples under 10kPa and 20kPa matric tension values in addition to an air dried sample (matric tension greater than 1500kPa). Mean increments of air porosity and Ds/Do within the 0 to 20kPa matric tension interval were 100 times greater than increments within 20 to 1500kPa interval. We concluded that the interval of matric tension in which the greatest air porosity and Ds/Do increments occur, can be identified from the water retention curve.The aim of this study was to test the possibility of using water retention curves to assess increments in the relative coefficient of gas diffusion in the soil, Ds/Do, during the drainage process of Inceptisol soil samples. We first used a water retention curve to obtain data on increments of air-filled pore space during the drainage of soil samples. The greatest increments were found for the matric tension interval of 0 to 20kPa. Next, we studied Ds/Do increments during the drainage process, by measuring the diffusion coefficient of methane through the soil samples (Ds) within a two-chamber diffusion cell. The Ds values were measured from soil samples under 10kPa and 20kPa matric tension values in addition to an air dried sample (matric tension greater than 1500kPa). Mean increments of air porosity and Ds/Do within the 0 to 20kPa matric tension interval were 100 times greater than increments within 20 to 1500kPa interval. We concluded that the interval of matric tension in which the greatest air porosity and Ds/Do increments occur, can be identified from the water retention curve.

Efeito de três manejos do lençol freático na adaptação fisiomorfológica do feijoeiro (Phaseolus vulgaris, L.) ao encharcamento

The effect of three water table management systems on the physical-morphological adaptation of snap beans (Phaseolus vulgaris, L. ), cv. BAT 477 to flooding tolerance was studied and the relative influence of the main physical, chemical and biological interfering factors discussed. The trial was conducted at ESALQ/USP, Piracicaba (SP) Brazil, from March to June, 1999, under maximal simulation of natural low land conditions. A 1.000 L concrete box was used as plot, under a completely randomized design, with four treatments and five replications. After induction at vegetative growth stage, management efficiency was tested by a short-term waterlogging event at a reproductive stage. The biometric characteristics of growth, although displaying damage caused by hypoxia, showed the plant used morphological (adventitious roots and lenticels), as well as biological (N fixation) and physical-morphological (diffusion resistance and transpiration) adaptive mechanisms. On the other hand, the yield biometric characteristics showed that the water table maintained at 15 cm, as well as the gradual elevation, although without any significant yield difference in relation to no inductive management, were effective, allowing the plant to complete its phenological cycle, resulting in better grain quality. Alternating relative biometric advantages between the two management systems caused difference in yield, suggesting that the use of longer-cycle cultivars under hypoxia is more advantageous.

Suscetibilidade do pimentão (Capsicum annuum L.) a inundações temporárias do sistema radicular

O presente trabalho foi conduzido no Departamento de Agricultura e Horticultura da ESALQ, de outubro de 1981 a fevereiro de 1982. Teve como objetivos determinar a sensibilidade da cultura de pimentao a inundacoes temporarias do sistema radicular, a fim de quantificar os prejuizos de sua producao em fases distintas do seu ciclo vegetativo. O trabalho procura contribuir ao estabelecimento do coeficiente de drenagem, necessario em projetos que visem a utilizacao dessa solanacea, com base nos seus parâmetros de producao. Os resultados revelaram que o pimentao e sensivel a condicoes de excesso de agua no solo, com acentuados prejuizos na producao, em numero e peso de frutos, quando as plantas foram submetidas a 2, 4 e 6 dias de inundacao. Em vista dos resultados, recomenda-se que o tempo de drenagem da zona radicular dessa cultura deve ser inferior a 2 dias.