Cleusa Adriane Menegassi Bianchi Krüger

Retenção e disponibilidade de água às plantas, em solo sob plantio direto e preparo convencional

This work had the objective of evaluating the soil water storage and availability to plants, when comparing the no-tillage (NT) and conventional tillage (CT) systems. The study was conducted in Eldorado do Sul, Brazil, in 2002. Soil density, total porosity, macroporosity, mesoporosity, microporosity, distribution of mesopores size, curves of water retention, field capacity (FC), and permanent wilting point (PWP) were analyzed in seven depths, into the soil profile. The highest differences occurred close to the soil surface. At 2.5 cm deep, the soil density was 7% lower while the total soil porosity was about 15% higher in NT than in CT. The mesoporosity showed an exponential distribution in NT, with highest values for largest mesopores, but it tended to a normal curve in CT. Considering the entire soil profile, the soil water storage was about 53% higher in CT than in NT. However, close to the soil surface (at 2.5 cm deep) it was 80% higher in NT than in CT. From the soil surface to 15 cm deep, 70% of the available water was retained above the limit of -80 kPa in NT, in comparison to 50% in CT. The no-tillage system increases the water availability to plants and reduces the energy of retention in the upper soil layers, in comparison to the conventional tillage.

Intercepted solar radiation by maize crops subjected to different tillage systems and water availability levels

The objective of this work was to evaluate changes in the photosynthetic photon flux density (PPFD) interception efficiency and PPFD extinction coefficient for maize crop subjected to different soil tillage systems and water availability levels. Crops were subjected to no-tillage and conventional tillage systems combined with full irrigation and non-irrigation treatments. Continuous measurements of transmitted PPFD on the soil surface and incoming PPFD over the canopy were taken throughout the crop cycle. Leaf area index and soil water potential were also measured during the whole period. Considering a mean value over the maize cycle, intercepted PPFD was higher in the conventional tillage than in the no-tillage system. During the initial stages of plants, intercepted PPFD in the conventional tillage was double the PPFD interception in the no-tillage treatment. However, those differences were reduced up to the maximum leaf area index, close to tasseling stage. The lowest interception of PPFD occurred in the conventional tillage during the reproductive period, as leaf senescence progressed. Over the entire crop cycle, the interception of PPFD by the non-irrigated plants was about 20% lower than by the irrigated plants. The no-tillage system reduced the extinction coefficient for PPFD, which may have allowed a higher penetration of solar radiation into the canopy

Arranjo de plantas na expressão dos componentes da produtividade de grãos de canola

O objetivo deste trabalho foi avaliar os efeitos do arranjo de plantas nos componentes diretos da produtividade de graos e na producao final em canola, com uso de hibridos de diferentes ciclos de desenvolvimento. Foram realizados tres experimentos com espacamento entre linhas de 0,20, 0,40 e 0,60 m, em delineamento experimental de blocos ao acaso, com quatro repeticoes para cada ano de cultivo (2008 e 2009), genotipo (Hyola 432 e Hyola 61) e densidade de plantas (20, 40, 60 e 80 plantas por metro quadrado). Hyola 432 apresentou maior producao de graos em comparacao a Hyola 61, independentemente do ano e da densidade de cultivo. Os efeitos do ano de cultivo influenciaram mais a producao e os componentes da produtividade de graos do que o potencial genetico da cultivar e a densidade de cultivo. O ajuste da densidade de plantas em canola e alterado pelo genotipo e pelo ano de cultivo.

Evaporação da água na superfície do solo em sistemas de plantio direto e preparo convencional

Este trabalho teve por objetivos quantificar a evaporacao da agua na superficie do solo, em plantio direto e em preparo convencional, e avaliar o uso de microlisimetros de pesagem para medir esse processo. As medicoes foram feitas em campo, nos veroes de 2001/2002, 2002/2003 e 2004/2005, em experimentos irrigados e nao irrigados. Utilizaram-se delineamentos inteiramente casualizados, com quatro repeticoes, cujos tratamentos consistiram de sistemas de manejo do solo – plantio direto e preparo convencional –, e a presenca ou ausencia de cultivo de milho. Mediu-se a evaporacao diaria durante periodos de secagem do solo, entre precipitacoes ou irrigacoes consecutivas. Em experimentos sem irrigacao, a evaporacao acumulada foi maior sob plantio direto, na maioria dos periodos de medicao, independentemente da presenca da lavoura de milho. Nos experimentos com irrigacao, a evaporacao nao apresentou diferencas regulares entre sistemas de manejo de solo. Normalmente, no inicio dos periodos de medicao, com dois a cinco dias de secagem do solo, a evaporacao foi maior em solo sob preparo convencional, tendo-se tornado maior em plantio direto, no restante do periodo de secagem. O emprego de microlisimetros de pesagem e eficiente para medir a evaporacao na superficie do solo.