O pinhão-manso (Jatropha curcas L.) tem-se destacado, no cenário do biodiesel, em função da porcentagem de óleo contido nas sementes e de sua capacidade adaptativa. No País, a cultura do pinhão-manso tem, como proposta, o desenvolvimento agronômico, razão pela qual o uso consorciado pode ser importante aos pequenos produtores. Este trabalho teve como objetivo avaliar algumas características fenológicas de pinhão-manso cultivado em dois regimes de luminosidade (pleno sol e sombrite 50%) relacionando com a sazonalidade climática e se utilizando de parâmetros da fluorescência da clorofila e de trocas gasosas. As plantas apresentaram crescimento vegetativo com padrão sazonal, com pico de crescimento no início de março, quando iniciou a senescência foliar. Alguns parâmetros da fluorescência transiente da clorofila analisados pelo Teste JIP, apresentaram relação com as flutuações ambientais. O PI ABS e o PItotal demonstraram que as plantas do tratamento sombreado foram sensíveis à redução de luminosidade. A taxa assimilatória líquida e a eficiência de carboxilação reduziram ao longo do experimento acompanhando a queda da radiação solar; já as plantas de pinhão-manso respondem negativamente a essas condições de sombreamento.

Jatropha curcas L. has been prominent in the scenario of biodiesel due to the percentage of oil contained in the seeds and its adaptive capacity. The cultivation of J. curcas in the country has as proposal the agronomic development and its consortium may be important for small producers. This study aimed to characterize the phenological behavior of J. curcas grown under different light conditions, full sun and 50% shade, relating them to the climatic seasonality, comparing their development with chlorophyll a fluorescence and gas exchange. Plants showed vegetative growth with seasonal pattern, with growth peak at the beginning of March, when the leaf senescence began. The analysis of the kinetic of the transient fluorescence of chlorophyll presented a relationship between certain parameters of the test JIP and the environmental fluctuations. The PI ABS and the PItotal demonstrated that in the shaded treatment plants were sensitive to luminosity reduction. The liquid assimilation rate and the carboxylation efficiency decreased throughout the experiment, accompanying the decline of the solar radiation. J. curcas plants respond negatively to these shaded conditions.

This study aimed to evaluate the effect of flooding and water restriction (drought) on the photosynthetic activity in plants of the hybrid rootstock 'GxN-9' (Prunus dulcis Mill. × Prunus persica L. Bastsch), grown in a greenhouse. Chlorophyll fluorescence and gas exchange were analyzed in plants of approximately 12 months. The reduction of photosynthetic activity in both the stresses were associated with decreased carboxylation efficiency, but without affecting the internal concentration of carbon dioxide. The JIP-test parameters revealed changes in the energy flux processes demonstrating that in terms of flooding the rootstock GxN-9 the rate of photosynthetic performance significantly decreases, resulting in a considerable decrease in net assimilation rate. The JIP-test analysis was efficient in determining the thresholds mainly of the flood response, proving to be useful in exploration of the photosynthetic activity as a physiological marker of the stress tolerance.

With Japonica rice BRS Firmeza and indica rice BRS Pelota (low and high grain yield, respectively) as materials, Chl content and Chl a fluorescence parameters in flag leaves from the heading to mature grain stage were investigated. The Chl content and the Chl a fluorescence were measured using a portable chlorophyll meter CL-01 and portables fluorometer Handy-PEA and FMS-2 (Hansatech, Kings Lynn, UK), respectively. All measurements were taken on middle part of the flag leaves (n = 10). The results showed that the Chl content and Chl a fluorescence parameters declined after full expansion of flag leaves in both rice cultivars. However, these biochemical and photochemical parameters did not show similar changing pattern and the behavior of flag leaves senescence showed some differences between BRS Pelota and BRS Firmeza rice cultivars. During the senescence of flag leaves, BRS Pelota, the rice cultivar with higher grain yield capacity, was characterized by significant reductions in Chl content, PI ABS,Total, TR0/ABS, ET0/ABS, ET0/TR0, RC/ABS compared to BRS Firmeza. On the other hand, DI0/RC, TR0/RC and ET0/RC were significantly higher in BRS Pelota. These results show that the decreased photosystem II activity, evaluated through chlorophyll fluorescence analysis, was resultant of leaves senescence process, which was much more expressive in BRS Pelota rice variety. We suggest that the higher productivity of BRS Pelota rice cultivar results from its higher assimilate mobilization ability or energy usage efficiency, in despite of its lower light absorption capacity.

Sweet potato (Ipomoea batatas L.) plants were cultivated in vitro in Murashige and Skoog (MS) medium with 20 and 40 g L-1 of sucrose under two different photon flux densities (21 and 60 µmol m-2 s-1). Leaves developed in vitro mostly showed high variable to maximum fluorescence ratio (F V/F M) , indicating good development of photosynthetic apparatus. This ratio decreased during leaf aging, especially in the plants cultivated in vitro on medium with higher sucrose concentration and higher photon flux. Leaves developed ex vitro showed high F V/F M ratio during whole experiment. The effective photochemical efficiency (F V'/F M') was maximum at 15th day after emergence of leaves. Photosynthetic potential rate was higher in leaves developed in vitro than in leaves originated ex vitro.

O efeito de doses de sulfentrazone foi avaliado no crescimento da soja BR-16, inoculadas com estirpe SEMIA 5079, em condições de casa de vegetação. A fitotoxicidade do sulfentrazone aumentou com o incremento na dose do herbicida, nos estádios V2 e R5, agravando-se com o passar do tempo. O sulfentrazone reduziu a área foliar, o acúmulo de matéria seca total e dos órgãos, a altura da planta e o comprimento das raízes tanto no estádio R3 quanto no R5. O crescimento das raízes foi mais afetado pelo sulfentrazone do que a parte aérea, sendo que a relação parte aérea/ raízes aumentou com o incremento na dose do herbicida. A cultivar de soja BR-16 apresentou baixa tolerância ao sulfentrazone, pois o herbicida influenciou negativamente todos os parâmetros analisados.

The effect of sulfentrazone rates was evaluated on growth of soybean cv. BR-16, inoculated with strain SEMIA 5079, under greenhouse conditions. The sulfentrazone phytotoxicity increased as herbicide rates enhanced at V2 and R5 stages, aggravating the damage with the time. Leaf area, organs and total dry matter accumulations, plant heigh and roots length were reducted by sulfentrazone at R3 and R5 stages. The roots growth was more affected by sulfentrazone than shoot, occuring increment of shoot/roots ratio with augment on herbicide rates. The soybean cv. BR-16 showed low tolerance to sulfentrazone, based on the negative effect of the herbicide for all parameters studied.