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abstractthis 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.

-The objective of this work was to investigate the injuries caused to the photosynthetic apparatus of three types of rice exposed to application of imidazolinone group herbicides. Two experiments were conducted using herbicides Imazethapyr+imazapic and Imazapyr+imazapic, in a split-plot experimental design, and a 3 x 3 factorial, with six replications. The first factor (A) consisted of the herbicide rates 0, 100 e 200 g ha -1 of Imazethapyr+imazapic and 0, 140 e 280 g ha -1 of Imazapyr+imazapic; factor B consisted of type of rice (cv. Puitá Inta CL, sensitive red rice ecotype and red rice ecotype with suspected herbicide tolerance to Imidazolinone). Chlorophyll a fluorescence parameters were evaluated in plants at 30 days after herbicide application, using a portable fluorometer (HandyPEA, Hanstech). The photosynthetic metabolism of cv. Puitá Inta CL was found to tolerate commercial dosages of both herbicides. High sensitivity to the herbicides was observed for the sensitive red rice ecotype, while the photosynthetic apparatus of red rice ecotype with suspected herbicide tolerance showed high tolerance to both herbicides applied at rates higher than the commercial rate. The application of chemical herbicides of the imidazolinone group on rice plants causes changes in the photosynthetic metabolism of plants, detected by evaluating the emission of transient chlorophyll a fluorescence. This method can be useful in helping detect resistance and/or tolerance of red rice plants to herbicides of the imidazolinone group.Keywords: ALS-inhibitors, Oryza sativa, photosystems, JIP-test. SOUSA, C.P. et al. RESUMO -Este estudo objetivou avaliar as injúrias causadas ao aparelho fotossintético de três tipos de arroz, expostos a herbicidas do grupo das imidazolinonas. Foram conduzidos dois experimentos utilizando os herbicidas imazethapyr+imazapic e imazapyr+imazapic, ambos em delineamento experimental de parcelas subdivididas, em fatorial 3 x 3, com seis repetições. O fator A consistiu de doses dos herbicidas correspondentes a 0, 100 e 200 g ha -1 de imazethapyr+imazapic e a 0, 140 e 280 g ha -1 de imazapyr+imazapic, e o fator B, do tipo de arroz (cv. Puitá Inta CL, ecótipo de arroz-vermelho sensível e ecótipo de arroz-vermelho com suspeita de tolerância aos herbicidas imidazolinonas). Foram avaliados os parâmetros da fluorescência da clorofila a nas plantas aos 15 e 30 dias após a aplicação dos herbicidas, utilizando-se um fluorômetro portátil (HandyPEA

-The attributes that confer seed quality can largely be considered dependent on the coat. The aim of this study was to evaluate the quality and hydration pattern of the seeds of four contrasting soybean genotypes for the coats characteristics; BMX Potência RR and CD 202 with yellow coats and IAC and TP with black coats. The first stage of the study consisted of seed multiplication in the 2012/2013 harvest. After storage for five months at a temperature of 17 ºC and a relative humidity of 50%, the seeds were subjected to the following tests: germination, first count and seedling height, with and without immersion of the seeds, emergence in soil, emergence speed and germination index; electrical conductivity; thousand weight seeds and imbibitions of seeds. The design was completely randomized, with five replicates. The data was subjected to variance analysis and the means compared using the Tukey test at a 5% level of probability. Regression analysis was used for the seeds imbibitions test. Genotypes with black coats (especially IAC) presented better physiological quality in relation to genotypes with yellow coats. The latter had greater thousand weight seeds. BMX Potência RR presented greater hydration than the other genotypes in the first hours of imbibitions and TP, the least. Genotypes with black coats emitted a radicle faster than the yellow coats genotypes.Key words: Seed performance. Glycine max. Hydration. Thousand weight seeds.RESUMO -Os atributos que conferem a qualidade das sementes podem ser considerados, em grande parte, dependentes do tegumento. O objetivo do trabalho foi avaliar a qualidade e o padrão de hidratação das sementes de quatro genótipos de soja contrastantes para as características de tegumento; BMX Potência RR e CD 202, de tegumentos amarelos e, IAC e TP, de tegumentos pretos. A primeira etapa do estudo constou da multiplicação das sementes, na safra 2012/2013. Depois de cinco meses armazenadas à temperatura de 17 ºC e 50% de umidade relativa do ar, as sementes foram submetidas aos testes de germinação, primeira contagem e comprimento de plântula, com e sem imersão das sementes; emergência em solo; índice de velocidade de emergência e germinação; condutividade elétrica; massa de mil sementes e embebição das sementes. O delineamento foi o inteiramente casualizado, com cinco repetições. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey, ao nível de 5% de probabilidade. Para o teste de embebição das sementes aplicou-se análise de regressão. Genótipos de tegumento preto (em especial o IAC) apresentam maior qualidade fisiológica em relação aos de tegumento amarelo. Estes últimos possuem maior massa de mil sementes. BMX Potência RR apresenta hidratação maior que os outros genótipos nas primeiras horas de embebição e TP, a menor. Genótipos de tegumento preto emitem a radícula mais rápido que genótipos de tegumento amarelo.Palavras-chave: Desempenho de sementes. Glycine max. Hidratação. Massa de mil sementes.

By generating stress conditions soil flooding can induce alterations in the cell metabolism and thus is detrimental to plant growth. This study was done under the greenhouse conditions to determine the effect of soil flooding on the chlorophyll fluorescence of some hybrids of canola (Brassica napus L.). Fifty five days old plants were subjected to flooding for six days. There was no difference in the parameters modulate chlorophyll fluorescence, in contrast, some the parameters related to the energy flux in photosystem II varied due to flooding stress. At the end of the six days, the performance indexes (PI total and PIABS) decreased, in all hybrids except in 'Hyola 420'. The difference kinetics of the chlorophyll a fluorescence transient showed different effects on different sites of the photosynthetic machinery. It could be concluded that compared to the other hybrids, 'Hyola 420' was less sensitive to flooding.