RESUMO: O objetivo deste trabalho foi estudar o efeito do genótipo e da aplicação de ácido indol butírico (AIB) no enraizamento de estacas semilenhosas de portaenxertos de pessegueiro. O trabalho dividiu-se em Experimento 1, onde avaliou-se as cultivares Capdeboscq e Nemaguard com quatro concentrações de AIB (0; 1.000; 2.000 e 3.000 mg L -1 ), onde obteve-se uma resposta quadrática com aproximadamente 50% de enraizamento no valor estimado de 2.500 mg L -1 de AIB, e um efeito linear crescente para o número de raízes com o aumento das concentrações de AIB, sendo 'Nemaguard' mais responsiva do que 'Capdeboscq'. No Experimento 2 avaliou-se 'Flordaguard', 'Hansen 2168', 'Kutoh' e 'Nagano Wild' e duas concentrações de AIB (0 e 2.000 mg L -1 ), verificando-se que o AIB possibilitou obter maiores taxas de enraizamento, número de raízes e comprimento de raízes nas quatro cultivares, em relação ao controle. 'Hansen 2168' apresentou a maior porcentagem de enraizamento (72,5%). 'Floradaguard' e 'Hansen 2168' apresentaram maior número de raízes por estaca (9,9 e 8,5, respectivamente), e 'Nagano Wild' apresentou o menor número e comprimento de raízes por estacas (4,8 e 3,3cm, respectivamente). Concluiu-se existir interação sinérgica entre os fatores avaliados, porém o uso de AIB é indispensável para obter satisfatórias porcentagens de enraizamento. Palavras-chave: Prunus persica, propagação vegetativa, estaquia, auxina, raízes adventícias. ABSTRACT:The aim of this work was to study the effects of genotype and the indolbutyric acid (IBA) on the rooting of semi hardwood cuttings of peach rootstocks. This work was divided into Experiment 1, in which the 'Capdeboscq' and 'Nemaguard' cultivars was treated with four IBA concentrations (0; 1,000; 2,000 and 3,000 mg L -1 ), and a quadratic behavior was observed with near 50% of rooting in the estimated concentration of 2,500 mg L -1 IBA, and a linear increase in the roots numbers occurred with increasing in IBA concentration, where 'Nemaguard' was more responsive than 'Capdeboscq'. In the Experiment 2, the 'Flordaguard', 'Hansen 2168', 'Kutoh', and 'Nagano Wild' were treated with two IBA concentrations (0 and 2,000 mg L -1 ) and the IBA treatment allowed to obtain higher rates of rooting, number of roots and root length in the four cultivars comparing to the control. 'Hansen 2168' showed the highest rooting percentage (72.5%). 'Floradaguard' and 'Hansen 2168' showed higher number of roots per cutting (9.9 and 8.5, respectively), and 'Nagano Wild' had the lowest number and length of roots per cutting (4.8 and 3.3 cm, respectively). It was concluded that exists synergistic interaction between the factors evaluated, but the IBA usage is essential for satisfactory rooting rates.

(1) Background: Eragrostis plana Ness is a invasive C4 perennial grass in South America and very adaptable to environmental stresses. Our hypothesis is that there is a transgenerational cross-talk between environmental stresses and weed response to herbicides. This study’s objectives were to: (1) evaluate if E. plana primed by drought stress (DRY), a sub-lethal dose of quizalofop-p-ethyl (QPE), or a combination of both drought and herbicide stresses (DRY × QPE), produce a progeny with decreased sensitivity to quizalofop and (2) investigate the potential mechanisms involved in this adaptation; (2) Methods: A population of E. plana was isolatedly submitted to treatments for drought, quizalofop or drought plus quizalofop for two generations. The progenies were analyzed for sensitivity to the herbicide quizalofop and performed biochemical, chromatographic and molecular analyses.; (3) Results: In the G2 generation, the quizalofop-treated CHK population had reduced stomatal conductance and increased hydrogen peroxide and lipid peroxidation. On the other hand, there was no change in stomatal conductance, hydrogen peroxide level, and lipid peroxidation in the quizalofop-treated DRY population. In addition, this population had increased antioxidant enzyme activity and upregulated CYP72A31 and CYP81A12 expression, which was accompanied by reduced quizalofop-p-ethyl concentrations; (4) Conclusions: E. plana demonstrated a capacity for transgenerational adaptation to abiotic stresses, with the population exposed to drought stress (DRY) becoming less sensitive to quizalofop-p-ethyl treatment.

Weedy rice (Oryza sp.) is one of the most troublesome global weeds in cultivated rice.Its troublesome status is associated with characteristics such as seed shattering and dormancy, allowing for long-term reinfestation and persistence in rice fields. However, the role of rising carbon dioxide levels (CO 2 ) and other climate variables on these characteristics has not, to date, been assessed. The current research objectives were to evaluate two aspects related to climatic change, increased CO 2 concentration (400 ± 50 μmol mol À1 and 700 ± 50 μmol mol À1 ) and water management (continuous and alternate-wetting drying), to assess plant development, seed shattering and seedbank longevity of weedy rice. Our results indicated that elevated CO 2 (700 ± 50 μmol mol À1 ) increased weedy rice growth and biomass, seed shattering and lengthened viability within the seedbank. Water management did not affect weedy rice growth, seed shattering and seed dormancy. These results suggest that in areas where weedy rice is dominant, its seed bank persistence and potential competition may be exacerbated with rising CO 2 levels, with negative consequences for rice production.

(1) Background: Elevated atmospheric CO2 concentration affects the growth and development of the rice crop. In Southern Brazil, rice is traditionally produced with continuous irrigation, implying a significant amount of water used. Besides, continuous flooding favors the uptake of toxic elements such as arsenic (As) and cadmium (Cd). In this work, one Brazilian rice cultivar (IRGA 424) was tested for the effects of elevated CO2 concentration and different water regimes on rice yield, and As and Cd accumulation in grain. (2) Methods: Rice was grown in two CO2 concentrations (400 and 700 µmol mol−1) and two irrigation regimes (continuous and intermittent). It was evaluated the number of tillers, plant height, aboveground dry weight (ADW), water use efficiency (WUE), rice yield components, and As and Cd concentration in rice grain. (3) Results: Rice plants were taller and had a higher WUE when cultivated at e[CO2]. The ADW and the rice yield component were not affected by CO2 levels nor water regimes. Intermittent flood regimes had a lower average As concentration. The Cd concentration in the samples in both growing seasons and all treatments was below the limit of quantitation (8.76 μg kg−1). (4) Conclusions: Enhanced CO2 concentration did not affect rice yield, increased the WUE, and reduced As concentration in grains. Regarding water management, the intermittent regime enhanced WUE and promoted a reduction in As concentration in grains.

Weedy rice (Oryza sativa L.) is widely recognized as a major constraint in cultivated rice systems globally. Seed shattering is related to the invasiveness and persistence of weedy ecotypes in field and exacerbates its control in cultivated rice systems. Shattering traits are controlled genetically and by different environmental conditions. At present, a rapidly changing environment, including rising levels of carbon dioxide [CO2], could alter shattering frequency, with subsequent effects on weed seed input and competition. The objective of the current study was to evaluate the interaction between weedy rice seed shattering and the transcriptional seed shattering-regulation genes as affected by weedy rice genotypes and atmospheric CO2 concentrations. We examined seven biotypes and two atmospheric CO2 concentrations: ambient {a[CO2]} and enhanced {e[CO2]} concentration, 400 and 700 µmol mol-1 respectively. Our results indicate that e[CO2] increases weedy rice seed shattering. The gene expression analysis demonstrates an effect of [CO2] in the expression of all gene shattering-related genes (OsCPL1, qSH1, Sh4, SHAT1, OsXTH8, OSH15, and SH5), with high variability observed between genotypes. Here we showed that increased CO2 concentration affects greatly seed shattering in weedy rice and in minor effect cultivated rice, by modulation of seed shattering-related genes and weedy genotypes showed the highest upregulation level of this genes. Thus, increased CO2 concentration positively affect panicle number and grain yield mainly in cultivated rice.