Phenology and thermal requirements of the species Cyperus difformis L. in southern Brazil

Cyperus difformis L. is a Cyperaceae, annual, of natural occurrence in marshy environments in southern Brazil, considered a weed in irrigated rice crops. Studies on its development are scarce, especially regarding its cycle and thermal requirements. Therefore, the objective of this work was to determine the base temperature, the thermal sum and the duration of the different sub-periods of the biological cycle of the species. The experiment was carried out at the Campus of the Universidade Federal de Santa Maria – UFSM, Santa Maria, Rio Grande do Sul, in four sowing seasons. In a completely delineated design and factorial scheme involving five soil water conditions (water depth and 50% soil water retention capacity [WRC]) from the sowing, water depth and 50% WRC introduced 21 days after emergence and 100% WRC during the whole cycle, with six repetitions each. Each experimental unit consisted of a cultivated in pot plant with 11 L capacity filled with soil. The cycle of the plants was subdivided into the sowing-emergence sub-periods, emergence-emission of the floral tassel and emission of the floral-maturing physiological tassel, being estimated the thermal requirements for the species. The conditions of the soil water condition the base temperature, the sum of the degree-days and the duration of the species cycle. The base temperature varies for each treatment, the sum of degrees-day decreases with the water deficit and the plants under flood accelerate the biological cycle.

Aplicação de extratos de folhas e tubérbulos de Cyperus rotundus L. e de auxinas sintéticas na estaquia caulinar de Duranta repens L. / Effect of Cyperus rotundus L. leaf and tuber extracts and synthetic auxins applied to stem cuttings of Duranta repens L.

É de conhecimento popular que extratos de tiririca aumentam o enraizamento adventício de várias espécies, sendo esse procedimento utilizado na propagação vegetativa caseira. Uma vez que nesses extratos concentram grandes quantidades de auxinas e compostos fenólicos, o objetivo deste estudo pioneiro foi avaliar o efeito da aplicação de extratos de folhas e de tubérculos de Cyperus rotundus L. na estaquia caulinar de Duranta repens L., espécie considerada de fácil enraizamento, comparando sua ação à de auxinas sintéticas. As estacas foram coletadas em abril, junho, agosto, outubro e dezembro/2006 e fevereiro/2007 e confeccionadas com 8 cm de comprimento, com base cortada em bisel e corte reto acima da última gema, mantendo-se 4 folhas apicais. Os tratamentos foram: água e solução alcoólica 50% como controles; extrato de folhas e de tubérculos de C. rotundus (25%, 50% e 100%); solução de ANA e AIB (500 e 1000 mg L-1), com imersão da base das estacas durante 10 segundos. As estacas foram mantidas sob nebulização, em tubetes contendo vermiculita, por 45 dias. Foram avaliadas a porcentagem de estacas enraizadas, número de raízes por estaca, comprimento das três maiores raízes por estaca (cm) e a porcentagem de estacas vivas. Estacas coletadas nos meses de outubro e dezembro/2006 apresentaram as maiores porcentagens de enraizamento (87,3% e 86,7%, respectivamente) e maior número de raízes por estacas (9,5 e 10,4 raízes, respectivamente). O comprimento máximo das 3 maiores raízes (10,2 cm) foi obtido em estacas coletadas em dezembro/2006 e a maior taxa de sobrevivência (60%) foi registrada na coleta de junho/2006 em estacas tratadas com 500 e 1000 mg L-1 de AIB. A aplicação dos extratos de folhas e de tubérculos de C. rotundus não apresentou diferença entre os resultados obtidos com a aplicação de ANA e AIB, os quais, por sua vez, também não influenciaram o enraizamento de estacas de D. repens em nenhuma das épocas avaliadas.

It is known from popular tradition that extracts from nut grass increase the adventitious rooting of different species, being this procedure used in home-made vegetative propagation. Since in these extracts it is possible to find a large amount of auxins and phenolic compounds, the objective of this study was to evaluate the effect of the application of Cypreus rotundus L. leaves and tubers extracts in stem cuttings of Duranta repens L., a species considered of easy rooting, in comparison with the action of synthetic auxins. Cuttings were collected in april, june, august, october and december/2006 and february/2007 with 8 cm in length, diagonal cut at the bottom and a straight cut above the last bud, keeping four upper leaves. Treatments consisted of control (water and ethanol 50%); extract from C. rotundus leaves and tubers (25, 50 and 100%); NAA and IBA (500 and 1000 mg L-1), with immersion of the base of the cuttings for 10 seconds. Cuttings were kept in greenhouse under high moisture, in plastic containers containing vermiculite, for 45 days. The percentage of rooted cuttings, number of roots per cutting, length of the three longest roots per cutting (cm) and the percentage of living cuttings were evaluated. Cuttings collected in october and december/2006 demonstrated the highest percentages of rooting (87.3% and 86.7%, respectively) and highest number of roots per cutting (9.5 and 10.4 roots, respectively). December/2006 cuttings showed the maximum length of the three largest roots (10.2 cm) and the best level of survival (60%) was found in cuttings collected in june/2006 and treated with 500 and 1000 mg L-1 of IBA. Therefore, we observed no statistical differences between the application of C. rotundus leaf and tuber extracts and the application of NAA and IBA.