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Gray mold caused by Botrytis cinerea is an important disease in strawberries. This fungus causes significant economic losses since it attacks plants and fruits. In this context, this work aimed to evaluate the effectiveness of Acibenzolar-S-methyl (ASM) and Harpin protein in pre- and post-harvest as inducers of resistance in strawberries to B. cinerea. Strawberry plants (Fragaria x ananassa) from ‘Aromas’ and ‘Camarosa’ cultivars were grown in greenhouse and evaluated in laboratory. Doses of Harpin and ASM in pre- and post-harvest applications were assessed. Yield parameters of strawberry, B. cinerea incidence and injured area in fruit, fruit firmness, CO2 assimilation rate, and phenylalanine ammonia-lyase (PAL) activity were analyzed. Elicitors application in pre- and post-harvest conditions promoted a decrease of B. cinerea incidence and injured area in strawberry fruits. The results suggest that Harpin and ASM treatment show a significant impact on strawberry fruit disease. The control may be associated with the PAL induction, responsible for inducing defense responses. Harpin and ASM represent a promising alternative to synthetic fungicides for B. cinerea control during post-harvest storage.

Yerba mate (Ilex paraguariensis) has both economic and cultural importance in South America. However, due to a lack of quality control during processing, adulteration can occur. The aim of the study was to measure adulteration of yerba mate brands marketed in southern Brazil with sucrose, through isotopic characterization. Fifteen brands from local grocery stores were analyzed using eight samples of yerba mate derived from plants of different environments. Five samples of other species of Ilex genus and Ligustrum japonicum, which commonly contaminate yerba mate, were also tested. The isotopic composition of C (δ13C) and % N pointed out that some brands may have been adulterated with sucrose and a combination of % N and δ15N may be sufficient to identify contamination by leaves from other species. This study shows that isotopic characterization can potentially identify yerba mate that is adulterated with sucrose, and this method can also be used for quality control in food industry and to warrant further investigation.

Galling insects gain food and shelter by inducing specialized anatomical structures in their plant hosts. Such galls often accumulate plant defensive metabolites protecting the inhabiting insects from predation. We previously found that, despite a marked natural chemopolymorphism in natural populations of Pistacia palaestina, the monoterpene content in Baizongia pistaciae-induced galls is substantially higher than in leaves of their hosts. Here we show a general up-regulation of key structural genes in both the plastidial and cytosolic terpene biosynthetic pathways in galls as compared with non-colonized leaves. Novel prenyltransferases and terpene synthases were functionally expressed in Escherichia coli to reveal their biochemical function. Individual Pistacia trees exhibiting chemopolymorphism in terpene compositions displayed differential up-regulation of selected terpene synthase genes, and the metabolites generated by their gene products in vitro corresponded to the monoterpenes accumulated by each tree. Our results delineate molecular mechanisms responsible for the formation of enhanced monoterpene in galls and the observed intraspecific monoterpene chemodiversity displayed in P. palaestina. We demonstrate that gall-inhabiting aphids transcriptionally reprogram their host terpene pathways by up-regulating tree-specific genes, boosting the accumulation of plant defensive compounds for the protection of colonizing insects.

Yield increase in soybean [Glycine max (L.) Merr.] has occurred due to plant breeding, as well as the improvement in management practices. Genetic gain for important traits in soybean due to plant breeding in South Brazil has not been evaluated. The objective of this study was to measure the genetic progress of several soybean agronomic, phenological and physiological traits, in a historical set of cultivars released for cultivation in South Brazil from 1965 to 2011. Twenty-nine cultivars were evaluated in a three replicate randomized complete block design at two locations in the 2016/17 crop season. Mean genetic gain for yield was 40.06 kg ha−1 year−1 averaged across locations. The modern cultivars had higher biological yield (BY), harvest index (HI), number of pods per plant (NPP), and lower number of branches per plant, plant height, and lodging score compared to older releases. There was a reduction in the vegetative period, and increase in ratio between reproductive and vegetative periods (R/V). Photosynthetic rate (PN) and transpiration rate (Tr) also increased with year of release. The traits BY, NPP, HI, R/V, number of seeds per pod, PN, Tr, and chlorophyll content (Chl a and b) was highly associated with seed yield. Breeding strategies that maximize the R/V ratio, and prioritize indirect selection through HI, BY, NPP, PN, Tr, and Chl a and b, will likely contribute to improving soybean yield in the future.

The objective of this study was to evaluate the effect of acibenzolar-S-methyl (ASM) and harpin protein, applied pre-harvest, in the induction of resistance in strawberry to pathogens and mites. The experiment was conducted in a greenhouse, in a randomized block design with three replications. Treatments with harpin protein and ASM were established through biweekly applications of these elicitors in plants of strawberry, from 60 to 120 days after transplanting of seedlings. The application of ASM and harpin protein induced resistance in the strawberry plants, resulting in an increase in phenylalanine ammonia-lyase activity and total phenol production, while reducing leaf blight and grey mould. The application of harpin protein also caused a reduction in mite damage, while increasing photosynthetic rate and the production of marketable fruits. The elicitors ASM and harpin, applied pre-harvest, can be used as part of the integrated pest management of diseases and pests of strawberry.

Commercial Artemisia annua crops are the sole source of artemisinin (ART) worldwide. Data on seasonal accumulation and peak of sesquiterpenes, especially ART in commercial A. annua, is lacking while current breeding programs focus only on ART and plant biomass, but ignores dihydroartemisinic acid (DHAA) and artemisinic acid (AA). Despite past breeding successes, plants richer in ART are needed to decrease prices of artemisinin-combination therapy (ACT). Our results show that sesquiterpene concentrations vary greatly along the growing season and that sesquiterpene profiles differ widely among chemotypes. Field studies with elite Brazilian, Chinese, and Swiss germplasms established that ART peaked in vegetative plants from late August to early September, suggesting that ART is related to the photoperiod, not flowering. DHAA peaks with ART in Chinese and Swiss plants, but decreases, as ART increases, in Brazilian plants, while AA remained stable through the season in these genotypes. Chinese plants peaked at 0.9% ART, 1.6% DHAA; Brazilian plants at 0.9% ART, with less than 0.4% DHAA; Swiss plants at 0.8% ART and 1% DHAA. At single-date harvests, seeded Swiss plants produced 0.55-1.2% ART, with plants being higher in DHAA than ART; Brazilian plants produced 0.33-1.5% ART, with most having higher ART than DHAA. Elite germplasms produced from 0.02-0.43% AA, except Sandeman-UK (0.4-1.1% AA). Our data suggest that different chemotypes, high in ART and DHAA, have complementary pathways, while competing with AA. Crossing plants high in ART and DHAA may generate hybrids with higher ART than currently available in commercial germplasms. Selecting for high ART and DHAA (and low AA) can be a valuable approach for future selection and breeding to produce plants more efficient in transforming DHAA into ART in planta and during post-harvest. This novel approach could change the breeding focus of A. annua and other pharmaceutical species that produce more than one desired metabolite in the same pathway. Obtaining natural variants with high ART content will empower countries and farmers who select, improve, and cultivate A. annua as a commercial pharmaceutical crop. This selection approach could enable ART to be produced locally where it is most needed to fight malaria and other parasitic neglected diseases.

Understanding the processes responsible for genetic progress in grain yield and relating them to the growth and developmental phases of the wheat plant are essential for improving yield potential. This study aimed to evaluate the duration of developmental phases and eco-physiological traits associated to grain yield in Brazilian wheat cultivars released in different decades. Wheat cultivars released from 1940 to 2009 were evaluated during 2010 and 2011 in Pato Branco, Parana, Brazil. The length of the following periods was compared: sowing-emergence (SW-EM), emergence-double ridge (EM-DR), double ridge-terminal spikelet (DR-TS), terminal spikelet-anthesis (TS-ANT), anthesis-physiological maturity (ANT-PM), sowing-anthesis (SW-ANT) and sowing-physiological maturity (SW-PM). Yield components were also measured. Breeding has reduced the days until anthesis by 14.2%, while it has extended the grain-filling period by 7.6%, compared to the first cultivars released in the country, thereby contributing to a significant increase in 1000-grain weight (12.4 and 9.0% in 2010 and 2011, respectively). The TS-ANT phase was the only phase prior to anthesis exhibiting an extension from old to modern cultivars; this phase increased 1.56 °Cd syear−1. Spike fertility index (SFI) showed increases of 37.8 and 23.8% in 2010 and 2011, respectively. Shortening of the time to flowering, shifting of critical phases of wheat development to better environmental conditions (i.e., TS-ANT phase), and selection for shorter cultivars have been directly responsible for the increase in spike dry weight at anthesis (SDWa) and SFI [i.e., grain number (GN)].

Drought stress on reproductive stages constitute a major problem for common bean (Phaseolus vulgaris L.) production because it affects flowering and pod-filling processes which are highly drought-sensitive. In this study, we used a greenhouse experiment to evaluate the response to drought stress in ten highly cultivated Brazilian genotypes in response to moderate intermittent drought during flowering and pod-filling periods (R7 and R8 stages). Morphological, biochemical, physiological and agronomic traits were used to identify tolerant cultivars and elucidate their strategies to cope this stress. The drought intensity index for the experiment reached 0.63. The cultivar IAC Imperador can be defined as a tolerant cultivar, presenting the lowest grain yield reduction (43%) and a reduced drought susceptibility index (0.65). This cultivar elevated their level of proline in roots under stress, which allowed the osmotic adjustment and the maintenance of an intermediate stomata closure during the day, which maintained the intrinsic WUE stable in NS and DS conditions. In addition, this cultivar was able to mobilize the assimilated carbon for the production of pods and grains, evidenced by the high harvest index and the high grain filling index. In this way, IAC Imperador can be used as a check in breeding programs to identify and select lineages with drought tolerance in common bean.

O objetivo deste trabalho foi avaliar o efeito de doses do regulador de crescimento trinexapac-ethyl e níveis de adubação nitrogenada sobre o desempenho agronômico e rendimento de grãos de três cultivares de trigo. O delineamento experimental foi de blocos ao acaso, em esquema fatorial, com três repetições, sendo: duas doses de adubação nitrogenada (60 e 120 kg ha-1), três cultivares de trigo (BRS 208, BRS 220 e BRS Guamirim), quatro doses de trinexapac-ethyl (0, 70, 140 e 210 g i.a. ha-1) e duas safras agrícolas (2008 e 2009). Na microrregião de Pato Branco, a dose de 60 kg ha-1 é suficiente para maximizar o potencial de rendimento de grãos dos cultivares avaliados. Independentemente da estatura dos cultivares, o regulador de crescimento não apresentou efeito positivo sobre o rendimento de grãos, com efeito negativo na presença de menor disponibilidade hídrica. The objective of this work was to evaluate the effect of trinexapac-ethyl and nitrogen doses on the agronomic performance and grain yield of three wheat cultivars. The experiment was arranged in a randomized block design in a factorial scheme, with three replications. The treatments were two nitrogen fertilization doses (60 and 20 kg ha-1), three wheat cultivars (BRS 208, BRS 220, and BRS Guamirim), four trinexapac-ethyl doses (0, 70, 140, and 210 g a.i. ha-1) and two harvest years (2008 and 2009). In the Pato Branco microregion, the nitrogen rate of 60 kg ha-1 was sufficient to maximize the yield potential of the evaluated cultivars. Regardless of the height of the cultivar plants, trinexapac-ethyl showed no positive effect on grain yield, with negative effect under water-deficit stress.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:26:15Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:36:29Z : No. of bitstreams: 1 2-s2.0-84860715853.pdf: 104673 bytes, checksum: 83517ecf4d3b7957622030cbda8fa85e (MD5) Made available in DSpace on 2014-05-27T11:26:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-01 The metabolic effects caused by hydric deficiency (HD) on Eucalyptus grandis clones were assessed by an experiment where plants were cultivated in four blocks. The first was the control block, normally irrigated, whereas the other three blocks were submitted to cycles of hydric deficiency. Analysis of photosynthetic efficiency, enzymatic activity of antioxidant response system, level of pigments and L-proline concentration were performed to evaluate the HD effects. Results showed that HD altered some parameters related to photosynthetic activity, pigments accumulation, proline and enzymatic activity. Clone 433 of E. grandis presented higher response ability to HD. Department of Chemistry and Biochemistry Institute of Biosciences São Paulo State University (Unesp), 18618-000, Botucatu, São Paulo Laboratory of Plant Physiology and Biochemistry Department of Agronomy Federal Technological University of Paraná (UTFPR), 85503-390, Pato Branco, Paraná Departamento de Riego Centro de Edafología y Biología Aplicada del Segura (CSIC), P.O. Box 164, E-30100 Murcia Department of Chemistry and Biochemistry Institute of Biosciences São Paulo State University (Unesp), 18618-000, Botucatu, São Paulo

Isotope screening is a simple test for determining the photosynthetic pathway used by plants. The scope of this work was to classify the photosynthetic type of some herbs and medicinal plants through studies of the carbon isotope composition (δ13C). Also, we propose the use of carbon isotope composition as a tool to control the quality of herbs and medicinal plants. For studies of δ13C, δ13C‰ = [R (sample)/R (standard) − 1] × 10−3, dry leaves powdered in cryogenic mill were analyzed in a mass spectrometer coupled with an elemental analyzer for determining the ratio R = 13CO2/12CO2. In investigation of δ13C of 55 species, 23 botanical families, and 44 species possessed a C3 photosynthetic type. Six species found among the botanical families Euphorbiaceae and Poaceae were C4 plants, and 5 species found among the botanical families Agavaceae, Euphorbiaceae, and Liliaceae possessed CAM-type photosynthesis. Carbon isotope composition of plants can be used as quality control of herbs and medicinal plants, allowing the identification of frauds or contaminations. Also, the information about the photosynthetic type found for these plants can help in introducing and cultivating exotic and wild herbs and medicinal plants.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:21:15Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:39:53Z : No. of bitstreams: 1 2-s2.0-18444399306.pdf: 117433 bytes, checksum: 65b6e2183e9543e563858c0210a43cf5 (MD5) Made available in DSpace on 2014-05-27T11:21:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-01-01 Leaves of Artemisia annua L. are a plentiful source of artemisinin, a drug with proven effectiveness against malaria. The aim of this study was to classify the photosynthetic mechanism of A. annua through studies of the carbon isotope composition (δ 13C) and the leaf anatomy. A. annua presented a δ 13C value of - 31.76 ± 0.07, which characterizes the plants as a typical species of the C3 photosynthethic mechanism, considering that the average δ 13C values for C3 and C4 species are -28 and -14, respectively. The leaf anatomy studies were consistent with the δ 13C results, where, in spite of the existence of parenchymatic cells forming a sheath surrounding the vascular tissue, the cells do not contain chloroplasts or starch. This characteristic is clearly different from that of the Kranz anatomy found in C4 species. Laboratory of Biochemistry and Plant Physiology Agronomy College CEFET-PR, Pato Branco 85503-390 Institute of Biosciences São Paulo State University, Botucatu 18618-000 Agronomic Sciences College São Paulo State University, Botucatu 18603-970 Plant Biology Department Viçosa Federal University, Viçosa 36570-000 Institute of Biosciences São Paulo State University, Botucatu 18618-000 Agronomic Sciences College São Paulo State University, Botucatu 18603-970

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:55:07Z No. of bitstreams: 1 S0102-05362004000200034.pdf: 375974 bytes, checksum: 022a39b88e88f3b4107360119c106462 (MD5) Made available in DSpace on 2013-08-22T18:55:07Z (GMT). No. of bitstreams: 1 S0102-05362004000200034.pdf: 375974 bytes, checksum: 022a39b88e88f3b4107360119c106462 (MD5) Previous issue date: 2004-06-01 Made available in DSpace on 2013-09-30T19:47:38Z (GMT). No. of bitstreams: 2 S0102-05362004000200034.pdf: 375974 bytes, checksum: 022a39b88e88f3b4107360119c106462 (MD5) S0102-05362004000200034.pdf.txt: 16576 bytes, checksum: cf796672703e45da5caacd43e1e20eb2 (MD5) Previous issue date: 2004-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:19:36Z No. of bitstreams: 2 S0102-05362004000200034.pdf: 375974 bytes, checksum: 022a39b88e88f3b4107360119c106462 (MD5) S0102-05362004000200034.pdf.txt: 16576 bytes, checksum: cf796672703e45da5caacd43e1e20eb2 (MD5) Made available in DSpace on 2014-05-20T13:19:36Z (GMT). No. of bitstreams: 2 S0102-05362004000200034.pdf: 375974 bytes, checksum: 022a39b88e88f3b4107360119c106462 (MD5) S0102-05362004000200034.pdf.txt: 16576 bytes, checksum: cf796672703e45da5caacd43e1e20eb2 (MD5) Previous issue date: 2004-06-01 Diagnosticou-se o perfil dos consumidores de supermercados em Pato Branco (PR), com relação às suas preferências pelas plantas medicinais e condimentares, como subsídio à produção por pequenos produtores rurais. Os consumidores preferem produtos orgânicos, observam a aparência e o preço do produto, e vão ao mercado uma vez por semana, preferencialmente aos sábados. As dez plantas medicinais preferidas, em ordem decrescente, são camomila, anis, boldo, carqueja, guaco, malva, poejo, espinheira-santa, menta e sálvia. As dez plantas condimentares preferidas, em ordem decrescente, são cebola, cravo, canela, orégano, alho, nóz-moscada, pimentão, cebolinha, endro e salsinha. The profile of supermarket users in Pato Branco city, Paraná State, Brazil, was obtained, related to their preference for medicinal and spice plants, as a subsidy to production by small farmers. The consumers prefer organic products observing the appearance and price of the product, and they go once a week to the market, preferably on Saturdays. The ten favorite medicinal plants are Chamomilla recutita, Pimpinella anisum, Vernonia condensata, Baccharis sp., Mikania sp., Malva sp., Cunilla sp., Maytenus sp., Mentha sp. and Salvia officinalis. The ten favorite spices are: Allium cepa, Eugenia caryophyllata, Cinnamomum zeylanicum, Origanum vulgaris, Allium sativum, Myristicia fragans, Capsicum annuum, Allium schoenoprasum, Anethum graveolens and Petroselinum crispum. Centro Federal de Educação Tecnológica Laboratório de Bioquímica e Fisiologia Vegetal Universidade Estadual Paulista Departamento de Química e Bioquímica Universidade Estadual Paulista Departamento de Produção Vegetal Universidade Estadual Paulista Departamento de Química e Bioquímica Universidade Estadual Paulista Departamento de Produção Vegetal

The effect of different doses of nitrogen (N) on gas exchange, relative chlorophyll (Chl) amount, and the content of N in the aerial biomass of lisianthus was evaluated. The treatments consisted of six different concentrations of N (50, 100, 150, 200, 250, and 300 g m−3 noted as N50, N100, N150, N200, N250, and N300, respectively), applied through the fertirrigation technique. N250 and N300 induced increase in the contents of foliar Chl and N in the aerial biomass, that in turn contributed to an increase of photosynthetic activity in lisianthus.

O objetivo do estudo foi avaliar por meio da análise de crescimento, as variações nas características fisiológicas do feijoeiro comum, cultivar IPR Tiziu, submetidos a diferentes densidades de semeadura, buscando identificar a melhor disposição espacial das plantas. O delineamento experimental foi de blocos ao acaso com quatro repetições, os tratamentos consistiram de cinco densidades de semeadura (DS): 8, 10, 12, 14 e 18 plantas m-1, respectivamente, 20, 25, 30, 35, 40 pl m-2. Para avaliação, semanalmente coletaram-se 12 plantas de cada parcela. Os resultados evidenciaram aumento do índice de área foliar (IAF) e da matéria seca total (MST) até 57 dias após a emergência (DAE), enquanto a taxa de crescimento da cultura (TCC), taxa de crescimento relativo (TCR), taxa assimilatória líquida (TAL) e razão de área foliar (RAF) apresentaram redução durante o ciclo da cultura. A DS de 30 pl m-2 foi a mais eficiente no aproveitamento dos recursos do ambiente quanto à conversão de energia luminosa e CO2 em MST, já que apresentou os maiores valores de MST, TCC e TAL. Entretanto, os tratamentos não diferiram significativamente entre si para os componentes do rendimento e rendimento de grãos. A maior DS promoveu menor TAL, TCC, RAF devido ao aumento do IAF, o que provocou auto-sombreamento na cultura, diminuindo a eficiência fotossintética do feijoeiro.

Despite the importance of Artemisia annua L. as the only source of the anti-parasitic drug artemisinin, little is known on the effects of biotic and abiotic stress on artemisinin accumulation. Water deficit is the most limiting factor on plant growth, however it can trigger secondary metabolite accumulation, depending on the plant growth stage and intensity. A. annua cultivated in growth chambers was submitted to five water deficit treatments (watered, 14, 38, 62 e 86 hours without irrigation). Water deficits of 38 and 62 hours (Yw = -1.39 and -2.51 MPa, respectively) increased leaf artemisinin content, but only 38 hours led to a significant increase in both leaf and plant artemisinin (29%), with no detriment to plant biomass production. The other treatments had no effect on, or decreased artemisinin accumulation. A. annua plants tolerated well water deficit treatments, including the most severe water deficit applied (Yw -3.97 MPa or 86 hs without irrigation) and recovered their turgor pressure after rehydration. These results suggest that moderate water deficit prior to harvesting the crop may not only reduce time and costs in drying the crop, but can also induce artemisinin accumulation, both of which increase crop profit margins. Results also suggest that artemisinin could be part of A. annua chemical system of defense against water deficit. A despeito da importância da Artemisia annua L. como a única fonte da droga anti-parasitária artemisinina, muito pouco é sabido sobre o papel dessa molécula em plantas sob estresses biótico e abiótico. A deficiência hídrica é o principal fator limitante no crescimento vegetal, mas pode induzir a acumulação de metabólitos secundários, dependendo da intensidade e fase de desenvolvimento da planta. Plantas de A. annua cultivadas em câmaras de crescimento foram submetidas a cinco tratamentos (plantas irrigadas e com 14, 38, 62 e 86 horas sem irrigação). Deficiências hídricas de 38 e 62 horas (Yw = -1.39 e -2.51 MPa, respectivamente) aumentaram o conteúdo foliar de artemisinina, mas somente a deficiência hídrica de 38 horas induziu um aumento significativo da molécula em folhas (29%) e planta inteira, sem afetar o acúmulo de biomassa. Os outros tratamentos não afetaram significativamente o conteúdo de artemisinina. As plantas de A. annua apresentaram uma boa tolerância a deficiência hídrica, incluindo o tratamento mais severo (Yw -3.97 MPa ou 86 h sem irrigação) e recuperaram a pressão de turgor após a reidratação. Estes resultados sugerem que uma deficiência hídrica moderada imediatamente antes da colheita de A. annua pode não somente reduzir o tempo e os custos de secagem da cultura, mas também induzir ao acúmulo de artemisinina, condições que, conjuntamente, são benéficas para o cultivo commercial da espécie. Finalmente, estes resultados sugerem que a artemisinina pode ser parte do sistema químico de defesa da A. annua contra a deficiência hídrica.

Na agricultura atual, o método mais utilizado para o controle de plantas daninhas é o químico, em razão da facilidade de uso, elevada eficiência e baixa necessidade de mão de obra. No entanto, a utilização inadequada desses produtos provoca problemas ao ambiente e à saúde humana. Cresce, portanto, a busca por métodos alternativos de controle de plantas daninhas, menos demandadores de energia e menos tóxicos e agressivos ao ambiente. Este trabalho objetivou avaliar o efeito alelopático da cultura do girassol (Helianthus annuus) sobre diferentes espécies de plantas daninhas e cultivadas, em dois experimentos realizados em delineamento experimental completamente casualizado, utilizando o método da semeadura em substituição. O primeiro experimento foi realizado com quatro repetições, em esquema bifatorial. O primeiro fator foi constituído por seis espécies indicadoras: picão-preto (Bidens pilosa), corda-de-viola (Ipomoea grandifolia), caruru (Amaranthus hybridus), alface (Lactuca sativa, cultivar Aurélia), tomate (Lycopersicon esculentum, cultivar Santa Cruz), trigo (Triticum aestivum, cultivar BRS 208); e o segundo, pela presença ou não de plântulas de girassol. O segundo experimento foi composto por 24 tratamentos, representados por 23 genótipos de girassol e por uma testemunha sem girassol, utilizando-se quatro repetições. A espécie indicadora foi apenas o picão-preto. Em ambos os experimentos, no final do período de sete dias de convívio, foram avaliados o número de sementes germinadas e o comprimento radicular e da parte aérea das espécies indicadoras. Não foram observadas diferenças entre as porcentagens de germinação de quaisquer das espécies indicadoras avaliadas, em função da presença ou não das plântulas de girassol. A presença de plântulas de girassol estimulou o crescimento radicular das plântulas de tomate e trigo e inibiu o crescimento da parte aérea de picão-preto, trigo e corda-de-viola. Houve grande variabilidade de potencial alelopático entre genótipos de girassol sobre a germinação e o crescimento radicular e da parte aérea de Bidens pilosa. Os resultados demonstram que a técnica da semeadura em substituição é adequada para detectar efeitos estimulativos ou inibitórios de girassol sobre espécies indicadoras e para discriminar genótipos de girassol quanto à habilidade em inibir ou estimular plântulas de Bidens pilosa. In modern agriculture, the chemical method is the most used for weed control because it is highly efficient, easy to apply, and demands limited labor. However, the inadequate use of chemical products can lead to environmental and human health problems. Thus, there is a growing need to search for alternative weed control methods using substances which are less energy-demanding, less toxic and less aggressive to the environment. This work aimed to evaluate the allelopathic potential of sunflower (Helianthus annuus) culture on different weed and cultivated species, in two experiments conducted in a completely randomized design, using the relay seeding technique. The first experiment was carried out with four repetitions, in a bi-factorial scheme. The first factor was constituted by six indicative target species: beggarticks (Bidens spp.), common morninglory (Ipomoea grandifolia), pigweed (Amaranthus hybridus), lettuce (Lactuca sativa, cv. Aurélia), tomato (Solanum lycopersicum, cv. Santa Cruz), and wheat (Triticum aestivum, cv. BRS 208).The second factor was constituted by the presence or absence of sunflower seedlings. The relay seeding technique was applied. The second experiment was composed by 24 treatments including 23 sunflower genotypes and a control without sunflower, with four repetitions. The indicative species was only the beggarticks. In both experiments, at the end of seven coexistence days, number of germinated seeds, and root and aerial part length of the target species were evaluated. No difference was observed among the germination percentages of the indicative species evaluated in the presence or absence of the sunflower plants. The presence of the sunflower plants stimulated tomato and wheat root growth and inhibited the growth of the beggartick, wheat and common morninglory aerial parts. There was great variability of the potential allelopathic effect of the sunflower genotypes on germination and root and aerial part length of Bidens pilosa. The results show that the relay seeding technique is adapted to discriminate stimulating and inhibiting effects of sunflower among indicative species and to discriminate sunflower genotypes in their ability to inhibit or stimulate Bidens pilosa plants.

We evaluated the growth and development of the medicinal species Pothomorphe umbellata (L.) Miq. under different shade levels (full sun and 30, 50, and 70 % shade, marked as I100, I70, I50, and I30, respectively) and their effects on gas exchange and activities of antioxidant enzymes. Photosynthetically active radiation varied from 1 254 µmol m−2 s−1 at I100 to 285 µmol m−2 s−1 at I30. Stomatal conductance, net photosynthetic rate, and relative chlorophyll (Chl) content were maximal in I70 plants. Plants grown under I100 produced leaves with lower Chl content and signs of chlorosis and necrosis. These symptoms indicated Chl degradation induced by the generation of reactive oxygen species. Stress related antioxidant enzyme activities (Mn-SOD, Fe-SOD, and Cu/Zn-SOD) were highest in I100 plants, whereas catalase activity was the lowest. Hence P. umbellata is a shade species (sciophyte), a feature that should be considered in reforestation programs or in field plantings for production of medicinal constituents.