Aromatic plants contain both volatile and non-volatile fractions and the chemical composition of these two fractions may be influenced by seasonal changes. The essential oil and solvent extracts of S. africana-caerulea, S. africana-lutea and S. lanceolata, collected at the same locality throughout the 2005 growing season, were compared in terms of essential oil composition, yields and biological activities. Mostly quantitative, rather than qualitative variationwas observed in the oil composition of each species.Major fluctuations in the composition of S. africana-caerulea oil included limonene (2–33%) and viridiflorol (2–24%). Levels of α-pinene (1–12%), myrcene (2–12%) and α-eusdesmol (trace-13%) fluctuated seasonally in the S. africana-lutea oil. In S. lanceolata, considerable changeswere noted for β-caryophyllene (1–19%), β-caryophyllene oxide (1–21%) and ledol (3–12%). The extract prepared from S. lanceolata harvested inwinterwas more active against Gram-positive bacteria. The S. africana-caerulea extract exhibited the most favourable antiplasmodial activity when harvested in winter (IC50 value: 12 μgml−1), which contrasts with the lowest anti-plasmodial activity of S. lanceolata obtained at the same period (IC50 value: 43 μgml−1). The anti-oxidant activity of the solvent extracts also displayed variation over seasons with thewinter collection of S. africana-lutea yielding the most favourable anti-oxidant activity (IC50 value: 10 μg ml−1). All the solvent extracts prepared from the winter collection exhibited the lowest toxicity (20bIC50 valuesb60 μg ml−1), while the three essential oils obtained from autumn collection were more toxic (0.03bIC50 valuesb0.4 μg ml−1).

Peppermint dry weight biomass was higher in Verona (8119 kg/ha) than in Stoneville (6115 kg/ha). Overall both, oil content and yield were higher in bud formation stage than flowering stage. The levels of major essential oil constitutes were (-)-menthol 26 – 30 %, (-)-menthone 14 – 21 %, (+)-menthofuran 5 – 11 %, and eucalyptol 3 – 4 % of total essential oil content at flowering stage. Menthone content and its yield were higher at first cut; however, (+)-menthofuran content and its yield were higher at the second cut at bud formation. Although N fertilizers at rate 80 kg/ha did not affect essential oil content and yield at cut 1, N rate at 80 + 80 kg/ha increased oil yield at cut 2.

This study investigated the effects of drought, nitrogen fertilizer and elevated CO2 and its interaction with nitrogen fertilizer on the physiology, growth, and production of the oil crop safflower (Carthamus tinctorius L.) in a semi-controlled glasshouse environment. Three levels of water stress were imposed: rosette (mid-season drought), stem elongation (terminal drought) and rosette to maturity (mid-season + terminal drought). Results indicated that all drought treatments imposed reduced stomatal conductance, but after the relief of mid-season drought plants recovered and as a result there were no significant differences from control in terms of yield components (branch and capital number) and seed number. Terminal drought and mid–season + terminal drought induced significant reductions in branch number (48% and 50%), in capitula number (33% and 67%), in seed number (89% and 92%), in above ground dry weight (30% and 54%) and in individual fresh seed weight (90% and 94%) respectively. However, water stress treatments had no significant effect on the maximum quantum efficiency of PSII (Fv/Fm) in dark adapted leaves compared with the control. Levels nitrogen fertilizer was studied equivalent to 0, 25, 50, 75, 100, 125, 150, 175 kg N ha-1 were evaluated. Safflower responded incrementally to increasing nitrogen applied in a curvilinear asymptotic fashion. Assimilation rate (42%), transpiration rate (32%), stomatal conductance (52%) and LAI (42%) increased III up to 100 kg N ha-1 compared with the control. The above ground dry weight and seed yield associated with WUE continued to increase with each increment in nitrogen rate and above ground dry weight (42%), individual seed fresh weight (76%) and WUE (41%) increased up to 175 kg N ha-1 compared with the control. The effect of elevated CO2, (1000 μmol mol-1) significantly increased assimilation rate (27%) reduced stomatal conductance (29%) and transpiration rate (18%), increased LAI (28%) and above ground dry weight (51%) when measured at anthesis compared with ambient (400 μmol mol-1). At the same time plant organ N content was reduced. At harvest, elevated CO2 increased above ground dry weight (42%) and individual fresh seed weight (49%). The interaction effect of elevated CO2 with nitrogen input was investigated using four nitrogen levels equivalent to 25, 75,125 and 175 kg ha-1. The nitrogen response rate was raised by elevated CO2 equally at each nitrogen application rate so that there was no significant interaction effect between the two for most parameters measured. In this way both CO2 and nitrogen were acting as “fertilizers”. Overall the results showed that despite being put forward as a drought resistant crop for low input agricultural systems safflower is capable of responding positively to well irrigate and well fertilized conditions. Furthermore under conditions of elevated CO2 it can be expected to increase its yield potential but to achieve this will require a higher degree of nitrogen fertilization. CO2 is capable of substituting for up to 100 kg N ha-1 without a decline in yield and this shows that CO2 is the primary limiting factor in safflower assimilation. IV Seed oil content and its fatty acid profile appeared to be relatively stable and were not affected drastically by either nitrogen fertilization or elevated CO2.This demonstrated the integrity of the oil filling process during seed fill and emphasized that this is primarily under genetic control with relatively little influence from environmental parameters.

Natural variation in the relative proportions of saturated and unsaturated fatty acids in seed oils of plants is enormous when considered across a broad taxonomic range of oil seeds. It has been shown that this variation follows a latitudinal cline where the proportions of unsaturated fatty acids increases with increasing latitude as the unsaturated fatty acids in seeds provide energy at a faster rate to germinating seeds at higher latitudes. This variation which follows a latitudinal cline suggests that there may be an adaptive role for this variation. We tested this hypothesis in Arabidopsis thaliana which followed the same trend seen in Helianthus and other angiosperms. In order to understand the underlying genetics of the regulation of the relative proportions of fatty acids and their role in plant evolution, we mapped quantitative trait loci (QTLs) and candidate genes. Here we identified 67 major QTLs responsible for fatty acid synthesis in A. thaliana in Ler-0 x Sha, Ler-0 x Col-4, Ler-2 x Cvi and Ler-0 x No-0 RIL populations. Eight candidate genes were identified based on what is known about seed oil biosynthesis in A. thaliana. Six of the candidate genes collocated to most of the major QTLs. In order to demonstrate that a particular allelic variant is indeed causally related to the phenotype, we investigated DNA polymorphisms in the parental and the RIL line alleles of the collocating candidate genes. Single nucleotide polymorphisms (SNPs) were identified in the collocating candidate genes to study the correlation between the sequence variants and the particular phenotype. We identified 232 SNPs with 77 in the putative regulatory regions upstream of the 5’UTR, 61 in the introns, 18 in the 5’UTR regions, 2 in the 3’UTR regions, and 45 occurring in the exons with 10 non-synonymous substitutions affecting the amino acid residues. We also detected 44 insertions/deletions in the coding, non-coding, 5’UTR, 3’UTR and the regulatory regions. Sequence variation in the fatty acid genes due to SNPs and insertions/deletions should be valuable in tests of association to investigate how the relative proportions of saturated and unsaturated fatty acids are regulated in wild plants and what role they have played in plant evolution and also in breeding oil seed crops that are healthier or have two types of fatty acids in proportions appropriate for different uses. / text

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Soil water availability is one of the major factors affecting the success or failure of an agricultural crop. Stresses caused by water deficit or surplus are harmful to the growth and sunflower yield. Plant growth pattern is changed and the yield is reduced with the growth of the intensity corresponding to stress. The main aims of this study were to evaluate the grain yield and quality of sunflower oil, root growth, deepening and distribution of roots in the soil, growth of shoot and roots in dry matter and modeling of sunflower plant growth, in response to stress caused by water surplus and water deficit in two sowing dates and two soils of Rio Grande do Sul. The experiments were carried out at early sowing date (sowing in early September) and late sowing date (sowing in early January), in two soils in the municipalities of Santa Maria (Ultisol) and Panambi (Oxisol). Three treatments of water availability were applied: water deficit (maintaining soil moisture between 40 and 60% of the available water capacity (AWC)), water surplus (maintained between 90% of AWC and the determine saturation point) and control (maintained between 75 and 100% of the AWC). To determine the water condition of the soil along the cycle was held daily sequential water balance. The water inlet by rain in the treatment of water deficit was controlled. The analyzed variables were yield and yield components, oil content and oil yield, fatty acid profile, root depth, root distribution, dry matter of different plant parts, in addition to intrinsic variables of growth analysis. Modeling of the root depth and sunflower growth in dry matter was held of different plant parts. The drought level applied was more harmful than the level of water surplus applied, with significant reduction in yield, yield components and sunflower growth. Sowing date had influence on yield, where the early sowing date produced more than late sowing date. Soil had great influence on the root deepening which was higher in Ultisol compared to Oxisol, which impacted the yield gap under water deficit. Water deficit was responsible for increased Oleic Acid and reduction of Linoleic Acid. The sowing at early sowing date enables deepening and increased dry matter production of roots than sowing at late sowing date. Sunflower growth models in dry matter and root depth had good fit to the measured data. In this way, it is concluded that soil water availability and sowing dates influences the yield and quality of sunflower and should be taken measures to mitigate the problems caused. / A disponibilidade hídrica do solo é um dos principais fatores responsáveis pelo sucesso ou insucesso de um cultivo agrícola. A ocorrência de estresses causados por déficit ou por excesso hídrico é prejudicial ao crescimento e à produtividade do girassol. O padrão de crescimento das plantas é alterado e a produtividade é reduzida com o aumento da intensidade correspondente ao estresse. Os principais objetivos deste trabalho foram avaliar a produtividade de grãos e de óleo e a qualidade do óleo do girassol, o crescimento, aprofundamento e distribuição de raízes no solo, o crescimento da parte aérea e raiz em matéria seca e a modelagem do crescimento de plantas de girassol, em resposta ao estresse causado por excesso e déficit hídrico, em duas épocas de semeadura e dois solos do Rio Grande do Sul. Os experimentos foram realizados na Safra (semeadura em início de setembro) e na Safrinha (semeadura em início de janeiro), em dois solos nos municípios de Santa Maria (Argissolo) e Panambi (Latossolo). Foram aplicados três tratamentos de disponibilidade hídrica: déficit hídrico (mantendo-se a umidade do solo entre 40 e 60% da capacidade de armazenamento de água disponível (CAD)), excesso hídrico (mantido entre 90% da CAD e o ponto de saturação determinado) e controle (mantido entre 75 e 100% da CAD). Para determinar a condição hídrica do solo ao longo do ciclo, realizou-se o balanço hídrico sequencial diário. A entrada de água por chuva no tratamento de déficit hídrico foi controlada. As variáveis analisadas foram a produtividade, os componentes da produtividade, o teor e o rendimento de óleo, o perfil de ácidos graxos, a profundidade radicular, a distribuição radicular, a matéria seca das diferentes partes da planta, além das variáveis intrínsecas a análise de crescimento. Foi realizada a modelagem do aprofundamento radicular e do crescimento do girassol em matéria seca das diferentes partes da planta. Verificou-se que o nível de déficit hídrico aplicado foi mais prejudicial do que o nível de excesso hídrico aplicado, com redução significativa da produtividade, dos componentes da produtividade e do crescimento do girassol. A época de semeadura teve influencia sobre a produtividade, em que a Safra produziu mais do que a Safrinha. O solo teve grande influencia sobre o aprofundamento radicular que foi maior no Argissolo em comparação ao Latossolo, o que impactou na diferença de produtividade. O déficit hídrico foi responsável pelo aumento do Ácido Oleico e pela redução do Ácido Linoleico. A semeadura na Safra possibilita um maior aprofundamento e maior produção de massa seca de raízes do que a semeadura da Safrinha. Os modelos de crescimento do girassol em matéria seca e em profundidade radicular apresentaram bom ajuste aos dados medidos. Dessa forma, conclui-se que a disponibilidade hídrica do solo e a época de semeadura influenciam na produtividade e na qualidade do girassol e se devem tomar medidas para mitigar os problemas causados.