Osmar Rodrigues

Water deficit effect on the accumulation of biomass and artemisinin in annual wormwood(Artemisia annua L., Asteraceae)

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.

Fifty years of wheat breeding in Southern Brazil: yield improvement and associated changes

The objective of this study was to assess the impact of genetic breeding on grain yield, and to identify the physiological traits associated to the increment in yield and their related growth processes, for wheat cultivars grown in Southern Brazil, in the past five decades. Seven wheat cultivars released between 1940 and 1992, were compared for physiological aspects associated with grain yield. Grain yield, biological yield, biomass partitioning, harvest index and grain yield components were also determined. The number of grains per square meter was more affected by plant breeding and was better correlated with grain yield (r = 0.94, p<0.01) than with grain weight (r = -0.39 ns ). The higher number of grains per square meter was better correlated with the number of grains per spike in the modern cultivars than in the older ones. The genetic gain in grain yield was 44.9 kg ha -1 per year, reflecting important efforts of the breeding programs carried out in Southern Brazil. Grain yield changes, during the period of study, were better associated with biomass production (r = 0.78, p<0.01) than with harvest index (r = 0.65, p<0.01).

Realocação de nitrogênio e de biomassa para os grãos, em trigo submetido a inoculação de Azospirillum

The effect of inoculating wheat (Triticum aestivum L.) seeds, cultivar Embrapa 16, with powder peat inoculant containing Azospirillum bacteria on yield and remobilization of nitrogen and biomass was studied under field conditions. The strain of Azospirillum brasilense 245 and the isolate 10 of Azospirillum lipoferum were used as inoculants. Different rates of nitrogen were applied at varying stages of plant growth for each inoculated and non-inoculated treatment, distributed in blocks at random with split plots. The accumulation of dry matter and total nitrogen in plant parts was evaluated at anthesis and physiological maturity stages. Harvest index for biomass and N, main yield components, and total N content in the seeds, in addition to yield, were also evaluated at harvest. The preliminary results showed that, even without inoculation effect on yield, there was a better allocation of nitrogen and biomass to the seeds, resulting in heavier seeds, with a lower amount of nitrogen remaining in the straw at physiological maturity. Such effects resulted from a lower number of spikes m-2, probably due to the death of tillers, determining a greater availability of N and biomass to the remaining spikes and seeds.Estudou-se, em condicoes de campo, o efeito de inoculante turfoso em po contendo bacterias do genero Azospirillum no rendimento de graos e na remobilizacao de N e de biomassa para os graos de trigo (Triticum aestivum L.), cultivar Embrapa 16. Usaram-se como inoculantes, a estirpe de Azospirillum brasilense 245 e o isolado 10 de Azospirillum lipoferum. Em cada tratamento de inoculacao, e tambem sem inoculacao, aplicaram-se diferentes doses de N em diferentes estadios de desenvolvimento das plantas, distribuidos em blocos ao acaso com parcelas subdivididas. Na antese e na maturacao fisiologica, avaliaram-se o acumulo de massa seca e N total nas diferentes partes da planta. Na colheita, alem do rendimento de graos, avaliaram-se tambem o indice de colheita para biomassa e para N, os principais componentes do rendimento e o teor de N total de graos. Os resultados ainda preliminares evidenciaram que, mesmo nao havendo efeito da inoculacao no rendimento de graos, houve um melhor alocamento de N e de biomassa para os graos, resultando em maior massa de mil graos e em menor quantidade de N restante na palha das plantas na maturacao fisiologica. Esses efeitos resultaram de um menor numero de espigas m-2, provavelmente devido a morte de afilhos, fator que determinou maior disponibilidade de N e de biomassa as espigas e graos restantes.

Reallocation of nitrogen and biomass to the seeds in wheat inoculated with Azospirillum bacteria

The effect of inoculating wheat (Triticum aestivum L.) seeds, cultivar Embrapa 16, with powder peat inoculant containing Azospirillum bacteria on yield and remobilization of nitrogen and biomass was studied under field conditions. The strain of Azospirillum brasilense 245 and the isolate 10 of Azospirillum lipoferum were used as inoculants. Different rates of nitrogen were applied at varying stages of plant growth for each inoculated and non-inoculated treatment, distributed in blocks at random with split plots. The accumulation of dry matter and total nitrogen in plant parts was evaluated at anthesis and physiological maturity stages. Harvest index for biomass and N, main yield components, and total N content in the seeds, in addition to yield, were also evaluated at harvest. The preliminary results showed that, even without inoculation effect on yield, there was a better allocation of nitrogen and biomass to the seeds, resulting in heavier seeds, with a lower amount of nitrogen remaining in the straw at physiological maturity. Such effects resulted from a lower number of spikes m-2, probably due to the death of tillers, determining a greater availability of N and biomass to the remaining spikes and seeds.Estudou-se, em condicoes de campo, o efeito de inoculante turfoso em po contendo bacterias do genero Azospirillum no rendimento de graos e na remobilizacao de N e de biomassa para os graos de trigo (Triticum aestivum L.), cultivar Embrapa 16. Usaram-se como inoculantes, a estirpe de Azospirillum brasilense 245 e o isolado 10 de Azospirillum lipoferum. Em cada tratamento de inoculacao, e tambem sem inoculacao, aplicaram-se diferentes doses de N em diferentes estadios de desenvolvimento das plantas, distribuidos em blocos ao acaso com parcelas subdivididas. Na antese e na maturacao fisiologica, avaliaram-se o acumulo de massa seca e N total nas diferentes partes da planta. Na colheita, alem do rendimento de graos, avaliaram-se tambem o indice de colheita para biomassa e para N, os principais componentes do rendimento e o teor de N total de graos. Os resultados ainda preliminares evidenciaram que, mesmo nao havendo efeito da inoculacao no rendimento de graos, houve um melhor alocamento de N e de biomassa para os graos, resultando em maior massa de mil graos e em menor quantidade de N restante na palha das plantas na maturacao fisiologica. Esses efeitos resultaram de um menor numero de espigas m-2, provavelmente devido a morte de afilhos, fator que determinou maior disponibilidade de N e de biomassa as espigas e graos restantes.

Effect of Inoculation of Wheat Seeds with Azospirillum brasilense (245) and Azospirillum lipoferum in Field Trials

Over the last years, several field trials involving seed inoculation of cereals with Azospirillum species have broadly shown contradictory results as to increases in yield. In recent reviews on the effects of field-inoculating such bacteria showed significant results reporting yield increases in about 60 to 70 % of trials (Baldani et al, 1997; Didonet et al., 1996; Bashan, Holguin, 1997). This study aimed to verify the effect of inoculating wheat seeds, cultivar Embrapa 119, under field conditions, on dry matter accumulation, total N, and grain yield.

Translocation of nitrogen and biomass to seeds in wheat inoculated with Azospirillum.

The effect of inoculating wheat (Triticum aestivum L.) seeds, cultivar Embrapa 16, with powder peat inoculant containing Azospirillum bacteria on yield and remobilization of nitrogen and biomass was studied under field conditions. The strain of Azospirillum brasilense 245 and the isolate 10 of Azospirillum lipoferum were used as inoculants. Different rates of nitrogen were applied at varying stages of plant growth for each inoculated and non-inoculated treatment, distributed in blocks at random with split plots. The accumulation of dry matter and total nitrogen in plant parts was evaluated at anthesis and physiological maturity stages. Harvest index for biomass and N, main yield components, and total N content in the seeds, in addition to yield, were also evaluated at harvest. The preliminary results showed that, even without inoculation effect on yield, there was a better allocation of nitrogen and biomass to the seeds, resulting in heavier seeds, with a lower amount of nitrogen remaining in the straw at physiological maturity. Such effects resulted from a lower number of spikes m-2, probably due to the death of tillers, determining a greater availability of N and biomass to the remaining spikes and seeds.Estudou-se, em condicoes de campo, o efeito de inoculante turfoso em po contendo bacterias do genero Azospirillum no rendimento de graos e na remobilizacao de N e de biomassa para os graos de trigo (Triticum aestivum L.), cultivar Embrapa 16. Usaram-se como inoculantes, a estirpe de Azospirillum brasilense 245 e o isolado 10 de Azospirillum lipoferum. Em cada tratamento de inoculacao, e tambem sem inoculacao, aplicaram-se diferentes doses de N em diferentes estadios de desenvolvimento das plantas, distribuidos em blocos ao acaso com parcelas subdivididas. Na antese e na maturacao fisiologica, avaliaram-se o acumulo de massa seca e N total nas diferentes partes da planta. Na colheita, alem do rendimento de graos, avaliaram-se tambem o indice de colheita para biomassa e para N, os principais componentes do rendimento e o teor de N total de graos. Os resultados ainda preliminares evidenciaram que, mesmo nao havendo efeito da inoculacao no rendimento de graos, houve um melhor alocamento de N e de biomassa para os graos, resultando em maior massa de mil graos e em menor quantidade de N restante na palha das plantas na maturacao fisiologica. Esses efeitos resultaram de um menor numero de espigas m-2, provavelmente devido a morte de afilhos, fator que determinou maior disponibilidade de N e de biomassa as espigas e graos restantes.