ABSTRACT
In this study,the leaves of autumn-sown Angelica dahurica var. formosana from Sichuan province in different growth years was used to explore the fitting model of photosynthetic response curve and the different photosynthetic physiological characteristics between annual and biennial A. dahurica var. formosana from Sichuan province. The results showed that the fitting model of the optimum light response curve of the leaves of A. dahurica var. formosana from Sichuan province with different growth years was all rectangular hyperbolic correction model. The light saturation points were 1 600,1 700 μmol·m-2·s-1,the light compensation points were17. 98,52. 23 μmol·m-2·s-1 in the leaves of annual and biennial plant,respectively. The diurnal variation curves of net photosynthetic rate,transpiration rate and stomatal conductance in the leaves all acted as a single peak value wave. The daily mean values of net photosynthetic rate and transpiration rate in the leaves of biennial plant were significantly higher than that of annual plant. There was no significant difference in daily mean stomatal conductance. The net photosynthetic rate was significantly positively correlated with stomatal conductance in both of the different growth years. The net photosynthetic rate of annual and biennial A. dahurica var. formosana from Sichuan province had extremely significant and significantly negative correlation with the intercellular CO2 respectively. The transpiration rate of annual plant was positively correlated with the effective photosynthetic radiation intensity and air temperature,but had significantly negative correlation with the intercellular CO2 concentration. The transpiration rate of biennial plant had extremely positive correlation with the effective photosynthetic radiation intensity,and negatively correlated with the intercellular CO2 concentration. In conclusion,the photosynthetic efficiency of the leaves in biennial plant of A. dahurica var. formosana from Sichuan province was higher than that in annual plant,but the ability to utilize weak light was lower than that of annual plant. It should be planted in the sunny field.
Subject(s)
Angelica , Physiology , Carbon Dioxide , China , Photosynthesis , Plant Leaves , Physiology , Plant Transpiration , Seasons , TemperatureABSTRACT
ABSTRACT To investigate the effect of arbuscular mycorrhiza fungi on maize growth, osmoregulation substances and photosynthetic physiology, a popular maize variety ZD 958 was measured under potted condition. Arbuscular mycorrhiza (AM) symbiosis promoted plant growth, and enhanced plant height, leaf length, mean leaf width and dry weight. Higher soluble sugar and protein, but lower proline concentrations were detected in AM seedlings than corresponding non-AM seedlings. Quantum yield of PSII photochemistry and potential photochemical efficiency increased by arbuscular mycorrhiza fungi, meanwhile, AM plants had lower primary fluorescence but higher maximal fluorescence and variable fluorescence than non-AM plants. AM enhanced apparent quantum efficiency, maximum net photosynthetic rate, dark respiration rate and light saturation point, but reduced light compensation point. The conclusion was that, after the seedling inoculated with Glomus. tortuosum, AM symbioses could protect cell from being hurt through regulating substances related to osmotic adjustment, besides, the efficiency of light utilization, the capacity of using low light and the capacity of fitting and using high light were all increased by AM symbiosis.
ABSTRACT
Isoprene emission from plants accounts for about one third of annual global volatile organic compound emissions. The largest source of isoprene for the global atmosphere is the Amazon Basin. This study aimed to identify and quantify the isoprene emission and photosynthesis at different levels of light intensity and leaf temperature, in three phenological phases (young mature leaf, old mature leaf and senescent leaf) of Eschweilera coriacea (Matamatل verdadeira), the species with the widest distribution in the central Amazon. In situ photosynthesis and isoprene emission measurements showed that young mature leaf had the highest rates at all light intensities and leaf temperatures. Additionally, it was observed that isoprene emission capacity (Es) changed considerably over different leaf ages. This suggests that aging leads to a reduction of both leaf photosynthetic activity and isoprene production and emission. The algorithm of Guenther et al. (1999) provided good fits to the data when incident light was varied, however differences among E S of all leaf ages influenced on quantic yield predicted by model. When leaf temperature was varied, algorithm prediction was not satisfactory for temperature higher than ~40 °C; this could be because our data did not show isoprene temperature optimum up to 45 °C. Our results are consistent with the hypothesis of the isoprene functional role in protecting plants from high temperatures and highlight the need to include leaf phenology effects in isoprene emission models.
O isopreno emitido pelas plantas corresponde em cerca de um terço das emissões globais de compostos orgânicos voláteis anualmente. A maior fonte de emissão de isopreno para a atmosfera global é a Bacia Amazônica. Este estudo objetivou identificar e quantificar a emissão de isopreno e fotossíntese em diferentes níveis de intensidade de luz e temperatura foliar, em três fases fenológicas (folha madura recente, folha madura tardia e folha senescente) de Eschweilera coriacea (Matamatá verdadeira) - a espécie com maior distribuição na Amazônia central. In situ, as medidas de fotossíntese e emissão de isopreno da folha madura recente apresentaram as maiores taxas em todos os níveis de luz e de temperatura. Adicionalmente, a capacidade de emissão de isopreno (ES) mudou consideravelmente entre as diferentes idades foliares, sugerindo que o envelhecimento reduz a atividade fotossintética e a produção/emissão de isopreno. O algoritmo de Guenther et al. (1999) demonstrou bom ajuste para a emissão de isopreno em diferentes intensidades de luz, entretanto, diferenças na ES entre as idades foliares influenciaram no rendimento quântico estimado pelo modelo. Em relação à temperatura foliar, a estimativa do algoritmo não foi satisfatória para as temperaturas acima de ~40 °C; isto provavelmente ocorreu pelo fato dos dados não apresentarem temperatura ótima até 45 °C. Nossos resultados são consistentes com a hipótese do isopreno ter um papel funcional para proteger as plantas de altas temperaturas e apontam a necessidade de incluir os efeitos da fenologia foliar em modelos de emissão de isopreno.
Subject(s)
Lecythidaceae/radiation effects , Terpenes/radiation effects , Botany/methodsABSTRACT
Sob condições de campo, as plantas estão sujeitas a períodos de déficit hídrico no solo e na atmosfera, durante todo o seu ciclo de vida. Foi avaliado o desempenho de duas cultivares enxertadas de seringueira ("RRIM 600" e "GT 1"), mantidas na UNESP-IBILCE, em São José do Rio Preto, SP, com e sem suplementação hídrica, a partir da idade de quatro meses. A resistência máxima ao período seco ininterrupto, considerada quando cessou a realização de fotossíntese com ganho líquido, foi de 17 e 20 dias, respectivamente. Trinta e três dias após a suspensão do estresse, a recuperação das trocas gasosas foi bastante similar para as duas cultivares, e apenas a concentração de dióxido de carbono intercelular retornou a valores equivalentes aos dos controles. Apenas o incremento relativo da área foliar, para "GT 1", e da altura, para "RRIM 600", não diferiram aos do grupo controle (P=0,05). As curvas de resposta à luz indicaram, para ambos os clones, decréscimos para a irradiância de compensação e a taxa fotossintética (P=0,05). Embora parcial, a melhor recuperação após o estresse foi verificada para "GT 1".
During their life cycle, plants growing under field condition are subject to periods of air and soil water deficits. In this study was evaluated the performance of two scion cultivar of rubber tree ('RRIM 600' and 'GT 1') growing in São José do Rio Preto, SP, with and without water supplementation since the age of 4 months. The maximum resistance to the uninterrupted dry period, considered when net photosynthesis was ceased, was 17 and 20 days, respectively. Thirty-three days later the water stress was ceased, the gas exchange recovery for both cultivars were quite similar, but just the intercellular carbon dioxide concentration returned to similar values of the control group. Only the relative increment of leaf area to 'GT 1', and plant height of 'RRIM 600' was similar to the control group (P=0.05). The light curve response showed, for both clones, decrease of the compensation irradiance and photosynthetic rate (P=0.05). Although partial, the best recovery after water stress was observed for 'GT 1'.