ABSTRACT
Abstract Growth of plants is severely reduced due to water stress by affecting photosynthesis including photosystem II (PSII) activity and electron transport. This study emphasised on comparative and priority targeted changes in PSII activity due to progressive drought in seven populations of Panicum antidotale (P. antidotale) collected from Cholistan Desert and non-Cholistan regions. Tillers of equal growth of seven populations of P. antidotale grown in plastic pots filled with soil were subjected progressive drought by withholding water irrigation for three weeks. Progressive drought reduced the soil moisture content, leaf relative water content, photosynthetic pigments and fresh and dry biomass of shoots in all seven populations. Populations from Dingarh Fort, Dingarh Grassland and Haiderwali had higher growth than those of other populations. Cholistani populations especially in Dingarh Grassland and Haiderwali had greater ability of osmotic adjustment as reflected by osmotic potential and greater accumulation of total soluble proteins. Maximum H2O2 under water stress was observed in populations from Muzaffargarh and Khanewal but these were intermediate in MDA content. Under water stress, populations from Muzaffargarh and Dingarh Fort had greater K+ accumulation in their leaves. During progressive drought, non-Cholistani populations showed complete leaf rolling after 23 days of drought, and these populations could not withstand with more water stress condition while Cholistani populations tolerated more water stress condition for 31 days. Moreover, progressive drought caused PSII damages after 19 days and it became severe after 23 days in non-Cholistani populations of P. antidotale than in Cholistani populations.
Resumo O crescimento das plantas é severamente reduzido devido ao estresse hídrico, afetando a fotossíntese, incluindo a atividade do fotossistema II (PSII) e o transporte de elétrons. Este estudo enfatizou as mudanças comparativas e prioritárias na atividade do PSII devido à seca progressiva em sete populações de Panicum antidotale (P. antidotale) coletadas no Deserto do Cholistão e regiões fora do Cholistão. Perfilhos de igual crescimento de sete populações de P. antidotale cultivadas em vasos de plástico cheios de solo foram submetidos à seca progressiva, retendo a irrigação com água por três semanas. A seca progressiva reduziu o teor de umidade do solo, teor de água relativo nas folhas, pigmentos fotossintéticos e biomassa fresca e seca dos brotos em todas as sete populações. Populações de Dingarh Fort, Dingarh Grassland e Haiderwali tiveram maior crescimento do que as de outras populações. As populações de Cholistani, especialmente em Dingarh Grassland e Haiderwali, apresentaram maior capacidade de ajuste osmótico, refletido pelo potencial osmótico e maior acúmulo de proteínas solúveis totais. H2O2 máximo sob estresse hídrico foi observado em populações de Muzaffargarh e Khanewal, mas estas foram intermediárias no conteúdo de MDA. Sob estresse hídrico, as populações de Muzaffargarh e Dingarh Fort tiveram maior acúmulo de K+ em suas folhas. Durante a seca progressiva, as populações não cholistanesas mostraram rolagem completa das folhas após 23 dias de seca, e essas populações não conseguiram suportar mais condições de estresse hídrico, enquanto as populações cholistani toleraram mais condições de estresse hídrico por 31 dias. Além disso, a seca progressiva causou danos ao PSII após 19 dias e tornou-se severa após 23 dias em populações não cholistanesas de P. antidotale do que em populações cholistanesas.
ABSTRACT
Abstract Growth of plants is severely reduced due to water stress by affecting photosynthesis including photosystem II (PSII) activity and electron transport. This study emphasised on comparative and priority targeted changes in PSII activity due to progressive drought in seven populations of Panicum antidotale (P. antidotale) collected from Cholistan Desert and non-Cholistan regions. Tillers of equal growth of seven populations of P. antidotale grown in plastic pots filled with soil were subjected progressive drought by withholding water irrigation for three weeks. Progressive drought reduced the soil moisture content, leaf relative water content, photosynthetic pigments and fresh and dry biomass of shoots in all seven populations. Populations from Dingarh Fort, Dingarh Grassland and Haiderwali had higher growth than those of other populations. Cholistani populations especially in Dingarh Grassland and Haiderwali had greater ability of osmotic adjustment as reflected by osmotic potential and greater accumulation of total soluble proteins. Maximum H2O2 under water stress was observed in populations from Muzaffargarh and Khanewal but these were intermediate in MDA content. Under water stress, populations from Muzaffargarh and Dingarh Fort had greater K+ accumulation in their leaves. During progressive drought, non-Cholistani populations showed complete leaf rolling after 23 days of drought, and these populations could not withstand with more water stress condition while Cholistani populations tolerated more water stress condition for 31 days. Moreover, progressive drought caused PSII damages after 19 days and it became severe after 23 days in non-Cholistani populations of P. antidotale than in Cholistani populations.
Resumo O crescimento das plantas é severamente reduzido devido ao estresse hídrico, afetando a fotossíntese, incluindo a atividade do fotossistema II (PSII) e o transporte de elétrons. Este estudo enfatizou as mudanças comparativas e prioritárias na atividade do PSII devido à seca progressiva em sete populações de Panicum antidotale (P. antidotale) coletadas no Deserto do Cholistão e regiões fora do Cholistão. Perfilhos de igual crescimento de sete populações de P. antidotale cultivadas em vasos de plástico cheios de solo foram submetidos à seca progressiva, retendo a irrigação com água por três semanas. A seca progressiva reduziu o teor de umidade do solo, teor de água relativo nas folhas, pigmentos fotossintéticos e biomassa fresca e seca dos brotos em todas as sete populações. Populações de Dingarh Fort, Dingarh Grassland e Haiderwali tiveram maior crescimento do que as de outras populações. As populações de Cholistani, especialmente em Dingarh Grassland e Haiderwali, apresentaram maior capacidade de ajuste osmótico, refletido pelo potencial osmótico e maior acúmulo de proteínas solúveis totais. H2O2 máximo sob estresse hídrico foi observado em populações de Muzaffargarh e Khanewal, mas estas foram intermediárias no conteúdo de MDA. Sob estresse hídrico, as populações de Muzaffargarh e Dingarh Fort tiveram maior acúmulo de K+ em suas folhas. Durante a seca progressiva, as populações não cholistanesas mostraram rolagem completa das folhas após 23 dias de seca, e essas populações não conseguiram suportar mais condições de estresse hídrico, enquanto as populações cholistani toleraram mais condições de estresse hídrico por 31 dias. Além disso, a seca progressiva causou danos ao PSII após 19 dias e tornou-se severa após 23 dias em populações não cholistanesas de P. antidotale do que em populações cholistanesas.
Subject(s)
Panicum , Photosynthesis , Plant Leaves , Desiccation , Droughts , Hydrogen PeroxideABSTRACT
Objective: To study the effects of exogenous trehalose on the growth and total flavonoids content of licorice (Glycyrrhiza uralensis) seedlings under NaCl stress. Methods: Using licorice seedlings as the material, the effects of NaCl stress on physiological growth, enzyme activity, ion content, osmotic regulation and total flavonoid content of licorice seedlings were studied in this experiment, Microsoft Excel 2010 was used for data processing and analysis, and SPSS19.0 statistical software was used for data analysis of variance. Results: Trehalose (10-20 mmol/L) significantly reduced the damage of NaCl to licorice seedlings, and the effect was the best when the concentration of exogenous trehalose was 15 mmol/L. Under NaCl stress, when exogenous trehalose concentration was 15 mmol/L, the growth of licorice seedlings was the most exuberant and the growth amount increased the most, and the K+ and K+/Na+ concentrations that affected the osmotic regulation of licorice seedlings increased the most, while the concentrations of Na+ and Cl- were decreased compared with those without NaCl stress. When the concentration of exogenous trehalose was 15 mmol/L, the activity of antioxidant enzymes in licorice seedlings under NaCl stress could be improved, and the content of light and chlorophyll in plant cells under NaCl stress could be increased. When the concentration of exogenous trehalose was 15 mmol/L, the contents of soluble sugar, proline and cellular regulatory substance MDA in licorice seedlings under NaCl stress could be reduced. Conclusion: The application of exogenous trehalose with appropriate concentration under NaCl stress can promote the growth of licorice seedlings and the accumulation of effective components, reduce the harm of salt damage to the growth of licorice, and enhance the growth ability of Licorice under NaCl stress.
ABSTRACT
Objective To study the physiological characteristics of Codonopsis Radix under drought stress; To reveal the physiological mechanism of Codonopsis Radix in response to drought stress. Methods Method of pot experiment was used to set up 4 water treatments: normal water supply, mild stress, moderate stress and severe stress. Through the determination of leaf relative water content, cell membrane permeability, osmotic adjustment contents and protective enzyme activity, the effects of drought stress on physiological characteristics of Codonopsis Radix were studied. Results With the drought stress increased, the chlorophyll a, total chlorophyll content and leaf relative water content of Codonopsis Radix decreased, but chlorophyll b had no obvious change; The conductivity increased first and then decreased; MDA contents increased first and then decreased and then increased; There was no significant change in the rate of superoxide anion production; POD and CAT activity increased; SOD had no significant change; The proline content increased first and then decreased; soluble sugar decreased; soluble protein had no significant change. Conclusion Under the condition of drought stress, by increasing the content of proline to regulate cell osmotic potential, Codonopsis Radixcan increase the antioxidant enzyme activity to reduce membrane lipid peroxidation damage to cells.
ABSTRACT
ABSTRACT: Ten cassava cultivars were grown in the field and evaluated to identify the most adapted to the Coastal Tablelands of northeast Brazil. The cultivars showed differences in proline and chlorophyll contents, plant height, number of leaves and branches, canopy area and root production, however they did not differ on photosynthetic rates. Cultivars 'Tianguá' and '9783-13' presented lower root yield, whereas 'BRS Tapioqueira' and 'Irará' had the highest root yield. Few leaves coupled with the highest water use efficiency for CO2 assimilation was found in 'BRS Kiriris' in contrast to 'BRS Jarina' and '9783-13'. 'BRS Caipira' had high proline content in both Umbaúba and Frei Paulo areas, traits usually associated to drought tolerance, that contribute to the adaptation. It is also important to consider that cultivar 'BRS Caipira' was the first to present increase in chlorophyll content after extended period of drought, that indicates a faster recovery after dry season. Furthermore, the results indicated that the most adapted cultivars for cultivation in this area are 'Irará', 'BRS Tapioqueira', 'BRS Kiriris' and 'BRS Caipira'.
RESUMO: Dez cultivares de mandioca foram cultivadas no campo e avaliadas para identificar a mais adaptada aos Tabuleiros Costeiros do Nordeste do Brasil. As cultivares apresentaram diferenças nos teores de prolina e clorofila, altura, número de folhas e ramos, área de copa e produção de raízes, no entanto, não diferiram quanto às taxas fotossintéticas. As cultivares 'Tianguá' e '9783-13' apresentaram menor rendimento de raízes e 'BRS Tapioqueira' e 'Irará' maior rendimento. Poucas folhas e maior eficiência no uso da água para a assimilação de CO2 foi verificado em 'BRS Kiriris', em contraste com 'BRS Jarina' e '9783-13'. 'BRS Caipira' teve alto teor de prolina em Umbaúba e em Frei Paulo, características geralmente associadas à tolerância à seca, que contribuem para adaptação. Também é importante considerar que a cultivar 'BRS Caipira' foi a primeira a apresentar aumento no teor de clorofila após longo período de seca, o que indica recuperação mais rápida após período seco. Além disso, os resultados indicam que as cultivares mais adaptadas ao cultivo nessa área são 'Irará', 'BRS Tapioqueira', 'BRS Kiriris' e 'BRS Caipira'.
ABSTRACT
Objective To investigate the effect of drought stress and organic fertilizer on German chamomile (Matricaria chamomilla) nutrient uptake, leaf chlorophyll content and osmotic adjustment under field conditions. Methods This experiment was carried out through a randomized complete block design with a split factorial arrangement of treatments in three replications. The main plots were subjected to the following irrigation treatments: irrigation after 60, 90, 120, 150 and 180 mm evaporation from Class A pan. The sub-plots were treated with three vermicompost doses (0, 5 and 10 t/ha). Results Although drought stress reduced the nutrient percentages in the shoots, application of vermicompost enhanced the nutrient percentages, particularly when the plants were subjected to moderate to severe drought stress conditions. Moreover, the results of this study showed that the interaction between irrigation treatments and vermicompost rates on leaf chlorophyll content was significant. Comparison between the combined treatments indicated that under normal irrigation and moderate drought stress conditions chamomile plants received 5 and 10 t/ha vermicompost showed significantly higher leaf chlorophyll content comparing to the control treatment. Conclusions Totally, organic fertilization by vermicompost could partly alleviate the effect of drought stress on chamomile by increasing N, P and K uptake and leaf soluble sugar, especially in stressed treatments.
ABSTRACT
Objective: To investigate the effect of drought stress and organic fertilizer on German chamomile (Matricaria chamomilla) nutrient uptake, leaf chlorophyll content and os-motic adjustment under field conditions. Methods: This experiment was carried out through a randomized complete block design with a split factorial arrangement of treatments in three replications. The main plots were subjected to the following irrigation treatments: irrigation after 60, 90, 120, 150 and 180 mm evaporation from Class A pan. The sub-plots were treated with three vermi-compost doses (0, 5 and 10 t/ha). Results: Although drought stress reduced the nutrient percentages in the shoots, appli-cation of vermicompost enhanced the nutrient percentages, particularly when the plants were subjected to moderate to severe drought stress conditions. Moreover, the results of this study showed that the interaction between irrigation treatments and vermicompost rates on leaf chlorophyll content was significant. Comparison between the combined treatments indicated that under normal irrigation and moderate drought stress conditions chamomile plants received 5 and 10 t/ha vermicompost showed significantly higher leaf chlorophyll content comparing to the control treatment. Conclusions: Totally, organic fertilization by vermicompost could partly alleviate the effect of drought stress on chamomile by increasing N, P and K uptake and leaf soluble sugar, especially in stressed treatments.
ABSTRACT
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
Na cultura da soja, o déficit hídrico é um dos fatores limitantes à obtenção da máxima produtividade. A identificação de genótipos com capacidade de tolerância à seca é fundamental para a solução desse problema. Objetivou-se, neste trabalho, analisar a qualidade fisiológica e as respostas bioquímicas de cultivares de soja (MG/BR 46 Conquista, UFUS Carajás, UFUS Impacta, UFUS Riqueza e UFUS Xavante) submetidas ao estresse hídrico com soluções de PEG 6000 em diferentes níveis de potencial osmótico (0; -0,1; -0,2; -0,3 e -0,4 MPa). Avaliou-se a qualidade fisiológica das cultivares por meio dos testes de comprimento de plântulas e biomassa fresca e seca de plântulas. As respostas bioquímicas foram avaliadas pela detecção do ácido indol-acético, pelo conteúdo de sacarose e pelo transporte de água nas plântulas. A cultivar UFUS Riqueza apresentou os melhores desempenhos nos testes de qualidade fisiológica, conteúdo de sacarose, absorção e velocidade de absorção de água em plântulas. A cultivar UFUS Xavante mostrou a maior concentração de AIA e o maior massa de plântulas no teste de transporte de água.
In soybean culture water deficit is one of the most limiting factors to the maximum yield obtained. Genotypes identification with drought tolerance capacity is fundamental to solve this problem. The objective in this paper was analyze the physiological quality and physiological and biochemical responses of soybeans cultivars (MG/BR 46 Conquista, UFUS Carajás, UFUS Impacta, UFUS Riqueza and UFUS Xavante) submitted to water stress with PEG 6000 solutions in different levels of osmotic potentials (0; -0,1; -0,2; -0,3 and -0,4 MPa). Physiological quality of cultivars were evaluated by seedling length test and fresh and dry biomass. The biochemical responses were evaluated by detection of indol-acetic acid (IAA), by saccharose content and seedling water transportation. UFUS Riqueza presented the best performance in physiological quality tests, saccharose content, absorption and water absorption velocity in seedling. UFUS Xavante showed the highest IAA's concentration and the greater weight of seedling in water transportation test.