Physiological and molecular characterization of drought responses and screening of drought tolerant rice varieties / Caracterização fisiológica, molecular e seleção da resposta a tolerância à seca em variedades de arroz

Drought stress has now become a severe threat to ensure food security in the developing world as well as in Malaysia. To dertermine physiological and molecular determinants of drought stress and screening of drought tolerant rice varieties, an experiment was conducted in a greenhouse at Universiti Putra Malaysia using eleven rice varieties and two irrigation regimes (well irrigated and water stressed). The present study indicated that traditional rice variety Puteh Perak and Siam is superior drought tolerant while IRRI 2011- IRLON Plot no: 064, MR 220 and BRRI Dhan 56 are moderately drought tolerant, and IRRI 2011- IRLON Plot no: 050 and MR 84 are drought sensitive rice variety. Drought tolerance of those varieties were measured based on rate of tiller reduction, leaf rolling score and drought score during water stress condition. Leaf rolling score was positively correlated to drought score, chlorophyll content and proline accumulation. Significant increase in the proline accumulation and antioxidant enzyme activities (peroxidase and catalase) were also observed under drought stress in all the rice varieties except Siam and Puteh Perak. All the rice varieties including drought tolerant and sensitive showed the existence of OsLEA 30 genes.

Tolerância à seca tornou-se um importante tema da segurança alimentar nos países em desenvolvimento, bem como na Malásia. Com o objetivo de determinar os fatores fisiológicos e moleculares da tolerância à seca em variedades de arroz foi conduzido um experimento em casa de vegetação na Universidade Putra da Malásia usando 11 genótipos e dois sistemas de irrigação (vaso contendo plantas irrigadas e estressadas). O estudo mostrou que a variedade Puteh Perak e Siam foram superiores em condições de estresse hídrico, enquanto IRRI 2011-IRLON ­ PLOT 064 e MR 220 e BRRI Dhan 56 foram de tolerância moderada e IRRI 2011-IRLON 050 foram genótipos que apresentaram sensibilidade à seca. A tolerância à seca foi quantificada pela taxa de crescimento, nota visual para o enrolamento das folhas durante e nível de estresse durante o tempo de estresse hídrico. Enrolamento das folhas foi correlacionado com o nível de estresse hídrico, teor de clorofila e acúmulo de prolina. Aumento significativo no acúmulo de prolina e na atividade enzimática anti-oxidante (peroxidase e catalase) foram também observadas sobre estresse hídrico em todas as variedades de arroz tanto tolerantes quanto as sensíveis que esteve associado a existência de genes OsLEA 30.

Comparative study of the application of jasmonic acid and pesticide in chilli: effects on physiological activities, yield and viruses control / Estudo comparativo da aplicação de ácido jasmônico e pesticida em pimenteira: efeito nas atividades fisiológicas, produção e controle de viroses

The excessive application of pesticides for agricultural production has raised quite some concern about environmental safety and sustainability. To reduce environmental impact of pesticide overuse, there is an increasing interest in using different elicitors including Jasmonic acid (JA) to induce resistance against pathogen and insect in crop. Chilli (Capsicum annuum L.), which is an important vegeTable cum spice crop around the world. The aims of this study were to compare the effectiveness of Jasmonic acid on growth, Phyto-physiological responses, yield and viruses control in chilli plant. It was evaluated the effectiveness of single spray of JA (JA1), double spray of JA (JA2), conventional pesticide (Malathion 50%) and without any of those or control. The experimental results showed that pesticide-treated plants perform much better at early growth stages and become less competitive to JA2 treatment at maturity. Double spray of jasmonic acid showed less stress symptoms in different antioxidant enzymes activities (GPX, APX and CAT), reduce percentage of disease incidence and severity as well as improve growth and yielding characters of chilli plant. Therefore application of Jasmonic acid in chilli could be a possible alternative of pesticide application and its two times exogenous spray (0.5mM) is most effective.

A aplicação excessive de pesticidas na produção agrícola tem provocado algumas alterações na segurança ambiental e na sustentabilidade. Para reduzir este impacto ambiental aumentou o interesse no uso de elicitores incluindo o ácido Jasmônico (AJ) para induzir resistência contra os patógenos e insetos na cultura da pimenteira (Capsicum annum L.), a qual é uma importante hortaliça ou planta olerícola ao redor do mundo. Neste estudo foi comparada a eficácia do ácido Jasmônico no crescimento, resposta fisiológica, produção e controle de viroses na pimenteira. Foi avaliada uma simples aplicação (AJ1), duas aplicações (AJ2), inseticida malathion 50 % e uma testemunha (controle). Os resultados experimentais demonstraram uma redução nos sintomas de doenças viróticas pela atividade das enzimas anti oxidantes (GPX, APX e CAT), que reduziram a porcentagem da incidência e severidade das mesmas e promoveram o crescimento e melhoram os caracteres da produtividade da pimenteira. Portanto, a aplicação do ácido jsmônico em pimenteira pode ser uma alternativa para reduzir o uso de inseticidas e sua aplicação em duas vezes durante o ciclo (0,5 mM) foi mais eficiência.

Impact of cyclic water stress on growth, physiological responses and yield of rice (Oryza sativa L.) grown in tropical environment / Impacto do estresse hídrico cíclico sobre o crescimento, as respostas fisiológicas e rendimento de arroz (Oryza sativa L.)

A series of water stress cycles [5, 10, 15, 20, 25 and 30 days of irrigation intervel including control flooded (CF), control saturated (CS)] were exposed to investigate the impact of cyclic water stress on growth, physiological responses and yield of a famous Malaysian rice variety, MR220. The study also aimed to determine optimum irrigation schedule for better production of rice. It was observed that grain yield, total biomass, filled spikelet, 1000 grain weight, total panicle, tillers mortality, plant height and number of tillers per plant reduces with increased duration of water stress cycles. Grain yield was higher both in CF and CS condition and those are statistically identical to 5 days of stress cycle or irrigation intervel. The present experiment shows that growth performance and physiological activities of rice differ marginally for 5 days of irrigation difference, exceding that time would reduce yield significantly. The study also showed that proline accumulation and malondialdehyde (MDA) contents in levels increased with increasing duration of water stress cycle. Depending on the findings of the present, it can be stated that rice variety MR220 do not require flooding irrigation and irrigation cycle of 5 days interval is more apprapriate to increase water use and higher yield of rice.

Deficiência hídrica com ciclos de 5, 10, 15, 20, 25 e 30 dias de intervalo e irrigação incluindo controle irrigado (CF), controle de saturação (CS)] foram usadas para investigar o impacto do estresse hídrico sobre o crescimento cíclico, fito-respostas fisiológicas e rendimento de variedade de arroz MR220. O estudo também teve como objetivo determinar o cronograma de irrigação ideal para melhorar a produção de arroz. Observou-se que a produção de grãos, biomassa total, spiguetas, 1000-peso de grãos, panículas totais, a mortalidade de perfilhos, altura de planta e número de perfilhos por planta foi reduzida com o aumento da duração do ciclo de estresse hídrico. O rendimento de grãos foi maior tanto na CF e CS condição e foi estatisticamente igual a cinco dias do ciclo de estresse. O experimento mostra que o desempenho do crescimento e atividades fisiológicas de arroz diferem ligeiramente para cinco dias de diferença de irrigação, aumentado esse tempo, reduziria o rendimento significativamente. O estudo também mostrou que o acúmulo de prolina e conteúdo de malondialdeído (MDA) em níveis aumentaram com o increremento da duração do ciclo de estresse hídrico. Pode-se afirmar que a variedade de arroz MR220 não necessita de irrigação e ciclos de irrigação de cinco dias de intervalo é mais apropriado, além de aumentar a utilização de água e assim ter uma maior produção de arroz.

Effectiveness of a water-saving super-absorbent polymer in soil water conservation for corn (Zea mays L.) based on eco-physiological parameters.

BACKGROUND: The objective was to study soil water conservation and physiological growth of corn (Zea mays L.) using water-saving super-absorbent polymer (SAP) at 30 kg ha(-1). The effectiveness of SAP was studied under three irrigation levels (adequate, moderate and deficit) using a new type of negative hydraulic pressure controlled auto-irrigator in the years 2009 and 2010 in a greenhouse at Beijing, P.R. China. RESULTS: Eight weeks after sowing, plant height and leaf area increased significantly by 41.6 and 79.6% under deficit irrigation for SAP treatment. The SAP had little effect on shoot dry mass under adequate and moderate irrigation but increased it significantly by 133.5% under deficit irrigation. Similarly, the efficiency of water use also increased by 97.1%. Leaf water potential under adequate and moderate irrigation differs slightly for SAP application, whereas under deficit irrigation the values were exceeded significantly by 27.8%. The superior growth and water use efficiency of corn treated with SAP under deficit irrigation was ascribed to maintenance of higher relative water contents in leaves as well as intercellular carbon dioxide concentration, net photosynthesis and transpiration rate. CONCLUSIONS: Our results suggested that plant growth and different physiological activities are restricted by drought stress and the application of super-absorbent polymer could conserve soil water, making same available to plants for increased growth and biomass accumulation especially under severe water stress. Thus, application of SAP is a suitable soil management practice for the locations characterised by severe water stress.

A lysimeter study of nitrate leaching, optimum fertilisation rate and growth responses of corn (Zea mays L.) following soil amendment with water-saving super-absorbent polymer.

BACKGROUND: Nitrate leaching and the resulting groundwater contamination from intensive cereal production has become a major concern for long-term farmland efficiency and environmental sustainability in northern China. The aim of this study was to evaluate a water-saving super-absorbent polymer (SAP) for minimising NO(3)(-) leaching from soil and optimising corn growth and yield. Thirty-six undisturbed soil lysimeters were installed in a field lysimeter facility in drought-affected northern China to study the growth and yield characteristics of summer corn (Zea mays L.) as well as the amount of NO(3)-leaching losses under different fertiliser (standard, medium or 75% and low, or 50% of conventional fertilisation rate) and SAP (control, 0; level-1, 15 kg ha(-1) and level-2, 30 kg ha(-1)) treatments. RESULTS: Corn yield fell by 19.7% under medium and 37.7% under low fertilisation; the application of SAP increased yield significantly by 44.4% on level-1 and 80.3% on level-2. Similarly, plant height, leaf area, number of grains as well as protein, soluble sugar and starch contents in the grain also increased with SAP treatment. Application of SAP at 30 kg ha(-1) plus half of conventional fertilisation can reduce maximum (64.1%) nitrate leaching losses from soil. CONCLUSIONS: Application of SAP at 30 kg ha(-1) plus only half the amount of conventional fertiliser rate (150 kg urea, and 50 kg each of superphosphate and potassium sulfate) would be a more appropriate practice both for minimising nitrate leaching and sustainable corn production under the arid and semiarid conditions of northern China.

Effects of water-saving superabsorbent polymer on antioxidant enzyme activities and lipid peroxidation in corn (Zea mays L.) under drought stress.

BACKGROUND: Drought is the most important abiotic stress factor limiting corn (Zea mays L.) growth and productivity. Therefore efficient management of soil moisture and study of metabolic changes in response to drought are important for improved production of corn. The objective of the present study was to gain a better understanding of drought tolerance mechanisms and improve soil water management strategies using a water-saving superabsorbent polymer (SAP) at 30 kg ha(-1) under three irrigation levels (adequate, moderate and deficit) using a new type of hydraulic pressure-controlled auto-irrigator. RESULTS: The results showed that relative water content and leaf water potential were much higher in corn treated with SAP. Although application of SAP reduced biomass accumulation by 11.1% under adequate irrigation, it increased the biomass markedly by 39.0% under moderate irrigation and 98.7% under deficit irrigation. Plants treated with SAP under deficit irrigation showed a significant decrease in superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase activities in leaves compared with control plants. CONCLUSION: The results of this study suggest that drought stress causes the production of oxygen radicals, leading to increased lipid peroxidation and oxidative stress in plants, and the application of a superabsorbent polymer could conserve soil water, making it available to plants for quenching oxidative stress and increasing biomass accumulation, especially under severe water stress.

Effects of water-saving superabsorbent polymer on antioxidant enzyme activities and lipid peroxidation in oat (Avena sativa L.) under drought stress.

BACKGROUND: Drought stress significantly limits oat (Avena sativa L.) growth and productivity. Thus an efficient management of soil moisture and study of metabolic changes in response to drought are important for improved production of oat. The objective was to gain a better understanding of drought tolerance mechanisms and improve soil water management strategies using water-saving superabsorbent polymer (SAP) at 60 kg ha(-1) under three irrigation levels (adequate, moderate and deficit) using a new type of hydraulic pressure-controlled auto irrigator. RESULTS: The results showed that the relative water content and leaf water potential (ψ(1) ) were much higher in oats treated with SAP. Although the SAP had little effect on plant biomass accumulation under adequate and moderate irrigation, it significantly increased the biomass by 52.7% under deficit irrigation. Plants treated with SAP under deficit irrigation showed a significant decrease in superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase activities in leaves compared with control plants. CONCLUSION: Our results suggested that drought stress leads to production of oxygen radicals, which results in increased lipid peroxidation and oxidative stress in the plant, and the application of SAP could conserve soil water, making same available to plants for increased biomass accumulation and reduced oxidative stress especially under severe water stress.

Antimicrobial and cytotoxic activities of Achyranthes ferruginea.

Chloroform extract (CE) of Achyranthes ferruginea and N-trans-feruloyl-4-methyldopamine (1) showed remarkable antimicrobial activities against a wide range of bacteria and fungi. Both crude extract (CE) and compound 1 showed significant cytotoxicity of LC(50) at 16.21 microg/ml and 11.70 microg/ml, respectively.

In vitro antimicrobial and cytotoxic activities of ferrocene derivative compounds.

The aim of the present study was to investigate the biocidal activity of four new ferrocene derivative based coordination complexes, [1,2,3-trithia-/3/-ferrocenophane, C1]; [disodium-1,1'-ferrocenedithiolate, C2]; [1,1'-(ferrocene-1,1'-diyl)-diethanol, C3]; [ferrocenyl(ethyl-phenyl)-methanol, C4]; against microbes (bacteria and fungi) and brine shrimp (Artemia salina Lech.) nauplii. C2 showed modest antibacterial activity at the concentration of 200 microg disc(-1) and gave its Minimum Inhibitory Concentration values at 32-64 microg mL(-1) against the tested bacteria. These complexes gave comparatively better antibacterial activity against the Gram-positives than the Gram-negatives. C3, C1 and C4 showed moderate antifungal activity at concentration of 200 microg disc(-1). Brine shrimp eggs were hatched in artificial sea water and exposed to the complexes. Median lethal concentration (LC50) values were calculated. Both complexes showed toxicity against brine shrimp but complex C3 explored its potent cytotoxicity having LC50 values at 6.031 microg mL(-1) (ppm).