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1.
Chemosphere ; 246: 125766, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31901662

RESUMO

Lead (Pb+2) is a heavy metal and one of the main environmental pollutant, toxic to plants, animals and humans. Present study was conducted to evaluate ten plant growth promoting bacteria strains (B1-10) for biofilm production and their effect on growth indices, physiology, yield, antioxidant profile and lead uptake in rapeseed (Brassica napus) and clover (Trifolium repens) in lead polluted soil under nutrient broth medium and pot condition. Three pre-characterized biofilm forming lead tolerant growth promoting strains (B3: Pseudomonas fluorescens), B6: Pseudomonas putida and (B8: Bacillus safensis) were used to inoculate rapeseed and clover growing in the soil polluted with different levels (400, 800 and 1200 mg kg-1) of Pb arranged in completely randomized design with factorial arrangement. Results from screening experiment exhibited that more biofilm was produced by B3, B6 and B8 under highest level of lead contamination (1200 mg kg-1). Further, lead contamination decreased rapeseed and clover growth, physiology and yield at all levels of lead stress. But biofilm forming lead tolerant growth promoting bacteria application in lead contaminated soil enhanced rapeseed and clover growth, physiology, yield, antioxidant profile, proline and decreased malanodialdehyde content (which was decreased by different strains application under lead stress) of rapeseed and clover over no inoculation. Inoculation with all strains also increased the lead uptake in roots, shoots and decreased lead uptake in seeds of rapeseed and clover than plants in lead stress without inoculation.

2.
Environ Sci Pollut Res Int ; 26(5): 4901-4912, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30569357

RESUMO

Currently, the urgency of balancing rice production and environmental risk from nitrogen (N) fertilization is gaining scientific and public attention. As such, a field experiment was conducted to investigate the rice yield and the fate of applied-15N for Yangliangyou 6 (a two-line hybrid cultivar) and Lvdaoq 7 (an inbred cultivar) using 10 combinations of N rates and splitting ratios in the middle reaches of the Yangtze River. The results showed that N application primarily affected fertilizer N loss to the environment, followed by plant N absorption, but had little effect on grain yield. Generally, there was no significant increase in grain yield and N accumulation in the aboveground plant when N inputs surpassed 130 or 170 kg ha-1. Fertilizer N residue in soil peaked at approximately 48 kg ha-1 at an N rate of 170 kg ha-1 for both varieties; however, a sharp increase of fertilizer N loss occurred with further incrementally increasing N rates. Although a higher ratio of panicle-N fertilizer together with a lower ratio of tillering-N fertilizer at rates of 130, 170, and 210 kg ha-1 had no grain yield benefit, it promoted aboveground N accumulation and plant N accumulation derived from fertilizer, and it reduced the amount of N residue in soil and N loss to the environment. Overall, reducing tillering-N ratios and increasing panicle-N ratios at an N rate between 130 and 170 kg ha-1 using fertilizer rates of 90-0-40 kg ha-1 and 90-40-40 kg ha-1 N at basal-tillering-panicle initiation stages could reduce the adverse environmental risks of chemical N from rice production without sacrificing rice yield.


Assuntos
Produção Agrícola/métodos , Fertilizantes/análise , Nitrogênio/análise , Oryza/crescimento & desenvolvimento , Rios/química , Poluição Química da Água/prevenção & controle , China , Grão Comestível/química , Risco , Solo/química
3.
Front Plant Sci ; 9: 1128, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30108604

RESUMO

More than 4 billion inhabitants in Asia depend on rice for 35-60% of the calories consumed in their diets, but new rice cultivars frequently do not reach expected yields because of poor rice grain filling. Here, we quantified the activities of enzymes involved in starch metabolization in rice to investigate the mechanisms regulating the accumulation and translocation of stem non-structural carbohydrates (NSC) under different levels of nitrogen fertilizer application. A pot experiment was conducted using two rice cultivars, Liangyoupeijiu (LYPJ) and Shanyou63 (SY63), under high and low nitrogen applications. Compared with high nitrogen application (HN), low nitrogen application (LN) increased stem NSC concentration before the heading stage and NSC translocation during the grain filling stage; concomitantly, LN significantly shortened the active grain filling period and increased the grain filling rate in superior spikelets. Compared with the LYPJ cultivar, SY63 exhibited a higher grain weight, higher grain filling percentage, and higher stem NSC concentration before heading and greater NSC translocation after heading. During the period between panicle initiation and heading, the activities of adenosine diphosphate-glucose pyrophosphorylase (AGP), starch synthase (StS), and starch branching enzyme (SBE), all enzymes involved in starch synthesis, increased under the LN treatment and positively correlated with increases in stem NSC. During grain filling, the activities of enzymes involved in starch-to-sucrose conversion [α-amylase, ß-amylase, and sucrose phosphate synthase (SPS)] increased under the LN treatment and positively correlated with stem NSC remobilization. Overall, the investigated enzymes exhibited higher activities in SY63 than in LYPJ. Our results suggest that low nitrogen increases the activities of AGP, StS, SBE, α-amylase, ß-amylase, and SPS, leading to increased accumulation and remobilization of stem starch and NSC in SY63. We conclude that calculated reductions in nitrogen application and the choice of an appropriate cultivar may improve rice grain yields via enhanced stem NSC accumulation and translocation, thereby reducing the costs and increasing the sustainability of rice production.

4.
Front Plant Sci ; 9: 172, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29487612

RESUMO

Seed priming is a successful practice to improve crop establishment under adverse environment. However, reduced longevity of primed rice (Oryza sativa L.) seeds during storage limited the adoption of this technique. Present study investigated the effect of temperature, relative air humidity (RH) and oxygen on the longevity of primed rice seeds in a range of 60 days storage. In addition, the biochemical and morphological mechanisms associated with deterioration of primed seeds during storage were explored. Three types of priming treated rice seeds and one non-primed control were stored under (1) low temperature-vacuum (LT-V), (2) room temperature-vacuum (RT-V), (3) room temperature-aerobic-low RH (RT-A-LH) and (4) room temperature-aerobic- high RH (RT-A-HH) for 0, 15, 30, 45, and 60 days. The results showed that storage of seeds under different conditions for 15-60 days did not influence the longevity of non-primed rice seeds. Meanwhile, the viability of primed rice seeds did not reduce when stored under LT-V, RT-V, and RT-A-LH, but was significantly reduced under RT-A-HH. Under vacuum condition, the increases of storage temperature (30°C) did not reduce the longevity of primed seeds. Likewise, the oxygen did not influence the longevity of primed rice seeds stored under low RH. Nevertheless, increase of RH significantly reduced the viability of primed seeds stored for 15-60 days. Reduced starch metabolism, the consumption of starch reserves in rice endosperms, the accumulation of malondialdehyde and the decreases of antioxidant enzyme activities might be associated with the deterioration of primed rice seeds during storage. In conclusion, storage of primed seeds under high RH condition beyond 15 days is deteriorative for germination and growth of rice. The primed rice seeds are recommended to store at vacuum or low RH or low temperature condition to ensure good crop establishment.

5.
Front Plant Sci ; 8: 1908, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29167676

RESUMO

Rice production is challenged by the asymmetric increases in day and night temperatures. Efforts are required to improve our understanding of the impact of climate change on rice production. To this end, 2-year experiment was conducted to evaluate the response of mid-season rice growth in the central and southern regions of China to elevated temperatures. Four replicates of four widely planted indica rice cultivars (Huanghuazhan: HHZ; Shanyou63: SY63; Yangliangyou6: YLY6; Liangyoupeijiu: LYPJ) were subjected to four elevated-temperature treatments (control: ambient temperature; NW: night-time warming; DW: daytime warming; AW: all-day warming) generated by an open-top hot-blast system under field conditions. This apparatus causes an ~2°C increase in the rice canopy temperature. Of all the elevated-temperature treatments, AW was the most devastating treatment for all rice cultivars, negatively affecting nearly all of investigated parameters, including grain yield and its components, dry matter accumulation, biomass, and harvest index (HI). The AW treatment decreased the grain yield by 11-35% and 43-78% in 2015 and 2016, respectively. No significant reduction in the grain yield was observed in the DW and NW treatments in 2015. However, the grain yield was decreased in DW and NW treatments by 20-52% and 18-55%, respectively, in 2016. Furthermore, the temperature-driven degradation of pollen viability, the number of pollen grains adhering to the stigma and pollen germination on the stigma caused spikelet sterility and thereby decreased the grain yield. The YLY6 and SY63 cultivars performed better than the HHZ and LYPJ cultivars with respect to grain yield and its components in all elevated-temperature treatments in both years. However, 42.97 and 61.01% reductions still occurred for the SY63 and YLY6 cultivars, respectively, in the AW treatment in 2016. The above results suggested that the elevated temperature may cause a noteworthy reduction in the productions of these widely planted genotypes in central and southern regions of China. To ensure the security of rice production in this region in an expected global warming environment, currently planted varieties will need to be replaced by heat-resistant varieties in the future.

6.
Front Plant Sci ; 8: 1369, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28848573

RESUMO

Remobilisation of non-structural carbohydrates (NSC) from leaves and stems and unloading into developing grains are essential for yield formation of rice. In present study, three recombinant inbred lines of rice, R91, R156 and R201 have been tested for source-flow-sink related attributes determining the nature of NSC accumulation and translocation at two nitrogen levels in the field. Compared to R91 and R156, R201 had lower grain filling percentage, harvest index, and grain yield. Meanwhile, R201 had significantly lower stem NSC translocation during grain filling stage. Grain filling percentage, harvest index, and grain yield showed the consistent trend with stem NSC translocation among the three lines. In comparison with R91 and R156, R201 had similarity in leaf area index, specific leaf weight, stem NSC concentration at heading, biomass, panicles m-2, spikelets per panicle, remobilization capability of assimilation in stems, sink capacity, sink activity, number and cross sectional area of small vascular bundles, greater number and cross sectional area of large vascular bundles, and higher SPAD, suggesting that source, flow, and sink were not the limiting factors for low stem NSC translocation and grain filling percentage of R201. However, R201 had significant higher stem and rachis NSC concentrations at maturity, which implied that unloading in the developing grains might result in low NSC translocation in R201. The results indicate that stem NSC translocation could be beneficial for enhancement of grain yield potential, and poor unloading into caryopsis may be the possible cause of low stem NSC translocation, poor grain filling and yield formation in R201.

7.
Sci Rep ; 7(1): 4878, 2017 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-28687785

RESUMO

Poor crop establishment of direct-seeded rice (DSR) is one of the major constraints to wide adoption of DSR, particularly in areas prone to flooding after sowing or where fields are not level. Seed pelleting is an effective, practical and facile technique to enhance crop establishment under unfavorable environmental conditions. To evaluate the effects of seed pelleting on rice germination, seedling growth and associated metabolic events under waterlogging stress, various seed pelleting treatments including formulae, pelleting times (the weight ratio of pelleting agents: rice seeds = 1:1~7:1 (w/w) and CaO2 contents were tested in series of experiments. Naked seeds were maintained for comparison as a control. Pelleting treatments with CaO2 significantly increased seed germination and seedling growth of DSR under waterlogging conditions compared with pelleted seeds without CaO2 and naked seeds. The optimum weight ratios of CaO2 to dry seeds were found to be in the range of 0.6:1-1:1 based on seed germination and seedling growth performance under waterlogging conditions. Under waterlogging conditions, high seed germination percentage and vigorous seedling growth of DSR due to seed pelleting with CaO2 was associated with an increase in α-amylase activity, but decrease in alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) activities in pelleted seeds.


Assuntos
Agricultura/métodos , Germinação , Oryza/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Peróxidos/metabolismo
8.
Front Plant Sci ; 8: 371, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28367158

RESUMO

Cytokinins (CTKs) regulate panicle size and mediate heat tolerance in crops. To investigate the effect of high temperature on panicle CTK expression and the role of such expression in panicle differentiation in rice, four rice varieties (Nagina22, N22; Huanghuazhan, HHZ; Liangyoupeijiu, LYPJ; and Shanyou63, SY63) were grown under normal conditions and subjected to three high temperature treatments and one control treatment in temperature-controlled greenhouses for 15 days during the early reproductive stage. The high temperature treatments significantly reduced panicle CTK abundance in heat-susceptible LYPJ, HHZ, and N22 varieties, which showed fewer spikelets per panicle in comparison with control plants. Exogenous 6-benzylaminopurine application mitigated the effect of heat injury on the number of spikelets per panicle. The high temperature treatments significantly decreased the xylem sap flow rate and CTK transportation rate, but enhanced cytokinin oxidase/dehydrogenase (CKX) activity in heat-susceptible varieties. In comparison with the heat-susceptible varieties, heat-tolerant variety SY63 showed less reduction in panicle CTK abundance, an enhanced xylem sap flow rate, an improved CTK transport rate, and stable CKX activity under the high temperature treatments. Enzymes involved in CTK synthesis (isopentenyltransferase, LONELY GUY, and cytochrome P450 monooxygenase) were inhibited by the high temperature treatments. Heat-induced changes in CTK transportation from root to shoot through xylem sap flow and panicle CTK degradation via CKX were closely associated with the effects of heat on panicle CTK abundance and panicle size. Heat-tolerant variety SY63 showed stable panicle size under the high temperature treatments because of enhanced transport of root-derived CTKs and stable panicle CKX activity. Our results provide insight into rice heat tolerance that will facilitate the development of rice varieties with tolerance to high temperature.

9.
Sci Rep ; 7: 38982, 2017 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-28079051

RESUMO

Information on maximum grain yield and its attributes are limited for double-season rice crop grown under the subtropical environment. This study was conducted to examine key characteristics associated with high yielding double-season rice crop through a comparison between an integrated crop management (ICM) and farmers' practice (FP). Field experiments were conducted in the early and late seasons in the subtropical environment of Wuxue County, Hubei Province, China in 2013 and 2014. On average, grain yield in ICM was 13.5% higher than that in FP. A maximum grain yield of 9.40 and 10.53 t ha-1 was achieved under ICM in the early- and late-season rice, respectively. Yield improvement of double-season rice with ICM was achieved with the combined effects of increased plant density and optimized nutrient management. Yield gain of ICM resulted from a combination of increases in sink size due to more panicle number per unit area and biomass production, further supported by the increased leaf area index, leaf area duration, radiation use efficiency, crop growth rate, and total nitrogen uptake compared with FP. Further enhancement in the yield potential of double-season rice should focus on increasing crop growth rate and biomass production through improved and integrated crop management practices.


Assuntos
Agricultura/métodos , Grão Comestível/crescimento & desenvolvimento , Oryza/crescimento & desenvolvimento , China , Humanos
10.
AoB Plants ; 82016.
Artigo em Inglês | MEDLINE | ID: mdl-27821516

RESUMO

Mechanization and simplification are inevitable trends in agriculture production to decrease input demands and simultaneously improve resource use efficiency. Dry direct-seeded rice is a resource-saving cropping system and has been considered as a replacement for traditional transplanted rice. However, the poor establishment of dry direct-seeded early rice, primarily induced by chilling stress, has limited the wide adoption of this system. To examine the effects of pre-sowing seed treatments on rice germination, seedling growth and associated metabolic events under chilling stress, two seed coating treatments (Hanyubaomu coating and Miaoboshi coating) and two seed priming treatments (selenium priming and salicylic acid priming) were tested in field and growth chamber experiments. The results revealed that under chilling stress, seed priming increased the rice seed germination by 20.96-26.31 %. The length and weight of shoots and roots were also significantly increased. The two seed coating treatments were not effective in enhancing seed germination and seedling growth under chilling stress. The improved germination and seedling growth of primed seeds under chilling stress were strongly linked with higher α-amylase activity and total soluble sugar content. Conclusively, these findings will provide new avenues for understanding and advancing pre-sowing seed treatments of dry direct-seeded early rice.

11.
Sci Rep ; 6: 34978, 2016 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-27713528

RESUMO

Heat stress causes morphological and physiological changes and reduces crop yield in rice (Oryza sativa). To investigate changes in phytohormones and their relationships with yield and other attributes under heat stress, four rice varieties (Nagina22, Huanghuazhan, Liangyoupeijiu, and Shanyou 63) were grown in pots and subjected to three high temperature treatments plus control in temperature-controlled greenhouses for 15 d during the early reproductive phase. Yield reductions in Nagina22, Huanghuazhan, and Liangyoupeijiu were attributed to reductions in spikelet fertility, spikelets per panicle, and grain weight. The adverse effects of high temperature were alleviated by application of exogenous 6-benzylaminopurine (6-BA) in the heat-susceptible Liangyoupeijiu. High temperature stress reduced active cytokinins, gibberellin A1 (GA1), and indole-3-acetic acid (IAA), but increased abscisic acid (ABA) and bound cytokinins in young panicles. Correlation analyses and application of exogenous 6-BA revealed that high temperature-induced cytokinin changes may regulate yield components by modulating the differentiation and degradation of branches and spikelets, panicle exsertion, pollen vigor, anther dehiscence, and grain size. Heat-tolerant Shanyou 63 displayed minor changes in phytohormones, panicle formation, and grain yield under high temperature compared with those of the other three varieties. These results suggest that phytohormone changes are closely associated with yield formation, and a small reduction or stability in phytohormone content is required to avoid large yield losses under heat stress.


Assuntos
Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Grão Comestível/crescimento & desenvolvimento , Grão Comestível/metabolismo , Resposta ao Choque Térmico/fisiologia , Temperatura Alta , Reprodução/fisiologia
12.
Front Plant Sci ; 7: 1125, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27516766

RESUMO

Submergence stress is a limiting factor for direct-seeded rice systems in rainfed lowlands and flood-prone areas of South and Southeast Asia. The present study demonstrated that submergence stress severely hampered the germination and seedling growth of rice, however, seed priming alleviated the detrimental effects of submergence stress. To elucidate the molecular basis of seed priming-induced submergence tolerance, transcriptome analyses were performed using 4-day-old primed (selenium-Se and salicylic acid-SA priming) and non-primed rice seedlings under submergence stress. Genomewide transcriptomic profiling identified 2371 and 2405 transcripts with Se- and SA-priming, respectively, that were differentially expressed in rice compared with non-priming treatment under submergence. Pathway and gene ontology term enrichment analyses revealed that genes involved in regulation of secondary metabolism, development, cell, transport, protein, and metal handling were over-represented after Se- or SA-priming. These coordinated factors might have enhanced the submergence tolerance and maintained the better germination and vigorous seedling growth of primed rice seedlings. It was also found that many genes involved in cellular and metabolic processes such as carbohydrate metabolism, cellular, and metabolic biosynthesis, nitrogen compound metabolic process, transcription, and response to oxidative stress were induced and overlapped in seed priming treatments, a finding which reveals the common mechanism of seed priming-induced submergence tolerance. Taken together, these results may provide new avenues for understanding and advancing priming-induced responses to submergence tolerance in crop plants.

13.
Front Plant Sci ; 7: 116, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26904078

RESUMO

Rice belongs to tropical and subtropical environments and is extremely sensitive to chilling stress particularly during emergence and early stages of seedling development. Seed priming can be a good approach to enhance rice germination and stand establishment under chilling stress. The present study examined the role of different seed priming techniques viz., hydropriming, osmopriming, redox priming, chemical priming, and hormonal priming, in enhancing the chilling tolerance in rice. The most effective reagents and their pre-optimized concentrations based on preliminary experiments were used in this study. Two different rice cultivars were sown under chilling stress (18°C) and normal temperatures (28°C) in separate growth chambers. A non-primed control treatment was also maintained for comparison. Chilling stress caused erratic and delayed germination, poor seedling growth, reduced starch metabolism, and lower respiration rate, while higher lipid peroxidation and hydrogen peroxide accumulation in rice seedlings of both cultivars. Nevertheless, all the seed priming treatments effectively alleviated the negative effects of chilling stress. In addition, seed priming treatments triggered the activities of superoxide dismutase, peroxidase, and catalase, and enhanced the accumulations of glutathione and free proline in rice seedlings, which suggests that these measures help prevent the rice seedlings from chilling induced oxidative stress. Chemical priming with selenium and hormonal priming with salicylic acid remained more effective treatments for both rice cultivars under chilling stress than all other priming treatments. The better performance and greater tolerance of primed rice seedlings was associated with enhanced starch metabolism, high respiration rate, lower lipid peroxidation, and strong antioxidative defense system under chilling stress.

14.
Sci Rep ; 6: 21049, 2016 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-26876641

RESUMO

The yield potential of rice (Oryza sativa L.) has experienced two significant growth periods that coincide with the introduction of semi-dwarfism and the utilization of heterosis. In present study, we determined the annual increase in the grain yield of rice varieties grown from 1936 to 2005 in Middle Reaches of Yangtze River and examined the contributions of RUE (radiation-use efficiency, the conversion efficiency of pre-anthesis intercepted global radiation to biomass) and NUE (nitrogen-use efficiency, the ratio of grain yield to aboveground N accumulation) to these improvements. An examination of the 70-year period showed that the annual gains of 61.9 and 75.3 kg ha(-1) in 2013 and 2014, respectively, corresponded to an annual increase of 1.18 and 1.16% in grain yields, respectively. The improvements in grain yield resulted from increases in the harvest index and biomass, and the sink size (spikelets per panicle) was significantly enlarged because of breeding for larger panicles. Improvements were observed in RUE and NUE through advancements in breeding. Moreover, both RUE and NUE were significantly correlated with the grain yield. Thus, our study suggests that genetic improvements in rice grain yield are associated with increased RUE and NUE.


Assuntos
Agricultura , Nitrogênio/metabolismo , Oryza/crescimento & desenvolvimento , China , Produtos Agrícolas/metabolismo , Produtos Agrícolas/efeitos da radiação , Oryza/efeitos da radiação , Radiação
15.
Sci Rep ; 6: 19637, 2016 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-26782108

RESUMO

Double direct-seeding for double rice cropping is a simplified, labor saving, and efficient cropping system to improve multiple-crop index and total rice production in central China. However, poor crop establishment of direct-seeded early rice due to chilling stress is the main obstacle to wide spread of this system. A series of experiments were conducted to unravel the effects of pre-sowing seed treatments on emergence, seedling growth and associated metabolic events of direct-seeded early rice under chilling stress. Two seed priming treatments and two seed coating treatments were used in all the experiments. A non-treated control treatment was also maintained for comparison. In both the field and growth chamber studies, seed priming with selenium or salicylic acid significantly enhanced the emergence and seedling growth of rice compared with non-treated control. Nevertheless, such positive effects were not apparent for seed coating treatments. Better emergence and vigorous seedling growth of rice after seed priming was associated with enhanced α-amylase activity, higher soluble sugars contents, and greater respiration rate in primed rice seedlings under chilling stress. Taking together, these findings may provide new avenues for understanding and advancing priming-induced chilling tolerance in direct-seeded early rice in double rice cropping system.


Assuntos
Oryza/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Estresse Fisiológico/fisiologia , China , Temperatura Baixa , Produtos Agrícolas/efeitos dos fármacos , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/metabolismo , Germinação/efeitos dos fármacos , Oryza/efeitos dos fármacos , Ácido Salicílico/farmacologia , Plântula/efeitos dos fármacos , Sementes/efeitos dos fármacos , Selênio/farmacologia , Estresse Fisiológico/efeitos dos fármacos , alfa-Amilases/metabolismo
16.
Sci Rep ; 5: 8101, 2015 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-25631923

RESUMO

Seed priming is a commercially successful practice, but reduced longevity of primed seeds during storage may limit its application. We established a series of experiments on rice to test: (1) whether prolonged storage of primed and non-primed rice seeds for 210 days at 25°C or -4°C would alter their viability, (2) how long primed rice seed would potentially remain viable at 25°C storage, and (3) whether or not post-storage treatments (re-priming or heating) would reinstate the viability of stored primed seeds. Two different rice cultivars and three priming agents were used in all experiments. Prolonged storage of primed seeds at 25°C significantly reduced the germination (>90%) and growth attributes (>80%) of rice compared with un-stored primed seeds. However, such negative effects were not observed in primed seeds stored at -4°C. Beneficial effects of seed priming were maintained only for 15 days of storage at 25°C, beyond which the performance of primed seeds was worse even than non-primed seeds. The deteriorative effects of 25°C storage were related with hampered starch metabolism in primed rice seeds. None of the post-storage treatments could reinstate the lost viability of primed seeds suggesting that seeds become unviable by prolonged post-priming storage at 25°C.


Assuntos
Oryza/crescimento & desenvolvimento , Preservação Biológica , Sementes/crescimento & desenvolvimento , Germinação , Raízes de Plantas/anatomia & histologia , Brotos de Planta/anatomia & histologia , Plântula/crescimento & desenvolvimento , Amido/metabolismo , Temperatura Ambiente
17.
Environ Sci Pollut Res Int ; 22(5): 3342-60, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25354441

RESUMO

Global warming is one of the gravest threats to crop production and environmental sustainability. Rice, the staple food of more than half of the world's population, is the most prominent cause of greenhouse gas (GHG) emissions in agriculture and gives way to global warming. The increasing demand for rice in the future has deployed tremendous concerns to reduce GHG emissions for minimizing the negative environmental impacts of rice cultivation. In this review, we presented a contemporary synthesis of existing data on how crop management practices influence emissions of GHGs in rice fields. We realized that modifications in traditional crop management regimes possess a huge potential to overcome GHG emissions. We examined and evaluated the different possible options and found that modifying tillage permutations and irrigation patterns, managing organic and fertilizer inputs, selecting suitable cultivar, and cropping regime can mitigate GHG emissions. Previously, many authors have discussed the feasibility principle and the influence of these practices on a single gas or, in particular, in the whole agricultural sector. Nonetheless, changes in management practices may influence more than one gas at the same time by different mechanisms or sometimes their effects may be antagonistic. Therefore, in the present attempt, we estimated the overall global warming potential of each approach to consider the magnitude of its effects on all gases and provided a comprehensive assessment of suitable crop management practices for reducing GHG emissions in rice culture.


Assuntos
Agricultura/métodos , Poluição do Ar/prevenção & controle , Oryza , Poluentes Atmosféricos , Gases , Efeito Estufa
19.
ScientificWorldJournal ; 2014: 596438, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25013859

RESUMO

Cadmium (Cd) and arsenic (As) accumulation in rice grains is a great threat to its productivity, grain quality, and thus human health. Pot and field studies were carried out to unravel the effect of different water management practices (aerobic, aerobic-flooded, and flooded) on Cd and As accumulation in rice grains of two different varieties. In pot experiment, Cd or As was also added into the soil as treatment. Pots without Cd or As addition were maintained as control. Results indicated that water management practices significantly influenced the Cd and As concentration in rice grains and aerobic cultivation of rice furnished less As concentration in its grains. Nonetheless, Cd concentration in this treatment was higher than the grains of flooded rice. Likewise, in field study, aerobic and flooded rice cultivation recorded higher Cd and As concentration, respectively. However, growing of rice in aerobic-flooded conditions decreased the Cd concentration by 9.38 times on average basis as compared to aerobic rice. Furthermore, this treatment showed 28% less As concentration than that recorded in flooded rice cultivation. The results suggested that aerobic-flooded cultivation may be a promising strategy to reduce the Cd and As accumulations in rice grains simultaneously.


Assuntos
Irrigação Agrícola , Arsênico/farmacologia , Cádmio/farmacologia , Grão Comestível/química , Oryza/efeitos dos fármacos , Arsênico/análise , Cádmio/análise , Ecossistema , Inundações , Oryza/crescimento & desenvolvimento
20.
Biotechnol Lett ; 36(7): 1407-20, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24658743

RESUMO

Rice diseases (bacterial, fungal, or viral) threaten food productivity. Host resistance is the most efficient, environmentally friendly method to cope with such diverse pathogens. Quantitative resistance conferred by quantitative trait loci (QTLs) is a valuable resource for rice disease resistance improvement. Although QTLs confer partial but durable resistance to many pathogen species in different crop plants, the molecular mechanisms of quantitative disease resistance remain mostly unknown. Quantitative resistance and non-host resistance are types of broad-spectrum resistance, which are mediated by resistance (R) genes. Because R genes activate different resistance pathways, investigating the genetic spectrum of resistance may lead to minimal losses from harmful diseases. Genome studies can reveal interactions between different genes and their pathways and provide insight into gene functions. Protein­protein interaction (proteomics) studies using molecular and bioinformatics tools may further enlighten our understanding of resistance phenomena.


Assuntos
Embaralhamento de DNA , Resistência à Doença , Oryza/imunologia , Oryza/fisiologia , Doenças das Plantas/prevenção & controle , Oryza/genética , Locos de Características Quantitativas
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