The study was conducted to investigate the effects of applying different concentrations of the macronutrients K＋,Ca2＋,and Mg2＋ on the responses of contrasting rice（Oryza sativa L.） genotypes under salt stress.A s...The study was conducted to investigate the effects of applying different concentrations of the macronutrients K＋,Ca2＋,and Mg2＋ on the responses of contrasting rice（Oryza sativa L.） genotypes under salt stress.A solution culture experiment was conducted in a phytotron at the International Rice Research Institute（IRRI）,under controlled temperature and humidity and natural sunlight.When subjected to salt stress of 100 mmol L-1 using NaCl,the salt tolerant genotypes FL478 and IR651,accumulated less Na＋ and maintained lower ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ than the sensitive genotypes IR29 and Azucena.These tolerant genotypes also had higher concentrations of K＋ in their shoots and greater root and shoot biomass and green leaf area.Tolerant genotypes also maintained much lower concentration of Na＋ and lower and more favorable ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in their active and developing tissues.Salt tolerance and shoot and root growth of both tolerant and sensitive genotypes were enhanced considerably when higher concentrations of Ca2＋ and Mg2＋ were applied in culture solution.The concentration of Na＋ and the ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in shoots also declined significantly.The beneficial effects of higher calcium were greater than that of magnesium and application of higher concentration of K＋ seems to have minor effects.Responses to salinity in rice can therefore be considerably enhanced through proper nutrient management,by increasing the concentrations of nutrient elements that have favorable effects such as Ca2＋ and Mg2＋.Calcium is particularly more effective than both magnesium and potassium,and can be applied at relatively larger quantities in salt affected soils.展开更多
The profiles of nutrient salts in the interstitial water of sediment were analyzed in the Zhu- jiang Estuary in the summer of 1999, and based on the profiles of content and characteristic of nutri- ents, the relations...The profiles of nutrient salts in the interstitial water of sediment were analyzed in the Zhu- jiang Estuary in the summer of 1999, and based on the profiles of content and characteristic of nutri- ents, the relationship between nutrients in the interstitial water and organic matter decomposition in sediment was discussed. The results showed that ammonium with high content was the main existence form of nutrients in the interstital water of sediment, and the organic matter decomposition was com- pleted in anaerobic condition. The increase of ammonium content in the bottom water resulted from the decomposition of organic matter and release of metabolic production, and the ammonium bottom flux was an important resource for nutrients geochemistry in the Zhujiang Estuary.展开更多
We used a salt-resistant poplar genotype Populus euphratica and two salt-sensitive genotypes, Populus 'popularis 35-44' (P. popularis) and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) to exami...We used a salt-resistant poplar genotype Populus euphratica and two salt-sensitive genotypes, Populus 'popularis 35-44' (P. popularis) and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) to examine genotypic differences in nutrient selectivity under NaCl stress. One-year-old seedlings of P. euphratica and one-year-old hardwood cuttings of P. popularis were used in a short-term study (24 hours), while in a long-term study, up to 4 weeks, two-year-old seedlings of P. euphratica and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) were compared. In the short-term study, K+ concentration in the xylem sap ([K+]xylem) of P. euphratica significantly increased after salt stress was initiated, and maintained 1-2 fold higher than control levels during the period of salt stress (24 hours). Xylem Ca2+ and Mg2+ concentrations ([Ca2+]xylem, [Mg2+]xylem) in P. euphratica resembled the pattern of K+ despite a lesser magnitude in elevation. However, [K+]xylem, [Ca2+]xylem and [Mg2+]xylem in P. popularis exhibited a transient increase at the beginning of salt treatment, thereafter, they all returned to control levels at 4 hours and no further rise was observed in the following hours. Xylem Na+/K+, Na+/Ca2+ and Na+/Mg2+ in P. popularis increased sharply upon NaCl stress and steadily reached the maximum at 24 hours. In contrast, xylem Na+/K+, Na+/Ca2+ and Na+/Mg2+ in NaCl-treated plants of P. euphratica did not significantly increase during the period of salt stress (24 hours). Noteworthy, Na+/K+ markedly declined after the onset of stress. These results suggest that P. euphratica had a higher nutrient selectivity in face of salinity. A same trend was observed in a 4-week study. Xylem Na+/K+, Na+/Ca2+ and Na+/Mg2+ in salinised plants of the hybrid abruptly increased after 4 days of stress, and then continuously increased to reach the highest level at day 8 or day 15. In comparison, the magnitude of Na+/K+, Na+/Ca2+ and Na+/Mg2+ elevation in the xylem of P. euphratica was much lower during the observation period. In conclusion, salt-tolerant genotype P. euphratica maintained a higher nutrient selectivity under saline stress, as compared to the two salt-sensitive genotypes. The high capacity for nutrient uptake and transport presumably contributes to the salt tolerance of P. euphratica in a longer term.展开更多
The main purpose of this presented article was to explain the need to study the amount of heavy metal salts in the environment where animals live, in the water, in air, and in the food and fodder consumed. This articl...The main purpose of this presented article was to explain the need to study the amount of heavy metal salts in the environment where animals live, in the water, in air, and in the food and fodder consumed. This article presents materials from the literature on the effects of heavy metal salts on the body of animals and the environment in which they live. The cited analytical data showed that the general information on the negative effects of heavy metal salts on the body is sufficient, but their effects on the digestive tract and morpho-functional properties of rabbits should be studied in depth. Therefore, we planned to focus our scientific work on this topic. The article mainly refers to salts of heavy metals cadmium, lead, and mercury (Cd, Pb, Hg). It is noted in the literature that heavy metal salts have a negative effect on the body of animals. We focused mainly on data on the effects of heavy metals on farm animals, including rabbits. But it is clear that the authors referred to were referring to experimental animals. These negative effects are manifested in the form of disorders of digestive functions, disorders of neurovegetative processes, increasing incidence of cardiovascular disease, rapid heart failure, deterioration of calcium metabolism, as well as impaired haemoglobin metabolism. Disorders of protein metabolism manifest themselves in the form of cases of hyperproteinaemia and dysproteinaemia. The results of the evaluation of the organism of healthy animals in chemically and radioactively contaminated areas showed the accumulation of significant levels of chemical elements in their organism. We mainly looked at the effects of heavy metal salts on farm animals. The cited analytical data showed that the general information on the negative effects of heavy metal salts on the body is sufficient, but the effects on the activity of organ systems in the body (respiration, blood and blood circulation, digestion, reproduction, productivity and immunological systems) have not been comprehensively studied.展开更多
基金the National Key Technology R&D Program of China(2007BAD87B11)the 948 Program,Minsitry of Agriculture,China (200803030)
文摘The study was conducted to investigate the effects of applying different concentrations of the macronutrients K＋,Ca2＋,and Mg2＋ on the responses of contrasting rice（Oryza sativa L.） genotypes under salt stress.A solution culture experiment was conducted in a phytotron at the International Rice Research Institute（IRRI）,under controlled temperature and humidity and natural sunlight.When subjected to salt stress of 100 mmol L-1 using NaCl,the salt tolerant genotypes FL478 and IR651,accumulated less Na＋ and maintained lower ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ than the sensitive genotypes IR29 and Azucena.These tolerant genotypes also had higher concentrations of K＋ in their shoots and greater root and shoot biomass and green leaf area.Tolerant genotypes also maintained much lower concentration of Na＋ and lower and more favorable ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in their active and developing tissues.Salt tolerance and shoot and root growth of both tolerant and sensitive genotypes were enhanced considerably when higher concentrations of Ca2＋ and Mg2＋ were applied in culture solution.The concentration of Na＋ and the ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in shoots also declined significantly.The beneficial effects of higher calcium were greater than that of magnesium and application of higher concentration of K＋ seems to have minor effects.Responses to salinity in rice can therefore be considerably enhanced through proper nutrient management,by increasing the concentrations of nutrient elements that have favorable effects such as Ca2＋ and Mg2＋.Calcium is particularly more effective than both magnesium and potassium,and can be applied at relatively larger quantities in salt affected soils.
基金This study was supported by the Science and Technology University of Hong Kong and the State Oceanic Administrationof China.
文摘The profiles of nutrient salts in the interstitial water of sediment were analyzed in the Zhu- jiang Estuary in the summer of 1999, and based on the profiles of content and characteristic of nutri- ents, the relationship between nutrients in the interstitial water and organic matter decomposition in sediment was discussed. The results showed that ammonium with high content was the main existence form of nutrients in the interstital water of sediment, and the organic matter decomposition was com- pleted in anaerobic condition. The increase of ammonium content in the bottom water resulted from the decomposition of organic matter and release of metabolic production, and the ammonium bottom flux was an important resource for nutrients geochemistry in the Zhujiang Estuary.
基金Foundation for the Author of National Excellent Doctoral Dissertation of PRC (Grant No. 200152)the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institution of MOE, PRC, the National Nat
文摘We used a salt-resistant poplar genotype Populus euphratica and two salt-sensitive genotypes, Populus 'popularis 35-44' (P. popularis) and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) to examine genotypic differences in nutrient selectivity under NaCl stress. One-year-old seedlings of P. euphratica and one-year-old hardwood cuttings of P. popularis were used in a short-term study (24 hours), while in a long-term study, up to 4 weeks, two-year-old seedlings of P. euphratica and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) were compared. In the short-term study, K+ concentration in the xylem sap ([K+]xylem) of P. euphratica significantly increased after salt stress was initiated, and maintained 1-2 fold higher than control levels during the period of salt stress (24 hours). Xylem Ca2+ and Mg2+ concentrations ([Ca2+]xylem, [Mg2+]xylem) in P. euphratica resembled the pattern of K+ despite a lesser magnitude in elevation. However, [K+]xylem, [Ca2+]xylem and [Mg2+]xylem in P. popularis exhibited a transient increase at the beginning of salt treatment, thereafter, they all returned to control levels at 4 hours and no further rise was observed in the following hours. Xylem Na+/K+, Na+/Ca2+ and Na+/Mg2+ in P. popularis increased sharply upon NaCl stress and steadily reached the maximum at 24 hours. In contrast, xylem Na+/K+, Na+/Ca2+ and Na+/Mg2+ in NaCl-treated plants of P. euphratica did not significantly increase during the period of salt stress (24 hours). Noteworthy, Na+/K+ markedly declined after the onset of stress. These results suggest that P. euphratica had a higher nutrient selectivity in face of salinity. A same trend was observed in a 4-week study. Xylem Na+/K+, Na+/Ca2+ and Na+/Mg2+ in salinised plants of the hybrid abruptly increased after 4 days of stress, and then continuously increased to reach the highest level at day 8 or day 15. In comparison, the magnitude of Na+/K+, Na+/Ca2+ and Na+/Mg2+ elevation in the xylem of P. euphratica was much lower during the observation period. In conclusion, salt-tolerant genotype P. euphratica maintained a higher nutrient selectivity under saline stress, as compared to the two salt-sensitive genotypes. The high capacity for nutrient uptake and transport presumably contributes to the salt tolerance of P. euphratica in a longer term.
文摘The main purpose of this presented article was to explain the need to study the amount of heavy metal salts in the environment where animals live, in the water, in air, and in the food and fodder consumed. This article presents materials from the literature on the effects of heavy metal salts on the body of animals and the environment in which they live. The cited analytical data showed that the general information on the negative effects of heavy metal salts on the body is sufficient, but their effects on the digestive tract and morpho-functional properties of rabbits should be studied in depth. Therefore, we planned to focus our scientific work on this topic. The article mainly refers to salts of heavy metals cadmium, lead, and mercury (Cd, Pb, Hg). It is noted in the literature that heavy metal salts have a negative effect on the body of animals. We focused mainly on data on the effects of heavy metals on farm animals, including rabbits. But it is clear that the authors referred to were referring to experimental animals. These negative effects are manifested in the form of disorders of digestive functions, disorders of neurovegetative processes, increasing incidence of cardiovascular disease, rapid heart failure, deterioration of calcium metabolism, as well as impaired haemoglobin metabolism. Disorders of protein metabolism manifest themselves in the form of cases of hyperproteinaemia and dysproteinaemia. The results of the evaluation of the organism of healthy animals in chemically and radioactively contaminated areas showed the accumulation of significant levels of chemical elements in their organism. We mainly looked at the effects of heavy metal salts on farm animals. The cited analytical data showed that the general information on the negative effects of heavy metal salts on the body is sufficient, but the effects on the activity of organ systems in the body (respiration, blood and blood circulation, digestion, reproduction, productivity and immunological systems) have not been comprehensively studied.
