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Silber Avner Ben-Jaacov Jaacov Ackerman Alexander Bar-Tal Asher Levkovitch Irit Matsevitz-Yosef Tania Swartzberg Dvora Riov Josef Granot David 《Plant and Soil》2002,245(2):249-260
Phosphorus, an essential plant nutrient, may become toxic when accumulated by plants to high concentrations. Certain plant species such as Verticordia plumosa L. suffer from P toxicity at solution concentrations far lower than most other plant species. In this study, exposure of V. plumosa plants to a solution containing as low as 3 mg l–1 P resulted in significant growth inhibition and typical symptoms of P toxicity. In a wide range of P levels studied, micronutrient concentrations in V. plumosa leaves were within the range considered adequate for optimal growth. Notably, tomato plants with high hexokinase activity due to overexpression of Arabidopsis hexokinase (AtHXK1) exhibited senescence symptoms similar to those of P toxic V. plumosa. The resemblance in senescence symptoms between P-toxic tomato plants and those with high hexokinase activity suggested that increased sugar metabolism could play a role in P toxicity in plants. To test this hypothesis, we determined the amount of hexose phosphate, the product of hexokinase, in V. plumosa leaves grown at various P levels in the nutrient solution. Positive correlations were found between concentration in the medium, P concentration in the plant, hexose phosphate concentration in leaves and P toxicity symptoms. Foliar Zn application suppressed P toxicity symptoms and reduced the level of hexose phosphate in leaves. Furthermore, Zn also inhibited hexokinase activity in vitro. Based on these results we suggest that P toxicity involves sugar metabolism via increased activity of hexokinase that accelerates senescence 相似文献
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Microbial activity and organic matter dynamics during 4 years of irrigation with treated wastewater 总被引:1,自引:0,他引:1
Elifantz H Kautsky L Mor-Yosef M Tarchitzky J Bar-Tal A Chen Y Minz D 《Microbial ecology》2011,62(4):973-981
The global changes in rainfall frequency and quantity have subjected arid and semi-arid regions to long periods of drought.
As this phenomenon corresponds to increasing trend of water shortage, the use of treated wastewater (TWW) has been suggested
as an alternative for irrigation of agricultural crops in these areas. The aim of the study was to investigate the short-
and middle-term effects of TWW irrigation on the soil microbial activities and organic carbon content. The microbial community
activity was measured every 1–3 months for 4 years in a persimmon (Diospyros kaki) orchard. These activities were used here as an indicator for the soil health. The hydrolysis activity (detected by fluorescein
diacetate hydrolysis (FDA) assay) increased during the irrigation season and was significantly higher in soils irrigated with
TWW compared to those irrigated with freshwater (FW). This activity was also negatively correlated with dissolved organic
carbon (DOC) concentrations during the irrigation season, suggesting that the community degraded the DOC in the soils regardless
of its origin. The irrigation season was also characterized by an increase in nitrification potential in both TWW- and FW-irrigated
soils, which coincided with high concentrations of nitrate (50 mg kg−1 soil). Overall, there was an increase in all measured activities during the irrigation season, and they were higher in the
TWW soils. However, it appears that after each irrigation season, the potential activity of the community returned to levels
similar to or even slightly lower than those of FW-irrigated soil during the wet season, suggesting that the periodic irrigation
did not significantly change the soil microbial activity. 相似文献
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Hakan Aktas Leah Karni Dong-Chil Chang Ece Turhan Asher Bar-Tal Beny Aloni 《Physiologia plantarum》2005,123(1):67-74
We investigated the possibility that oxidative stress contributes to blossom-end rot (BER) initiation in bell pepper ( Capsicum annuum L.) grown under high salinity. Pepper plants (cv. Mazurka, Rijk Zwaan, the Netherlands) were grown in a greenhouse and irrigated with nutrient solution made up with either desalinated water (control — rising from E.C. 1.9 to 2.4 dS m−1 ) or saline water (salinity – rising from E.C. 3.2 to 7.0 dS m−1 ). Irrigation was by a circulation system. BER symptoms were observed throughout the experiment but were highly enhanced in the salinity–grown plants during the spring and summer. The fruit calcium concentration was not affected by salinity, but manganese concentrations in both leaves and fruits were significantly reduced under these conditions. Under salinity there was an enhancement of apoplast reactive oxygen species (ROS) production, which was partly a result of increase in NAD(P)H oxidase activity in the pericarp of pepper fruit at the stage that it was most sensitive to BER. Apoplast ROS production and extracted NAD(P)H oxidase activity were inhibited by manganese, zinc and to a lesser extent by calcium. These cations also negated the enhancement of ROS production caused by incubation of fruit pericarp discs in NaCl solutions. Manganese, zinc and calcium also inhibited NAD(P)H oxidase activity, extracted following their infiltration into fruit pericarp discs. The results suggest that generation and scavenging of oxygen free radicals in the apoplast may contribute to the appearance of BER symptoms in pepper fruits under saline conditions. It is suggested that manganese may serve as antioxidant in pepper fruit and that manganese addition to peppers grown under salinity may alleviate BER symptoms in the fruits. 相似文献
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