The objective of this study is to clarify the effects of the thickness of soil dressing, the percolation patterns of plowsole and subsoil on reducing cadmium (Cd) uptake, and growth and yields of rice plants. Six st...The objective of this study is to clarify the effects of the thickness of soil dressing, the percolation patterns of plowsole and subsoil on reducing cadmium (Cd) uptake, and growth and yields of rice plants. Six stratified paddy field models, three patterns of soil dressing layer and two percolation patterns were used for the experiments. These models had 12.5 cm, 15.0 cm and 25.0 cm thickness of soil dressing layer and 15 cm thickness of underlying polluted soil layer, whose Cd concentration was about 1.81 mg·kg^-1. As a result Cd concentration of brown rice was lower than 0.04 mg·kg^-1 for the models with the close system percolation, while that in the open system percolation models were lower than 0.17 mg.kgl.When the thickness of soil dressing became lower, Cd concentrations with the open system percolation models showed significantly higher values than those of the other models (5% of significant level). But any significant difference was not found in the growth and yield among these models. As above mentioned, it was found that Cd concentration in rice grains was affected by the thickness of soil dressing and percolation patterns.展开更多
The morphological characters, physiological characters, yield traits and yield per plant of total 49 rice cultivars from Ningxia were investigated under conditions of water stress and non-water stress so as to determi...The morphological characters, physiological characters, yield traits and yield per plant of total 49 rice cultivars from Ningxia were investigated under conditions of water stress and non-water stress so as to determine the relationship between each trait and yield per plant under water stress and the relationship between each relative character and drought resistance coefficient under water stress and non-water stress. The correlation, grey correlation, stepwise regression and path analyses showed that the tiller number per plant, plant height, grain density, effective panicle number per plant and grain number per panicle, total 5 traits, were significantly correlated with the drought resistance of rice, and they could be used to identify the drought resistance of rice in Ningxia. In addition, the drought resistance of rice was graded qualitatively according to the subordinate function value of corresponding drought resistance coefficient. The results showed that among the 49 rice cultivars from Ningxia,6 rice cultivars were highly drought resistant, and 9 rice cultivars were moderately drought resistant, suggesting that the evaluation method was feasible and effective.展开更多
In future climates, rice could more frequently be subjected to simultaneous high temperature (HT) and water stress (WS) during sensitive developmental stages such as flowering. In this study, two rice genotypes we...In future climates, rice could more frequently be subjected to simultaneous high temperature (HT) and water stress (WS) during sensitive developmental stages such as flowering. In this study, two rice genotypes were exposed to HT, WS and combined high temperature and water stress (WS + HT) during flowering to quantify their response through anther dehiscence. Gene expression profiles of 15 selected OsDIRs revealed differences among stresses and between varieties. The targeted gene OsDIR-08, which was considered to be a HT stress candidate gene, was de- creasingly expressed from the 1st d to the 4th d under HT stress in Nagina 22 (N22) while increased in Moroberekan. Varies of the expression of OsDIR genes in stresses intuitively reflects on the lignin-staining at the anther dehisced sites, which implied a negative relationship between the lignin biosynthesis and OsDIRs' ex- pression. Anther dehiscence disturbed by HT and WS + HT stress showed a nega- tive cumulative effect in HT sensitive variety Moroberekan but not in N22. Higher level of anther dehiscence in /V22 under HT and WS + HT stress indicated its true tolerance of HT and to WS + HT during anthesis. The differentially expressed of OsDIR(s) under various managed stresses caused the difference of the lignin-stain- ing at the anther dehisced site in N22, and thus transformed anther dehiscence correspondingly might be one of the main reasons for the tolerance.展开更多
Laboratory and greenhouse studies were conducted to assess the allelopathic potential of 12 rice cultivars on barnyard grass. Polyethylene glycol (PEG) was used to determine the influence of osmotic potential on the...Laboratory and greenhouse studies were conducted to assess the allelopathic potential of 12 rice cultivars on barnyard grass. Polyethylene glycol (PEG) was used to determine the influence of osmotic potential on the bioassay materials. Effect of different concentrations of stem, root, and leaf extracts of rice cultivars on seed germination, radicle and primary shoot length of barnyard grass seedlings, and rate of respiration of root pieces were investigated in the laboratory experiments. Shoot height and dry weight of weed stands were studied in the greenhouse, Also total peroxidase activity, chlorophyll pigment and mitotic index were determined. Results indicated that, among rice cultivars, Mehr, Tarom-mahali, G3, Nemat, and Shahpasand caused the most inhibition effects on investigated factors. Amol-3 showed the least negative effects on growth of seedlings and stands of barnyard grass. In laboratory, the Mehr cultivar demonstrated the maximum inhibitory effects by reducing barnyard grass seed germination percentage (88%), radicle length (100%), primary shoot length (83%), and root respiration (85%) Cell division, expressed as mitotic index, was significantly reduced in the presence of rice aqueous extracts. Mehr cultivar had higher inhibitory effect on mitosis compared to Amol-3. In greenhouse, the same cultivar showed the maximum inhibitory effect by reducing barnyard grass height (45%) and dry weight (64%). With increase in extract concentration, the inhibitory effect increased. Leaf extract from rice plants was more effective compared with the root and stem extracts. Comparison of rice cultivars and PEG indicated that any reduction in germination and growth of barnyard grass using rice extract concentrations of 5% and 10% must have been the result of allelochemicals in the extracts. Lower extract concentrations showed a more pronounced inhibitory effect in the laboratory as compared to the greenhouse studies. These results suggest that rice leaf extracts may be a source of natural herbicide.展开更多
From 2003 to 2005, in pot and field experiments, rice response to salinity stress of 15 rice varieties was studied at germination and young seedling stages using salt affected soils collected from rice production area...From 2003 to 2005, in pot and field experiments, rice response to salinity stress of 15 rice varieties was studied at germination and young seedling stages using salt affected soils collected from rice production areas in the Office du Niger zone of Mali. The rice varieties were composed of 10 rice genotypes from the breeding program of Mali and five from West African Rice Development Association (WARDA) program (Saint Louis, Senegal). Soil samples were collected from the visually affected soils which were characterized by the appearance of white or black efflorescence on the soil surface. In pot experiments, the genotypes were allowed to germinate in both affected soil types (white efflorescence and black efflorescence) and salt effects on plant seedling growth were observed. Results showed that all varieties were significantly sensitive to salinity stress based on germination, young seedling shoot and root dry weights. Among the rice varieties, the most salt tolerant variety was BG90-2 (a high yielding genotype from the Institut d'Economie Rurale (IER) breeding program) while the most sensitive variety was Telimani (also from the breeding program of IER). All other varieties were intermediary between these two genotypes. A three year field experiment conducted in a highly affected area near Niono confirmed the results of the pot experiment. The relatively salt tolerant genotypes were found in both Malian (BG90-2, Kogoni91-1, SK51-5-2) and WARDA (Was30-11-1-1-4-6-1B) rice breeding programs.展开更多
In this study, four combinations of crops: rice (C), rice-maize (MCSI), rice-cassava (MCS2) and rice-maize-cassava (MCS3) with 3 m × 3 m each plots at two field areas--Saptosari and Tanjungsari were obse...In this study, four combinations of crops: rice (C), rice-maize (MCSI), rice-cassava (MCS2) and rice-maize-cassava (MCS3) with 3 m × 3 m each plots at two field areas--Saptosari and Tanjungsari were observed. Both field areas are located in Gunungkidul district, South-Central of Java Island, with that 93% at those areas are 185 m to 500 m above sea level and high proportion of multiple cropping systems (MCS). The aim of this study was to investigate the effect of different cropping method on growth, crop index and yield response to water of rice in rainfed agriculture. Mathematical models were developed to describe rice growth. The rice height was followed monomolecular function and the number of tillers followed exponential polynomial function. Crop index was calculated from climate data during plant growth phase. And yield response to water was calculated from actual evapotranspiration (ETa) and the maximum evapotranspiration (ETm). The results showed that the height of rice was not significantly different between each combination (P 〉 0.05). Number of tillers was also not significant (P 〉 0.05). However, monoculture treatment had more number of tillers than rice in MCS. Crop index of rice at Saptosari was higher than at Tanjungsari. Based on the calculation of evapotranspiration (ET), water deficit at initial was less than at mid-season (ETa 〈 ETm) and affected water stress. Statistical analysis showed that cropping methods did not significantly affect rice growth and yield (P 〉 0.05).展开更多
文摘The objective of this study is to clarify the effects of the thickness of soil dressing, the percolation patterns of plowsole and subsoil on reducing cadmium (Cd) uptake, and growth and yields of rice plants. Six stratified paddy field models, three patterns of soil dressing layer and two percolation patterns were used for the experiments. These models had 12.5 cm, 15.0 cm and 25.0 cm thickness of soil dressing layer and 15 cm thickness of underlying polluted soil layer, whose Cd concentration was about 1.81 mg·kg^-1. As a result Cd concentration of brown rice was lower than 0.04 mg·kg^-1 for the models with the close system percolation, while that in the open system percolation models were lower than 0.17 mg.kgl.When the thickness of soil dressing became lower, Cd concentrations with the open system percolation models showed significantly higher values than those of the other models (5% of significant level). But any significant difference was not found in the growth and yield among these models. As above mentioned, it was found that Cd concentration in rice grains was affected by the thickness of soil dressing and percolation patterns.
基金Supported by Natural Science Foundation of Ningxia(NZ1189)National Rice Industrial Technology System(CARS-01-84)
文摘The morphological characters, physiological characters, yield traits and yield per plant of total 49 rice cultivars from Ningxia were investigated under conditions of water stress and non-water stress so as to determine the relationship between each trait and yield per plant under water stress and the relationship between each relative character and drought resistance coefficient under water stress and non-water stress. The correlation, grey correlation, stepwise regression and path analyses showed that the tiller number per plant, plant height, grain density, effective panicle number per plant and grain number per panicle, total 5 traits, were significantly correlated with the drought resistance of rice, and they could be used to identify the drought resistance of rice in Ningxia. In addition, the drought resistance of rice was graded qualitatively according to the subordinate function value of corresponding drought resistance coefficient. The results showed that among the 49 rice cultivars from Ningxia,6 rice cultivars were highly drought resistant, and 9 rice cultivars were moderately drought resistant, suggesting that the evaluation method was feasible and effective.
文摘In future climates, rice could more frequently be subjected to simultaneous high temperature (HT) and water stress (WS) during sensitive developmental stages such as flowering. In this study, two rice genotypes were exposed to HT, WS and combined high temperature and water stress (WS + HT) during flowering to quantify their response through anther dehiscence. Gene expression profiles of 15 selected OsDIRs revealed differences among stresses and between varieties. The targeted gene OsDIR-08, which was considered to be a HT stress candidate gene, was de- creasingly expressed from the 1st d to the 4th d under HT stress in Nagina 22 (N22) while increased in Moroberekan. Varies of the expression of OsDIR genes in stresses intuitively reflects on the lignin-staining at the anther dehisced sites, which implied a negative relationship between the lignin biosynthesis and OsDIRs' ex- pression. Anther dehiscence disturbed by HT and WS + HT stress showed a nega- tive cumulative effect in HT sensitive variety Moroberekan but not in N22. Higher level of anther dehiscence in /V22 under HT and WS + HT stress indicated its true tolerance of HT and to WS + HT during anthesis. The differentially expressed of OsDIR(s) under various managed stresses caused the difference of the lignin-stain- ing at the anther dehisced site in N22, and thus transformed anther dehiscence correspondingly might be one of the main reasons for the tolerance.
文摘Laboratory and greenhouse studies were conducted to assess the allelopathic potential of 12 rice cultivars on barnyard grass. Polyethylene glycol (PEG) was used to determine the influence of osmotic potential on the bioassay materials. Effect of different concentrations of stem, root, and leaf extracts of rice cultivars on seed germination, radicle and primary shoot length of barnyard grass seedlings, and rate of respiration of root pieces were investigated in the laboratory experiments. Shoot height and dry weight of weed stands were studied in the greenhouse, Also total peroxidase activity, chlorophyll pigment and mitotic index were determined. Results indicated that, among rice cultivars, Mehr, Tarom-mahali, G3, Nemat, and Shahpasand caused the most inhibition effects on investigated factors. Amol-3 showed the least negative effects on growth of seedlings and stands of barnyard grass. In laboratory, the Mehr cultivar demonstrated the maximum inhibitory effects by reducing barnyard grass seed germination percentage (88%), radicle length (100%), primary shoot length (83%), and root respiration (85%) Cell division, expressed as mitotic index, was significantly reduced in the presence of rice aqueous extracts. Mehr cultivar had higher inhibitory effect on mitosis compared to Amol-3. In greenhouse, the same cultivar showed the maximum inhibitory effect by reducing barnyard grass height (45%) and dry weight (64%). With increase in extract concentration, the inhibitory effect increased. Leaf extract from rice plants was more effective compared with the root and stem extracts. Comparison of rice cultivars and PEG indicated that any reduction in germination and growth of barnyard grass using rice extract concentrations of 5% and 10% must have been the result of allelochemicals in the extracts. Lower extract concentrations showed a more pronounced inhibitory effect in the laboratory as compared to the greenhouse studies. These results suggest that rice leaf extracts may be a source of natural herbicide.
文摘From 2003 to 2005, in pot and field experiments, rice response to salinity stress of 15 rice varieties was studied at germination and young seedling stages using salt affected soils collected from rice production areas in the Office du Niger zone of Mali. The rice varieties were composed of 10 rice genotypes from the breeding program of Mali and five from West African Rice Development Association (WARDA) program (Saint Louis, Senegal). Soil samples were collected from the visually affected soils which were characterized by the appearance of white or black efflorescence on the soil surface. In pot experiments, the genotypes were allowed to germinate in both affected soil types (white efflorescence and black efflorescence) and salt effects on plant seedling growth were observed. Results showed that all varieties were significantly sensitive to salinity stress based on germination, young seedling shoot and root dry weights. Among the rice varieties, the most salt tolerant variety was BG90-2 (a high yielding genotype from the Institut d'Economie Rurale (IER) breeding program) while the most sensitive variety was Telimani (also from the breeding program of IER). All other varieties were intermediary between these two genotypes. A three year field experiment conducted in a highly affected area near Niono confirmed the results of the pot experiment. The relatively salt tolerant genotypes were found in both Malian (BG90-2, Kogoni91-1, SK51-5-2) and WARDA (Was30-11-1-1-4-6-1B) rice breeding programs.
文摘In this study, four combinations of crops: rice (C), rice-maize (MCSI), rice-cassava (MCS2) and rice-maize-cassava (MCS3) with 3 m × 3 m each plots at two field areas--Saptosari and Tanjungsari were observed. Both field areas are located in Gunungkidul district, South-Central of Java Island, with that 93% at those areas are 185 m to 500 m above sea level and high proportion of multiple cropping systems (MCS). The aim of this study was to investigate the effect of different cropping method on growth, crop index and yield response to water of rice in rainfed agriculture. Mathematical models were developed to describe rice growth. The rice height was followed monomolecular function and the number of tillers followed exponential polynomial function. Crop index was calculated from climate data during plant growth phase. And yield response to water was calculated from actual evapotranspiration (ETa) and the maximum evapotranspiration (ETm). The results showed that the height of rice was not significantly different between each combination (P 〉 0.05). Number of tillers was also not significant (P 〉 0.05). However, monoculture treatment had more number of tillers than rice in MCS. Crop index of rice at Saptosari was higher than at Tanjungsari. Based on the calculation of evapotranspiration (ET), water deficit at initial was less than at mid-season (ETa 〈 ETm) and affected water stress. Statistical analysis showed that cropping methods did not significantly affect rice growth and yield (P 〉 0.05).