Sele</span><span style="font-family:Verdana;">ction for tolerance to low phosphorus (P) using morphological trait</span><span style="font-family:Verdana;">s alone is slow an...Sele</span><span style="font-family:Verdana;">ction for tolerance to low phosphorus (P) using morphological trait</span><span style="font-family:Verdana;">s alone is slow and often confounded by environmental effects. This study identified </span></span><span style="font-family:Verdana;">some Quantitative Trait Loci (QTLs) associated with grain yield (</span><span style="font-family:Verdana;">GYLD)</span><span style="font-family:Verdana;">, Plant (PHT) and Ear heights (EHT) under low P in maize using single nucleotide polymorphic markers</span><span style="font-family:Verdana;">. 228 F2:3 individuals derived from a cross between two contrasting maize inbred lines together with 239 SNPs were mapped onto ten linkage groups (LGs) spanning 2255 centiMorgans (cM) with an average inter-marker distance of 9.44 cM. Majority of the SNP markers (63%) followed the Mendelian segregation and were fairly distributed in all the LGs. Mean performance for all the traits in the F3 population was higher than the parental values, which suggested transgressive segregation for all traits. Low to moderate broad sense heritability (0.35 - 0.50) in the F3 population for GYLD</span><span style="font-family:Verdana;">, PHT and EHT </span><span style="font-family:Verdana;">indicated that tolerance to low P is controlled by complex multi genetic factors. A full multi-QTL model analysis suggested </span><span style="font-family:Verdana;">six QTLs (2 QTLs each for GYLD, PHT and EHT) located on chromosomes 1, 3, 4 and 8. </span><span style="font-family:Verdana;">The two QTLs for GYLD increased maize yield under low P soils by 173 kg/ha while the 2 QTLs for PHT increased plant growth by 18.14 cm. The % phenotypic variance explained by these QTLs under low P environments had a wide range (0.242% - 53.34%) and was much lower for GYLD compared to plant growth. Both additive and dominance gene actions contributed differentially to the observed phenotypic variance for tolerance to low P soils with dominance contributing more genetic effects compared additive effects for majority of the QTLs. The findings of this study will provide some basis for marker-assisted selection for yield improvement and further guide breeding strategies under low P soils of western Kenya.展开更多
A field trial was conducted to investigate main morphological and physiological changes of different maize landraces to low-P stress at the stage of seedling. P-deficiency significantly decreased root volume, total le...A field trial was conducted to investigate main morphological and physiological changes of different maize landraces to low-P stress at the stage of seedling. P-deficiency significantly decreased root volume, total leaf area, and plant dry weight, but greatly increased density of root hairs and root top ratio. In addition, P-deficiency induced the significant enhancement of phosphorus utilization efficiency and the amount of proline, malondialdehye (MDA), acid phosphatase (APase), peroxidase (POD) and superoxide dismutase (SOD), but the significant reduction of P uptake and soluable protein content. Since P-deficiency had smaller effects on the P-tolerant maize landraces DP-44, DP-32 and DP-33 as compared with P-sensitive landraces DP-29 and DP-24, it was demonstrated that differences of tolerance to P-deficiency existed among different maize landraces. The results based on the correlation analysis showed that the economic yield of maize landraces had relationships with their morphological and physiological characteristics under P-deficiency.展开更多
A number of previous papers have studied the problem of recovering low-rank matrices with noise, further combining the noisy and perturbed cases, we propose a nonconvex Schatten p-norm minimization method to deal with...A number of previous papers have studied the problem of recovering low-rank matrices with noise, further combining the noisy and perturbed cases, we propose a nonconvex Schatten p-norm minimization method to deal with the recovery of fully perturbed low-rank matrices. By utilizing the p-null space property (p-NSP) and the p-restricted isometry property (p-RIP) of the matrix, sufficient conditions to ensure that the stable and accurate reconstruction for low-rank matrix in the case of full perturbation are derived, and two upper bound recovery error estimation ns are given. These estimations are characterized by two vital aspects, one involving the best r-approximation error and the other concerning the overall noise. Specifically, this paper obtains two new error upper bounds based on the fact that p-RIP and p-NSP are able to recover accurately and stably low-rank matrix, and to some extent improve the conditions corresponding to RIP.展开更多
To understand whether genotypic variation in acid phosphatase (APase) activity in rapeseed (Brassica napus L.) induced by phosphorus (P) deficiency has impact on P efficiency,soil APase activity in the rhizosphere for...To understand whether genotypic variation in acid phosphatase (APase) activity in rapeseed (Brassica napus L.) induced by phosphorus (P) deficiency has impact on P efficiency,soil APase activity in the rhizosphere for rapeseed P-efficient genotype 102 and P-inefficient genotype 105 was measured against organic and inorganic P sources in the pot experiment,and the activities of root-secreted APase and leaf intracellular APase were investigated in different P-starvation periods in the nutrient solution.Higher activity of root-secreted APase in B.napus was induced under low P conditions.However,P nutrition and P uptake efficiency of the plants supplied with organic P were not directly related to the activity of root-secreted APase due to several confounding factors affecting APase availability.The higher activity of leaf APase improved P remobilization in plants and played important roles in enhancing P use efficiency,shown by the significant correlation between leaf APase activity and P use efficiency in a rapeseed recombinant inbred population of 135 lines.展开更多
Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake effi...Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake efficiency was the main contributor to P tolerance, and the relative P content in P-tolerant genotypes, 99180 and 99239 were higher than that in sensitive genotype, 99152. At earing stage, P-tolerant genotypes, compared to P-sensitive ones, had higher accumulation of P in upper leaves. When came to the silking stage, P uptake and redistribution efficiency of P-tolerant genotypes were higher than those in 99152. The results also suggested that there are different mechanisms of P nutrient uptake and distribution in different P-tolerant genotypes. Inbred line 99239, according to the investigation, was considered as an efficient stock in the P-uptake while 99180 fallen to the efficient stock of P redistribution.展开更多
The F-rich granites in South China could be distinguished as the high-p subtype andthe low-p subtype according to their P2O5 contents. There are obvious differences in chemicalcomopition of these two subtypes. The hig...The F-rich granites in South China could be distinguished as the high-p subtype andthe low-p subtype according to their P2O5 contents. There are obvious differences in chemicalcomopition of these two subtypes. The high-p subtype is strongly peraluminous and characterized by low silica and very low REE contents, while the low-p subtype is weakly peraluminousand characterized by high silica and very high REE contents. There are also some differences inchemical compositions of feldspars and micas for these two subtypes. The phosphorus of thehigh-p subtype mainly appears to be in the feldspar structure as PAISi-2 substitution or subordinately in amblygonite as an accessory mineral, while the phosphorus of the low-p subtype ismainly in apatite and other phosphate minerals.展开更多
Applicability of regional P/S amplitude ratios for the discrimination of low-magnitude seismic events was tested and proved using earthquakes and explosions in Central Asia. Results obtained show that regional P/S amp...Applicability of regional P/S amplitude ratios for the discrimination of low-magnitude seismic events was tested and proved using earthquakes and explosions in Central Asia. Results obtained show that regional P/S amplitude ratios which may discriminate medium or large magnitude events well, are also applicable to low magnitude events Their performances for low magnitude events are almost as good as that for medium or large events. Statistical comparisons based on 25 P/S discriminate from the four seismic stations WMQ, BLK, MUL and MAK showed that the average misclassification rate for low-magnitude seismic events averagely was only 2 percent higher than that for medium and large magnitude seismic events.展开更多
Lower temperature or polyphosphate limitation is the favorable condition to enrich polyphosphate-accumulating organisms (PAOs) or glycogen accumulating organisms (GAOs) in biological phosphorus removal process. In thi...Lower temperature or polyphosphate limitation is the favorable condition to enrich polyphosphate-accumulating organisms (PAOs) or glycogen accumulating organisms (GAOs) in biological phosphorus removal process. In this study,a sludge highly enriched in PAOs was used to investigate the metabolic pathways and carbon transformation in batch tests under the two conditions for elucidating the contradiction. The results showed that the PAOs are able to take up acetate and store it as polyhydroxyalkanoates (PHA) in anaerobic phase although the poly-P pool is emptied through washing with negligible P release. The stoichiometric ratios of the PHB and PHV production and glycogen degradation to the acetate uptake combined with the Nile blue staining indicated that the PAOs possess the anaerobic metabolism of GAOs using glycogen as the sole energy source,but no transformation of PAOs to GAOs is observed. After reconverting to the normal operation,phosphorus uptake and release are recovered the same as the parent reactor.展开更多
文摘Sele</span><span style="font-family:Verdana;">ction for tolerance to low phosphorus (P) using morphological trait</span><span style="font-family:Verdana;">s alone is slow and often confounded by environmental effects. This study identified </span></span><span style="font-family:Verdana;">some Quantitative Trait Loci (QTLs) associated with grain yield (</span><span style="font-family:Verdana;">GYLD)</span><span style="font-family:Verdana;">, Plant (PHT) and Ear heights (EHT) under low P in maize using single nucleotide polymorphic markers</span><span style="font-family:Verdana;">. 228 F2:3 individuals derived from a cross between two contrasting maize inbred lines together with 239 SNPs were mapped onto ten linkage groups (LGs) spanning 2255 centiMorgans (cM) with an average inter-marker distance of 9.44 cM. Majority of the SNP markers (63%) followed the Mendelian segregation and were fairly distributed in all the LGs. Mean performance for all the traits in the F3 population was higher than the parental values, which suggested transgressive segregation for all traits. Low to moderate broad sense heritability (0.35 - 0.50) in the F3 population for GYLD</span><span style="font-family:Verdana;">, PHT and EHT </span><span style="font-family:Verdana;">indicated that tolerance to low P is controlled by complex multi genetic factors. A full multi-QTL model analysis suggested </span><span style="font-family:Verdana;">six QTLs (2 QTLs each for GYLD, PHT and EHT) located on chromosomes 1, 3, 4 and 8. </span><span style="font-family:Verdana;">The two QTLs for GYLD increased maize yield under low P soils by 173 kg/ha while the 2 QTLs for PHT increased plant growth by 18.14 cm. The % phenotypic variance explained by these QTLs under low P environments had a wide range (0.242% - 53.34%) and was much lower for GYLD compared to plant growth. Both additive and dominance gene actions contributed differentially to the observed phenotypic variance for tolerance to low P soils with dominance contributing more genetic effects compared additive effects for majority of the QTLs. The findings of this study will provide some basis for marker-assisted selection for yield improvement and further guide breeding strategies under low P soils of western Kenya.
文摘A field trial was conducted to investigate main morphological and physiological changes of different maize landraces to low-P stress at the stage of seedling. P-deficiency significantly decreased root volume, total leaf area, and plant dry weight, but greatly increased density of root hairs and root top ratio. In addition, P-deficiency induced the significant enhancement of phosphorus utilization efficiency and the amount of proline, malondialdehye (MDA), acid phosphatase (APase), peroxidase (POD) and superoxide dismutase (SOD), but the significant reduction of P uptake and soluable protein content. Since P-deficiency had smaller effects on the P-tolerant maize landraces DP-44, DP-32 and DP-33 as compared with P-sensitive landraces DP-29 and DP-24, it was demonstrated that differences of tolerance to P-deficiency existed among different maize landraces. The results based on the correlation analysis showed that the economic yield of maize landraces had relationships with their morphological and physiological characteristics under P-deficiency.
文摘A number of previous papers have studied the problem of recovering low-rank matrices with noise, further combining the noisy and perturbed cases, we propose a nonconvex Schatten p-norm minimization method to deal with the recovery of fully perturbed low-rank matrices. By utilizing the p-null space property (p-NSP) and the p-restricted isometry property (p-RIP) of the matrix, sufficient conditions to ensure that the stable and accurate reconstruction for low-rank matrix in the case of full perturbation are derived, and two upper bound recovery error estimation ns are given. These estimations are characterized by two vital aspects, one involving the best r-approximation error and the other concerning the overall noise. Specifically, this paper obtains two new error upper bounds based on the fact that p-RIP and p-NSP are able to recover accurately and stably low-rank matrix, and to some extent improve the conditions corresponding to RIP.
基金supported by the National Basic Research and Development Program of China (Grant No. 2005CB120905)the National High Technology Program of China (Grant No. 2006AA10A112)
文摘To understand whether genotypic variation in acid phosphatase (APase) activity in rapeseed (Brassica napus L.) induced by phosphorus (P) deficiency has impact on P efficiency,soil APase activity in the rhizosphere for rapeseed P-efficient genotype 102 and P-inefficient genotype 105 was measured against organic and inorganic P sources in the pot experiment,and the activities of root-secreted APase and leaf intracellular APase were investigated in different P-starvation periods in the nutrient solution.Higher activity of root-secreted APase in B.napus was induced under low P conditions.However,P nutrition and P uptake efficiency of the plants supplied with organic P were not directly related to the activity of root-secreted APase due to several confounding factors affecting APase availability.The higher activity of leaf APase improved P remobilization in plants and played important roles in enhancing P use efficiency,shown by the significant correlation between leaf APase activity and P use efficiency in a rapeseed recombinant inbred population of 135 lines.
基金This work was supported by the National 863 Program of China(2001AA241051).
文摘Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake efficiency was the main contributor to P tolerance, and the relative P content in P-tolerant genotypes, 99180 and 99239 were higher than that in sensitive genotype, 99152. At earing stage, P-tolerant genotypes, compared to P-sensitive ones, had higher accumulation of P in upper leaves. When came to the silking stage, P uptake and redistribution efficiency of P-tolerant genotypes were higher than those in 99152. The results also suggested that there are different mechanisms of P nutrient uptake and distribution in different P-tolerant genotypes. Inbred line 99239, according to the investigation, was considered as an efficient stock in the P-uptake while 99180 fallen to the efficient stock of P redistribution.
文摘The F-rich granites in South China could be distinguished as the high-p subtype andthe low-p subtype according to their P2O5 contents. There are obvious differences in chemicalcomopition of these two subtypes. The high-p subtype is strongly peraluminous and characterized by low silica and very low REE contents, while the low-p subtype is weakly peraluminousand characterized by high silica and very high REE contents. There are also some differences inchemical compositions of feldspars and micas for these two subtypes. The phosphorus of thehigh-p subtype mainly appears to be in the feldspar structure as PAISi-2 substitution or subordinately in amblygonite as an accessory mineral, while the phosphorus of the low-p subtype ismainly in apatite and other phosphate minerals.
基金Foundation of Verification Researches for Army Control Technology (513310101).
文摘Applicability of regional P/S amplitude ratios for the discrimination of low-magnitude seismic events was tested and proved using earthquakes and explosions in Central Asia. Results obtained show that regional P/S amplitude ratios which may discriminate medium or large magnitude events well, are also applicable to low magnitude events Their performances for low magnitude events are almost as good as that for medium or large events. Statistical comparisons based on 25 P/S discriminate from the four seismic stations WMQ, BLK, MUL and MAK showed that the average misclassification rate for low-magnitude seismic events averagely was only 2 percent higher than that for medium and large magnitude seismic events.
基金Sponsored by the Major Science and Technology Program for Water Pollution Control and Treatment (Grant No.2008ZX07207-005-02)
文摘Lower temperature or polyphosphate limitation is the favorable condition to enrich polyphosphate-accumulating organisms (PAOs) or glycogen accumulating organisms (GAOs) in biological phosphorus removal process. In this study,a sludge highly enriched in PAOs was used to investigate the metabolic pathways and carbon transformation in batch tests under the two conditions for elucidating the contradiction. The results showed that the PAOs are able to take up acetate and store it as polyhydroxyalkanoates (PHA) in anaerobic phase although the poly-P pool is emptied through washing with negligible P release. The stoichiometric ratios of the PHB and PHV production and glycogen degradation to the acetate uptake combined with the Nile blue staining indicated that the PAOs possess the anaerobic metabolism of GAOs using glycogen as the sole energy source,but no transformation of PAOs to GAOs is observed. After reconverting to the normal operation,phosphorus uptake and release are recovered the same as the parent reactor.