Determining nitrogen status of young loblolly pine by leaf reflectance

Five-year-old lobloliy pine (Pinus taeda L.) seedlings were grown in sand culture in a completely randomized experimental design with eight nitrogen concentrations and three replications. Nitrogen concentration in the nutrient solution varied from 2 to 400 ppm. After a full growing season under treatment, percent reflectance of sunlight by new foliage was determined. Foliar samples were analyzed for nitrogen and chlorophyll. There was a strong positive correlation between nitrogen content and chlorophyll content (r = 0.895). The natural logarithm of percent reflectance was negatively correlated with both percent nitrogen content (r = -0.845) and chlorophyll content (r = -0.838). From these results, prediction equations for estimating nitrogen and chlorophyll content, as a function of reflectance, were formulated by regression analysis.     

10种玉米胚乳突变基因型淀粉糊化的热力学特性

玉米淀粉粝化过程的热力学特性对于淀粉在食品和非食品工业中的利用具有重要意义，本文以近等基因系为材料，采用差热扫描分析仪（ＤＳＣ）研究了ｏｈ４３和Ｂ３７遗传背景的＋／＋；ａｅ／ａｅ；ｄｕ／ｄｕ；ｓｕ２／ｓｕ２；ｗｘ／ｗｘ；ａｅ／ａｅ；ｄｕ／ｄｕ；ａｅ／ａｅ，ｗｘ／ｗｘ；ｄｕ／ｄｕ，ｓｕ２／ｓｕ２；ｄｕ／ｄｕ，ｗｘ／ｗｘ；和ｓｕ２／ｓｕ２ｗｘ／ｗｘ胚乳突变基因型对淀粉糊化的热力学性状的效应。结果表明，     

Variability and Relationships Among Mixolab,Mixograph, and Baking Parameters Based on Multienvironment Spring Wheat Trials

Because of the large number of cultivars that require examination in the development of spring wheat (Triticum aestivum L.) cultivars, breeding programs use predictive methods to test end use quality. The Mixograph is a widely used predictive test with which end use quality of many genotypes can be assessed in a short time. By comparison, the Mixolab is a relatively new device with additional capability that might be used for the same purpose. Our objective was to document variability of, and relationships among, 20 parameters obtained from Mixolab, Mixograph, and bake tests. Tests were performed on flour from 18 genotypes grown in 20 environments. Both genotype and environment had significant effects on quality parameter values. Several Mixograph and Mixolab parameters were highly significantly correlated, particularly when genotype mean values over environments were considered. Correlations between loaf volume and Mixolab parameters within environments were inconsistent and suggest that average genotype values over environments will be most useful. For example, the correlation between Mixolab stability and loaf volume (r = 0.25, P < 0.001) was much higher when genotype averages (r = 0.70, P < 0.001) were considered. Our results show that selection for Mixolab stability and water absorption should help delineate and improve the selection of genotypes with greater loaf volume.     

A QTL on chromosome 2DS of ‘Sumai 3’ increases susceptibility to <Emphasis Type="Italic">Fusarium</Emphasis> head blight in wheat

Much effort has been invested in identifying molecular markers in wheat (Triticum aestivum L.) linked to quantitative trait loci (QTL) that confer resistance to Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schwein) Petch]. Even after several generations of crossing and selection by many wheat breeding programs, resistance of the Chinese spring wheat cultivar ‘Sumai 3’ (PI 481542) remains among the most effective. It therefore seems that undocumented resistance QTL present in Sumai 3 were not detected in various mapping studies. Using an extremely susceptible Tibetan landrace (‘Y1193-6’; unknown pedigree) in the creation of a mapping population with Sumai 3, the objective of this research was to identify undocumented resistance QTL in Sumai 3. This was accomplished through collecting disease index (DI) and Fusarium damaged kernel (FDK) phenotypic values along with 305 Diversity Array Technology (DArT) and 52 Simple Sequence Repeat (SSR) marker genotypes on 160 F_2:6 recombinant inbred lines (RILs). Disease response evaluations were based on four (two greenhouse and two field) experiments where spray inoculation methods were used. Three QTL were identified on chromosome arms 3BS, 6BL and 2DS explaining 26.1, 10.7 and 18.9% of the phenotypic variation for DI, respectively. The same QTL were also significantly associated with reduced FDK scores and explained 28.0, 11.0 and 23.0% of phenotypic variation. Lines within the mapping population were placed in eight categories with respect to their various QTL combinations. Lines with no QTL were the most susceptible, whereas those with the Sumai 3-derived 3BS and 6BL QTL combined with the 2DS QTL from Y1193-6 were the most resistant. Though the 3BS and 6BL QTL are well-documented, the 2DS resistance QTL, which was contributed by the susceptible parent, confers increased susceptibility when derived from Sumai 3. In this study no new FHB QTL from Sumai 3 was discovered, but results suggest that Sumai 3 contains a QTL for susceptibility on chromosome arm 2DS. Selection against this QTL may potentially increase resistance levels among Sumai 3-derived populations.     

Prediction of Starch Amylose Content Versus Total Grain Amylose Content in Corn by Near-Infrared Transmittance Spectroscopy

A study was conducted to investigate methods of improving a near-infrared transmittance spectroscopy (NITS) amylose calibration that could serve as a rapid, nondestructive alternative to traditional methods for determining amylose content in corn. Calibrations were developed using a set of genotypes possessing endosperm mutations in single- and double-mutant combinations ranging in starch-amylose content (SAC) from -8.5 to 76%, relative to a standard curve. The influence of three factors were examined including comparing calibrations made against SAC versus grain amylose content (GAC), developing calibrations using partial least squares (PLS) analysis versus artificial neural networking (ANN), and using all samples in the calibrations set versus using progressively narrower ranges of SAC or GAC in the calibration set. Grain samples were divided into calibration and validation sets for PLS analysis while samples used in ANN were assigned to a training set, test set, and validation set. Performance statistics of the validation sets that were considered were the coefficient of determination (R), the standard error of prediction (SEP), and the ratio of the standard deviation of amylose values to the SEP (RPD), which were used to compare all NITS models. The study revealed an NITS prediction model for SAC (R = 0.96, SEP = 5.1%, RDP = 3.8) of similar precision to the best GAC model (R = 0.96, SEP = 2.7%, RPD = 3.5). Narrowing the amylose range of the calibration set generally did not improve performance statistics except for PLS models for SAC in which a decrease in SEP values was observed. In one model, the SEP improved while R and RPD remained constant (R = 0.94, SEP = 4.2%, RPD = 2.8) when samples with SAC values <20% were removed from the calibration set. Although the NITS amylose calibrations in this study are of limited precision, they may be useful when a rough screening method is needed for SAC. For example, NITS may be useful to detect severe contamination during transport and storage of specialty grains or to aid breeders when selecting for amylose content from large numbers of grain samples.     

中国蒙药资源可持续利用现状和对策

蒙药是蒙医师用于防治疾病的药物,是蒙医药事业发展的物质基础。蒙医药事业的可持续发展必须保障药材的质量和供应。随着蒙药资源使用量的增加和蕴藏量的减少,蒙药资源的可持续利用显得越来越重要。因此,一定要重视蒙药资源的可持续利用研究。文章着重介绍了蒙药资源可持续利用情况。     

2,3,7,8-Tetrachlorodibenzo-p-dioxin: a potent inducer of -aminolevulinic acid synthetase

2,3,7,8-Tetrachlorodibenzo-p-dioxin, a toxic contaminant frequently formed during the synthesis of the herbicide 2,4,5-trichlorophenoxyacetic acid, was shown to be a potent inducer of hepatic delta-aminolevulinic acid synthetase in the chick embryo. As little as 4.66 x 10(-12) mole of the contaminant per egg produces a significant increase in the activity of the enzyme. Induction of the enzyme is related to the dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin and, in contrast to that produced with other drugs, is prolonged in time, with 70 percent of the maximum induced activity present 5 days after a single dose. This contaminant is implicated as the likely causative agent in an outbreak of porphyria cutanea tarda in workers in a factory where 2,4,5-trichlorophenoxyacetic acid was being synthesized.