The external application of nitrogen (N) fertilizers is an important practice for increasing crop production. However, the excessive use of fertilizers significantly increases production costs and causes environmental problems, making the improvement of crop N-use efficiency (NUE) crucial for sustainable agriculture in the future. Here we show that the rice (Oryza sativa) NUE quantitative trait locus DULL NITROGEN RESPONSE1 (qDNR1), which is involved in auxin homeostasis, reflects the differences in nitrate (NO3−) uptake, N assimilation, and yield enhancement between indica and japonica rice varieties. Rice plants carrying the DNR1indica allele exhibit reduced N-responsive transcription and protein abundance of DNR1. This, in turn, promotes auxin biosynthesis, thereby inducing AUXIN RESPONSE FACTOR-mediated activation of NO3− transporter and N-metabolism genes, resulting in improved NUE and grain yield. We also show that a loss-of-function mutation at the DNR1 locus is associated with increased N uptake and assimilation, resulting in improved rice yield under moderate levels of N fertilizer input. Therefore, modulating the DNR1-mediated auxin response represents a promising strategy for achieving environmentally sustainable improvements in rice yield.

Attempts to use the linear behavior of Raman spectroscopic measurements in operations such as spectral subtraction may be vitiated by abscissa errors which are smaller than one sampling interval. This paper describes methods, based upon least-squares fitting and Fourier-domain phase shifting, which can be used to locate the positions of peak maxima within 0.05 cm−1. A procedure is described to allow use of these determinations to shift the position of data sets along the X-axis by amounts less than one sampling interval. The effectiveness of this detection and correction procedure is demonstrated by measuring adjusted peak positions. Factor analysis is also used as a probe to examine the operation.

Seven samples of linear polyethylene which show quite different levels of crystallinity were prepared and Raman spectra of them were measured. The spectra of these samples show a series of narrow bands superimposed on very broad bands. This pattern is recognized to be the consequence of partial crystallization to give material consisting of lamellar crystallites connected with amorphous material. The narrow peaks are identical to those of crystalline polyethylene. The broad bands are identical to those of a polyethylene melt. Factor analysis of the spectra shows the existence of a third component which has a spectrum quite similar to that of the crystalline region. An estimation of the spectrum of this component is presented. It is based upon combinations of abstract factors and upon subtraction of the contributions by the two prominent components from mixture spectra. The third spectrum, attributed to an interracial region surrounding the crystallites in which partial order exists, closely resembles that of crystalline polyethylene, but with somewhat broader peaks that are shifted in position.

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SUMMARYEvaluation of the results of factor analysis of sets of spectroscopically detected chromatograms is carried out by examining the shapes of the abstract factors. This is done either by visual inspection or by analysis of the power density spectra produced from them. Owing to constraints imposed by the column function and the spectroscopic instrument function, the information content of the chromatograms necessarily occurs at low spatial frequencies. As a consequence, it appears as relatively broad features in the abstract chromatograms and as a peak in the low-frequency region of the corresponding power density plot. On the basis of examination of the power density distribution, a well-defined distinction is made between primary and secondary abstract factors. The major uncertainty encountered in determining the number of chemical components appears to arise from effects of contaminants in reagents.