Effect of growth stage and variety on spectral radiance in winter wheat     

H. Sembiring  H. L. Lees  W. R. Raun  G. V. Johnson  J. B. Solie  M. L. Stone 《Journal of plant nutrition》2013,36(1):141-149

Before sensor‐based variable rate technology (VRT) can be used to reduce nitrogen (N) fertilizer rates in winter wheat (Triticum aestivum L.) spectral radiance readings must be understood. One prominent issue is the impact of crop growth stage on spectral radiance readings, and the ensuing problem of relating databases gathered at different locations and different stages of growth. In order to evaluate the impact of growth stage on spectral radiance, sensor readings were taken from a winter wheat variety trial and two long‐term N and phosphorus (P) fertility trials. The normalized difference vegetative index was computed using red and near infrared (NIR) spectral radiance measurements [NDVI=(NIR‐red)/(NIR+red)]. TotalNuptake in winter wheat at Feekes growth stages 4, 5, 7, and 8 was highly correlated with NDVI. In the variety trial, non‐significant differences in ND VI readings were noticed between the five common genotypes (by growth stage) grown in this region. However, slopes from linear regression of total N uptake on NDVI were different at different stages of growth, which suggests the need for growth stage specific calibration. Freeze injury (altered tissue color) affected the relationship between total N uptake and NDVI, however, NDVI continued to be a good predictor of in‐season total N uptake in wheat even though cell blasting altered tissue color. This work showed that NDVI is a good predictor of biomass, but not necessarily total N concentration in plant tissue. The amount of variability in total N uptake as explained by NDVI increased with advancing growth stage (Feekes 4 to 7), largely due to an increased percentage of soil covered by vegetation.  相似文献   

Extractable nitrogen using hot potassium chloride as a mineralization potential index     

H. Sembiring  G. V. Johnson  W. R. Raun 《Journal of plant nutrition》2013,36(6):1253-1271

Inorganic nitrogen (N) in soils is a primary component of soil‐plant N buffering. This study was conducted to determine if non‐exchangeable ammonium‐nitrogen (NH₄‐N) could serve as an index of potentially mineralizable organic N which is an important sink in N buffering. Four long‐term winter wheat (Triticum aestivum L.) experiments that had received annual fertilizer N at 0 to 272 kg N ha^‐1 were used. Soils from these experiments were extracted by four 10 mL portions of 2M potassium chloride (KC1) at room temperature followed by extraction with 20 mL of 2M hot KC1. Extraction at 100°C for four hours using 3 g soil and 20 mL 2M KC1 was found to be the most effective. Hot KC1‐extractable NH₄‐N minus room temperature KCl‐extractable NH₄‐N was considered non‐exchangeable NH₄‐N. Non‐exchangeable NH₄‐N was correlated with the long‐term N rates, and believed to be a reliable index of potentially mineralizable organic N. The relationship was linear for NH₄‐N where the lowest N rate had the lowest extractable N. The mean non‐exchangeable NH₄‐N concentration ranged from 8.42 to 16.34 mg kg^‐1; whereas, nitrate‐nitrogen (NO₃‐N) ranged from 0.07 to 1.87 mg kg¹. Total inorganic N extracted was similar to that mineralized in a 42‐day aerobic water saturated incubation. In addition, using a linear‐plateau model, extractable NH₄‐N was highly correlated with long‐term average yield (R²=0.92). For the soils evaluated, this method provided a rapid measure of potentially mineralizable N.  相似文献   

Analysis of genetic diversity and discrimination of Oil Palm DxP populations based on the origins of pisifera elite parents     

Upit Sarimana  Javier Herrero  Pratiwi Erika  Nurcahyono Indarto  Fahmi Wendra  Baitha Santika  Enrique Ritter  Zulhermana Sembiring  Dwi Asmono 《Breeding Science》2021,71(2):134

A total of 251 Dura cross Pisifera (DxP) hybrid palms from six populations descending from six parental African Pisifera origins and involving 12 progenies were analyzed with 19 selected Simple Sequence Repeats (SSR) markers. A total of 110 alleles were produced, ranging from three to eight per SSR, with a mean of 5.8 alleles per SSR locus. Of these, 68.5% were considered shared alleles by more than one population and the remaining 31.5% were population specific alleles. They generated between six and 21 haplotypes in all populations, and depending on the SSR marker, between one and 10 haplotypes within populations. Various parameters for analyzing genetic variability, differentiation and genetic structure were computed using GenAlEx, Structure and Darwin software. The obtained results confirmed microsatellites as a robust, feasible and trustful method for obtaining DNA fingerprints, tracing the source of oil palm samples. With respect to the authenticity of materials or for solving legitimacy issues, accession belonging to each population by SSR markers could be distinguished, but additional SSR should be screened for improving this process.  相似文献   

Detection of nitrogen and phosphorus nutrient status in winter wheat using spectral radiance     

H. Sembiring  W.R. Raun  G.V. Johnson  M. L. Stone  J. B. Solie  S. B. Phillips 《Journal of plant nutrition》2013,36(6):1207-1233

Nitrogen (N) and phosphorus (P) are major limiting nutrient elements for crop production and continued interest lies in improving their use efficiency. Spectral radiance measurements were evaluated to identify optimum wavelengths for dual detection of N and P status in winter wheat (Triticum aestivum L.). A factorial treatment arrangement of N and P (0, 56, 112, and 168 kg N ha^‐1 and 0, 14.5, and 29 kg P ha^‐1) was used to further study N and P uptake and associated spectral properties at Perkins and Tipton, Oklahoma. A wide range of spectral radiance measurements (345–1, 145 nm) were obtained from each plot using a PSD 1000 Ocean Optics fiber optic spectrometer. At each reading date, 78 bands and 44 combination indices were generated to test for correlation with forage biomass and N and P uptake. Additional spectral radiance readings were collected using an integrated sensor which has photodiode detectors and interference filters for red and NIR. For this study, simple numerator/denominator indices were useful in predicting biomass, and N uptake and P uptake. Numerator wavelengths that ranged between 705 and 735 nm and denominator wavelengths between 505 and 545 nm provided reliable prediction of forage biomass, and N and P uptake over locations and Feekes growth stages 4 through 6. Using the photodiode sensor, NDVI [(NIR‐red)/(NIR+red)] and NR [(NIR/red)], were also good indices to predict biomass, and N and P uptake. However, no index was found to be good for detecting solely N and P concentration either using the spectrometer or photodiode sensor.  相似文献   

Detection of nitrogen and phosphorus nutrient status in bermudagrass using spectral radiance     

H. Sembiring  W. R. Raun  G. V. Johnson  M. L. Stone  J. B. Solie  S. B. Phillips 《Journal of plant nutrition》2013,36(6):1189-1206

Nitrogen (N) and phosphorus (P) are two of the most limiting nutrients for crop production. Because of this, continued interest focuses on improving N‐and P‐use efficiency. Spectral radiance measurements were evaluated to identify optimum wavelengths for dual detection of N and P status in bermudagrass (Cynodon dactylon L.). A factorial arrangement of treatments (0, 112, 224, and 336 kg N ha^‐1 and 0,29, and 58 kg P ha^‐1) was applied to an established bermudagrass pasture for further study using a randomized complete block design. A wide range of spectral radiance measurements (276–831 nm) was obtained from each plot using a PSD 1000 Ocean Optics fiber optic spectrometer. The resulting spectra were partitioned into 10‐nm bands. Added indices were generated to test for correlation of N and P content with spectral radiance. The 435‐nm band (430–440 nm) was found to be independent of N and P treatment, and as a covariate, significantly decreased residual error. Using 435 nm as a covariate, it was found that biomass, N uptake, P uptake, and N concentration could be predicted using 695/405. No index reliably predicted bermudagrass forage P concentration. Spectral radiance has the potential to be used for predicting N and P nutrient status, but further work is needed to document response in different environments.  相似文献   

Nitrogen accumulation efficiency: Relationship between excess fertilizer and soil‐plant biological activity in winter wheat     

H. Sembiring  W. R. Raun  G. V. Johnson 《Journal of plant nutrition》2013,36(6):1235-1252

The point at which nitrogen (N) applied approaches 100% recovery in the soil once plant and microbial sinks have been saturated has not been determined in winter wheat (Triticum aestivum L.) production systems. In dryland winter wheat, subsoil accumulation has not been found to occur until N rates exceed that required for maximum yield. Many conventional N rate experiments have not properly evaluated subsoil N accumulation due to the lack of equally spaced N rates at the high end of the spectrum over which accumulation is expected to occur. Therefore, the objectives of this study were to (i) determine when soil profile accumulation efficiencies reach 100% in continuous winter wheat production and (ii) to evaluate the potential for nitrate‐nitrogen (NO₃ ^‐N) leaching in continuous winter wheat when extremely high rates of fertilizer N are used. Two field experiments (T505 and T222) were conducted for two years using ten N rates (preplant‐incorporated) ranging from 0 to 5376 kg N ha¹. No additional preplant fertilizer was applied in the second year. Following the first and second year wheat harvest, soil cores were taken to 2.4 m and bulk density, ammonium‐nitrogen (NH₄‐N) and NO₃‐N were determined. Crop N‐use efficiency (NUE) (N uptake treated ‐ N uptake check/rate applied) and soil profile inorganic N accumulation efficiencies (NAE) [net inorganic N accumulation in the soil profile/(fertilizer applied ‐ net N removed in the crop)] changed with fertilizer rate and were inversely related. Priming (increased net mineralization of organic N pools when low rates of fertilizer N are applied) may have occurred since increased NUE was observed at low N rates. The highest N‐accumulation efficiencies were at N rates of 168 and 448 kg ha^‐1 in experiments T505 and T222, respectively. At both T222 and T505, no subsoil accumulation of NH₄‐N or NO₃‐N beyond 100 cm was observed for any of the N treatments when compared to the 0‐N check, even when N rates exceeded 448 kg ha^‐1.  相似文献