Characterization of brown planthopper damage on rice crops through hyperspectral remote sensing under field conditions

Field experiments were conducted to characterize the brown planthopper (BPH) (Nilaparvata lugens (Stål.) damage stress on rice crops through hyperspectral remote sensing. The BPH-damaged rice crop had higher reflectance in visible (VIS) and lower reflectance in near-infrared regions (NIR) of the electromagnetic spectrum compared with uninfested plants. Mean reflectance of the rice crop varied among different BPH damage levels in various wavebands, with the greatest variation in NIR (740–925 nm). Correlations between plant reflectance and BPH damage depicted four sensitive wavelengths, at 764, 961, 1201 and 1664 nm in relation to BPH stress on the rice crop. Three new brown planthopper spectral indices (BPHI) were formulated by combining two or more of these sensitive wavelengths. Some of the hyperspectral indices reported in the literature were also tested for their suitability to detect BPH stress on rice crops. Based on crop reflectance corresponding to the sensitive wavelengths, a multiple-linear regression model was developed (R²=0.71, RMSE=1.74, P<0.0001) and validated (R²=0.73, RMSE?=?0.71, P<0.0001) that would help to monitor BPH stress on a rice crop and to issue forewarnings to growers.     

印度的加瓦尔喜马拉雅山丘中部南北坡的传统农林复合系统中生产力状况

2004-2006年间,调查印度的加瓦尔喜马拉雅山丘中部南北坡的传统农林复合系统（作物＋树）中生产力状况。为了分析农林复合系统的植物社会学特性,在南北坡共选育19个树种,其中在南坡有17个树种,在北坡有12个树种。最优树种为Grewia optiva,朴树（Celtis australis）和苦楝（Melia azedarach）。结果表明：南北坡上的树种的年生产量分别为3101kg&#183;ha^-1．a^-1和3775kg&#183;ha^-1．a^-1。在南北坡的所有树种中,Goptiva有最高的生产量,其他种依次为苦楝（M.azedarach）,橡树（Quercus leucotrichophora）和朴树（Caustralis）。优势农作物为龙爪稷（Eleusine coracana,夏季谷物）,菜豆（Phaseolus vulgaris,夏季油料作物）,小麦（Triticum aestivum,冬季作物）。北坡的平均农作物生产量比南坡的高16％。北坡的单一农作物系统中的农作物产量比南坡的高。在南北坡,树种和农作物年生产量都有明显差别。农林复合系统中,树种和农作物的生产量比单一农作物系统中的高24％（北坡）和21％（南坡）。图1表5参33。     

Swietenine: A potential oral hypoglycemic from Swietenia macrophylla seed

Swietenine, a tetranortriterpenoid, was isolated from the Swietenia macrophylla seeds. The in vivo hypoglycemic activity was evaluated against neonatal-streptozotocin induced type 2 diabetic rats. Oral administration of swietenine at 25 and 50 mg/kg body weight per day to diabetic rats was found to possess significant dose dependant hypoglycemic and hypolipidemic activity in type 2 diabetic rats.     

Detection of Sprouted and Midge‐Damaged Wheat Kernels Using Near‐Infrared Hyperspectral Imaging

Sprout damage which results in poor breadmaking quality due to enzymatic activity of α‐amylase is one of the important grading factors of wheat in Canada. Potential of near‐infrared (NIR) hyperspectral imaging was investigated to detect sprouting of wheat kernels. Artificially sprouted, midge‐damaged, and healthy wheat kernels were scanned using NIR hyperspectral imaging system in the range of 1000–1600 nm at 60 evenly distributed wavelengths. Multivariate image analysis (MVI) technique based on principal components analysis (PCA) was applied to reduce the dimensionality of the hyperspectral data. Three wavelengths 1101.7, 1132.2, and 1305.1 nm were identified as significant and used in analysis. Statistical discriminant classifiers (linear, quadratic, and Mahalanobis) were used to classify sprouted, midge‐damaged, and healthy wheat kernels. The discriminant classifiers gave maximum accuracy of 98.3 and 100% for classifying healthy and damaged kernels, respectively.     

Nitrogen transformation and carbon sequestration in wetland paddy field of Bangladesh

Paddy and Water Environment - Rice-based cropping systems in Bangladesh have received little consideration of changing nitrogen (N) and carbon (C) in soil. Therefore, this study was conducted at...     

Genetic diversity of <Emphasis Type="Italic">Danthonia spicata</Emphasis> (L.) Beauv. based on genomic simple sequence repeat markers

Danthonia spicata (L.) Beauv., commonly known as poverty oatgrass, is a perennial bunch-type grass native to North America. D. spicata is often found in low input turfgrass areas on the East Coast of the United States and has potential for development as a new native low input turfgrass species. Roche 454 sequenced randomly sheared genomic DNA reads of D. spicata were mined for SSR markers using the MIcroSAtellite identification tool. A total of 66,553 singlet sequences (approximately 37.5 Mbp) were examined, and 3454 SSR markers were identified. Trinucleotide motifs with greater than six repeats and possessing unique PCR priming sites within the genome, as determined by Primer-BLAST, were evaluated visually for heterozygosity and mutation consistent with stepwise evolution using CLC Genomics software. Sixty-three candidate markers were selected for testing from the trinucleotide SSR marker sites meeting these in silico criteria. Ten primer pairs that amplified polymorphic loci in preliminary experiments were used to screen 91 individual plants composed of at least 3–5 plants from each of 23 different locations. The primer pairs amplified 54 alleles ranging in size from 71 to 246 bp. Minimum and maximum numbers of alleles per locus were two and 12, respectively, with an average of 5.4. A dendrogram generated by unweighted pair group method with arithmetic mean cluster analysis using the Jaccard’s similarity coefficient was in agreement with the grouping obtained by Structure v2.3. The analyses were dominated by clonal groupings and lack evidence for gene flow with some alleles present in a single plant from a single location. Fourteen multilocus genotype groups were observed providing strong evidence for asexual reproduction in the studied D. spicata populations.