Depth dynamics of soil N contents and natural abundances of 15N after 43 years of long-term fertilization and liming in sub-tropical Alfisol     

Avijit Ghosh  Brahma Swaroop Dwivedi  Dipak Ranjan Biswas  Mahesh Chandra Meena  Abhijit Sarkar 《Archives of Agronomy and Soil Science》2018,64(9):1290-1301

The aim of this study was to understand impacts of long-term (43 years) fertilization on soil aggregation, N accumulation rates and δ¹⁵N in surface and deep layers in an Alfisol. Soil samples from seven treatments were analysed for N stocks, aggregate-associated N in 0–30 cm and the changes in δ¹⁵N in 0–90 cm depths. The treatments were: unfertilized control (control); recommended N dose (N); recommended N and phosphorus doses (NP); recommended N, P and potassium doses (NPK); 150% of recommended N, P and K doses (150% NPK); NPK + 10 Mg FYM ha^?1 (NPK + FYM) and NPK + 0.4 Mg lime ha^?1 (NPK + L). Results revealed that plots under NPK + FYM had ~39% higher total N concentrations than NPK + L in 0–30 cm soil layers. In NPK + L, macro-aggregates had 35 and 11% and microaggregates had 20 and 9% lower δ¹⁵N values than NPK + FYM in 0–15 and 15–30 cm soil layers, respectively. However, plots receiving NPK + FYM had ~39% greater deep soil (30–90 cm) N accumulation than NPK + L. These results would help understanding N supplying capacity by long-term fertilization and assist devising N management strategies in sub-tropical acidic Alfisols.  相似文献   

Genetic relationships of boxwood (<Emphasis Type="Italic">Buxus</Emphasis> L.) accessions based on genic simple sequence repeat markers     

Chandra S. Thammina  Richard T. Olsen  Matthew Kramer  Margaret R. Pooler 《Genetic Resources and Crop Evolution》2017,64(6):1281-1293

Boxwoods (Buxus L., Buxaceae) are popular woody landscape shrubs grown for their diverse forms and broad-leaved evergreen foliage. We used genic simple sequence repeat (genic-SSR) markers to assess genetic diversity and relatedness of 275 accessions from the National Boxwood Collection at the U.S. National Arboretum. Flow cytometry was conducted to determine the relative ploidy of each accession. Genic-SSR loci were highly variable among the accessions, detecting an average of 6.7 alleles per locus based on 17 primer pairs. Data were analyzed with a distance matrix based on Jaccard’s similarity index, followed by Unweighted Pair Group Method with Arithmetic Mean clustering. Two major clusters were identified, with four subclusters consisting of individual accessions from B. balearica Lam., B. bodinieri Lévl., B. harlandii Hance, B. microphylla Siebold et Zuccarini, B. sempervirens L., B. sinica (Rehd. et Wils.) M. Cheng, and their putative interspecific hybrids. The accessions generally clustered by cultivar, provenance, or species. Clustering within each group typically reflected breeding pedigrees, when known, and the clusters were supported by bootstrap results. This information will be used for breeding programs and collection management, and for identifying possible sources of disease tolerance for boxwood blight and other diseases and pests.  相似文献