University of Hohenheim

About: University of Hohenheim is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Population & Soil water. The organization has 8585 authors who have published 16406 publications receiving 567377 citations.

Ammonium Triggers Lateral Root Branching in Arabidopsis in an AMMONIUM TRANSPORTER1;3-Dependent Manner

Abstract: Root development is strongly affected by the plant’s nutritional status and the external availability of nutrients. Employing split-root systems, we show here that local ammonium supply to Arabidopsis thaliana plants increases lateral root initiation and higher-order lateral root branching, whereas the elongation of lateral roots is stimulated mainly by nitrate. Ammonium-stimulated lateral root number or density decreased after ammonium or Gln supply to a separate root fraction and did not correlate with cumulative uptake of 15N-labeled ammonium, suggesting that lateral root branching was not purely due to a nutritional effect but most likely is a response to a sensing event. Ammonium-induced lateral root branching was almost absent in a quadruple AMMONIUM TRANSPORTER (qko, the amt1;1 amt1;2 amt1;3 amt2;1 mutant) insertion line and significantly lower in the amt1;3-1 mutant than in the wild type. Reconstitution of AMT1;3 expression in the amt1;3-1 or in the qko background restored higher-order lateral root development. By contrast, AMT1;1, which shares similar transport properties with AMT1;3, did not confer significant higher-order lateral root proliferation. These results show that ammonium is complementary to nitrate in shaping lateral root development and that stimulation of lateral root branching by ammonium occurs in an AMT1;3-dependent manner.

Genomic selection using regularized linear regression models: ridge regression, lasso, elastic net and their extensions

Abstract: Background Genomic selection (GS) is emerging as an efficient and cost-effective method for estimating breeding values using molecular markers distributed over the entire genome. In essence, it involves estimating the simultaneous effects of all genes or chromosomal segments and combining the estimates to predict the total genomic breeding value (GEBV). Accurate prediction of GEBVs is a central and recurring challenge in plant and animal breeding. The existence of a bewildering array of approaches for predicting breeding values using markers underscores the importance of identifying approaches able to efficiently and accurately predict breeding values. Here, we comparatively evaluate the predictive performance of six regularized linear regression methods-- ridge regression, ridge regression BLUP, lasso, adaptive lasso, elastic net and adaptive elastic net-- for predicting GEBV using dense SNP markers.

Fertilization and Nitrogen Balance in a Wheat–Maize Rotation System in North China

Abstract: Over N fertilization is a common problem for the winter wheat (Triticum aestivum L.)-summer maize (Zea mays L.) rotation system in the North China Plain. A field experiment which included control (no N), conventional N (Con. N) fertilization, and optimized N (N min ) fertilization treatments, was conducted from 1999 to 2003 near Beijing, China. Soil nitrate (NO 3 ) dynamics were measured and N balance was calculated for the period of the eight successive cropping seasons. Soil NO 3 -N in the 0- to 90-cm profile for the Con. N treatment ranged from 157 to 700 kg ha -1 during the eight successive cropping seasons, much greater than those in the no N and optimized N treatments. Large amounts of soil NO 3 -N were detected in the 90- to 200-cm layer under the conventional N fertilization treatment, especially in the summer maize season. For the N min treatment, the total amount of N applied was 511 kg N ha -1 in the eight successive crops as compared with 2400 kg N ha -1 of the Con. N treatment. Grain yields were not different between the fertilized treatments except for maize in 2003. Soil NO 3 -N in the root zone under conditions of optimized N fertilization was maintained at a relatively low level as compared with the Con. N treatment, therefore dramatically decreasing NO 3 -N movement to deeper soil profile. This study indicates that soil NO 3 movement out of the effective crop root zone is an important pathway of N losses in this winter wheat-summer maize rotation system in the North China Plain and the optimized N fertilization by an improved N min method shows high potential of reducing N-leaching losses.