Compositional analysis of phosphorus pools in Canadian Mollisols

During cultivation, the internal phosphorus cycle of Mollisols (Chernozems) of the Canadian Prairies is perturbed by crop sequences including wheat phases, tillage practices, and regular applications of fertilizers. To monitor these changes, a proximate sequential phosphorus (P) fractionation procedure was developed by Hedley et al. (1982) to extract inorganic and organic P fractions as very labile (resin-P), labile (NaHCO3-P), slowly available (NaOH-P), and very slowly available (HCl-P) pools. Models used so far to monitor P pools do not address the interactive behaviour of P fractions constrained to a closed compositional space. Compositional data analysis using isometric log ratio (ilr) coordinates is appropriate for modelling the interactive P pools using sequential binary partitions of P pools. Our objective was to model changes of P pools in Mollisols in response to management and time using ilr coordinates. We used a dataset with treatments and another where a Mollisol was analyzed at time zero and 4, 65, and 90 yr after sod breakup. Seven P fractions were assigned to P reactivity groups to compute six ilr coordinates. The ilr2 contrasting inorganic (geochemical) and organic (biological) P pools and ilr4 between the most readily available and less P bioavailable pools were the most sensitive to crop sequence and fertilization. Using composition at time zero as reference, the Aitchison distance reached a plateau after the 4th year in the Bm horizon compared to continuous change in the Ah horizon. Time changed the P balance of cultivated Mollisols primarily in the inorganic vs. organic P pools. The risks of yield loss and environmental damage can be minimized using soil tests that quantify the rapidly bioavailable inorganic P pools and crop management strategies that promote biological P pools

Élaboration de normes DRIS provisoires pour des transplants de céleri

Nous avons utilisé une banque de données contenant 215 observations pour obtenir des normes DRIS (Diagnosis and Recommandation Integrated System) provisoires pour des transplants de céleri (Apium graveolens var. Dulce). La détermination des normes s'est faite en considérant un groupe de tête au rendement supérieur ou égal à 1600 g/plant (27 % de la population). Sur 45 rapports nutritionnels mesurés dans la partie aérienne des transplants, 26 ont présenté des rapports de variance permettant de distinguer significativement le groupe produisant des rendements supérieurs. Le coefficient de corrélation entre l'indice de déséquilibre nutritionnel (IDN) et les rendements s'est révélé très significatif. Les normes provisoires ont été confrontées à un ensemble indépendant de données obtenues chez des producteurs de la région du sud de Montréal (Québec). Les IDN calculés sur ces plantes échantillonnées au stade implantation (environ 27 jours après la plantation) ont été significativement corrélés aux rendements, malgré le fait que le tissu échantillonné et le stade de croissance aient été relativement éloignés de ceux correspondant aux normes. Les normes ont permis d'identifier la cause probable d'un problème de croissance induit par l'utilisation d'une solution fertilisante ne convenant pas à la production de transplants.A data bank of 215 observations was used to elaborate preliminary DRIS norms for celery (Apium graveolens var.Dulce) transplants. The threshold yield for high yielders was set at 1600 g/plant (27% of the population). Of the 45 nutrient ratios obtained, 26 presented significant variance ratios between low and high yielders. The correlation coefficient between nutrient imbalance index (Nil) and yield was highly significant. The norms were tested on an independent set of data obtained from celery growers located south of Montreal (Quebec). The Nil obtained from plants at the implantation stage (about 27 days after transplanting) was significantly correlated to yield even if the sampled tissue was different from that used for norm calculations. The norms were also used to identify the likely cause of a growth problem induced by a nutrient solution not suited for transplant production

African-specific improvement of a polygenic hazard score for age at diagnosis of prostate cancer

Polygenic hazard score (PHS) models are associated with age at diagnosis of prostate cancer. Our model developed in Europeans (PHS46) showed reduced performance in men with African genetic ancestry. We used a cross-validated search to identify single nucleotide polymorphisms (SNPs) that might improve performance in this population. Anonymized genotypic data were obtained from the PRACTICAL consortium for 6253 men with African genetic ancestry. Ten iterations of a 10-fold cross-validation search were conducted to select SNPs that would be included in the final PHS46+African model. The coefficients of PHS46+African were estimated in a Cox proportional hazards framework using age at diagnosis as the dependent variable and PHS46, and selected SNPs as predictors. The performance of PHS46 and PHS46+African was compared using the same cross-validated approach. Three SNPs (rs76229939, rs74421890 and rs5013678) were selected for inclusion in PHS46+African. All three SNPs are located on chromosome 8q24. PHS46+African showed substantial improvements in all performance metrics measured, including a 75% increase in the relative hazard of those in the upper 20% compared to the bottom 20% (2.47-4.34) and a 20% reduction in the relative hazard of those in the bottom 20% compared to the middle 40% (0.65-0.53). In conclusion, we identified three SNPs that substantially improved the association of PHS46 with age at diagnosis of prostate cancer in men with African genetic ancestry to levels comparable to Europeans

Evidence of Novel Susceptibility Variants for Prostate Cancer and a Multiancestry Polygenic Risk Score Associated with Aggressive Disease in Men of African Ancestry

Background: Genetic factors play an important role in prostate cancer (PCa) susceptibility. Objective: To discover common genetic variants contributing to the risk of PCa in men of African ancestry. Design, setting, and participants: We conducted a meta-analysis of ten genome-wide association studies consisting of 19 378 cases and 61 620 controls of African ancestry. Outcome measurements and statistical analysis: Common genotyped and imputed variants were tested for their association with PCa risk. Novel susceptibility loci were identified and incorporated into a multiancestry polygenic risk score (PRS). The PRS was evaluated for associations with PCa risk and disease aggressiveness. Results and limitations: Nine novel susceptibility loci for PCa were identified, of which seven were only found or substantially more common in men of African ancestry, including an African-specific stop-gain variant in the prostate-specific gene anoctamin 7 (ANO7). A multiancestry PRS of 278 risk variants conferred strong associations with PCa risk in African ancestry studies (odds ratios [ORs] >3 and >5 for men in the top PRS decile and percentile, respectively). More importantly, compared with men in the 40–60% PRS category, men in the top PRS decile had a significantly higher risk of aggressive PCa (OR = 1.23, 95% confidence interval = 1.10–1.38, p = 4.4 × 10–4). Conclusions: This study demonstrates the importance of large-scale genetic studies in men of African ancestry for a better understanding of PCa susceptibility in this high-risk population and suggests a potential clinical utility of PRS in differentiating between the risks of developing aggressive and nonaggressive disease in men of African ancestry. Patient summary: In this large genetic study in men of African ancestry, we discovered nine novel prostate cancer (PCa) risk variants. We also showed that a multiancestry polygenic risk score was effective in stratifying PCa risk, and was able to differentiate risk of aggressive and nonaggressive disease

Unbiased approach to diagnose the nutrient status of red guava (Psidium guajava)

Fertilization of guava relies on soil and tissue testing. The interpretation of tissue test is currently conducted by comparing nutrient concentrations or dual ratios with critical values or ranges. The critical value approach is affected by nutrient interactions. Nutrient interactions can be described by dual ratios where two nutrients are compressed into a single expression or a ternary diagrams where one redundant proportion can be computed by difference between 100% and the sum of the other two. There are D(D-1) possible dual ratios in a D-parts composition and most of them are thus redundant. Nutrients are components of a mixture that convey relative, not absolute information on the composition. There are D-1 balances between components or ingredients in any mixture. Compositional data are intrinsically redundant, scale dependent and non-normally distributed. Based on the principles of equilibrium and orthogonality, the nutrient balance concept projects D-1 isometric log ratio (ilr) coordinates into the Euclidean space. The D-1 balances between groups of nutrients are ordered to reflect knowledge in plant physiology, soil fertility and crop management. Our objective was to evaluate the ilr approach using nutrient data from a guava orchard survey and fertilizer trials across the state of São Paulo, Brazil. Cationic balances varied widely between orchards. We found that the Redfield N/P ratio of 13 was critical for high guava yield. We present guava yield maps in ternary diagrams. Although the ratio between nutrients changing in the same direction with time is often assumed to be stationary, most guava nutrient balances and dual ratios were found to be non-stationary. The ilr model provided an unbiased nutrient diagnosis of guava. © ISHS

Guava waste to sustain guava(Psidium guajava) agroecosystem: nutrient "Balance" concepts.

201