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Abstract: Winter triticale, an abundant biomass source for producing biogas in Central Europe, has been bred until now for increased grain yield but not for early biomass yield. Therefore, our objectives were to assess the feasibility of breeding triticale for simultaneous improvement of early biomass and grain yield as well as to predict the early biomass yield using an index of traits measured at maturity stage. A representative sample of 100 triticale lines was evaluated in Experiment I at four locations in Germany. Traits were measured at two growth stages (early dough and full maturity). Genetic variances were significantly different from zero for all traits. The correlated response for early biomass yield estimated from grain yield (0.53) was high, which points to the efficiency of indirect selection. A multiple regression model was developed to predict early biomass yield. The reliability of the model was confirmed in an independent Experiment II with 49 lines. The calibration model explained 55% of total variation for early biomass yield. This clearly underlines that at least during earlier stages of selection, field testing can be carried out for grain yield and related traits to select potential genotypes with high biomass yield based on the developed regression model. [Copyright &y& Elsevier]

Abstract: This study examined the effect of tree species identity and diversity on soil respiration in a 3-year-old tropical tree biodiversity plantation in Central Panamá. We hypothesized that tree pairs in mixed-species plots would have higher soil respiration rates than those in monoculture plots as a result of increased primary productivity and complementarity leading to greater root and microbial biomass and soil respiration. In addition to soil respiration, we measured potential controls including root, tree, and microbial biomass, soil moisture, surface temperature, bulk density. Over the course of the wet season, soil respiration decreased from the June highs (7.2±3.5μmolCO2/(m2 s−1) to a low of 2.3±1.9μmolCO2/(m2 s−1) in the last 2 weeks of October. The lowest rates of soil respiration were at the peak of the dry season (1.0±0.7μmolCO2/(m2 s−1)). Contrary to our hypothesis, soil respiration was 19–31% higher in monoculture than in pairs and plots with higher diversity in the dry and rainy seasons. Although tree biomass was significantly higher in pairs and plots with higher diversity, there were no significant differences in either root or microbial biomass between monoculture and two-species pairs. Path analyses allow the comparison of different pathways relating soil respiration to either biotic or abiotic controls factors. The path linking crown volume to soil temperature then respiration has the highest correlation, with a value of 0.560, suggesting that canopy controls on soil climate may drive soil respiration. [Copyright &y& Elsevier]