Glycine max and Glycine soja are capable of cold acclimation

Soybean has been considered a cold intolerant species; based largely upon seed germination and soil emergent evaluations. This study reports a distinct acquisition of cold tolerance, in seedlings, following short acclimation periods. Diversity in cold responses was assessed in eight cultivars of Glycine max and six accessions of G. soja. All varieties of soybean significantly increased in freezing tolerance following acclimation. This study indicates soybean seedlings are indeed capable of sensing cold and acquiring cold tolerance. Germination rates after cold imbibition were negatively correlated with maturity group, but positively correlated with cold acclimation potential in G. soja. Seed fatty acid composition was varied between the species, with Glycine soja accessions containing about 2‐times more linolenic acid (18:3) than G. max. Furthermore, high levels of linoleic acid (18:2) in seeds were positively correlated with germination rates following cold imbibition in G. soja only. We suggest that domestication has not impacted the overall ability of soybean to cold acclimate at the seedling stage and that there is little variation within the domesticated species for ability to cold acclimate. Thus, this brief comparative study reduces the enthusiasm for the “wild” species as an additional source of genetic diversity for cold tolerance.     

Some Agronomic Strategies for Organic Quinoa (Chenopodium quinoa Willd.)

Quinoa is a potential new seed crop for protein feed and human consumption in Europe, with tolerance to a range of abiotic stresses. For this purpose the study was planned to analyse the effect of important agronomic strategies like nitrogen level, N application strategy, row spacing and harvest time on yield and quality of quinoa. The experiments took place in the field of the experimental station of the Faculty of Science, University of Copenhagen. Three levels of organic nitrogen from slurry was used (60, 120 and 180 kg N ha^?1), supplied either all at once at sowing, or split between sowing and beginning of the reproductive phase. The effect of row spacing and harvest time was studied by harvesting seeds at seed maturity, which occurred 2–3 weeks prior to the mechanical harvest by threshing, and a couple of months after. Yield increased significantly (P ≤ 0.05) with an application up to 180 kg N ha^?1, reaching 2200 kg ha^?1. Increasing N also caused a significantly increased seed weight (up to 3.3 mg) and protein content (up to 17 %). N level did not affect number and amount of weeds. Split application with part of the N applied at bud formation did not have a significant effect on yield. Delayed harvest had a negative influence on seed weight, whereas protein content was stable after harvesting even a month after seed maturity. A late harvest significantly reduced seed germination, being reduced by 50 % after a 2‐month delay. A conclusion from this study is that both yield and protein content of seed can be manipulated by N level and application strategy. Harvest time is important for securing a high seed quality measured as seed germination, seed weight and protein content. A fast germination of quinoa is an important characteristic demonstrating that the crop has good possibilities for being well‐established in the field when free from weeds at the time of sowing. The choice of row spacing is important and depends on weed control method. Weed control strategy should be developed based on modern precision tools.     

Morphological and Physiological Responses of Plantain (Plantago lanceolata) and Chicory (Cichorium intybus) to Water Stress and Defoliation Frequency

Plants are often subjected to periods of water stress. There are little data examining the effect of water stress on the forage species Plantago lanceolata and Cichorium intybus. In two pot experiments with P. lanceolata and C. intybus, morphological responses under optimum, dry, and very‐dry water treatments with weekly, fortnightly and 3‐weekly defoliation intervals and physiological responses under optimum and very‐dry water treatments were measured. A third experiment compared the rooting depths of P. lanceolata and C. intybus under field conditions. These findings suggest that both P. lanceolata and C. intybus can survive and continue to grow under water stress conditions with the main differences between the two species being attributable to morphological characteristics (root mass, taproot diameter and shoot mass fraction) rather than differences at a physiological level. Overall, the results suggest plantain may be more productive under moderate drought due to its greater shoot mass fraction, whereas chicory may be more productive and persistent under severe drought due to its greater root mass, taproot diameter and root depth under field conditions.     

Investigation of Interspecies Interactions within Marine Micromonosporaceae Using an Improved Co-Culture Approach

With respect to bacterial natural products, a significant outcome of the genomic era was that the biosynthetic potential in many microorganisms surpassed the number of compounds isolated under standard laboratory growth conditions, particularly among certain members in the phylum Actinobacteria. Our group, as well as others, investigated interspecies interactions, via co-culture, as a technique to coax bacteria to produce novel natural products. While co-culture provides new opportunities, challenges exist and questions surrounding these methods remain unanswered. In marine bacteria, for example, how prevalent are interspecies interactions and how commonly do interactions result in novel natural products? In an attempt to begin to answer basic questions surrounding co-culture of marine microorganisms, we have tested both antibiotic activity-based and LC/MS-based methods to evaluate Micromonosporaceae secondary metabolite production in co-culture. Overall, our investigation of 65 Micromonosporaceae led to the identification of 12 Micromonosporaceae across three genera that produced unique metabolites in co-culture. Our results suggest that interspecies interactions were prevalent between marine Micromonosporaceae and marine mycolic acid-containing bacteria. Furthermore, our approach highlights a sensitive and rapid method for investigating interspecies interactions in search of novel antibiotics, secondary metabolites, and genes.     

Nitrous oxide emissions from dairy farm effluent applied to a New Zealand pasture soil

A field experiment on permanent ryegrass–white clover pasture at AgResearch's Ruakura dairy farm near Hamilton, New Zealand quantified nitrous oxide (N₂O) emissions from different types of dairy effluent applied to soil at three seasons and evaluated the potential of dicyandiamide (DCD) (a nitrification inhibitor) to decrease gaseous N₂O emissions. Fresh or stored manure and farm dairy effluent (FDE; from dairy shed washings), with or without DCD (10 kg/ha), were applied at approximately 100 kg N/ha to plots on a well‐drained soil on volcanic parent material. A field chamber technique was used to measure N₂O emissions. Application of manure or FDE, both in fresh and stored forms, to pasture generally increased N₂O emissions. Overall N₂O emission factors (EF) varied between 0.01% and 1.87%, depending on application season and effluent type. EFs in spring and autumn were greater than those in summer (P < 0.05). Among the effluents, N₂O EFs were largest from fresh FDE (1.65%) during the spring measurement period, stored manure (1.87%) during the autumn and stored FDE (0.25%) during the summer. DCD was effective in decreasing N₂O EFs from fresh FDE, fresh manure, stored FDE and stored manure by 40–80%, 69–76%, 24–84% and 60–70%, respectively. DCD reduced N₂O emissions during the spring and autumn seasons more effectively than in the summer season.     

Enhancing pedotransfer functions with environmental data for estimating bulk density and effective cation exchange capacity in a data‐sparse situation

Soil bulk density (BD) and effective cation exchange capacity (ECEC) are among the most important soil properties required for crop growth and environmental management. This study aimed to explore the combination of soil and environmental data in developing pedotransfer functions (PTFs) for BD and ECEC. Multiple linear regression (MLR) and random forest model (RFM) were employed in developing PTFs using three different data sets: soil data (PTF‐1), environmental data (PTF‐2) and the combination of soil and environmental data (PTF‐3). In developing the PTFs, three depth increments were also considered: all depth, topsoil (<0.40 m) and subsoil (>0.40 m). Results showed that PTF‐3 (R²; 0.29–0.69) outperformed both PTF‐1 (R²; 0.11–0.18) and PTF‐2 (R²; 0.22–0.59) in BD estimation. However, for ECEC estimation, PTF‐3 (R²; 0.61–0.86) performed comparably as PTF‐1 (R²; 0.58–0.76) with both PTFs out‐performing PTF‐2 (R²; 0.30–0.71). Also, grouping of data into different soil depth increments improves the estimation of BD with PTFs (especially PTF‐2 and PTF‐3) performing better at subsoils than topsoils. Generally, the most important predictors of BD are sand, silt, elevation, rainfall, temperature for estimation at topsoil while EVI, elevation, temperature and clay are the most important BD predictors in the subsoil. Also, clay, sand, pH, rainfall and SOC are the most important predictors of ECEC in the topsoil while pH, sand, clay, temperature and rainfall are the most important predictors of ECEC in the subsoil. Findings are important for overcoming the challenges of building national soil databases for large‐scale modelling in most data‐sparse countries, especially in the sub‐Saharan Africa (SSA).     

Can additional N fertiliser ameliorate the elevated CO2‐induced depression in grain and tissue N concentrations of wheat on a high soil N background?

Elevated CO₂ stimulates crop yields but leads to lower tissue and grain nitrogen concentrations [N], raising concerns about grain quality in cereals. To test whether N fertiliser application above optimum growth requirements can alleviate the decline in tissue [N], wheat was grown in a Free Air CO₂ Enrichment facility in a low‐rainfall cropping system on high soil N. Crops were grown with and without addition of 50–60 kg N/ha in 12 growing environments created by supplemental irrigation and two sowing dates over 3 years. Elevated CO₂ increased yield and biomass (on average by 25%) and decreased biomass [N] (3%–9%) and grain [N] (5%). Nitrogen uptake was greater (20%) in crops grown under elevated CO₂. Additional N supply had no effect on yield and biomass, confirming high soil N. Small increases in [N] with N addition were insufficient to offset declines in grain [N] under elevated CO₂. Instead, N application increased the [N] in straw and decreased N harvest index. The results suggest that conventional addition of N does not mitigate grain [N] depression under elevated CO₂, and lend support to hypotheses that link decreases in crop [N] with biochemical limitations rather than N supply.