The Nutrient Status of Some Graminaceous Species in Britain. 2. Deschampsia Flexuosa (L.) Trin

Above-ground biomass of Deschampsia flexuosa from 40 sites throughout Britain was analysed for concentrations of elements (N, P, K, Ca, Mg, Fe, Mn, Cu, Zn and Na), with matching analyses of nutrient levels in the soils, together with pH and LOI. Seasonal variation in the nutrients was also studied in detail at one of the sites. the grass was found on acid sites ranging between pH 3.1 and 4.7. the soil humus content varied widely, and there were significant correlations between that and elements (N, P, K, Ca, Mg, Zn and Na) in the soil. Concentrations of zinc and manganese in the plant material were the only elements that significantly correlated with extractable levels in the soils. Tissue concentrations of nitrogen, phosphorus, and potassium declined throughout the growing season, whereas the other elements showed a tendency to build up until the end of September. Calcium, magnesium and manganese concentrations then declined as growth ceased. the results are compared with above-ground concentrations of minerals in other plants and the growth strategy of this perennial grass.     

Metabolism of n-C10:0 and n-C11:0 fatty acids by Trichoderma koningii,Penicillium janthinellum and their mixed culture: I. Biomass and CO2 production,and allocation of intracellular lipids

The capacity of two soil fungi, Trichoderma koningii and Penicillium janthinellum, to oxidize n-C_10:0 and n-C_11:0 fatty acids to CO₂ and store intracellular lipids during growth is unknown. This article reports for the first time the metabolism of decanoic acid (DA, C_10:0), undecanoic acid (UDA, n-C_11:0), a mixture of the acids (UDA+DA) and a mixture of UDA+ potato dextrose broth (PDB) by T. koningii and P. janthinellum and their mixed culture. A control PDB complex substrate was used as a substrate control treatment. The fungal cultures were assayed for their capacity to: (1) oxidize n-C_10:0 and n-C_11:0 fatty acids to CO₂ and (2) store lipids intracellularly during growth. On all four fatty acid substrates, the mixed T. koningii and P. janthinellum culture produced more biomass and CO₂ than the individual fungal cultures. Per 150 mL culture, the mixed species culture grown on UDA+PDB and on PDB alone produced the most biomass (7,567 mg and 11,425 mg, respectively). When grown in DA, the mixed species culture produced the least amount of biomass (6,400 mg), a quantity that was lower than those obtained in UDA (7,550 mg) or UDA+DA (7,270 mg). Amounts of CO₂ produced ranged from 210 mg under DA to 618 mg under PDB, and these amounts were highly correlated with biomass (r² = 0.99). Fluorescence microscopy of stained lipids in the mixed fungal cell cultures growing during the exponential phase demonstrated larger fungal cells and higher accumulation of lipids in membranes and storage bodies than those observed during the lag and stationary phases. T. koningii and P. janthinellum grown on n-C_10:0 and n-C_11:0 fatty acids produced lower amounts of biomass and CO₂, but stored higher amounts of intracellular lipids, than when grown on PDB alone.     

The Nutrient Status of Some Graminaceous Species in Britain. 1. Molinia Caerulea (L.) Moench

Above-ground biomass biomass of Molinia caerulea from 36 sites throughout Britain was analysed for concentrations of elements (N, P, K, Ca, Mg, Fe, Mn, Cu, Zn and Na), with matching analyses of soil nutrients, together with pH and LOI. Between-year and seasonal variation in the nutrients was also studied at one of the sites. the grass was found on acid sites ranging between pH 3.1 and 5.8. the soil humus content varied widely, and there were significant correlations between that and elements (N, P, K, Ca, Mg and Na) in the soil. Concentrations of calcium, magnesium, zinc and manganese in the plant material were significantly correlated with extractable levels in the soils. Between year variation in the plant nutrient concentrations at one site was of a similar order to variation between the sites. Generally there was less variation in nitrogen, phosphorus and potassium tissue levels than in calcium, magnesium, zinc and copper. Iron and sodium were the most variable. Tissue concentrations of nitrogen, phosphorus, potassium and copper declined throughout the growing season, whereas magnesium, calcium and iron built up until August/September after which a decline set in as the leaves senesced. the results are discussed in relation to the importance of standardizing the time of sampling, in comparison with concentrations of tissue levels in other plants and the growth strategy of this deciduous grass.