Nitrogen status and biomass determination of oilseed rape by laser-induced chlorophyll fluorescence

Site-uniform nitrogen fertilization can lead to local over- or under-supply of nitrogen on heterogeneous sites. Suitable sensor solutions are needed to perform on-the-fly measurements of the local N-requirement. Sensor systems already in use to this end in agricultural practice are based on light reflectance measurements.By contrast, a measurement principle based on laser-induced two-wavelength chlorophyll fluorescence (LICF) presents some major advantages given that the measurement signals originate only from plant material. The LICF measurement principle measures the chlorophyll fluorescence induced by red laser light at 630 nm at wavelengths of 690 nm and 730 nm. The ratio of the two wavelengths correlates strongly with aboveground N content, with statistical analysis of measurement data providing biomass information. Thus, both N content and biomass can be determined simultaneously using this technology.This work tested the accuracy of this measurement principle in determining N content and biomass of oilseed rape in field trials. LICF measurements were compared to reflectance-based measurements, both of which were referenced against conventionally determined values for N content and biomass dry weight.Our results show that the N status and aerial biomass dry weight determination by LICF measurements are possible with the same accuracy as with the conventional determination. Furthermore, it could be shown that the LICF measurement allows for the determination of biomass independent of the N content. The good performance of LICF-based protocols in determining local N content and biomass supports their potential utility in site-specific fertilizer application.     

Hereditary phosphofructokinase deficiency in wachtelhunds

Hereditary phosphofructokinase (PFK) deficiency was diagnosed in two Wachtelhund dogs and suspected in three related Wachtelhund dogs with exercise intolerance, hemolytic anemia, and pigmenturia. Severe, persistent reticulocytosis in light of only mild anemia together with hemoglobinuria after strenuous exercise suggested PFK deficiency. Low erythrocyte PFK activity together with low 2,3-diphosphoglycerate concentrations and a high hemoglobin-oxygen affinity confirmed the diagnosis. The PFK deficiency is due to a single missense mutation in the muscle-type PFK M-PFK gene in English springer and American cocker spaniels, whippets, and mixed-breed dogs; however, these PFK-deficient Wachtelhunds do not have the same PFK mutation.     

Adaptation of ecotypes and cultivars of subterranean clover (<Emphasis Type="Italic">Trifolium subterraneum</Emphasis> L.) to German environmental conditions and its suitability as living mulch

Abstract A total of 320 accessions of subterranean clover (Trifolium subterranenum L.) were screened for adaptation to the environmental conditions in southern Germany, as well as their suitability as cover crops or living mulches. The accessions, derived from collections of the Department of Agriculture and Food Western Australia and the International Research Center for Agriculture in Dry Areas, were propagated in the greenhouse and grown in rows. Selected accessions were then tested in plots and as an intercrop in wheat, in order to test their suitability as living mulch. Moreover, a frost resistance screening was carried out in a climate chamber. Adaptation to southern German conditions and frost tolerance was generally better than expected, as most accessions survived winters with snow cover and transitory temperatures as low as \(-\,10\,^\circ \)C. Accessions with particularly high frost tolerance were identified and several accessions persisted over four generations of self-reseeding. Although there was a large range of morphological characteristics, no differences concerning their suitability as living mulch could be observed. The results suggest that subterranean clover is sufficiently winter hardy to be grown as an overwintering cover crop or living mulch in southern Germany. Commercially available cultivars appear suitable in the first instance, even though these have not been selected for cold winters. However, adaptation might be further improved by targeted selection among accessions.     

Relation between respiratory activity and sperm parameters in boar spermatozoa cryopreserved with alpha‐tocopherol and selected by Sephadex

Our aim was to evaluate the effect of Sephadex filtration on respiratory activity of porcine spermatozoa and its relation with quality and functional sperm parameters. Samples were evaluated regarding oxygen uptake and sperm parameters: motility, plasma and acrosome membrane integrity, capacitation and acrosome reaction induction in vitro, plasma membrane functionality, determined by the hypo‐osmotic swelling test (HOST), and lipid peroxidation assessed by thiobarbituric acid assay. Sephadex filtration improved all routine quality parameters (motility, plasma and acrosome membrane integrity) and functional parameters (HOST, in vitro capacitation and true acrosome reaction levels) and produced a significant decrease in cryocapacitation and lipid peroxidation. Oxygen uptake increased in Sephadex samples (41 ± 7%) respect to single washing. Oxygen addition of carbonyl‐cyanide‐m‐chlorophenylhydrazone (CCCP) confirmed mitochondrial coupling in washed and Sephadex samples; showing an increase of 2.6 and 4.2 times for oxygen consumption in single washing and Sephadex ones, respectively. The increase in oxygen uptake with succinate addition with respect to basal oxygen uptake was significantly lower in Sephadex samples (63 ± 25%) than in the washed ones (183 ± 35%). Sephadex samples showed higher mitochondrial activity measured by oxygen consumption and improved quality and functional parameters. Our study recommends this protocol due to the fact that this filtration method removes dead or damaged spermatozoa allowing to obtain cryopreserved boar spermatozoa with optimized fertilizing capacity.