Investigations on sprout growth in cv. Maris Piper: tuber wounding effects and growth from tuber cores of different dimensions

Summary Sprout dry weight accumulation was stimulated by an increase in the amount of tuber substrate available. Wounding had an additional promotory effect on both dry weight accumulation and extension growth. Sprout dry weight accumulation from tuber cores of the same fresh weight was enhanced by an increase in the diameter of the core when samples were planted either in perlite or UC compost. In compost, elongation rates of both main and branch sprouts were inversely related to core fresh weight but positively related to core diameter when fresh weight was kept constant. The number of branch sprouts per eye was positively related to core fresh weight.

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Zusammenfassung Der Verlauf des Keimwachstums wurde mit Knollen, die in verschiedenen Abst?nden vom keimenden Auge verletzt waren. untersucht. Die Inkubation erfolgte bei 12°C im Dunkeln in feuchtem ‘University of California’ Kompost. Obwohl die Steigerung des Keimtrockengewichtes mit der Zunahme an verfügbarem Knollensubstrat erh?ht wurde, hatte die Verletzung noch einen zus?tzlichen steigernden Einfluss, sowohl auf das Keimtrockengewicht als auch auf das L?ngenwachstum, das noch st?rker gef?rdert wurde (Abb. 1). Wahrscheinlich sind sowohl das Ausmass der Verletzung als auch der Abstand der Verletzung vom Keim wichtig in bezug auf den Wachstumseinfluss. Der Einfluss der Gr?sse der Knollenstücke auf das Keimwachstum wurde ebenfalls untersucht. Zus?tzlich zu der positiven Wirkung des steigenden Knollenstückgewichtes auf die Erh?hung des Keimtrockengewichtes zeigte sich noch ein weiterer Einfluss durch eine Vergr?sserung des Knollenstückdurchmessers (Abb. 2). Wurden die Knollenstücke in Kompost gepflanzt, zeigte sich in bezug auf das L?ngenwachstum sowohl der Haupt-als auch der Seitentriebe ein umgekehrtes Verh?ltnis zum Frischgewicht der Knollenstücke, aber ein positives zum Durchmesser der Knollenstücke bei konstantem Frischgewicht (Abb. 3). Die Zahl der Seitentriebe pro Auge war mit dem Frischgewicht der Knollenstücke positiv korreliert.

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Résumé La cinétique de la croissance du germe a été étudiée à l'aide de tubercules blessés à différentes distances des yeux, en maintenant des explantats à 12°C et à l'obscurité, dans un compost humide mis au point à l'Université de Californie. Bien que l'accumulation de matière sèche dans le germe ait été stimulée par l'augmentation du substrat assimilable provenant des gros explantats, la blessure a provoqué un effet cumulatif sur la teneur en matière sèche du germe et, de fa?on plus conséquente, sur son élongation (fig. 1). Il semble que l'importance de la blessure ainsi que sa distance par rapport à l'oeil jouent un r?le déterminant sur le dégré de réponse du germe. Des expériences ont également été réalisées sur des fragments de tubercules pour déterminer l'effet de la dimension de l'explantat sur la croissance du germe. En plus de l'effet positif sur la teneur en matière sèche, d? à l'augmentation du poids de l'explantat, on a observé un effet favorable lorsque le diamètre de ce dernier était plus élevé (fig. 2). Après plantation dans le compost, le taux d'élongation du germe principal et des germes ramifiés tendait à être inversé par rapport au poids frais de l'expplantat mais restait positif par rapport à son diamètre, à poids frais égal (fig. 3). Le nombre de ramifications par oeil était en relation directe avec le poinds frais de l'explantat.

     

Belleisle1: A new maincrop variety with excellent table quality and bruise resistance

Belleisle is a maincrop variety with good yield, exceptional table and handling quality. It has some resistance to common scab, late blight andFusarium sambucinum.     

The dynamic matrix predicts population response to long-term experimental forest fragmentation

Landscape Ecology - Earth's forests are fragmented. Species' long-term persistence depends on their conservation in fragmented landscapes with remnants embedded in a matrix of human land...     

Advances in Functional Genomics and Genetic Modification of Potato

The challenges facing potato breeding have actually changed very little over the years with resistance to pests and pathogens remaining high on the agenda together with improvements in storability, reduction in blemishes, and novelty and consistency in cooking/processing qualities. The need to expand the range of targets for potato improvement is being driven by requirements for reduced agrochemical usage and by predictions of the effects of changing climates. Thus fertiliser and water use efficiency are moving up the political agenda. Genetic variation present in germplasm collections needs to be harnessed to provide the genes and alleles required. This paper provides examples of the functional genomics tools and approaches being developed and deployed to provide new options for advancing the breeding of next generation crops. Whilst genetic modification (GM) approaches remain contentious in Europe, this paper will also provide some recent examples of the range of potential impacts that GM approaches could make. It will also consider the value of so-called intragenic or cisgenic approaches to potato genetic engineering.     

Establishment and production of common sainfoin (Onobrychis viciifolia Scop.) in the UK. 2. Effects of direct sowing and undersowing in spring barley on sainfoin and sainfoin-grass mixtures

The dry matter (DM) yield and herbage quality of swards of sainfoin ( Onobrychis viciifolia ), meadow fescue ( Festuca pratensis ,) and tetraploid perennial ryegrass ( Lolium perenne ) grown in monocultures and in four sainfoin:grass mixtures (0·33 sainfoin:0·66 meadow fescue, 0·66 sainfoin:0·33 meadow fescue, 0·33 sainfoin:0·66 perennial ryegrass and 0·66 sainfoin:0·33 perennial ryegrass), established by direct sowing or undersowing in spring barley, were investigated over 3 years in a field experiment in the UK. Direct sowing produced a mean yield across all species and mixtures of 1·8 t DM ha⁻¹ in the establishment year, whereas undersowing produced no measurable yield except for that of the spring barley. Undersowing reduced the yields of sainfoin and sainfoin-grass mixtures in the first full-harvest year but not in the second. The annual yield of a monoculture of sainfoin was 7·53 t DM ha⁻¹ and that of sainfoin-grass mixtures was 8·33 t DM ha⁻¹ averaged over 3 years. Both sainfoin and the sainfoin-grass mixtures had higher annual DM yields than the grass monocultures. The mixture of 0·66 sainfoin:0·33 meadow fescue gave the highest mean annual yield (9·07 t DM ha⁻¹) over the 3 years. There was a higher proportion of sainfoin maintained in mixtures with perennial ryegrass than with meadow fescue. The proportion of sainfoin in sainfoin–meadow fescue mixtures declined from 0·62 in the first year to 0·32 in the third year, whereas the proportion in sainfoin–perennial ryegrass increased from 0·48 in the first year to 0·67 in the second year and remained stable in the third year.     

The contribution of structural indices to the modelling of Sitka spruce (Picea sitchensis) and birch (Betula spp.) crowns

Crown dimensions are important for the quantification of tree interactions in some growth models. This study investigates the potential for structural indices and other spatial measures to improve the prediction of crown radius and crown length for birch (Betula spp.) and Sitka spruce (Picea sitchensis (Bong.) Carr.) in forests in Wales. Crown dimensions were measured for 125 birch and 154 spruce in six fully stem-mapped research plots. These data were used to test the performance of a crown radius model and a crown length model which estimated crown dimensions on the basis of allometric relationships with stem dimensions. Spatial data from the six plots were used to calculate the structural indices mean directional index, diameter correlation index, species mingling, dbh and height dominance, and dbh differentiation, as well as the Hegyi competition index, and basal area of neighbours and larger neighbours, for each crown measurement sample tree, using various numbers of nearest neighbours. Two non-spatial indices, BAL and BALMOD, were also calculated for all sample trees for comparison. These spatial and non-spatial variables were then incorporated into modified crown dimension models. Model performances, in terms of efficiency and relative bias, were compared to determine whether the inclusion of spatial or non-spatial variables resulted in any improvements over models using tree dimensions alone. Crown length and radius were found to be correlated with most of the spatial measures studied. Models incorporating spatial variables gave improvements in performance over allometric models for every data set, and performed more consistently than models containing non-spatial variables. The greatest improvements were achieved for suppressed birch in unthinned forests which had irregularly shaped and strongly displaced crowns. The spatial variable contributing to the most efficient model for each data set varied widely. This points to the complexity of tree spatial interactions and indicates that there is a great deal of scope for investigating other structural indices and crown dimension model forms.     

Efficacy of various concentrations of synthetic hormones on the induced breeding of Channa marulius (Sole)

A study was conducted to determine the artificial breeding response, embryonic and larval development of giant snakehead, Channa marulius, with the application of various dosages of stimulatory hormones: Suprefact® (LHRH) agonist and Ovaprim® (GnRH + dopamine inhibitor). First and second hormonal dosages of Suprefact® (diluted) and Ovaprim® (0.3, 0.4, and 0.5 ml for male and 0.8, 0.9, and 1.0 ml for females per kilogram body weight) were used. There were three treatments T₁, T₂, and T₃ and each treatment had three replicates. Male fish were treated with T₁ (0.3), T₂ (0.4), T₃ (0.5) ml kg⁻¹ of body weight while female fish with T₁ (0.8), T₂ (0.9), T₃ (1.0) ml kg⁻¹ of body weight. The results showed that fish stimulated with T₃ (1.0) obtained better fecundity rate (2951.7) followed by T₂ (0.4) (2678.3), while the lowest fecundity (466.7) was recorded in T₁. The numerically higher values of gonado-somatic index (males and females) and fertilization rate appeared in T₂. The highest survival rate (97.1%) was found in T₃ followed by T₂ (97.0%), while the lowest (32.2%) in T₁. In conclusion, the application of Suprefact® and Ovaprim® at 0.4 and 0.5 ml kg⁻¹ body weight for male and 0.9 and 1.0 ml kg⁻¹ for female fish successfully stimulated snakehead fish induced breeding.     

Soybean meal alters autochthonous microbial populations, microvilli morphology and compromises intestinal enterocyte integrity of rainbow trout, Oncorhynchus mykiss (Walbaum)

Rainbow trout were fed either a diet containing fishmeal (FM) as the crude protein source or a diet containing 50% replacement with soybean meal (SBM) for 16 weeks. An enteritis-like effect was observed in the SBM group; villi, enterocytes and microvilli were noticeably damaged compared with the FM group. The posterior intestine microvilli of SBM-fed fish were significantly shorter and the anterior intestine microvilli significantly less dense than the FM-fed fish. Electron microscopy confirmed the presence of autochthonous bacterial populations associated with microvilli of both fish groups. Reduced density of microvilli consequently led to increased exposure of enterocyte tight junctions, which combined with necrotic enterocytes is likely to diminish the protective barrier of the intestinal epithelium. No significant differences in total viable counts of culturable microbial populations were found between the groups in any of the intestinal regions. A total of 1500 isolates were tentatively placed into groups or genera, according to standard methods. Subsequent partial 16S rRNA sequencing revealed species that have not been identified from the rainbow trout intestine previously. Compared with the FM group levels of Psychrobacter spp. and yeast were considerably higher in the SBM group; a reduction of Aeromonas spp. was also observed.     

MRI has limited agreement with CT in the evaluation of vertebral fractures of the canine trauma patient

Complete assessment of vertebral trauma in dogs currently requires CT and MRI for evaluation of the osseous and soft tissue structures that contribute to vertebral stability. Some studies in people have suggested that MRI may be sensitive and specific at detecting vertebral fractures making this potentially a single modality that could be used in spinal trauma evaluation. This study aimed to assess the ability for observers to evaluate vertebral fractures using MRI when compared to CT, which was used as the reference standard. Twenty‐nine dogs with previously diagnosed acute vertebral fractures and four dogs with no vertebral fracture that had undergone sequential CT and MRI were included into the study. One hundred twenty‐eight vertebrae were evaluated for the presence of fractures. Imaging studies were read by two observers blinded to the history. While both observers had similarly high sensitivity and specificity for simple detection of any fractured vertebrae, interobserver agreement was only moderate (κ = 0.584). When evaluations were specifically limited to detection of structurally unstable fractured vertebrae both observers showed improved specificity and interobserver agreement became substantial (κ = 0.650). Complete agreement for exact fracture location between MRI and CT results was only achieved in 14.3‐32.6% of fractured vertebra with up to 79% of fractures being missed in some vertebral structures. This suggests that although MRI may be able to detect the presence of fractured vertebrae, it is not able to replace CT for the complete evaluation of the traumatized spine and documentation of fracture morphology.