Screening for Fusarium resistance in seedling populations of Asiatic hybrid lily

A test to select Fusarium resistant seedlings of the Asiatic hybrid lily is described. Young seedlings of 28 populations, obtained from an incomplete diallel between eight parents with different levels of Fusarium resistance, were tested for resistance. Significant differences in Fusarium resistance between and within populations were detected. The average percentage of selected seedlings ranged from 34% in resistant × resistant crosses to 2% in susceptible × susceptible crosses. Although resistant descendants were obtained in susceptible × susceptible crosses, using at least one resistant parent produced higher percentages of resistant seedlings. The resistance level of the parents correlated highly with the general combining ability for Fusarium resistance based on the seedling test. For eight populations, seedlings selected for Fusarium resistance and non-tested (control) seedlings of the same cross were compared, after propagation, in a clonal test. Variation between and within populations, found at seedling level, was confirmed at clonal level. A positive selection response was found for all eight populations. In the seedling test, approximately 18% of the seedlings were selected as resistant of which 15% (2.7% of seedlings tested) appeared to be susceptible escapes. Comparison between selection at seedling level and at clonal level indicated that approximately 25% of the seedlings tested were missed (rejected resistant plants) in the seedling test. The practical use of a seedling test for Fusarium resistance in lily breeding programs is discussed.     

Een aantasting door een mijt,vermoedelijk phyllocoptes fockeui nal., bij perziken en pruimen onder glas

Samenvatting In het Westland is in den zomer van 1946 op perziken en pruimen onder glas een aantasting door een mijt, vermoedelijkPhyllocoptes fockeui Nal., waargenomen. Deze parasiet was voorheen in die cultuur in het Westland niet bekend.Het blad van de aangetaste boomen krijgt een kleur als bij loodglans en krult dikwijls naar boven om. Mogelijk is de mijt afkomstig van de boomkweekerijen.Stuifzwavel en nicotine gaven goede resultaten bij de bestrijding.

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Avec un résumé: Un acarien, probablement Phyllocoptes fockeui Nal., attaque des pêchers et des pruniers (cultures de serres)

Resume L'été 1946 on a observé un acarien, probablementPhyllocoptes fockeui Nal., qui attaque des pêchers et des pruniers (cultures de serres) en Westland. Avant 1946, dans ces cultures de serres, ce parasite était inconnu.Le feuillage des plantes parasitées, présente une teinte plombée et plusieurs feuilles sont repliées en forme de cornet, dont l'ouverture est tournée vers le haut.Probablement l'acarien fut importé en serres pendant l'hiver de 1945–1946 avec des jeunes arbres, qui venaient des pépinières.Contre cet acarien on a obtenu des bons résultats avec du soufre et de la nicotine.

     

Hybrid dwarfness in wheat

Hybrid dwarfness is the phenomenon that after crossing of normal genotypes dwarfs are obtained in the F₁ or not before the F₂-generation. The literature on hybrid dwarfness in wheat is critically discussed. A new hypothesis on its genetic basis is given, taking McMillan's (1937) as a starting point. Dwarfness is assumed to be determined by the additive interaction of three genes D ₁, D ₂ and D ₃, differing in dominance relations and in quantitative contribution to the dwarf phenotype.Three dwarf types are described. Type 1-dwarfs are dwarf during their whole life cycle and normally do not produce seeds. Type 2-dwarfs start as normal seedlings, become dwarfs while tillering and die dwarfs; some produce seeds, others do not. Type 3-dwarfs emerge as normal seedlings, become dwarfs during the tillering stage, but after some time they start to shoot and develop into nearly or even completely normal plants; in the F₂ the proportion of dwarfs decreases during the growing season. The occurrence and genetic basis of the three dwarf types is discussed.On the basis of their genotype 315 varieties and lines are divided into six genotypeclasses. Over 1000 intra- and inter-class crosses were made and F₁, F₂, F₃, and BC studied. Also some triple crosses and crosses with pure breeding dwarfs were investigated. In general the results obtained fit the hypothesis. Unstable ratios involving type 3-dwarfs are discussed separately.Linkage of the dwarf gene D ₂ and the necrosis gene Ne ₂ (both on chromosome 2B (XIII) was apparent from F₂-data and from results of a triple cross in which both forms of hybrid weakness occurred. Crossing-over between D ₂ and Ne ₂ is calculated to be 34%.Methods are outlined to use hybrid dwarfness in a wheat breeding programme. The possible incompleteness of the three-gene hypothesis and the variability of dwarfness are discussed and finally some suggestions are made for future research.     

Chloroplast degeneration as a consequence of “hybrid necrosis” in wheat

The results of a cytological study of hybrid necrosis in wheat are presented. Two types of necrosizing of the leaves have been found viz. necrosis via dull green discoloration, and necrosis via a yellow intermediate colour. In the first case the conglomeration of the cell contents starts when the size of the chloroplasts is only little reduced. In the second case the chloroplasts become very small before forming small lumps or bunches. It is suggested that the conglomeration of the cell contents is more disastrous for the plant than the decrease in size of the chloroplasts. The problem of the genetical and physiological causes of hybrid necrosis is discussed.     

Basic information for the use of primary trisomics in genetic and breeding research

Summary An attempt is made to arrange the basic information needed for using primary trisomics in localizing single and complementary dominant and recessive genes, accounting for random complete chromatid and random chromosome association, for heterozygosity of the trisomics and for female and male transmission rates. The expected ratios are given separately for the di-, tri- and tetrasomic group in each population. Also the ratios in the total populations have been calculated for different rates of female and male transmission of the extra chromosome. Both the backcross procedure and that of selfing trisomic F₁ plants are considered. Finally the use of trisomics for studying quantitative characters is discussed in connection with the breeding and incompatibility system of the crops and in relation to the frequent morphological differences among trisomics as well as between trisomics and their disomic counterpart.     

Functional Teas from the Leaves of <Emphasis Type="Italic">Arbutus unedo</Emphasis>: Phenolic Content,Antioxidant Activity,and Detection of Efficient Radical Scavengers

The phenolic content/composition and antioxidant activity of hot/cold infusion and decoction from the leaves of Arbutus unedo were studied for the first time. 1,1-diphenyl-2-picrylhydrazyl (DPPH^●), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS^●+), crocin-bleaching, copper-reducing, and liposome accelerated oxidation assays were used for the evaluation of the activity in vitro. In vivo, the extracts were examined for their ability to protect S. cerevisiae cells from H₂O₂ induced oxidative stress. An on-line high-performance liquid chromatography-DPPH^● assay was applied to identify potent radical scavengers and comment on their contribution to the total activity. The addition of leaves to boiling water (decoction) was the most appropriate practice to apply since the highest phenol intake (220.2 mg gallic acid/cup served) was obtained. Additionally, its antioxidant activity was equal or superior to that of the other extracts. Flavonols (~51–61 mg/g dry extract) were the main phenols in all the extracts, with quercitrin accounting for ~20% of the total phenol amount. The on-line DPPH^● method verified the high potency of the decoction and indicated as the most active radical scavengers, two galloylquinic acid derivatives and myricitrin, accounting for ~28–45% and ~11–13% of the total scavenging, respectively. Present data may contribute to the future exploitation of A. unedo leaves by the food industry for health-promoting herbal tea preparations and dietary supplements.     

Extractability of trace metals during co-composting of biosolids and municipal solid wastes

 Composts made from biosolids and municipal solid wastes contain heavy metals which may be exported outside soil systems by plants, animals and surface and subsurface waters after the compost has been added to soils. Chemical distributions of Cu, Zn, Cr, Pb, Ni and Co were determined by eight sequential extractions of co-composted materials sampled on days 0, 13, 27 and 41. The concentrations of residual Zn, Cr, Cu and Pb increased by 145, 124, 73.6 and 26.3% during the composting period, respectively, whereas the concentration of residual Ni remained relatively constant and that of Co decreased by 60% over the same period. These results show that co-composting contaminated residues substantially reduces the extractability and exchangeability of four out of six heavy metals, suggesting that the risks of entering the food chain and contaminating crops, animals and water reserves would be equally reduced. Fourier-transform infrared spectra showed that heavy metals in the compost are bonded to COO- groups of the organic matter. Received: 20 March 1998     

Devaluating Drainage Design Parameters for the Fourth Drainage Project, Pakistan by using SWAP Model: Part I – Calibration

A transient drainage simulation model,SWAP, was used to evaluate the performanceof drainage systems in (semi-) arid zones.Before application, the model wascalibrated by using 14-months datacollected from two sample fields of theFourth Drainage Project (FDP), Punjab,Pakistan. During the calibration process,emphasis was given to the accuratedetermination of soil hydraulic parameters,reference evapotranspiration, drainage fromsample fields and bottom boundarycondition. Laboratory determined soilhydraulic parameters were foundnon-representative of the field conditions.Difference between laboratory and fielddetermined soil water retention curves werefound significant. The pressure heads andsoil water contents measured in depthincrements of 15 cm were in good agreementwith the simulated values after applying afield measured retention curve. A closeproximity was also found between measuredand simulated average root zone salinity at0–1.0 m depth. The referenceevapotranspiration calculated by thePriestly-Taylor (PT-ET _o) methodwas found physically more realistic thanthe Penman-Monteith (PM-ET _o)method due to ignorance of the feed backmechanism of vapor pressure deficit onstomatal closure. The simulated cumulativedrainage from two sample fields wascomparable with the calculated values. Theanalysis of piezometer data shows thatthere is a negligible water exchangebetween the deep aquifer and theunsaturated zone. Therefore for scenarioanalysis, no flow conditions at the bottomof the soil profile can be applied as abottom boundary.     

Chemische Untersuchungen an Verbindungen aus Lignin mit Cyanamid,Kalkstickstoff sowie Dicyandiamid

Chemical investigations on reaction products from lignin and cyanamide, Ca-cyanamide, as well as dicyandiamide Chemical interactions between lignin from Triticum aestivum and cyanamide, “Kalkstickstoff” (Ca-cyanamide) as well as dicyandiamide were proved. The methods used to indicate the oxygen absorption, gas release, typical structures and reaction procedures, specially carbonylgroups, the nucleophilic addition and esterification were the WARBURG-Technik, infrared-spectroscopy, measurement of pH-values and color reactions with phloroglucine/HCl. Additionally the C- and N-content was determined. The N-containing reaction products formed at maximal 30°C were isolated after 3–5 weeks and purified. Dyanamide (H₂CN₂) and “Kalkstickstoff” (CaCN₂) reacted already in water with lignin. In opposite dicyandiamide first displayed chemical interactions to a larger extent after CaO had been added. The reaction with the nitrogen-containing compounds by nucleophilic addition only reduced the carbonyl groups (keto and aldehyde) of lignin. The N-content of the reaction products ranged from (0,37 % lignin with cyanamide + CaO or CaCN₂ + CaO) to 1,2 % (lignin + dicyandiamide + CaO). Even the lowest of these values corresponds already a maximal bond of ～ 7 kg poor N/ha with respects to the lignin of a wheat harvest.