Powdery mildew resistance of Nordic spring wheat cultivars grown in Estonia

Abstract

A group of spring wheat cultivars originating from Sweden, Finland, Norway, Germany, and the Netherlands was analysed for powdery mildew resistance. Using functional molecular markers, two alleles of the major resistance gene Pm3 were detected among the cultivars under the study. One of the alleles, Pm3d, was detected in the resistant cultivars ‘Vinjett’, ‘SW Estrad’, and ‘Zebra’, and in ‘Tjalve’, a cultivar of earlier release susceptible to the local population of powdery mildew. The second allele of Pm3 detected in the analysed group of cultivars was the allele Pm3f, rarely used in Europe. It was identified in the resistant cultivars ‘Satu’, ‘Helle’, and in the moderatively resistant cultivar ‘Mahti’. Pm3f was found to be effective against the local population of powdery mildew in Estonia, while Pm3d provided no protective effect. Besides the Pm3d allele on chromosome 1A, monosomic analysis of the cultivar ‘Vinjett’,which is almost immune to powdery mildew, identified two additional loci on chromosomes 5D and 7D, respectively, presumably responsible for the high resistance in this cultivar. In contrast to the earlier cultivars, six recently released cultivars (‘Vinjett’, ‘SW Estrad’, ‘Zebra’, ‘Satu’, ‘Helle’, ‘Meri’) demonstrated a high resistance to the powdery mildew fungus Blumeria graminis DC. f. sp. tritici both in the field and seedling tests, showing that the genetic basis of powdery mildew resistance in Nordic spring wheat has been improved noticeably in the last ten years.     

Forage systems for beef production from conception to slaughter: I. Cow-calf production.

Six year-round, all-forage, three-paddock systems for beef cow-calf production were used to produce five calf crops during a 6-yr period. Forages grazed by cows during spring, summer, and early fall consisted of one paddock of 1) tall fescue (Festuca arundinacea Schreb.)-ladino clover (Trifolium repens L.) or 2) Kentucky blue-grass (Poa pratensis L.)-white clover (Trifolium repens L.). Each of these forage mixtures was combined in a factorial arrangement with two paddocks of either 1) fescue-red clover (Trifolium pratense L.), 2) orchardgrass (Dactylis glomerata L.)-red clover, or 3) orchardgrass-alfalfa (Medicago sativa L.), which were used for hay, creep grazing by calves, and stockpiling for grazing by cows in late fall and winter. Each of the six systems included two replications; each replicate contained 5.8 ha and was grazed by eight Angus cow-calf pairs for a total of 480 cow-calf pairs. Fescue was less than 5% infected with Acremonium coenophialum. Pregnancy rate was 94%. Cows grazing fescue-ladino clover maintained greater (P less than .05) BW than those grazing bluegrass-white clover, and their calves tended (P less than .09) to have slightly greater weaning weights (250 vs 243 kg, respectively). Stockpiled fescue-red clover provided more (P less than .05) grazing days and required less (P less than .05) hay fed to cows than stockpiled orchardgrass plus either red clover or alfalfa. Digestibilities of DM, CP, and ADF, determined with steers, were greater (P less than .05) for the orchardgrass-legume hays than for the fescue-red clover hay. All systems produced satisfactory cattle performance, but fescue-ladino clover combined with fescue-red clover required minimum inputs of harvested feed and maintained excellent stands during 6 yr.     

Motivations and Performance Conditions for Ethnic Entrepreneurship

Ethnic entrepreneurship has become a popular concept in a modern multi–cultural society. This paper seeks to offer an overview of the potential of ethnic entrepreneurship for solving inter alia the structural unemployment problems of ethnic groups in cities. There is a general lack of empirical evidence on this issue in the current literature. The present paper aims to fill this gap by addressing in particular the critical success conditions for ethnic entrepreneurs. The focus of the research is on variations in success across three ethnic groups in the Amsterdam area. By means of structured personal interviews with many ethnic entrepreneurs, a systematic qualitative data base was created. The paper sets out to identify empirically the driving forces for business success, such as education or the role of informal networks. The explanatory framework deployed for the identification of these qualitative success factors for distinct ethnic groups is based on a particular, recently developed artificial intelligence method, viz. rough set analysis. This multidimensional classification approach appears to be able to identify various important factors for the motivation and performance of ethnic enterprises. Two major findings emerge from this investigation: (i) performance conditions vary across ethnic groups, and (ii) informal networks are crucial for business success.     

The effect of stem population on tuber yield in a trial with single-stem seed pieces

Summary Excised eyes on 5 g of seed tuber tissue were used to grow plants with single stems. These were transplanted in the field at densities of 120 000, 180 000 and 240 000 plants/ha, with in-row spacings of 16 or 33 cm. Total tuber yield was not affected, although more tubers were produced at the high densities. Tuber numbers did not increase in proportion to the number of stems. This was due to the fact that the number of tubers per stem decreased from a mean of 4.8 to 2.9 with increasing stem populations.     

Net photosynthetic rate of potato at high temperatures

Summary Potato cultivars were grown in a glasshouse and plants periodically transferred to a growth chamber. When the ambient temperature in the growth chamber was raised from 15 to 40°C in steps of 5°C per hour, net photosynthetic rate decreased at temperatures above 20°C. At 40°C the rate was 37% of the rate at 20°C. A greater decrease in net photosynthetic rate occurred with plants of the cultivar Up-to-Date than with cultivars R100 and BP13. Low values of leaf diffusive resistance were recorded and changes in photosynthetic rate could not be explained by changes in this factor. When a constant ambient air temperature of 20°C was maintained while soil temperature was increased, net photosynthetic rate decreased.     

Pelleting or Priming Seed with Calcium Improves Groundnut Seedling Survival in Acid Soils

A growth chamber experiment and a field experiment were conducted to investigate the effects of pelleting or priming groundnut seed with calcium (Ca), either as calcium sulfate (CaSO₄), calcium chloride (CaCl₂), calcium nitrate [Ca(NO₃)₂], calcium carbonate (CaCO₃) or Calcimax on growth of groundnut seedlings in acid soils. In the growth chamber experiment, Ca-treated and non-treated groundnut seeds were planted in acid-washed sand and watered with a dilute nutrient solution of pH 4.0 or 5.5. In the field experiment, the seeds were planted in an acid sand clay loam of pH [potassium chloride (KCl)] 4.8. Generally, pelleting or priming the seed with a Ca compound significantly reduced seedling mortality. Also, pelleting groundnut seed with Ca enhanced plant growth. An additional effect of priming was earlier emergence. The most effective Ca compound was CaSO₄ among the priming treatments, whereas CaCO₃ was the most effective among the pelleting treatments to reduce seedling mortality.     

INTERACTIONS OF POD-ZONE PH AND CALCIUM CONCENTRATION ON FRUCTIFICATION OF GROUNDNUT GROWN IN SOLUTION CULTURE

Low soil pH and calcium (Ca) deficiency in both the root and pod-zone are important problems for groundnut production world-over on account of the light-textured nature of the soils suitable for its production. An experiment was conducted to examine the interaction of pH and calcium (Ca) supply in the pod-zone on reproductive growth of groundnut. Attached gynophores were cultured singly in solutions at three pH levels (3.5, 5.0, and 6.5) in factorial combination with three solution Ca concentration levels (500, 1000, and 2000 μM). Generally, low pH had an adverse effect on the reproductive growth of groundnut. Approximately 58% of the gynophores cultured in treatment combinations with pH 3.5 produced normal pods, compared to 94% in combinations with pH 5.0 and 6.5. In addition, both pod mass and seed mass were severely depressed in treatment combinations with pH 3.5 compared to combinations with pH 5.0 and pH 6.5. Increasing Ca from 500 to 2000 μM Ca at low pH had limited ameliorative effect on pod-set, pod mass and seed mass, whereas positive responses were higher at the intermediate pH of 5.0. A combination of high Ca and pH appeared to be detrimental to pod and seed growth.