Stable resistance against the leaf miner <Emphasis Type="Italic">Leucoptera coffeella</Emphasis> expressed by genetically transformed <Emphasis Type="Italic">Coffea canephora</Emphasis> in a pluriannual field experiment in French Guiana

Summary A pluriannual field trial of transgenic clones of Coffea canephora (the Robusta coffee tree) transformed for resistance to the lepidopteran coffee leaf miner Leucoptera coffeella was installed in French Guiana. Fifty-eight transformed clones produced by transformation of the C. canephora clone 126 were planted. They were harbouring the pEF1α constitutive promoter of Arabidopsis thaliana controlling either the Bacillus thuringiensis native gene for the cry1Ac insecticidal protein (eight clones) or a synthetic cry1Ac gene (53 clones). The vectors for the transformation were a strain of the bacterium Agrobacterium tumefaciens and one of Agrobacterium rhizogenes. The transformed clones were generally independent, presenting different integration patterns of the genetic construct. Four randomly distributed groups of five plants per transformed clone were planted along with 60 untransformed control trees. Over a 4-year period after plantation six releases of L. coffeella were performed. Mines on the leaves are the marks of larvae development and were counted on plants. A majority of the independent transformed clones harbouring the synthetic gene and transformed by the strain of A. tumefaciens displayed constantly much less mines than the control, therefore expressing a stable resistance. The need for complementary research is presented.     

Simulation of growth and production in sheep-model 1: A computer program to estimate energy and nitrogen utilisation,body composition and empty liveweight change,day by day for sheep of any age

A computer program based on empirical relationships is described. It predicts daily energy and nitrogen utilisation repetitively for sheep of any age, before, during and after weaning; provision is also made for pregnancy, lactation and cold stress. Input information includes: intake, protein content and digestibility of the diet; age, empty body weight, fat content and feeding activity of the sheep; ambient temperature and wind speed; times of shearing and mating.Metabolisable energy from milk and/or dry feed is estimated and energy requirements for maintenance, including the cost of feeding activities and homeostasis in the cold, are deducted to obtain energy balance. The amount of amino acid nitrogen absorbed from the small intestine is estimated, and nitrogen balance in body tissues and wool is calculated from this, allowing for body weight and net energy intake. Potential wool growth is calculated from nitrogen and energy intakes, and potential conceptus growth or milk production is estimated primarily from stage of pregnancy or lactation. The use of nitrogen and energy for these products is assessed and balances of energy and nitrogen in body tissues are then obtained by difference. If achievement of the potential rates of production in pregnant or lactating animals would cause excessive loss of energy or nitrogen from body tissues, production of wool and conceptus or milk is reduced sufficiently to avoid this problem. Gain or loss of body fat and protein, and hence change of empty live weight, are finally derived and the animal parameters are incremented before proceeding to calculation for the next day.Evidence is presented that the model is stable in predicting lifetime performance, and that predictions of growth curves, body composition and various nutritional parameters are reasonably accurate in a variety of circumstances.     

III. Buchbesprechungen

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XX. Forstliche Versuche

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水条播对寒地水稻农艺性状和产量构成因素的影响

随着劳动力的短缺,直播水稻具有省工省力的优点逐渐受到重视,因此筛选适宜水条播（直播）的水稻品种是极其重要的。为此,以29份寒地水稻为材料,采用随机区组试验设计,研究水条播对寒地水稻农艺性状、产量构成因素和产量的影响。结果表明,水条播对寒地水稻单位面积穗数的影响为偏正向,对株高、穗长、穗重、一次枝梗数、二次枝梗数、穗粒数、成粒率、千粒重、生物产量、经济系数和理论产量的影响都是偏负向的。水条播提高了穗重、一次枝梗数、二次枝梗数、单位面积穗数、穗粒数、成粒率、千粒重、生物产量、经济系数和理论产量的变异程度,而千粒重的变异系数较小。穗重、成粒率和生物产量对水条播反应较敏感的材料,一般其理论产量对水条播的反应也较敏感。     

Does Public Lands Policy Affect Local Wage Growth?

The effects on wage growth of management practices applied on public lands in the Northern Forest region of the United States are quantified. A central objective is to determine if the management of public lands for preservationist uses results in lower average wages. This is a frequent claim made by critics of land preservation who argue that preservationist management, by prohibiting resource extraction, causes the composition of employment to shift from high‐wage jobs in resource‐based manufacturing to low‐wage jobs in the service sector. A model of simultaneous employment and net migration growth is estimated with data on non‐metropolitan counties over the period 1990 to 1999 and applied in a recursive relationship to wage growth. In earlier studies, models of this type have typically been specified in levels. Time‐series evidence that supports a preference for growth rates is provided as the form for such models. Exogenous variables in this model include the 1990 shares of the county land base that are publicly owned and managed for preservationist (non‐extractive) uses and multiple (including extractive) uses. It was found that wage growth rates are not significantly affected by the shares of land under either management regime. As well, recent declines in national forest timber sales are found to have no effect on wage growth.     

Genetic male sterility in wheat

The occurrence of genetic male sterility and development of highly sterile lines have been reported. The male sterility was not accompanied by any visible chromosomal aberration. It behaved as recessive and was governed by multiple factors. It was hypothesised that three major genes with additive effect were operating to produce highly sterile forms while less sterile forms would be dependent on one or two genes. The expression of male sterility was also influenced by modifying factors and environments.