Dominance of a resistance trait can be defined as a measure of the relative position of the phenotype of the heterozygote RS compared with the phenotype of the two corresponding homozygotes, SS and RR. This parameter has been shown to have primary importance in the dynamics of pesticide resistance evolution. Literature on insecticide resistance suggests that dominance levels in the presence of insecticide vary greatly from completely recessive to completely dominant. With insecticides, both the chemical applied and the dosages used have been demonstrated to affect the dominance. By contrast, almost all herbicide resistances have been found to be inherited as partially to totally dominant traits. This discrepancy between weeds and insects may partly result from the methodologies applied to measure the dominance, ie a single dose for herbicide versus several doses for insecticide. Using two well-known resistances (csr1-1 and csr1-2) to acetolactate synthase (ALS) inhibitors in Arabidopsis thaliana (L) Heynh (mouse-ear cress), we used several herbicide doses to determine the dominance level to six ALS-inhibiting herbicides. The dominance level in the presence of herbicide varied from completely dominant to completely recessive, depending on the resistance allele and the herbicide tested. The dominance of the csr1-1 and csr1-2 resistance alleles ranged from 0 (completely recessive) to 1.1 (dominant) and from 0 to 0.3 (partially dominant), respectively. The recessivity of some resistance alleles in the presence of herbicide could lead to the development of improved resistance management in order to delay or avoid herbicide resistance evolution, especially in the control of outcrossing weed species. 相似文献
Data of long-term investigations of the suitability of widespread apple varieties for producing high-quality juice are given. A purposeful breeding program made it possible to create forms with a high juice yield and quality for orchards producing raw materials. 相似文献
The length of chromosomal segments retained around the Vrn‐B1 gene controlling sensitivity to vernalization in wheat (Triticum aestivum L.) was studied in the first and third backcrosses by using microsatellite markers. Eleven polymorphic markers located on chromosome 5B were used for microsatellite analysis. It was shown in the first backcross that plants with a donor segment around the gene of interest not longer than 50% of chromosome 5B could be selected. When selection is not molecular‐marker assisted, the length of the chromosomal donor segment with the target gene may reach 94% of chromosome 5B even in plants of the third backcross generation. The considerable length differences in the 5B microsatellite loci between the winter and spring lines of wheat studied indicate that these markers are promising in marker‐assisted backcrossing or marker‐assisted selection for the Vrn‐B1 gene using different combinations of Spring and Winter genotypes. 相似文献
An experiment was conducted to investigate the effect of replacing soybean meal with soya waste at different levels on intake, digestibility and growth in goats. Eighteen male goat kids with initial body weight (BW) of 13.0 kg were distributed equally to three dietary groups. They were fed Napier grass (Pennisetum purpureum) and concentrate mixture, and each goat was assigned to an individual pen. Soybean meal in the concentrate mixture was replaced with soya waste at 0% (T1), 50% (T2) and 100% (T3) levels in respective dietary groups. These diets were isocaloric and isonitrogenous. Results showed that animals fed T3 diet exhibited higher Napier grass intake than those fed T1 or T2 diet. There was no influence on total intakes of dry matter (DM), organic matter (OM), crude protein (CP), metabolic BW, per cent BW and metabolisable energy by the dietary groups. However, there was an increasing trend on intake and digestibility of neutral detergent fibre (NDF) with increasing levels of soya waste in the diets. Animals fed T3 diet showed higher intake and digestibility of NDF than those fed T1 diet. There was no influence of the dietary groups on digestibilities of DM, OM and CP. Similarly, there was no effect of them on the final BW, total BW gain, daily BW gain, feed conversion ratio and feed cost. Soya waste can replace 100% soybean meal in diets for growing goats, because no change was observed in nutrient intake, digestibility and growth performance; inclusion of soya waste enhanced the intake and digestibility of NDF.
Rubber trees were introduced into the Malay Peninsula more than a century ago. The normal economical lifespan of a rubber
tree is about 25 years, and, traditionally, rubberwood was used as firewood by the rural community. In recent decades, rubberwood
has become an important timber for wood products, particularly in the furniture manufacturing sector, due to its attractive
features, cream color, and good working properties. Sapstain, mold, and wooddecaying fungi are serious threats to rubberwood.
Conventional chemical control has been a successful method of preventing staining fungal growth, but the effects of these
chemicals are of concern because they create problems for the environment and public health. Thus, biological control has
been recognized as an alternative approach to the problem. This article reviews the properties, potential utilization, and
problems of protecting rubberwood against sapstain, mold, and wood-decaying fungi, and discusses the treatment methods available.
Advances in biological control, particularly biofungicides, are emphasized as an alternative method for rubberwood treatment. 相似文献
Optimized palm press fiber composites of poly(?-caprolactone)/poly(lactic acid) were produced and their mechanical and thermal properties were studied. The composites were melt blended using twin screw extruder and test specimens were produced by injection molding. The composites mechanical and thermal performances were tested using standard methods. The incorporation of dicumyl peroxide as compatibilizer significantly increased the tensile strength, flexural modulus and impact strength of the composites as compared to the uncompatibilized composites. Crystallization temperature of the composites initially increased after which it dropped as fiber load increased. The composites melting point and percentage crystallinity slightly decreased as fiber load increased. 相似文献
New Forests - In forests affected by heavy fires and continuous grazing of exotic herbivorous mammal species, Nothofagus pumilio (lenga) cannot recover naturally. The main factors that hinder the... 相似文献
