Computer-Simulated Evaluation of the Hybrid Weakness Gene System as a Means of Preventing Genetic Contamination of Rice Cultivars     

K. Yonezawa    Y. L. Sato    T. Nomura  H. Morishima 《Plant Breeding》1990,104(3):241-247

Effectivness of the hybrid-weakness caused by a complementary interaction of two dominant genes Hwc₁ and Hwc₂ to suppress the spread of the red-grain gene into ordinary white-grained rice cultivars was investigated using the Monte Carlo computer simulation method. It was shown that the weakness genes, as far as being capable of reducing the fitness of the carrier by 80 percent or more, work quite effectively to suppress the genetic contamination of white-grained cultivars due to inflow of pollen from red-grained cultivars due to inflow of pollen from red-grain gene once the gene has been incorporated in to the population in the form of red-grained progeny produced as a result of the imperfect lethality of the initial hybrid between red-and white-grained cultivars. The weakness genes have little or no effect cultivars. The weakness genes have little or no effect either, when the contamination is initiated by an inflow of seeds or seedlings from ed-grained cultivars in these situations, removal (selection)of red grained plants Is the only countermeasure to exterminate the red-grain gene. The removal of red grained plants need not be intensive if carried out continuously. The spread of the red-grain gene after initial contamination is suppressed if the red-grain gene and weakness genes are linked. The suppressing effect of the linkage, however, is not substantial when the outcrossing rate is around or smaller than 0.01 as can be assumed in most rice cultivars.  相似文献   

玉米田的群体结构与光能分布   总被引：2，自引：0，他引：2  

赵可夫  许仙太  袁玉信  张慧娟 《作物学报》1963,2(3):321-332

玉米田的群体结构和光能分布随密度而异,与播方式的关系不大。就结构与光分布而论,以每亩3,000株的最为理想亦最有利于高产。玉米叶片的伸展方向,可以通过叶片的向光性来自动调节。  相似文献   

Effects of potato–grain rotations on soil erosion, carbon dynamics and properties of rangeland sandy soils     

A. Al-Sheikh  J.A. Delgado  K. Barbarick  R. Sparks  M. Dillon  Y. Qian  G. Cardon 《Soil & Tillage Research》2005,81(2):227-238

The potential for wind erosion in South Central Colorado is greatest in the spring, especially after harvesting of crops such as potato (Solanum tuberosum L.) that leave small amounts of crop residue in the surface after harvest. Therefore it is important to implement best management practices that reduce potential wind erosion and that we understand how cropping systems are impacting soil erosion, carbon dynamics, and properties of rangeland sandy soils. We evaluate the effects of cropping systems on soil physical and chemical properties of rangeland sandy soils. The cropping system included a small grain–potato rotation. An uncultivated rangeland site and three fields that two decades ago were converted from rangeland into cultivated center-pivot-irrigation-sprinkler fields were also sampled. Plant and soil samples were collected in the rangeland area and the three adjacent cultivated sites. The soils at these sites were classified as a Gunbarrel loamy sand (Mixed, frigid Typic Psammaquent). We found that for the rangeland site, soil where brush species were growing exhibited C sequestration and increases in soil organic matter (SOM) while the bare soil areas of the rangeland are losing significant amounts of fine particles, nutrients and soil organic carbon (SOM-C) mainly due to wind erosion. When we compared the cultivated sites to the uncultivated rangeland, we found that the SOM-C and soil organic matter nitrogen (SOM-N) increased with increases in crop residue returned into the soils. Our results showed that even with potato crops, which are high intensity cultivated cropping systems, we can maintain the SOM-C with a rotation of two small grain crops (all residue incorporated) and one potato crop, or potentially increase the average SOM-C with a rotation of four small grain crops (all residue incorporated) and one potato crop. Erosion losses of fine silt and clay particles were reduced with the inclusion of small grains. Small grains have the potential to contribute to the conservation of SOM and/or sequester SOM-C and SOM-N for these rangeland systems that have very low C content and that are also losing C from their bare soils areas (40%). Cultivation of these rangelands using rotations with at least two small grain crops can reduce erosion and maintain SOM-C and increasing the number of small grain crops grown successfully in rotation above two will potentially contribute to C and N sequestration as SOM and to the sequestration of macro- and micro-nutrients.  相似文献   

Factors influencing the rate of formation of nitrosomorpholine from morpholine and nitrite: acceleration by thiocyanate and other anions   总被引：2，自引：0，他引：2  

T Y Fan  S R Tannenbaum 《Journal of agricultural and food chemistry》1973,21(2):237-240

  相似文献   

Colorimetric determination of caffeic acid in plant materials   总被引：1，自引：0，他引：1  

K L Bajaj  Y K Arora 《Journal of the Association of Official Analytical Chemists》1979,62(5):1160-1161

A new colorimetric method is described for determining caffeic acid content in plant materials. Caffeic acid is separated by thin layer chromatography from the alcoholic extract, and color is developed using 0.5% aqueous thiosemicarbazide solution under alkaline conditions. The absorbance is read at 475 nm. Lambert-Beer's law is obeyed in the concentration range 0.37-17.5 micrograms caffeic acid/mL. The method is reproducible and has been applied to the estimation of caffeic acid in carrot roots.  相似文献   

Output of methylmercury from a Catchment in northern Sweden     

Y. H. Lee  K. Bishop  H. Hultberg  C. Pettersson  Å. Iverfeldt  B. Allard 《Water, air, and soil pollution》1995,80(1-4):477-481

The runoff output of methylmercury (MeHg) from the 50 ha Svartberget Catchment in northern Sweden was studied during 1993. These outputs are compared to those from the Gårdsjön Catchment in the southwestern part of Sweden. Although the wet deposition of MeHg is several times higher in southern Sweden the output of MeHg per unit area from the two catchments was comparable (0.12 g /km_* ²yr). Furthermore, the concentration of MeHg (0.4 ng/L) in the Svartberget Catchment was more than twice that from the Gårdsjön Catchment. These results suggest that the contemporary wet deposition of MeHg in itself is not a good indicator of runoff concentration or output per unit area. DOC transport and catchment characteristics such as wetland area, or possibly other forms of contemporary atmospheric deposition may all be more important for explaining MeHg output from the terrestrial ecosystem.  相似文献   

Regional Characteristics of Cooper Corrosion Components in East Asia     

M. Kitase  S. Hatakeyama  T. Mizoguchi  Y. Maeda 《Water, air, and soil pollution》2001,130(1-4):1463-1468

Copper plates were exposed under shelters at 13 sampling sites in East Asia and their corrosion was analyzed. The corrosion products were first dissolved in water and then oxalic acid. Sulfate, nitrate and chloride in the solutions were measured by ion chromatography. The amounts of the three anions significantly differed depending on the atmospheric environment at the sites. Sulfate was a major part of the anions at Chongqing and Shanghai in China. Especially, at the urban sites in Japan, nitrate remarkably changed with the seasons, and often became the large anionic component in the summer. The amounts of chloride at most sites were at higher concentration levels compared with those at the rural sites in Japan. The anions in the copper corrosion must mainly reflect the impact of acid deposition.  相似文献   

Internal Distribution of Acid Materials within Snow Crystals     

H. Fushimi  T. Kawamura  H. Iida  M. Ochiai  T. Nakajima  Y. Azuma 《Water, air, and soil pollution》2001,130(1-4):1709-1714

We found that river water is acidified not only in the first stage but also in the later stage of the snowmelt season in Japan, which differs from the so called acid shock occurring in the first stage of the snowmelt in the northern Europe. The acid shocks depend on the regional characteristics of the melt-refreeze processes forming the internal distribution of acid materials within snow crystals under the warm metamorphism. In a warm climatic region like the central Japan, there are possibilities to have the complicated distribution structure of acid materials within granular-snow crystals due to the repeated melt-refreeze processes even in midwinter. Consequently, the pH value of meltwater does not always increase as the snowmelt proceeds. Then, we showed the possibility by using the X-ray computed tomography that the domains with the acid materials exist in the inner parts of snow crystals. So, the acidification of the river water may occur even in the later stage of the snowmelt.  相似文献   

Mutagenicity determination of the wastewater emitted from petrochemical industry in Taiwan     

I. F. Mao  M. L. Chen  C. F. Lan  Y. P. Chang  S. C. Chang 《Water, air, and soil pollution》1994,76(3-4):459-466

Thirty-eight wastewater samples were collected from 19 petrochemical plants located in Taiwan during 1991. These plants represented most of petrochemical industry in Taiwan. Water samples were passed through an XAD-2 resin column and then eluted by acetone. The mutagenicity of wastewater was determined by the Ames Salmonella/microsome test. 52.6 and 26.3% of wastewater collected respectively in summer and winter were found to exhibit mutagenic activity in Salmonella typhimuriumTA 98 and TA 100. Four samples collected from 2 plants had higher levels of mutagenicity. The measurement and identification of mutagenic pollutants in this kind of wastewater need further investigation.  相似文献   

Glass transition and water effects on sucrose inversion by invertase in a lactose-sucrose system     

Kouassi K  Roos YH 《Journal of agricultural and food chemistry》2000,48(6):2461-2466

Enzymatic changes are often detrimental to quality of low-moisture foods. In the present study, effects of glass transition and water on sucrose inversion in a lactose-sucrose food model were investigated. Amorphous samples were produced by freeze-drying lactose-sucrose (2:1)-invertase (20 mg invertase/49.4 g of carbohydrate) dissolved in distilled water. Sorption isotherms were determined gravimetrically at 24 degrees C. Sucrose hydrolysis was determined by monitoring glucose content using a test kit and the amounts of fructose, glucose, and sucrose using HPLC. The glass transition temperatures, T(g), at various water contents were measured using differential scanning calorimetry (DSC). The BET and the GAB sorption models were fitted to experimental data up to a(w) 0.444 and 0.538, respectively. Water sorption and DSC results suggested time-dependent crystallization of sugars at a(w) 0.444 and above. Significant sucrose hydrolysis occurred only above T(g), concomitantly with crystallization. Sucrose hydrolysis and crystallization were not likely in glassy materials.  相似文献