食物对三突花蛛生长发育的影响 Ⅱ.食物对三突花蛛营养指标的影响

研究不同食物对三突花蛛相对生长率(RGR)、相对取食量(RCR)、食物利用率(ECI)的影响。结果表明,三突花蛛各龄相对生长率以取食混合食物为高,取食单一食物为低。各龄相对取食量对棉铃虫和果蝇较高,对摇蚊则较低,食物利用率则以对摇蚊的利用率为最高,对棉铃虫和果蝇的利用率较低。

Variation Character of Grain Yield per Unit Area in Main Grain-producing Area of Northeast China

Based on the surveys and the statistic data during 1980-2003, the variation character of grain yield per unit area in Northeast China and its main factors have been discussed by the methods of statistics and grey correlation analysis. The results show that: 1) the grain yield per unit area has been taking on an increasing trend in the recent 20 years. It increased from 2519.80kg/ha in 1980 to 4216.11kg/ha in 2003, with an increasing rate of 67.32%; 2) the variation of grain yield per unit area is considerably prominent and its range is also very great, with the maximal increase rate of 42.59% and maximal decrease rate of 21.13%, respectively, which are far above the whole Chinese average level; 3) the variation of main crops' yield per unit area is remarkable, which takes on the character that the yield of corn is much higher than that of soybean and rice; and 4) the grey correlation analysis shows that the most important factors impacting the variation of grain yield per unit area are the total power of agricultural machinery, the consumption of chemical fertilizer and effective irrigated area. However, the influence of natural disaster and income level should not be ignored. Effective ways to improve grain yield per unit area are to construct farmland improvement groundwork, reclaim the middle- and low-yield farmland, etc.

Dynamics of Soil Fauna in Da Hinggan Mountains, Northeast China

The dynamics of soil animals was studied in seven representative forest communities in the north of the Da Hinggan Mountains, Northeast China. The results indicate that it was distinctive in the changes of the numbers of soil animals and groups and diversity in relationship with seasons for macrofauna and meso-micro fauna in the study area. The numbers of the observed soil animals in different months were: October>August>June. Group number was larger in August and October, but smaller in June. The change of diversity index in different months was: August>June>Oc- tober. The biomass for macrofauna in different months was: October>June>August. The composition and number of each functional group was relatively stable. In the community of the predominant soil environment, the percentage of saprophagous animals was higher than carnivorous animals and herbivorous animals. The dynamics changes of sapro- phagous and carnivorous animals were distinctive, increasing from June to October, while the change of herbivorous animals was unremarkable.

GxE Interaction Effects on Yield of Twenty-five Genotypes of Bread Wheat （Triticum Aestivum L.） during 2009 Winter in Zimbabwe

AMMI analysis was performed to assess yield stability of twenty-five bread wheat （Triticum aestivum L.） genotypes grown in a 5 ×5 Lattice Square Design at seven sites under irrigation during 2009 season. AMMI ANOVA for grain yield indicated that genotypes, environments and G×E interaction were significantly different （P 〈 0.001）. Environments, genotypes and GxE accounted for 78.9, 4.6 and 16.4% of the treatment sum of squares, respectively. The proportion of environmental and G×E interaction variation for grain yield was larger than genotypes main effects. Genotype dendogram showed nine clusters with a yield range of 6,373.546 kg·ha-1 to 7,687.243 kg.hal. W1494/6/1, SC Sky and W2045/6/13 had high yields and exhibited negligible interactions with the environment. These were widely adapted and stable across high yielding sites. RARS （Normal）, ART （Normal） and ART （Deficit） were best yielding sites among eight environmental groups. ART （Deficit） had the best mean （9,764.479 kg·ha-1） followed by RARS （Normal） at 9,522.119 kg·ha-1 Chiredzi （Group 6） had the lowest mean yield （4,393.400 kg.hal）. Results show that high yields （〉 9,000 kg·ha-1） are achievable in high altitude areas of Zimbabwe （≥1,200 masl）. Dendograms were used to characterize both genotypes and environments and the AMMI model was used to select genotypes with specific or broad adaptation.

Analysis of Nitrosamines in Organic Foods

Nitrosamines are classified by IARC as Group 2B carcinogens. Usually they might be present in organic foods as products of reaction between secondary amines and nitrosation system. The aim of the study was to test the concentration of nitrosamines in Bulgarian products. High performance liquid chromatography with UV detector was used for identification and quantitation. A standard solution of N-nitrosodiethanolamine was used as a reference substance and in the validation procedure of samples. The limit of detection of the method was determined to 14× 10^-9 g/mL. The results of the testing showed that analyzed organic foods produced in Bulgaria did not contain nitrosamines above the limit of detection of the method.