Lipid components of mustard seeds (Brassica juncea L.) as influenced by cadmium levels

In a pot experiment the soil application of different levels of Cd²⁺ (0, 10, 20, 30, 40 and 60 µg g^–1 soil) affected the lipid components of mustard seeds (Brassica juncea L. Cv. RH-30) markedly. Total lipids declined with the Cd²⁺ levels regularly while phospho and glycolipids increased only at higher levels. Fatty acids profile of total, neutral and polar lipid fractions were affected considerably. Erucic acid in total and neutral lipids was observed to increase while it decreased in polar lipids with Cd²⁺ as compared to control. On the other hand palmitic, oleic and linoleic acids had reverse trend. Cadmium concentration increased consistently with increasing levels of Cd²⁺. Plant dry weight was also decreased significantly with Cd²⁺ levels.     

Comparison of illuminations to identify wheat classes using monochrome images

Wheat class identification using machine vision is an objective method which can be used for online testing to automate handling, binning and shipping operations in grain industry. The efficiencies of a monochrome camera-based vision system with three different illuminations (incandescent light (IL), fluorescent ring light (FRL), fluorescent tube light (FTL)) were determined to identify eight western Canadian wheat classes at four moisture levels (11%, 14%, 17% and 20%). The monochrome images of the bulk wheat samples were acquired at each moisture level (3 illuminations × 8 classes × 4 moisture contents × 100 replications = 9600 images). A linear discriminant function was used for the classification of wheat samples using 32 gray level textural features extracted from the monochrome images. The mean gray values of the wheat classes were in the ranges of 75–103, 73–115, and 107–143 for IL, FRL and FTL, respectively. The mean gray values of wheat classes were significantly different within each illumination and between different illuminations (α = 0.05). Mean gray value was the highest for FTL and the lowest for IL illumination. The moisture content of the wheat samples had significant effect on the mean gray values. The overall classification accuracies were 90%, 81% and 96% for IL, FRL and FTL, respectively, when all the wheat classes were at the same moisture levels. It was 66%, 53% and 85% for IL, FRL and FTL, respectively, when the wheat classes were at different moisture levels. The classification accuracies of a 2-stage classification system for the classes with different moisture levels were 68%, 56% and 90% for IL, FRL and FTL, respectively.     

刍议中职艺术设计教改

新世纪人才的竞争和挑战,对艺术设计职业教育提出了前所未有的新要求,要使艺术设计专业教育与时代同步,转变教育观念,准确专业定位势在必行,优化课程体系,培养创新人才,是艺术设计专业生存和发展的基础和前题。     

Soil phosphorus fractions in aggregate size classes in southwestern China

The build‐up of topsoil phosphorus (P) through excess fertilizer application can increase P losses in run‐off leading to negative impacts on aquatic ecosystems. To better understand the risk of P losses, the fractions of soil P in four aggregate size classes were quantified for two vegetable production sites (<10 and >25 yrs) and a conservation buffer site (8 yrs) in southwestern China. Sequential extraction methods of inorganic P (Pi) and organic P (Po) were carried out on samples from Nitisol and Gleysol soils from 0 to 5 cm and 5 to 10 cm depths. On average, soil Pi concentrations exceeded Po concentrations threefold, primarily in the bioavailable Pi fractions (labile Pi, loosely bound Pi and non‐occluded Pi). Soil Po fractions and bioavailable Pi fractions were significantly greater under the >25 yrs field than in the <10 yrs field. The conversion of fields under vegetable production to forested buffer substantially decreased the levels of the bioavailable Pi and labile Po in the Gleysol after 8 yrs. Soil macro‐aggregates (>0.25 mm) had greater concentrations of bioavailable Pi fractions and of labile and moderately labile Po than did micro‐aggregates and silt and clay size components. Although more P was stored in recalcitrant P forms, a larger percentage of all P fractions was found in macro‐aggregates in these soils. Small active P‐enriched aggregates potentially intensify export of P from the vegetable soils by run‐off, and therefore, management practices must be optimized to enhance agricultural P efficiencies.     

Pros and cons of eliminating veld burning

Fire has been a factor of the environment in Africa since time immemorial and it is often caused by natural agencies such as lightning. It is maintained that there is much prejudice against veld burning, often ill‐founded. Fire has caused and maintained most of the world's grassland. When fire has been prevented plant succession has resulted in bush encroachment in the savanna and surrounding areas or in fynbos encroachment in others. Fire results in much old grass being wasted but, if this is not removed in some manner, the grazing deteriorates. Old grass can be removed by fire, mowing or grazing, using high protein supplements. The consequences of the different methods of removal, other than mowing, may be equally deleterious.     

Results of Long-term Experiments with Growing Flue-cured Tobacco (Nicotiana tabacum L.) in Monoculture and Different Types of Crop Rotations

In broadly conceived long-term experiments, tobacco was grown in monoculture and with different crop rotations. This paper presents results in terms of the yields achieved and the major yield components for the crops grown, and the proportion of particular tobacco quality classes obtained. In addition to tobacco monoculture (initially only fertilized and later also unfertilized) as the key crop, different types of crop rotations included, besides tobacco, the following crops: winter wheat, maize, soybean, oil-seed rape, and red clover. Experiments involved two 2-year and two 4-year crop rotations, and a 3-year, a 5-year, and a 6-year crop rotation. Experiments were set up on luvic semigley on multilayered Pleistocene sands. Average 10-year results suggest that there is an advantage of crop rotation over monoculture for tobacco leaf yields. The influence of different crop rotation types on yields of other crops was variable, tending towards higher values as the number of crops in rotation was increased. Values obtained for yield components should be considered from two angles: some of the values were primarily influenced by genetic factors, while others were influenced by ecological factors, including crop rotation as an overall biological buffer. With regard to quality classes (IB-III), the growing of flue-cured tobacco in crop rotation represents a great advancement relative to its growth in monoculture, even in a narrower crop rotation.     

Performance of height-classified Eucalyptus camaldulensis seedlings after one year in the field

Eucalyptus camaldulensis seedlings of 16–25, 26–35, 36–45 and 46–55cm height classes were used to examine the effect of planting stock quality on field performance. Survival, height and diameter (10cm above ground) were assessed 6 and 12 months after planting out. Significant height differences (P 0.05) existed between the 16–25 and 46–55cm height classes at 6 months age. There were no significant (P 0.05) differences in all these parameters at 12 months after planting out throughout the four height classes. It is concluded that the height classification approach for E. camaldulensis seedlings has very little value if the seedlings are in the 16–55cm height range. Until other nursery stock grading approaches are studied, 16–25cm seedling height class is as effective as the taller ones and would therefore be more economical for dry zone afforestation in Malawi.     

黄土高原刺槐根系垂直分布特征研究

在中国西北黄土高原地区，水分是树木生长发育的主要限制因子。根系分布特征由于反映了树木对环境条件的利用程度而具有更加特殊的生态意义。本研究选择阳坡和阴坡不同立地上年龄一致的刺槐林调查了根系分布特征。根系垂直分布特征的调查结果表明，在所有立地上，根系生物量随着深度的增加而降低，其中细根的分布深度大于粗根的分布深度。方差分析结果表明：不同立地上不同径级根系的分布特征也有明显的差别，粗根是差异存在的主要原因，阴坡立地上的根系生物量，特别是细根生物量大于阳坡立地上的。对根系消弱系数的分析结果表明，阴坡立地上的根系消弱系数大于0．982，而阳坡立地上的根系消弱系数小于0．982，说明阴坡市地上刺槐根系的生物量在深层土壤中的分布相对量更大一些。其中细根的根系消弱系数大于粗根的，这种根系分布特征有利于根系对深层土壤水分养分的吸收利用，进而促进树木地上部分的生长发育。图3表3参15。     

基于GIS和RS的广州市森林植被分类研究

首先对森林植被类型分类方法的研究概况进行了综述，提出采用植被指数进行植被分类，根据广州市中心城区植被冠层反射率数据，通过对多种植被指数的计算和分析，得出植被指数和植被类型的关系。进而对TM影像数据处理。得出广州市中心城区森林植被分类情况。     

浅谈科学发展观与和谐班级建设

中华民族的发展离不开教育，尤其是高等教育，高校是培养高素质人才的摇篮，在高校中，班级作为大学生组织的基本单元，是大学生自我教育、自我管理、自我服务的重要组织平台。将科学发展观的重要理论应用于和谐班级建设，可以进一步促进我国培养高素质人才。