Colony development and physiological characterization of the edible blue-green alga, Nostoc sphaeroides (Nostocaceae, Cyanophyta)

The edible blue-green alga, Nostoc sphaeroides Kutzing, is able to form microcolonies and spherical macrocolonies. It has been used as a potent herbal medicine and dietary supplement for centuries because of its nutraceutical and pharmacological benefits. However, limited information is available on the development of the spherical macrocolonies and the environmental factors that affect their structure. This report described the morphogenesis of N. sphaeroides from single trichomes to macrocolonies. During the process, most structural features of macrocolonies of various sizes were dense maculas, rings, the compact core and the formation of liquid core; and the. laments within the macrocolonies showed different lengths and arrays depending on the sizes of macrocolonies. Meanwhile temperature and light intensity also strongly affected the internal structure of macrocolonies. As microcolonies further increased in size to form 30 mm macrocolonies, the colonies differentiated into distinct outer, middle and inner layers. The. laments of the outer layer showed higher maximum photosynthetic rates, higher light saturation point, and higher photosynthetic effciency than those of the inner layer; whereas the. laments of the inner layer had a higher content of chlorophyll a and phycobiliproteins than those of the outer layer. The results obtained in this study were important for the mass cultivation of N. sphaeroides as a nutraceutical product. (c) 2008 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.

碳离子辐照对甜高粱种子萌发及幼苗酶活的影响(摘要)(英文)

[目的]研究辐射能量为100MeV/u时不同剂量的碳离子辐照对2个甜高粱品种的种子萌发及几种酶活性的影响,为甜高粱品种的选育提供理论依据。[方法]对2个甜高粱品种雷伊和BJ0601种子进行辐射处理,能量为100MeV/u,辐射剂量分别为40、80、120、160和200Gy。甜高粱种子萌发后,统计发芽势和成苗率,并测定幼苗叶片中过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)和乳酸脱氢酶(LDH)的活性。[结果]随着剂量的增加,发芽势先升后降,而成苗率逐渐下降,呈"类肩形",发芽势和成苗率均为40Gy>80Gy>CK>120Gy>160Gy>200Gy;GSH-Px、CAT、SOD及LDH酶活性的总体趋势是随着剂量的增加先升后降,不同酶略有不同。GSH-PX活性,雷伊在160Gy和200Gy处活性达最大,而BJ0601在40Gy处活性达最大,这可能是因为雷伊的耐受能力较强。雷伊GSH-PX最大活性是对照的1.28倍,BJ0601是对照的1.30倍。CAT活性在160Gy处达最大,其中雷伊是对照的4.42倍(P(0.05),BJ0601是对照的2.13倍。SOD活性,雷伊在40Gy处活性最大,是对照的1.3倍;BJ0601在40Gy和120Gy处活性最大,是对照的1.2倍。LDH活性随着剂量增大而降低,而后又上升,有一个低峰位置,其中雷伊在120Gy处,BJ0601在80Gy处。BJ0601的酶活变化趋势较雷伊变化明显,且二者酶活都小于对照。这可能是LDH对辐射比较敏感,受到的损害较大的缘故。[结论]低剂量辐射促进了种子萌发,使酶的活性维持在较高的水平;高剂量时酶活下降,会抑制甜高粱的生长。

中国粮食生产的区域演进研究

Grain is one of the primary material conditions of the human survival and the grain production concerns the stability and development of the society directly. The regional patterns influence greatly on the grain production and the rational production distribution the regional comparative advantages and promotes grain production. This thesis starts with summarizing of the characteristics of changes and the overall trend of regional pattern of grain production of our country since 1949. Then it carries on network analyses to the factors, which influences the evolvement of regional grain production patterns of our country. And finally it gives some proposals to the grain production distribution in the future. The main content includes: Firstly, Reviewing the regional evolvement of grain production in our country, and analyzing the changes of the regional pattern of grain production of our country on the provincial scale and county scale separately, since 1949, especially since the reform and opening up policy. The main grain production areas are acting an important position in ensuring the national grain security, so this thesis analyses the main matter of the main grain production areas, forecasts the grain production situation in the future, and selects the Northeastern main grain production areas as the typical area to carry on the positive research. Secondly, this thesis analyzes the origin causes from two respects of natural and social economy of the regional evolvement pattern of grain production in China. Thirdly, based on the summarizing to the status of the regional pattern of the grain production, this thesis proposes the precept of the grain production distribution in the future in our country. Therefore, the areas of three major cereal crops, rice, wheat and corn, are confirmed on the basis of the comparative advantages. Finally, this thesis puts forward the security system of guaranteeing the grain production progressing steady in China. According to the above analysis, some conclusions have been achieved as follows: (1) The grain gross production gets on extricating itself from awkward position frequently while fluctuating greatly annually since 1949 in China. (2) Since the reform, its traditional regional pattern of grain production, the most of which was concentrated in the south area, has changed rapidly. China's center of gravity of grain production has shifted from the south to the north, and on the belts of latitude, the grain production has represented a trend of focusing to the middle area in China. (3) The main grain production areas play a very important role in ensuring China's food security. With their relative severe situation of the problems of agriculture, rural area and peasant, China has carried out a series of measures, which aim at improving the food-producing conditions of the main grain production areas, and enhancing the grain yields there. Under this condition, a forecast of the producing amount of the main grain production areas under the nation's self-supplying rate of over 95% shows that the increasing provision production in these areas can meet the demand of the country. (4) The natural and social economic factors influence together on the changes of the grain production regional pattern. Along with the state system transition and progress of agricultural science and technology, the regional pattern of grain production is affected heavier by the agricultural policy and technological elements. (5) The grain production will be concentrated to the middle province in the future, which economic development level being medium-sized; According to crop allocation, although the rice superiority production area located in the South, its comparative advantage index is little in some degree. Meanwhile, the wheat and corn superiority production areas are in the North mainly and its scale superiority and production level advantage are all comparatively obviously.

Evaluation for use efficiency of agricultural resources in grain production: A case study of Changshu, Taihe and Ansai in China

National Natural Science Foundation of China [70673097]