吉林西部新开水田生物有机肥筛选报告

为促进吉林省西部盐碱地水稻开发,筛选适宜当地新开田的生物有机肥品牌,做此试验。通过对水稻生育性状、产量、病害情况调查,总结出适合当地施用的两种生物有机肥料,以期为稻农正确选用有机肥产品提供科学依据。     

基于ANN-产量的耕地地力定量评价模型及其应用

管理水平近似条件下的作物实际产量是耕地地力等级的直观反映,在目前传统耕地地力评价AHP-模糊评判方法的基础上,尝试建立耕地地力的ANN-产量定量评价模型,并以山东省鱼台县为研究对象进行了实例研究.采用相对隶属度对各评价指标进行描述,以实际产量为目标输出标准,经神经网络训练得到评价模型.与传统方法相比,模型不仅能反映耕地地力评价的非线性特征,而且评价过程中不需要确定权重,消除了传统方法确定权值时人为因素的影响,增加了评价结果的客观性.通过与传统方法的对比发现,该模型评价结果与现行耕地地力评价方法的结果较为一致,为耕地地力的定量评价探索了一条新路.     

Millettia ferruginea from southern Ethiopia: Impacts on soil fertility and growth of maize

Growing agricultural crops under Millettia ferruginea (Hochst.) Baker, a tree that is endemic to Ethiopia, is an age-old practice in the country, but the beneficial effects of the tree on crops have not been scientifically quantified. To achieve this, four isolated and nearly identical Millettia trees growing on similar site conditions were selected and canopy coverage of each tree was divided into four radial transects. Four plots of 0.5 × 0.5 m were established on each radial transect at 0.5 to 1, 2.5 to 3, 4.5 to 5, and 6.5 to 7 m away from the tree bases. The control plot was established at 29.5 to 30 m. Composite soil samples from each of the four plots located at a comparable distance and at two soil depths, 0 to 10 and 20 to 30 cm, were collected and analyzed. The level of surface soil P, organic C, exchangeable base-forming cations and cation exchange capacity were all significantly higher (P < 0.000 to P < 0.015) under the trees than in the open field. Nutrient levels declined with depth and increasing distances from the tree trunk. Soil pH values did not show significant horizontal or vertical variations in all the soil samples analyzed. Maize plants grown on soils collected from underneath Millettia trees resulted in significantly better growth responses and higher dry matter yield as compared to the control (P < 0.001). Socioeconomic studies indicated that Millettia trees have good standing in the region both because of their desirable biological characteristics and because of their economic benefits.This revised version was published online in November 2005 with corrections to the Cover Date.     

杉木萌芽林林冠下营造木荷后土壤肥力状况的研究

通过对杉木萌芽林林冠下营造木荷后形成的混交林土壤肥力变化的测定与分析表明：与杉木纯林相比，混交林凋落物量较多，且易于分解，灰分养分较为丰富，土壤有机质含量较高，土壤结构稳定性好，土体疏松多孔，养分贮量大，供肥能力较强，这表明杉木萌芽林经改造形成稳定的混交林后土壤肥力状况有较大程度的改善。     

Comparison of fertility between the F1, F2 and anther derived lines in the crosses of indica/japonica and japonica/indica in rice (Oryza sativa L.)

Summary Response of anthers in in vitro culture was examined in the indica-japonica hybrids of rice (Oryza sativa L.). Significant genotypic differences were observed for callus induction and regeneration among the different interracial hybrids of indica-japonica races. Induction frequency of haploids ranged from 57.7 to 72.9 per cent and doubled haploid androgenic lines ranged from 27.1 to 42.3 per cent in the anther culture of the different hybrids. The indica-japonica hybrids recorded partial pollen grain and spikelet fertility in F1 (29.9 to 41.5% and 19.4 to 48.7% respectively) as well as in F2 (42.7 to 50.6% and 37.1 to 54.4% respectively). In contrast, the androgenic doubled haploid lines recorded significant increase and the pollen grain and spikelet fertility was 76.3 and 78.6 per cent respecitively. The results suggested that the sterility barriers for realising genetic recombinants and fixation of fertile homozygous lines in indica-japonica hybridization programme could be overcome through F1 anther culture technique.Abbreviations BAP Benzyl Amino Purine - 2,4-D 2,4-Dichlorophenoxy acetic acid - MS Murashige & Skoog medium - IAA Indole Acetic Acid     

The development of Raparadish (x Brassicoraphanus, 2n=38), a new crop in agriculture

Summary Raparadish, x Brassicoraphanus, the amphidiploid hybrid between Brassica rapa (syn. B.campestris) and Raphanus sativus (fodder radish) was made by Dolstra (1982). Primary hybrid plants grew vigorously, suggesting that the amphidiploid AARR might be useful as a fodder crop. Three populations of this new material were studied, with special attention to improvement of fertility and resistance to beet cyst nematode (Heterodera schachtii), whilst preserving genetic variability. For lack of progress one of the populations was abandoned after the fourth generation. The other two populations were observed through nine or ten generations. Apart from the last two generations mass selection for seed set was carried out on the basis of single plants. This led to a considerable increase in average seed production, without losing a wide variation for this trait. Thus more progress is being expected. Five cycles of mass selection for resistance to beet cyst nematodes led to a considerable increase of the level of resistance of both populations. The prospects of this new agricultural crop are discussed.     

Diversity of polyporous fungi (Polyporaceae) in northern boreal forests: effects of forest site type and logging intensity

The effects of forest site type and logging intensity on polyporous fungi were studied in subxeric, mesic and herb-rich forests and spruce mires in northern Finland. The species richness of polypores did not follow the fertility gradient of the site types, but was connected with the amount and diversity of coarse woody debris (CWD). The total number of species, and the numbers of indicator and threatened species were equal in subxeric pine forests and in more fertile spruce-dominated stands. The species composition of pine-dominated forests differed conspicuously from that of spruce-dominated site types. The total number of species was not affected by logging intensity, but no virgin forest species or threatened species were found on the sites where the number of cut stumps exceeded 150 stumps ha^?1. Increasing logging intensity decreased the number of polypore observations, indicating reduced substrate availability. The results stress the importance of protecting not only fertile spruce-dominated stands, but also poorer, pine-dominated forests, and sites with high and diverse CWD content.     

Ericaceous shrubs affect black spruce physiology independently from inherent site fertility

Vegetative layering of black spruce (Picea mariana [Mill.] B.S.P.) is the principal mode of regeneration for over mature, uneven-aged stands subject to long fire cycles (>300 years) in northeastern Québec, Canada. However, growth response of black spruce layers following disturbance by fire or harvest can be slow, due to a lag of morphological acclimation and potential nutrient limitation. This phenomenon can be accentuated if black spruce is associated with ericaceous shrubs such as Kalmia angustifolia and Rhododendron groenlandicum, which are known to interfere with conifer growth through direct and indirect competition. Such interactions can result in productive stands being converted to unproductive heathlands. It is not known whether these effects of ericaceous shrubs on black spruce are accentuated on low fertility sites, or if the impacts are independent of inherent site fertility. The objectives of this study were to evaluate the effects of ericaceous shrubs on both resource availability and on functional traits of black spruce advance regeneration across a gradient of site fertility (as defined by a site classification system). We monitored black spruce advanced regeneration physiology and soil nutrient availability over two growing seasons on a gradient of ecological site types in northeastern Québec (Canada). The eradication of competing vegetation favored higher soil NH₄-N and K availability, with increases of 67% and 28% compared to control conditions, respectively. Black spruce photosynthesis rate (A) and foliar K content were higher in plots where vegetation was eradicated, compared to the control plots, but did not vary among ecological site types. Photosynthesis did not appear to be limited by nitrogen or water relations, but was possibly limited by a deficit of foliar K⁺, probably resulting from reduced availability following sequestration by the ericaceous root systems. The absence of interaction between inherent site fertility and the eradication of ericaceous shrubs suggests that vegetation management of ericaceous shrubs must be planned independently from the ecological site type.     

三明格氏栲自然保护区土壤条件和肥力状况的研究

研究表明 ,天然格氏栲林下土壤的质地大都为重壤土至轻粘土 ,其土壤的全氮、有机质及速效养分含量都明显高于其他林分的土壤。天然格氏栲林下土壤进入红壤土壤成土过程的最高阶段 ,形成具有较高肥力的土壤     

Productivity of intensified crop—fallow rotations in the Trenbath model

Management of crop—fallow rotations should strike a balance between exploitation, during cropping, and restoration of soil fertility during the fallow period. The Trenbath model describes build-up of soil fertility during a fallow period by two parameters (a maximum level and a half-recovery time) and decline during cropping as a simple proportion. The model can be used to predict potential crop production for a large number of management options consisting of length of cropping period and duration of fallow. In solving the equations, the model can be restricted to sustainable systems, where fallow length is sufficient to restore soil fertility to its value at the start of the previous cropping period. The model outcome suggests that the highest yields per unit of land can be obtained by starting a new cropping period after soil fertility has recovered to 50–60% of its maximum value. This prediction is virtually independent of the growth rate of the fallow vegetation. The nature of the fallow vegetation (natural regrowth, planted trees, or cover crops) mainly influences the crop yield by modifying the required duration of fallow periods. Intensification of land use by shortening fallow periods will initially increase returns per unit land at the likely costs of returns per unit labor. When fallows no longer restore soil fertility to 50% of the maximum, overall productivity will decline both per unit land and per unit labor, unless external inputs replace the soil fertility restoring functions of a fallow.This revised version was published online in November 2005 with corrections to the Cover Date.