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21.
水分胁迫对玉米幼苗几种生理生化指标的影响及其与抗旱性的关系 总被引:9,自引:0,他引:9
通过对67个玉米品种幼苗在—6.2巴水分胁迫条件下生理生化变化的研究证明:水分胁迫时,玉米幼苗叶片的水势下降、电解质渗漏率增加、脯氨酸含量增加,抗坏血酸含量减少。并且在一定水势以下,电解质渗漏率、脯氨酸变化率对数、抗坏血酸变化率均与水势在极显著水平相关。因此我们认为三者是玉米幼苗抗旱性的较好指标。随着水势的下降,三者都有一个发生变化的临界点,该点水势分别为:抗坏血酸为—8巴,电解质渗漏率为—9巴,脯氨酸为—10巴。这说明干旱对植株的损伤顺序为:活性氧增加,抗氧化剂减少,生物膜损伤;代谢发生调整。同时也说明三个指标对干旱的敏感性为:抗坏血酸>电解质渗漏率>脯氨酸。 相似文献
22.
Osama M El-Husseiny Galal El Din M Abdul-Aziz & Rania S Mabroke 《Aquaculture Research》2008,39(3):291-300
Reducing feed cost has been a major issue in fish nutrition. Mixed protein schedules have been proposed as one of the methods successfully tested in many fish species to reduce feed cost. Meanwhile, the effect of dietary choline and betaine supplementation on fish performance was assessed. The aim of the present study was to investigate the effect of mixed protein schedules, combined with choline and betaine, on Nile tilapia performance. This experiment was conducted in a (4 × 3) factorial arrangement of treatments. Four mixed protein schedules were examined, in the presence of choline 0.3% and/or betaine 0.5%. The four mixed protein schedules were achieved by alternating diet (A; 31%CP) and diet (B; 24%CP) as follows: (6 days‐A), (5 days‐A/1 day‐B), (4 days‐A/2 days‐B) and (3 days‐A/3 days‐B). The results indicated that in the presence of betaine 0.5% and choline 0.3%, the optimal mixed protein schedule for tilapia was (3A/3B). Fish fed on the 4A/2B or 3A/3B schedules utilized protein more efficiently than fish fed on the (6A) schedule. Fish fed diets supplemented with betaine (b) only showed the highest energy retention. The lowest feed cost was recorded for fish fed on (3A/3B) in the presence of betaine 0.5% and choline 0.3% in fish diet. 相似文献
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Sheikh El Din Abdel Gadir El-Awad 《Soil & Tillage Research》2000,55(3-4):167-173
A water crisis that occurs in Sudan during winter due to the competition for water to irrigate cotton (Gossipium barbadense L.) and wheat (Triticum aestivum L.) and to produce hydroelectric power necessitates a search for efficient means and ways of conserving water. Tillage is one of the methods for soil moisture conservation. Experiments were conducted in Gezira, Sudan on a Vertisol to determine if tillage practices and the lengthening of irrigation interval beyond two weeks during the period October–February would conserve irrigation water and maintain cotton yields. The residual effects of cotton tillage systems on the following wheat were also evaluated. The cotton experiment was conducted in split plot design with three replications. Three irrigation treatments of two-, three- and four-week intervals during the period October–February were used as main plots. Six tillage treatments were used as split plots (combinations of disc ploughing, cultivator and ridging). Treatments were compared by measuring cotton plant height and yields. Significant decreases in cotton yield were found between the four-week, and the two- and three-week irrigation intervals. However, no significant differences in cotton yields between the two- and the three-week irrigation intervals were detected. The lengthening of irrigation interval from two to three weeks during the period of irrigation water crisis (October–February) would result in conservation of about 3000 m3 ha−1 of irrigation water. This corresponds to about 600 000 000 m3 of water for the cotton irrigated area in the Sudan. Therefore, the three-week irrigation interval during the period October–February has the potential for water conservation for cotton production in Gezira Vertisols, with the use of economical shallow tillage. The tested deep and shallow cotton tillage treatments did not have residual effects on the following wheat crop. 相似文献
25.
研究表明,苎麻生长发迹了5~20cm土层的温度状况,缩小了不同季节的最高与最低温度值的变幅。苎麻地在9月至次年3月的早晨8:00,5~20cm土层均具有升温效应,10月升温最高1.10℃;7~8月则有较强的降温效应,8月10cm土层隆温最多,为1.61℃。在下午14:00,4~9月苎麻地小区5~20cm土层表现显著的降温效应,高温的8月10cm土层的降温值平均高达3.19℃。苎麻地具有减少一年中土壤高于30℃和低于5℃温度的天数和累积量。 相似文献
26.
Maldonado LA Hamid ME Gamal El Din OA Goodfellow M 《Journal of the South African Veterinary Association》2004,75(3):147-149
Fifteen of 100 mastitic milk samples from goats suffering from mastitis were tentatively identified as members of the genus Nocardia on the basis of selected phenotypic and chemotaxonomic characteristics. Six of the 155 strains were confirmed as Nocardia farcinica by 16S rDNA gene sequencing and subsequent aligning with relevant actinomycetes found in electronic databases and 2 by other identification criteria. N. farcinica is a serious cause of mastitis with a significant prevalence (15%) among the examined goats. Efforts are needed to optimise and simplify isolation and identification methods. 相似文献
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A model for estimating how variability of biological parameters affects economic factors in an integrated turkey farm 总被引:1,自引:0,他引:1
Gregory Yom Din Shaike GiladZinaida Zugman 《Computers and Electronics in Agriculture》2011,75(1):100-106
Turkeys, as well as other poultry meat, are marketed as a healthier alternative to red meat. At the same time, the necessary investment in integrated turkey projects is 65% higher than for similar broiler projects. This explains the importance of rigorous evaluation of new turkey farms, including their sensitivity to biological parameters. We present a method of evaluating poultry projects that takes simultaneous variability of several biological parameters into account, using a bio-economic model, stochastic simulation, and an integrated turkey farm in Russia as a real-life example. The algorithm based on the Cholesky decomposition of the covariance matrix was used to generate a multivariate normal random vector of biological parameters. The bio-economic model takes into account simultaneous variability of major input biological parameters related to all stages of an integrated poultry farm: survival, hatchability, ratio of carcass weight to live weight, and number of eggs per layer. The highest variability of the output economic indices was estimated for internal rate of return: the coefficient of variation (CV) of this major economic index was approximately 240% of the CV of the input biological parameters. Such estimation can be used to analyze a project's economic risks, i.e., variability in production cost and profitability. 相似文献
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