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31.
《Communications in Soil Science and Plant Analysis》2012,43(10):891-897
Abstract Soil tests should produce data useful for making accurate lime and fertilizer recommendations aimed at optimizing chemical conditions for plant growth or providing available nutrient levels sufficient for maximum yields. In order to attain these objectives, we believe, quicktest‐computed rates have to be made equivalent to actual values through a regression adjustment. Although it may not be most desirable to use this adjustment for each new population of soils, it may be worse to try to use a function derived from one group of soils on a second group not well represented by the first. 相似文献
32.
氧气对低地鸡蛋胚胎死亡和孵化率的影响 总被引:4,自引:0,他引:4
通过模拟常压低氧和高海拔增氧孵化试验,研究了氧气浓度对低地良种鸡蛋胚胎死亡率和孵化率的影响。死亡胚胎的分布用2阶段增长模型分析。模拟2900m海拔常压低氧孵化增加了胚胎后期死亡率,使孵化率降低到接近2900m海拔实际孵化率水平;2900m海拔全期增氧孵化可以有效降低前期和后期胚胎死亡率,大大提高孵化率;阶段增氧孵化也能不同程度提高孵化率,改变胚胎死亡分布,其中效果最好的为前期增氧组。结果说明低氧是影响2900m海拔鸡蛋孵化的最主要因素。 相似文献
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油菜内生生防菌BY-2在油菜体内的定殖与对油菜菌核病的防治作用 总被引:17,自引:0,他引:17
从油菜植株体内分离出的内生细菌BY-2,经过生物学鉴定为枯草芽孢杆菌(Bacillus subtilis)。用BY-2回接油菜,重新分离到具有BY-2相同形态特征和抑制病原真菌能力的内生菌株。油菜接种后的第10 d,体内的BY-2菌数达(2.24~9.02)×103 cfu/g鲜植株,25 d仍然保持在(3.13~8.59)×103 cfu/g鲜植株。BY-2与油菜核盘菌[Sclerotinia sclerotiorum(Lib.) de Bary]对峙培养可以形成直径为3.1 cm的抑菌圈;可使油菜核盘菌菌丝细胞浓缩变短,细胞壁破裂,原生质外溢,从而抑制真菌生长发育;同时还能抑制菌核的萌发,抑制率达60%~70%;在油菜离体叶片试验中,BY-2对菌核病的防治效果达100%。 相似文献
35.
半导体二极管(LED)是应用最为广泛的电子元件之一,本文介绍了半导体二极管(LED)的发光原理、特性、分类、检测、应用及发展前景。 相似文献
36.
本文介绍画法几何、工程制图时采用审题后将难题分解成相关与本题解题有关的小题,并采用提问及启发方法,将思路归纳到本题,随后解题.解题后可以根据本题意给予展开成相应的题目再深入讨论. 相似文献
37.
绥芬河滩头雅罗鱼孵化放流的初步试验 总被引:1,自引:0,他引:1
本文首次报道绥芬河滩头雅罗鱼大批量人工孵化放流。1989年5~6月,在绥芬河东宁河段采捕、利用(?)河亲鱼3037尾,采卵1867万粒,利用自然产卵场生态条件孵化放流的雅鱼1323万尾(全长6.5mm)。 相似文献
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The activities of main digestive enzyme (proteases, amylase and lipase) and animal husbandry (mainly growth and survival) were studied in common pandora Pagellus erythrinus larvae until 30 days after hatching (DAH). Three different illumination levels (10, 30 and 100 lx) were compared in triplicate and green water technique was carried out. At the end of the experiment, illumination did not affect neither survival nor growth except 10 lx treatment. Similarly, specific growth rate (SGR) was different in 10 lx treatment (p < 0.05), although no differences were found in group 30 and 100 lx treatments (p > 0.05). In all groups, trypsin and chymotrypsin specific activities were firstly detected on day 3 related with mouth opening and slightly increased until 20 and 25 DAH respectively, and after this date specific activities of those decreased. Although, there was a significant difference between 10 lx treatment and other experimental groups (p < 0.05), no differences were found in other treatments (p > 0.05). Pepsin was firstly detected on day 25 related with stomach formation and sharp increase was observed until 30 DAH and then slight decrease was measured from this date and no differences were found between all groups. Amylase was firstly determined on day 2 and increased to day 5. After this date, slight decreases were measured in all groups and continued until end of experiments. The highest specific activity of amylase was determined in 30 lx treatment and no significant differences were found between groups (p > 0.05). Lipase was firstly detected on day 4 and increased to day 10. Then, activity of lipase decreased until day 15 and increased again until 25 DAH. Slight decreases were found in all groups until day 30 and continued to end of experiments. No significant differences were detected among groups (p > 0.05).
Finally, the significant improvement in survival, larval development and specific enzyme activities of larvae were determined in 30 lx treated group. It is thought that this phenomenon is related to optimal keeping conditions provided by the medium illumination level for Pagellus erythrinus larvae. 相似文献