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101.
通过对不同青贮玉米品种群体光合性能指标的研究结果表明,不同青贮玉米品种叶面积指数、光合势、群体生长率在整个生育期均呈单峰曲线变化,峰值出现在散粉至乳熟期间,因不同品种而异。净同化率则呈“马鞍”型曲线变化。多分蘖品种科试1号、植株高大品种东陵白与农大647在生育期间叶面积指数和光合势均较高,东陵白生育前、中期群体生长率显著高于其它品种,且高值持续时间较长,这是其生物产量高的生理基础。生产中,采取合理栽培措施,克服此类品种植株高大、个体繁茂、群体郁蔽导致植株病害和倒伏严重的不足,可实现青贮玉米群体生物产量的进一步提高。 相似文献
102.
Impact of low-molecular-weight organic acids on the availability of phenanthrene and pyrene in soil 总被引:1,自引:0,他引:1
Wanting Ling Yanzheng Gao Xuezhu Zhu Bingqing Sun 《Soil biology & biochemistry》2009,41(10):2187-2195
The impact of low-molecular-weight organic acids (LMWOAs) on the availability of phenanthrene and pyrene was investigated using laboratory batch assays. Experiments were conducted with two types of soil with different organic contents. The LMWOAs used were citric and oxalic acid. A mild solvent extraction procedure and a sorption-desorption experiment were used to predict the availability of phenanthrene and pyrene. Results showed that the extractable amounts of phenanthrene and pyrene in both soil types increased with increased citric or oxalic acid concentration. Citric acid addition promoted phenanthrene and pyrene extraction to a greater degree than oxalic acid. Compared with freshly spiked soils, the extractable amounts of phenanthrene and pyrene with the addition of LMWOAs decreased significantly after 60 days of cultivation. Soils with higher values of soil organic carbon content (foc) showed decreased phenanthrene and pyrene availability after the addition of LMWOAs. The sorption and desorption results also demonstrated the enhanced availability of PAHs with LMWOA addition. Phenanthrene sorption could be described using a linear model, regardless of the addition of LMWOAs. The simulated distribution constants (Kd) for phenanthrene sorption decreased significantly with the addition of LMWOAs. In contrast, phenanthrene desorption clearly increased with the addition of LMWOAs. These results suggest that the availabilities of phenanthrene and pyrene can be increased with the addition of suitable LMWOAs. 相似文献
103.
Response of labile organic C and N pools to plastic film removal from semiarid farmland soil 下载免费PDF全文
S. S. Luo L. Zhu J. L. Liu L. D. Bu S. C. Yue Y. F. Shen S. Q. Li 《Soil Use and Management》2016,32(4):535-542
To examine the effects of plastic film removal on grain yield and soil organic matter (SOM), a spring maize (Zea may L.) field experiment was conducted for 5 yr at Changwu Agricultural and Ecological Experimental Station of Northwest China. Compared with traditional plastic film mulching during entire growing stages (FM), plastic film removal at the silking stage (RM) resulted in a 6.3% higher average maize yield. Under the RM treatment, soil organic carbon and total nitrogen significantly increased after the 5‐yr cultivation in the 0‐ to 20‐cm layer. Significant increases in extractable organic C (EOC), KMnO4‐oxidizable C (KMnO4‐C) and C management index (CMI) in the 0‐ to 20‐cm layer, and light fraction organic C and EOC in the 20‐ to 40‐cm layer were observed in response to plastic film removal after the 1‐yr treatment; the responses were more significant after 5 yr. Under the RM treatment, significant increases in microbial biomass C, light fraction organic N, extractable organic N, KMnO4‐C and CMI were also observed after five years in the 20‐ to 40‐cm layer. Moreover, KMnO4‐C and EOC were much more sensitive than other labile SOM fractions to the application of RM, even after only 1 yr of cultivation. Therefore, compared with mulching for the whole growing season, plastic film removal at the maize silking stage is an effective option for increasing yields and enhancing SOM concentration and soil sustainability in the regions with semiarid monsoon climates that have sufficient rainfall during maize reproductive stages. 相似文献
104.
提高天然气流量计量的准确度 总被引:3,自引:1,他引:3
叙述了天然气计算技术的现状及发展趋势,分析了孔板流量计在天然气工业应用中存在的问题,指出了提高天然气流量计量准确度的措施,提出了解决孔板开孔直角入口边缘尖锐度钝化和测量范围窄等问题的新思路。 相似文献
105.
106.
Oz Barazani Einav Mayzlish-Gati Dikla Lifshitz Rivka Hadas Alexandra Keren-Keiserman Sivan Golan Tomer Faraj Alon Singer Andrey Beerman Avi Perevolotsky 《Genetic Resources and Crop Evolution》2017,64(1):1-5
The ex situ collection of the Israel Plant Gene Bank (IGB) aims to encompass the rich local flora and its genetic diversity with an emphasis on crop wild relatives. However, to properly establish a core collection, collection efforts must be prioritized and strategized. We previously classified local plant genetic resources into four priority groups that assisted in strategizing the collection activities. The following years of intensive collection activity yielded over 4200 banked accessions. However, these do not necessarily represent the distribution range of the target species for collection (TSC) and consequently, their genetic diversity. To best cover the latter, the collecting area was divided into botanical districts and the magnitude of the collection was determined according to prioritization group, e.g., a wild relative of an agricultural crop with a vast distribution range should be represented by a larger number of banked accessions than one with a smaller range. Continuous evaluation of specific needs shapes the collection scheme of the IGB to maximize collection efforts, better represent the presumed genetic diversity of TSC, and establish its core collection. 相似文献
107.
108.
氮肥去向的研究--Ⅰ.稻田土壤中氮肥的去向 总被引:4,自引:0,他引:4
氮肥施入土壤后的去向,直接关系到作物增产和环境保护,是农业和环境科学研究中的基本资料。对氮肥去向的研究,以在田间条件下进行的意义比较大。因此,1978-1980年,我们在华东地区三种不同土壤上,采用田间微区15N示踪的方法,分别测定了施用于水稻和小麦的几种常用氮肥的去向,并以尿素为重点,研究了施肥方法、施肥时期、土壤水分状况以及硝化抑制剂等对氮肥去向的影响。所得结果将分别整理。本文是稻田试验方面的初步总结。 相似文献
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