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11.
Unbalanced data are a common problem in plant research based on designed experiments. Such data are often conveniently analysed using linear mixed models. Recent developments in mixed model theory have been implemented in major packages. This paper describes the use of the mixed procedure of the SAS System for the analysis of designed experiments. Special emphasis is given to the specification of options as depending on the assumed mixed model and on the unbalancedness in the data. In addition, we consider a compact representation of multiple comparisons for unbalanced data (letter display). Two small data sets are used to exemplify the methods. 相似文献
12.
H.-P. Piepho 《Journal of Agronomy and Crop Science》1998,180(4):193-213
The stability of yield is an important characteristic to be considered when judging the value of a cropping system relative to others. In the context of agricultural research, the analysis of yield stability has been largely confined to multienvironment trials of crop cultivars. This review emphasizes that methods for comparing the stability of cultivars can also be used for comparing different agronomic treatments in general, of which cultivars are but a special case. Throughout the paper, different agronomic treatments are referred to as cropping systems. Some of the methods useful for stability analysis of cropping systems are discussed and a brief review of applications of these methods is given. The paper puts different stability measures into a unifying mixed model perspective. 相似文献
13.
S. Orlandi E. Nucera E. Mosimann G. D'Adda D. Garzoli M. Bertossa M. Lonati G. Lombardi 《Grass and Forage Science》2017,72(1):154-162
Invasive grasses (especially Setaria pumila (Poir.) Roem. et Schult) increasingly threaten meadows and pastures as a consequence of human impact and climate change. We conducted a study in 2012 and in 2013 to better understand the growing cycle and the influence of S. pumila on forage quality of lowland meadows. We observed a rapid increase of S. pumila presence and phytomass on the southern side of the Alps across the growing season. We measured (i) above‐ground phytomass, with a modified Corral‐Fenlon method; (ii) botanical composition using the linear point quadrat method; and (iii) grassland chemical composition by NIRs (near‐infrared spectroscopy) analyses. To test the hypothesis that S. pumila summer growth is related to specific climatic conditions, meteorological data (temperature, precipitation and evapotranspiration) were collected from meteorological stations near the study sites. Total phytomass was sorted into S. pumila and other species. We used a generalized linear mixed models (GLMM) and found the abundance of S. pumila to be inversely correlated with rainfall and the presence of other species, but positively correlated with temperature increase. The increase of S. pumila above‐ground phytomass production was linked to a reduction of forage quality. 相似文献
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15.
发芽纸是种子发芽试验必需的材料。国内首次研制成的专用种子发芽纸具有吸水快、持水性好、韧度大、厚度适中等特点。该纸无毒性、幼根不易穿透,且成本低。它既可衬垫于发芽容器中,更宜作发芽纸卷。试用结果表明,它能广泛适用于农作物、蔬菜、牧草、瓜、豆类等各种种子的发芽试验。在植物种子科学研究和生产实际中,经常需要进行种子发芽试验,一般的种子发芽试验常采用纸张作为发芽床。为使种子正常发芽和便于检查发芽结果,要求发芽纸有良好的理化特性。对此,国际种子检验协会对种子发芽纸的质地、灰分、韧度和吸水性能等有明确的规定指标,如要求纸张有足够强度,在发芽试验操作中不致撕破;质地要通透多孔,但幼根不能穿入纸中。国外已有不少国家都生产有专用的种子发芽纸,而国内至今还没有一种专门供种子发芽用的纸张,长期以来使用的是普通滤纸、卫生纸、乃至黄草纸等代用品。这些纸张在协调种子发芽所需的水气条件方面存有不少缺陷,其质地、强度或吸水性等都达不到要求。为了填补国内这一空白,浙江农业大学种子科学中心和浙江民丰造纸厂造纸研究所自1987年开始进行种子发芽纸的研制。经过多次反复研制和测试,已研制成功一种种子发芽纸。它厚度适中,既可平垫于玻皿之中,又可用作发芽纸卷,且成本低于目前代用的普通滤纸。经数家种子部门试用,反应良好。此将发芽纸研制过程中生物学适用性测试的部分内容报告如下。 相似文献
16.
17.
鱼蛋白的综合利用途径2.酸贮液体鱼蛋白 总被引：5，自引：1，他引：5
酸贮液体鱼蛋白是开发低值鱼及水产加工废弃物中鱼蛋白的有效途径之一,本文就酸贮液体鱼蛋白的生产和使用状况进行了分析和讨论,并将鱼粉和酸贮液体鱼蛋白二者进行了比较。 相似文献
18.
The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg–1 fish·h–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g–1·ml–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min–1·g–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min–1·g–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated. 相似文献
19.
在干湿粮混合实验台上进行混合粮降水幅度△Ｍ与原粮水分Ｍ，热介质温度Ｔ及干湿粮混合比ｎ的关系研究。以玉米小麦为例，分析各参数对△Ｍ及温风去水和冷风去水两工艺对△Ｍ的影响。 相似文献
20.
采用苦槠裸根苗、容器苗在不同立地条件下与桂花、杉木、木荷进行混交造林试验,连续2 a的观测结果表明:苦槠容器苗的造林成活率、树高、地径生长量均比裸根苗高;Ⅰ级地苦槠的造林成活率、树高、地径生长量均比Ⅱ、Ⅲ级地高。说明营建苦槠人工林选择立地条件较好,采用容器苗造林较为适宜。 相似文献