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Understory light is essential to the growth and survival of plants, yet the light varies temporally and spatially within forest gaps. Measurement of understory light levels using light sensors is both time and labor intensive. Sunshine duration (SD) has a strong correlation with solar radiation and has been the variable most widely used for estimating solar radiation. The power of SD-based methods for estimating solar radiation lies in its ability to quickly estimate light levels. Although several calculation methods for SD within canopy gaps are available, all the methods oversimplify canopy gaps by classifying them as cylindrical or ellipsoid and thus have a relatively low level of accuracy. In this study we developed a calculation method for SD at any given point within natural canopy gaps and we used SD to estimate solar radiation within 12 canopy gaps on Mt. Taibai in China based on the Angström-Prescott model. We then evaluated the SD-based solar radiation by the total and direct solar radiation derived from a gap light index based on hemispherical photographs (HP). Finally, we analyzed the spatial-temporal characteristics of light levels within these 12 gaps by using the solar radiation derived from SD at hundreds of simulated points in each gap. Our results showed that (1) SD-based solar radiation was not statistically different from HP-based direct solar radiation and had a strong linear correlation with HP-based total solar radiation; (2) growing-season daily mean solar radiation within the 12 gaps varied from 0.08 to 13.28 MJ m−2 day−1 with an average of 4.13 MJ m−2 day−1; (3) solar radiation had a positive correlation with the ratio of the square root of the canopy gap area to the mean canopy height. This relationship was significant but solar radiation had no correlation with the canopy gap area; (4) among most gaps solar radiation was greatest in May while potential SD was longest in June 2008. From these results we can conclude that the SD-based method for estimating solar radiation developed in this study can quickly and accurately estimate light levels at any specified point within canopy gaps. SD-based solar radiation appears to be a good choice for studies on the spatial-temporal characteristics of gap light levels.  相似文献   
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四川省部分小麦新品系醇溶蛋白遗传多样性分析   总被引:14,自引:1,他引:13  
利用酸性聚丙烯酰胺凝胶电泳 (APAGE)对 2 0 0 1年参加四川省区试的 2 0个小麦新品系和 2个对照品种进行了醇溶蛋白基因位点的特异性检测 ,分析了不同品系 (种 )间醇溶蛋白带型的遗传差异。结果表明 ,2 2个小麦品系(种 )具有 2 2种带型 ,每个材料分离出 18~ 2 9条带 ,2 2个材料共分离出 5 6条带 ,其中 4 9条具有多态性 ,占 87 5 %。2 0个新品系中具有 1RS/ 1BL易位系标记性位点Gli B1l的有 11个 ,占供试新品系的 5 5 %。 2 2个材料间的遗传距离在 0 0 4 3~ 1 0 0间 ,平均值为 0 4 4 4 ;1RS/ 1BL易位系与非 1RS/ 1BL易位系间的遗传距离较大。基于遗传距离的聚类分析表明 :供试材料在遗传距离 0 5 0水平上明显聚为 4类。分析表明 ,供试四川小麦新品系具有较为广泛的基于醇溶蛋白带谱的遗传多样性。同时还探讨了供试材料中Gli B1l位点高频率存在的原因及进一步合理利用1B/ 1R易位系的可能性  相似文献   
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两个小麦-黑麦远缘杂交高代抗病株系的贮藏蛋白分析   总被引:1,自引:0,他引:1  
通过SDS PAGE、A PAGE方法对两个小麦 -黑麦远缘杂交高代抗病株系 98- 110 4、98- 917共 2 6个材料的高分子量谷蛋白亚基的组成、醇溶蛋白Gli B1l特异位点的有无分别进行了分析。结果表明 ,在这 2 6个材料的Glu A1、Glu B1、Glu D1位点上分别检测到了 2、3、2个等位基因 ,在每个位点上 ,出现频率最高的等位基因分别为Glu A1a(96 15 % )、Glu B1b(92 30 % )、Glu D1d(84 6 2 % )。Nei’s遗传变异系数H分析表明 :供试材料在Glu D1位点上变异最大 ,其次是Glu B1、Glu A1;其中株系 98- 110 4在Glu A1、Glu B1、Glu D1位点上的遗传变异系数H分别为 0、0 180、0 180 ,株系 98- 917在这 3个位点上的遗传变异系数H相应为 0 117、0 117、0 30 5。从高分子量谷蛋白亚基组成分析可知 ,此高代抗病株系高分子量谷蛋白亚基组合方式共有 5种 :(1、7+8、5 +10 )、(1、7+9、2 +12 )、(1、7+8、2 +12 )、(N、7+8、5 +10 )、(1、14 +15、5 +10 ) ;其中亲本A4 2 912类型 (1、7+8、5 +10 )所占比例最多 ,为80 77%。另外通过A PAGE方法检测出 4个具有亚基组成变异的材料 98- 110 4 - 9(1、7+9、2 +12 )、98- 917- 15(1、7+8、2 +12 )、98- 917- 2 7(N、7+8、5 +10 )、98- 917- 2 9(1、14 +15、5 +10 )均为 1RS/ 1BL易  相似文献   
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