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61.
Guillermo Trincado V. Raúl Quezada P. Klaus von Gadow 《Forest Ecology and Management》2003,180(1-3):443-451
The study compares two methods of stand table projection based on data from young Eucalyptus nitens (Maiden) plantations in Chile. The projected diameter distributions were estimated using the methods proposed by Nepal and Somers (1992) [For. Sci. 38 (1992) 120] and Cao and Baldwin (1999) [For. Sci. 45 (1999) 506]. The evaluation compared the observed and estimated diameter distributions for different projection intervals, using the Kolmogorov–Smirnov test and an error index called ‘relative discrepancy’. The evaluation showed that both methods are suitable for application in the Eucalypt plantations. However, the method proposed by Nepal and Somers proved to be more accurate, especially when the projection period extends over 4 years or more. Expected error and bias for the observed and estimated total and merchantable volumes at stand level were also evaluated. The observed error and bias were relatively low for both methods; however, some differences were detected when the volume distributions were analyzed at diameter class level. 相似文献
62.
麦秸还田及氮肥管理技术对水稻产量的影响 总被引:31,自引:0,他引:31
以水稻武香粳14和扬粳9538为材,大田设麦秸还田与不还田、不施氮肥、习惯施肥法(FFP)和基于叶绿素仪(SPAD)测定值的氮肥管理(SSNM)等处理。结果表明,SSNM较FFP氮肥施用量减少40.0%~41.7%,而产量平均增加3.81%。秸秆还田的较秸秆未还田的产量平均增加2.49%。氮肥的农学利用率、吸收利用率和生理利用率均以秸秆还田高于秸秆不还田处理。与秸秆未还田或FFP相比,秸秆还田和SSNM降低了生育前期的分蘖数、叶面积指数和干物质积累(但抽穗及以后差异较小);提高了茎蘖成穗率、结实期叶片光合速率和根系活力。说明秸秆还田和SSNM有利于生育后期群体光合生产和提高物质生产效率。秸秆还田和实地氮肥管理提高了氮收获指数和氮肥利用效率。对秸秆还田和SSNM的产量、生育特性及氮肥利用效率进行了讨论。 相似文献
63.
利用“永久F2”群体剖析玉米产量及其相关性状的遗传机制 总被引:4,自引:0,他引:4
利用RIL群体构建了一套包含441个杂交组合的玉米“永久F2”群体,通过253个SSR标记的等位基因频率分析,发现“永久F2”群体的遗传组成与基因频率与F2群体相似,理论上可以代替F2群体进行相关遗传研究。通过两年一点的田间试验,利用复合区间作图法对玉米产量及其3个主要构成因子进行了遗传分析。结果表明,玉米产量与穗长、穗行数及百粒重呈显著或极显著正相关,而穗长与穗行数和百粒重显著负相关。共定位3个产量QTL、8个穗长QTL,11个穗行数QTL和5个百粒重QTL。 相似文献
64.
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66.
籽粒硬度是影响小麦磨粉品质和食品品质的重要因素。利用单粒谷物特性测定仪、PCR扩增和核苷酸测序技术,对121份西藏地方品种进行籽粒硬度性状遗传多样性研究。结果表明:西藏品种籽粒硬度平均值为43.73%,硬度值大于60%的品种有43种,占35.5%;混合麦22个,占18.2%;软质麦56个,比例为46.3%。符合优质饼干硬度特性的品种有42种,达到34.7%。有5种硬度基因组合类型:野生型、PinaD1b、Pinb-D1b、Pinb-D1c、Pinb-D1p。野生型比例最高,占51.22%。Pinb-D1c次之,占21.31%,其余依次为Pinb-D1b、Pina-D1b、Pinb-D1p。各种组合类型的SKCS硬度值Pinb-D1cPina-D1bPinb-D1bPinb-D1p野生型。西藏小麦品种籽粒硬度性状遗传多样性的研究将为青藏高原以及其他地区的育种提供种质资源和理论依据。 相似文献
67.
基于Fluent的大豆脱粒机旋风分离器模拟与优化 总被引:1,自引:0,他引:1
为了对大豆脱粒过程中未脱净荚果进行有效的分选、回收并进行二次脱粒,在已设计的有吊桶旋风分离器基础上,利用Fluent软件对有、无吊桶2种模型进行对比试验,结果显示2种模型压降无明显差异,有吊桶旋风分离器分离效率更高。建立了吊桶长度、吊桶直径两因素同逃逸时间、损失率及压降的数学关系模型,模拟试验结果表明:吊桶直径主要影响螺旋上升气流速度,吊桶长度主要影响入口区域气流场分布,确定吊桶最佳参数为长度94mm,直径为196mm,以该参数改进的模型进行试验验证,结果表明损失率降低为2.2%。 相似文献
68.
Anette Moldestad Bernt Hoel Ulrike Böcker Shiori Koga Ellen Færgestad Mosleth Anne Kjersti Uhlen 《Journal of Cereal Science》2014
The aim of this study was to investigate effects of temperature during grain filling on gluten quality characteristics at a lower to moderate temperature range. Experiments with two wheat varieties grown in field covered by polypropylene tunnels during grain filling were performed in two seasons. Mean day temperature differences achieved within the tunnel were approximately 2–2.5 °C from the open to the closed end. There were significant effects of temperature on grain maturity time, thousand grain weight and protein content. The resistance to stretching of the gluten doughs increased with the increasing day temperatures. This was reflected in the proportion of unextractable polymeric proteins (UPP). The results suggest that increases in temperature within this temperature range affect the polymerization of polymeric proteins, giving higher molecular weights, and hence increased Rmax and stronger gluten. The two varieties differed in their response to temperature. In addition, there were seasonal variations in gluten functionality that may be associated with fluctuations in day temperatures between the seasons. 相似文献
69.
Nimesha Fernando Joe Panozzo Michael Tausz Robert M. Norton Glenn J. Fitzgerald Samuel Myers Marc E. Nicolas Saman Seneweera 《Journal of Cereal Science》2014
In order to investigate the intra-specific variation of wheat grain quality response to elevated atmospheric CO2 concentration (e[CO2]), eight wheat (Triticum aestivum L.)cultivars were grown at two CO2 concentrations ([CO2]) (current atmospheric, 389 CO2 μmol mol−1vs. e[CO2], FACE (Free-Air CO2 Enrichment), 550 ± 10% CO2 μmol mol−1), at two water levels (rain-fed vs. irrigated) and at two times of sowing (TOS1, vs. TOS2). The TOS treatment was mainly imposed to understand whether e[CO2] could modify the effects of timing of higher grain filling temperatures on grain quality. When plants were grown at TOS1, TKW (thousand kernel weight), grain test weight, hardness index, P, Ca, Na and phytate were not significantly changed under e[CO2]. On the other hand, e[CO2] increased TKW (16%), hardness index (9%), kernel diameter (6%), test weight (2%) but decreased grain protein (10%) and grain phytate (11%) at TOS2. In regard to grain Zn, Mn and Cu concentrations and some flour rheological properties, cultivar specific responses to e[CO2] were observed at both sowing times. Observed genetic variability in response to e[CO2] in terms of grain minerals and flour rheological properties could be easily incorporated into future wheat breeding programs to enable adaptation to climate change. 相似文献
70.
选用具有高产潜力的6个玉米杂交种,采用12万株/hm2的密度大田种植,研究高产玉米不同品种子粒灌浆特征的差异及其与粒重的关系。结果表明,6个玉米杂交种均可实现15 000 kg/hm2的高产水平。良玉66和中单909前中期灌浆速率高,且最早到达最大灌浆速率;灌浆速率下降慢的品种,成熟相对偏晚。品种间差异主要是灌浆速率和到达最大灌浆速率的时间不同,活跃灌浆期并没有明显差异。影响不同品种粒重的主要因素是线性灌浆期和缓慢灌浆期的灌浆速率。因此提高品种的线性灌浆期和缓增期灌浆速率可以增加粒重。在新疆伊犁春播玉米高产区,适宜的高产品种为中单909和良玉66。 相似文献