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1.
ABSTRACT

A study to determine the quality of laminated veneer lumber (LVL) from samama wood (Anthocephalus macrophyllus) was carried out. Samama is a fast-growing endemic wood in eastern Indonesia. Factorial of three factors in RAL design was used to investigate the influence of veneer thickness, juvenile proportion and veneer lay-up to the quality of the resulted samama LVL. The veneer thicknesses were 1.5 and 3.0?mm. Juvenile proportions were arranged in five levels, which were 100% of juvenile veneer, 100% of mature veneer and combination of both juvenile and mature with juvenile proportion of 14%, 43% and 71%. Two veneer lay-up used in this study were loose side met loose side and tight side met loose side. The result of the study showed various specific gravity of LVL by different proportions of juvenile. This factor also affected the other physical traits. Shear strength of the LVL was equal to the solid wood, yet MOE and MOR were affected by juvenile proportion and veneer lay-up. LVL developed from 100% of mature veneer exhibited the highest MOE and MOR, yet no significant difference was noted in MOE and MOR between LVL 100% of juvenile and other tested juvenile proportions.  相似文献   
2.
为促进陕北丘陵沟壑区山地苹果的优质高效生产,本研究将传统稀植果园中主要采用的主干疏层形改造为小冠疏层形、纺锤形或圆柱形、高干开心形和开心形,测定不同树形的树冠透光率、树冠大小、一年生枝和结果枝的数量及组成比例、果实产量和品质等指标,并估算其产值。结果表明:与对照主干疏层形相比,高干开心形和开心形的树冠大而扁,树冠透光率较高。开心形的叶丛枝和短枝占全树枝条的61.21%,树势中庸偏上;主干疏层形、小冠疏层形和高干开心形的叶丛枝和短枝占全树枝条的70.00%以上,树势较弱。开心形的短果枝占结果枝的60.68%,中果枝占28.67%,利于连年优质丰产;主干疏层形的短果枝占结果枝的85.00%,中果枝仅占8.79%,易形成隔年结果。不同树形的果实产量以主干疏层形的最高,其次为开心形;果实品质、均匀度和价格均以开心形的最高,主干疏层形的最低;经济产值以开心形的最高,其次为主干疏层形,高干开心形的最低。综上,建议将陕北丘陵沟壑区山地稀植苹果园的主干疏层形改造为开心形。  相似文献   
3.
The breadmaking quality of wheat is affected by the composition of gluten proteins and the polymerisation of subunits that are synthesised and accumulated in developing wheat grain. The biological mechanisms and time course of these events during grain development are documented, but not widely confirmed. Therefore, the aim of this study was to monitor the accumulation of gluten protein subunits and the size distribution of protein aggregates during grain development. The effect of desiccation on the polymerisation of gluten proteins and the functional properties of gluten were also studied. The results showed that the size of glutenin polymers remained consistently low until yellow ripeness (YR), while it increased during grain desiccation after YR. Hence, this polymerisation process was presumed to be initiated by desiccation. A similar polymerisation event was also observed when premature grains were dried artificially. The composition of gluten proteins, the ratios of glutenin to gliadin and high molecular weight-glutenin subunits to low molecular weight-glutenin subunits, in premature grain after artificial desiccation showed close association with the size of glutenin polymers in artificially dried grain. Functional properties of gluten in these samples were also associated with polymer size after artificial desiccation.  相似文献   
4.
ABSTRACT

The content of macronutrients in potato tubers arouses interest because of their substantial consumption in the world and significant role in elements' budget in human diet. The research objective has been to evaluate the content of macronutrients in tubers of potatoes grown in different systems of crop production in Poland. In 2012–2014, an experiment was conducted to test potato cultivation in three-crop production systems: conventional, integrated and organic. In each of the six-field crop rotation systems, there were five potato cultivars classified into different earliness groups. The following macronutrients in dry mass of potato tubers were determined: N, P, K, Ca, Mg, Na, S and Cl, and the various ratios between them were calculated. The research carried out proved that potatoes production systems affect the chemical composition of tubers, which is additionally modified by whether condition and genetic features of cultivars. Potato tubers from organic farming contained by about 20% less N than tubers from conventional or integrated systems. Potato tubers from organic production system displayed lower content of Ca and Na in comparison with the conventional and integrated systems. The least of P and S were detected in tubers of the potatoes grown conventionally.  相似文献   
5.
土壤团聚体的数量和质量直接影响着土壤性质和有机碳固存。研究长期不同施肥措施及复垦年限对采煤塌陷区土壤团聚体的重量分布比例及其稳定性的影响,为该区域的农业生产和土壤质量提升提供科学依据。采集复垦6年和11年定位试验不同施肥处理耕层土样,选取不施肥(CK)、平衡施氮磷钾肥(NPK)、单施有机肥(M)、有机无机肥配施(MNPK)4个处理,利用干筛法和湿筛法获得4种粒径的团聚体/粉黏粒组分(> 2 mm、0.25-2 mm、0.053-0.25 mm和< 0.053 mm),用> 0.25 mm团聚体含量(R0.25)、平均重量直径(MWD)、团聚体破坏率(PAD)和土壤不稳定团粒指数(ELT)表示团聚体的稳定性,并测定了土壤有机碳含量。结果表明:复垦年限对土壤团聚体的含量及稳定性影响产生了显著影响。干筛条件下,复垦6年和11年均显著降低了各处理0.053-0.25 mm团聚体和< 0.053 mm组分的含量,降幅分别为68.39%-87.37%、69.63%-78.32%(6年)和90.01%-93.68%、78.29%-83.93%(11年);湿筛条件下,复垦11年显著提高了各处理> 2 mm团聚体的含量,增幅达473.35%-645.16%,但是显著降低了0.053-0.25 mm团聚体的含量,降幅为43.67%-57.54%。土壤团聚体的稳定性也随着复垦年限的增加而逐渐增强,表现为DR0.25、WR0.25和MWD值呈增加趋势,而PAD和ELT值呈降低趋势。土壤有机碳含量与DR0.25、WR0.25、MWD水稳性呈极显著正相关关系,而它与PAD和ELT呈极显著负相关关系。本研究表明,该区域连续复垦11年提高了土壤大团聚体的含量而伴随着微团聚体含量的显著减少,导致土壤结构越来越稳定。它对提高采煤塌陷区复垦土壤肥力、改善土壤结构效果最佳。  相似文献   
6.
Red clover (Trifolium pratense) grown in mixtures with grasses often constitutes a lower proportion of total yield in spring than in summer growth. A more even red clover proportion between the harvests would benefit forage quality and management at feeding. We investigated whether inclusion of early versus late‐maturing red clover varieties could reduce this disproportionality. In a two‐year field trial harvested three times per season, each of six red clover varieties was grown in two grass mixtures. Rate of phenological development did not differ during spring growth, but did so in regrowth after first and second cuts. Here, the earliest varieties constituted the highest proportion. At all harvests, the early varieties had lower crude protein concentrations and a higher content of neutral detergent fibre (NDF) and indigestible NDF than the late varieties. Clover proportion was higher in swards with a mixture of timothy and meadow fescue than in swards with perennial ryegrass during the first year and lower in the second year. It is concluded that developmental rate should be explored further as a key character for red clover competiveness in spring growth of rapidly elongating grasses.  相似文献   
7.
Tall fescue is the main perennial grass of the pastures of the temperate region of Argentina. However, after flowering in spring, tall fescue loses productivity and quality. Based on this, the objective of this work was to evaluate the effects of different post‐grazing mechanical cutting managements on the forage mass, leaf proportion, stocking rate, liveweight gain and liveweight production of tall fescue pastures. The treatments were post‐grazing mechanical cutting at anthesis (FC), post‐grazing mechanical cutting throughout spring and summer (SSC), and no post‐grazing mechanical cutting (NC). The experiment was performed from 2011 to 2014 in Argentina. The greatest and lowest forage mass were determined in September–November and May–September respectively. The leaf proportion of the SSC treatment was greater than that of the NC treatment, except in September–November. NC had higher stocking rate and lower liveweight gain than SSC, and neither NC nor SSC differed from FC. The liveweight production of the treatments was characterized by a trade‐off between stocking rate and liveweight gain. We conclude that FC is an attractive management because, with a single post‐grazing cutting, swards remain productive and leafy.  相似文献   
8.
以番茄品种"福美十号"为材料,采用随机区组试验设计,研究不同基质配比对番茄幼苗生长与叶片叶绿素荧光参数的影响。结果表明:采用A3[V(草炭)∶V(玉米秸秆)∶V(牛粪)∶V(食用菌下脚料)∶V(蛭石)=1∶2∶0.5∶0.5∶1]的基质配比,幼苗在出苗率、株高、茎粗、叶片数和根冠比等性状上表现最优,分别为98.25%、44.60 cm、0.50 cm、9.12片与7.95;叶片光系统Ⅱ(PSIⅡ)原初光能转化效率(Fv/Fm)与PSⅡ潜在活性(Fv/Fo)的值在幼苗生长前期、中期和末期也均为最高,Fv/Fm值分别为0.82、0.74和0.79,Fv/Fo值分别为3.92、2.97和3.23;其叶片内丙二醛(MDA)含量最低为6.02μmol/g,其根系活力最强、超氧化物歧化酶(SOD)、过氧化物酶(POD)与可溶性蛋白含量等指标最高,分别为158.26μg/(g·h)、386.23 U/g、6.26 U/(g·min)和0.203 mg/g,显著高于其他处理。说明采用处理A3的基质配比更适宜于番茄幼苗的生长。  相似文献   
9.
基于25年定位试验,设置6个大田试验处理(CK,不施肥;NPK,常规施用化肥;1/4M+3/4NPK,25%有机肥替代化肥;1/2M+1/2NPK, 50%有机肥替代化肥;M,100%有机肥替代化肥;MNPK, 100%化肥+100%有机肥),研究了长期有机肥无机肥配施对水稻氮素吸收和利用的影响。结果表明,水稻地上部N素总积累量与产量大小均表现为MNPK>1/4M+3/4NPK> NPK>1/2M+1/2NPK>M>CK,与NPK处理相比,MNPK和1/4M+3/4NPK处理的地上部氮素总积累量增加20.11%~27.86%、产量增加2.04%~12.42%。各处理花前N素转运量对籽粒贡献率(69.54%~84.60%)显著高于花后积累量对籽粒贡献率(15.40%~30.46%),花前N素积累是水稻植株N素的主要来源。1/4M+3/4NPK处理的氮肥偏生产力及氮收获指数均高于NPK处理,分别提高16.42%、10.29%。有机无机肥配施比单施化肥处理显著改善了稻米品质,提高了籽粒氨基酸含量,其中,非必需氨基酸含量是必需氨基酸含量的2倍左右。长期施肥条件下,25%有机肥替代化肥处理在化肥减施基础上,可以提高肥料利用率、促进水稻养分吸收,是黄壤性水稻土地区实现水稻增产、品质提升的最佳施肥措施。  相似文献   
10.
【目的】 研究氮磷钾配施对平欧杂交种榛果实发育时期光合特性和产量的影响,为提高平欧杂种榛产量、改善品质提供科学参考。【方法】 以8年生新榛1号为材料,采用“3414”田间肥料效应试验,测定不同施肥配比条件下榛子果实发育时期的叶片光合特性和产量。【结果】 (1)在土壤中等条件下,施用适量的N肥可以提高新榛1号果实坐果期(N纯量<0.71 kg/株)、速生生长期(N纯量<0.95 kg/株)、脂化期(N纯量<0.89 kg/株)和成熟期(N纯量<0.66 kg/株)的净光合速率(Pn);施用适量P肥可以提高果实脂化期(P纯量<0.29 kg/株)的净光合速率;施用适量K肥可以提高果实速生生长期(K纯量<0.25 kg/株)的净光合速率。(2)N肥与P肥的交互作用(N×P)可以提高果实速生生长期的净光合速率,但会降低新榛1号果实坐果期、脂化期、成熟期的净光合速率;N肥与K肥的交互作用(N×K)会降低果实速生生长期、脂化期的净光合速率;P肥与K肥的交互作用(P×K)会降低果实成熟期的净光合速率。【结论】 平欧杂种榛果实发育时期N肥、P肥、K肥施肥(纯量)分别为0.81 、0.23 和0.19 kg/株。经换算,尿素、重过磷酸钙、硫酸钾施肥量分别为1.75、0.50 和0.37 kg/株。  相似文献   
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