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91.
92.
土壤有机碳矿化是土壤向大气释放CO2的最大净输出途径,其与植被的净初级生产力的差值是判断生态系统碳“源”或“汇”的关键。采用室内模拟试验,在10、20、30℃ 3个温度条件下,研究施肥施用对柑橘果园土壤有机碳矿化的影响。结果表明:3种温度处理下,各施氮处理土壤有机碳矿化速率都表现为培养前期快速下降,培养后期保持相对稳定的趋势。在整个培养过程中,3种温度条件下各施氮处理的土壤CO2累积排放量为1328.25~2219.42 mg/kg,100 mg/kg(N4)处理土壤有机碳矿化量最大,CK处理最低,100 mg/kg(N4)和80 mg/kg(N3)2个高氮处理显著高于低氮50 mg/kg(N2)、30 mg/kg(N1)处理。土壤有机碳矿化速率随温度升高而增长,不同的土壤施氮条件下土壤有机碳矿化的温度敏感性不同,N2处理土壤有机碳矿化的温度敏感性最低,N4处理最高。柑橘果园土壤有机碳矿化受高施氮量影响较大,低施氮影响不明显。随着施氮量的增加土壤有机碳矿化的温度敏感性增加,氮肥施用和温度的共同作用可能使柑橘林向大气中排放的CO2增加。 相似文献
93.
The genetic relationship between popping expansion volume and two yield components in popcorn using unconditional and conditional QTL analysis 总被引:2,自引:0,他引:2
Y. L. Li Y. B. Dong D. Q. Cui Y. Z. Wang Y. Y. Liu M. G. Wei X. H. Li 《Euphytica》2008,162(3):345-351
Popping expansion volume (PEV) is the most important quality trait in popcorn, while its germplasm is inferior to normal dent/flint
corn in yield. In this study, 259 F2:3 families, developed from the cross between a dent corn inbred Dan232 and a popcorn inbred N04, were evaluated for their PEV,
grain weight per plant (GWP) and 100-grain weight (100 GW) in two environments. The genetic relationship between PEV and GWP,
and 100 GW on individual gene loci were evaluated using unconditional and conditional QTL mapping methods. In total, five,
one and three unconditional QTL were identified for PEV, GWP, and 100 GW, respectively. The positive alleles of all QTL for
PEV were from N04, while positive alleles of all QTL for GWP and 100 GW were from Dan232. In conditional mapping, one and
two QTL failed to be detected, and all four additional QTL were detected. Nevertheless, three QTL were identified, which controlled
PEV independently from GWP/100 GW. They seemed to be potential candidates in popcorn breeding to increase PEV without decreasing
GWP/100 GW. The results suggested that for significantly correlated traits, the conditional QTL mapping method could be used
to dissect the genetic interrelationship between traits at the level of individual QTL, as well as reveal additional QTL that
were undetectable by unconditional mapping. 相似文献
94.
95.
冷藏运输厢内流场和温度场协同控制 总被引:3,自引:0,他引:3
基于杨梅多孔介质特征推导热传导平衡方程,在冷藏车厢物理模型中分析了流场的流动特性,得到了车厢内各横、纵截面的流场和温度场的分布状况。采用协同控制车门右侧顶部隔热气帘风机,使其风向垂直于等温线方向间歇性定速运行,实车温度数据采集显示横截面最高温度由3.8℃降至1.67℃,在沿长度方向截面3层中温度标准差最大值为0.387。结果表明,仅调节冷风机转速无法有效改善温度均匀分布,根据等温线梯度方向和流线切线夹角开启隔热气帘风机协同调节风向,能够有效改善温度场均匀性分布程度。 相似文献
96.
97.
Y型果树动力学模型假设与分析 总被引:2,自引:0,他引:2
果树振动动力学模型分析是果树振动动态特性研究的基础。通过对Y型果树(变侧主干形果树)在不受外部载荷作用下的自由振动及受激振力作用下的受迫振动,进行动力学模型分析;在参考Y型果树形态特征的前提下,对模型进行简化,建立振动微分方程,并给出求解微分方程的方法,得到了Y型果树自由振动下振型函数的解析解表达式及系统的各阶响应。在此基础上,对模型进行等截面处理,建立Y形果树受迫振动的动力学模型,对其建立微分方程,给出求解微分方程的方法,得到了Y型果树受迫振动下振型函数的解析解表达式及受迫振动的各阶响应,为果树动态特性研究和果树振动采收机械的工作参数设定提供理论数据。 相似文献
98.
R.Q. Cannell 《Soil & Tillage Research》1985,5(2):129-177
The main features of the climate and soils of the main crop production areas of different countries in north-west Europe are outlined, and the main crops grown are summarised. The need for tillage is considered; provided that suitable conditions exist for germination, root growth is most likely to be influenced by mechanical impedance and aeration. Traditional tillage may not always be necessary and may hinder timely sowing of crops. Shallow tillage can facilitate planting a larger area of crops closer to the optimum dates in autumn and in spring, which also saves energy and labour.Research experience with reduced tillage over the last 20–25 years is reviewed. Shallow tillage has been as good as mouldboard ploughing at the traditional depth in most countries on a wide range of soil types, if weed control was satisfactory. Direct drilling has often proved satisfactory in the absence of crop residues for autumn sown crops (wheat, barley, oil-seed rape and beans) where drainage (and therefore soil aeration) was not limiting. Direct drilling has not generally been successful for spring sown crops. Direct drilling is inappropriate for root crops, but strip tillage for sugar beet may become practicable. Some research on soil conditions associated with these experiments is considered.Crop residues are a major constraint to shallow tillage or direct drilling of autumn sown crops. The limitations of reduced tillage due to inadequate weed control, wheel-traffic damage and unsatisfactory drainage are reviewed. The need for occasional deep loosening is also discussed. Where the amount of residues is small, much tillage may be unnecessary, except to relieve compaction by wheels; bed systems or wide-span gantries to avoid wheel damage could become practical developments for some crops. 相似文献
99.
Aggregates and gel network structure of globin hydrolysates 总被引:4,自引:0,他引:4
Liu XQ Ohtani T Nakajima M Xu QY Ogawa Y Sano Y 《Journal of agricultural and food chemistry》2001,49(5):2518-2522
A gel with excellent functional properties was prepared successfully using the hydrolysates of globin. In the present study, the structures of intermediate aggregates and gel network were observed directly with an electronic microscope. It was shown clearly that the intermediate aggregates were in a thin rod shape with a length of 130--140 nm, which was in good accordance with the results of the light scattering obtained in a previous study. The diameter of intermediate aggregates was 4--5 nm. Each unit of the intermediate aggregate was composed of beta-chain and peptide beta-1 in a ratio of 1:1. Its molecular weight was 26922 Da, and it had a diameter of 4.1 nm. The thin rod-shaped aggregates were formed with units through the hydrophobic interaction. The length of intermediate aggregate was >30--33 times the diameter. Furthermore, the cross-linked structure formed by peptide alpha-1 and the thin rod-shaped aggregates was also confirmed by the photography of the electronic microscope. These results supported the model proposed in previous papers as proper to depict exactly the formation and structure of the gel network of globin hydrolysates. 相似文献
100.
Short term soil priming effects and the mineralisation of biochar following its incorporation to soils of different pH 总被引:2,自引:0,他引:2
The aim of this work was to determine the magnitude of the priming effect, i.e. short-term changes in the rate (negative or positive) of mineralisation of native soil organic carbon (C), following addition of biochars. The biochars were made from Miscanthus giganteus, a C4 plant, naturally enriched with 13C. The biochars were produced at 350 °C (biochar350) and 700 °C (biochar700) and applied with and without ryegrass as a substrate to a clay-loam soil at pH 3.7 and 7.6. A secondary aim was to determine the effect of ryegrass addition on the mineralisation of the two biochars.After 87 days, biochar350 addition caused priming effects equivalent to 250 and 319 μg CO2-C g−1 soil, in the low and high pH soil, respectively. The largest priming effects occurred at the start of the incubations. The size of the priming effect was decreased at higher biochar pyrolysis temperatures, which may be a way of controlling priming effects following biochar incorporation to soil, if desired. The priming effect was probably induced by the water soluble components of the biochar. At 87 days of incubation, 0.14% and 0.18% of biochar700 and 0.61% and 0.84% of biochar350 were mineralized in the low and high pH soil, respectively. Ryegrass addition gave an increased biochar350 mineralisation of 33% and 40%, and increased biochar700 at 137% and 70%, in the low and high pH soils, respectively. Certainly, on the basis of our results, if biochar is used to sequester carbon a priming effect may occur, increasing CO2-C evolved from soil and decreasing soil organic C. However, this will be more than compensated for by the increased soil C caused by biochar incorporation. A similar conclusion holds for accelerated mineralisation of biochar due to incorporation of fresh labile substrates. We consider that our results are the first to unequivocally demonstrate the initiation, progress and termination of a true positive priming effect by biochar on native soil organic C. 相似文献