Effects of loading rate on root pullout performance of two plants in the eastern Loess Plateau,China

Root pullout performance of plants is an important mechanical basis for soil reinforcement by plant roots in the semi-arid areas.Studies have shown that it is affected by plant factors(species,ages,root geometry,etc.)and soil factors(soil types,soil moisture,soil bulk densities,etc.).However,the effects of loading rates on root pullout performance are not well studied.To explore the mechanical interactions under different loading rates,we conducted pullout tests on Medicago sativa L.and Hippophae rhamnoides L.roots under five loading rates,i.e.,5,50,100,150,and 200 mm/min.In addition,tensile tests were conducted on the roots in diameters of 0.5-2.0 mm to compare the relationship between root tensile properties and root pullout properties.Results showed that two root failure modes,slippage and breakage,were observed during root pullout tests.All M.sativa roots were pulled out,while 72.2%of H.rhamnoides roots were broken.The maximum fracture diameter and fracture root length of H.rhamnoides were 1.22 mm and 7.44 cm under 100 mm/min loading rate,respectively.Root displacement values were 4.63%(±0.43%)and 8.91%(±0.52%)of the total root length for M.sativa and H.rhamnoides,respectively.The values of maximum pullout force were 14.6(±0.7)and 17.7(±1.8)N under 100 mm/min for M.sativa and H.rhamnoides,respectively.Values of the maximum pullout strength for M.sativa and H.rhamnoides were 38.38(±5.48)MPa under 150 mm/min and 12.47(±1.43)MPa under 100 mm/min,respectively.Root-soil friction coefficient under 100 mm/min was significantly larger than those under other loading rates for both the two species.Values of the maximum root pullout energy for M.sativa and H.rhamnoides were 87.83(±21.55)mm•N under 100 mm/min and 173.53(±38.53)mm•N under 200 mm/min,respectively.Root pullout force was significantly related to root diameter(P<0.01).Peak root pullout force was significantly affected by loading rates when the effect of root diameter was included(P<0.01),and vice versa.Except for the failure mode and peak pullout force,other pullout parameters,including root pullout strength,root displacement,root-soil friction coefficient,and root pullout energy were not significantly affected by loading rates(P>0.05).Root pullout strength was greater than root tensile strength for the two species.The results suggested that there was no need to deliberately control loading rate in root pullout tests in the semi-arid soil,and root pullout force and pullout strength could be better parameters for root reinforcement model compared with root tensile strength as root pullout force and pullout strength could more realistically reflect the working state of roots in the semi-arid soil.

Simulating leaf net CO_2 assimilation rate of C_3 & C_4 plants and its response to environmental factors

Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.

Simulating leaf net CO2 assimilation rate of C3 & C4 plants and its response to environmental factors

Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.

Response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 in Northeast China

The objective of this study was to identify the response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 and grown extensively in Northeast China.Twenty-one hybrids were grown for 2 years in Northeast China at densities of 30,000,52,500,75,000,and 97,500 plants ha^(-1)and N application levels of 0,150,300,and 450 kg N ha^(-1).Irrespective of density or nitrogen application rate,grain yields both per plant and per unit area were significantly higher for newer than older hybrids.As plant density increased from 30,000 to 97,500 plant ha^(-1),yield per plant of 1970 s,1980 s,1990 s,and 2000 s hybrids decreased by 50%,45%,46%,and 52%,respectively.The response of grain yield per unit area to plant density was curvilinear.The estimated optimum plant densities were about 58,000,49,000,65,000,and 65,000 plants ha^(-1)for hybrids released in the 1970 s,1980s,1990 s,and 2000 s,respectively.The theoretical optimum densities for the hybrids released from the 1970 s to the 2000 s increased by 1750 plants ha^(-1)decade^(-1).Nitrogen fertilization significantly increased grain yields per plant and per unit area for all hybrids.The theoretical optimum N application rates for high yield for hybrids released in the 1970 s and 1980 s were about 280 and 360 kg ha^(-1),and the hybrids from the 1990 s and 2000 s showed highest yield at 330 kg ha^(-1)N.No significant difference in the grain yields of 2000 s hybrids between the N levels of 150 to 450 kg ha^(-1)was found.Significant yield gains per plant and per unit area were found,with average increases of 17.9 g plant^(-1)decade^(-1)and936 kg ha^(-1)decade^(-1)over the period 1970–2010,respectively.Yield gains were attributed mainly to increased yield per plant,contributed by increases in kernel number per ear and1000-kernel weight.The rates of lodging and barren plants of newer hybrids were significantly lower than those of older ones,especially at high plant density.

Increased plant density and reduced N rate lead to more grain yield and higher resource utilization in summer maize

Planting at an optimum density and supplying adequate nitrogen（N） to achieve higher yields is a common practice in crop production, especially for maize（Zea mays L.）; however, excessive N fertilizer supply in maize production results in reduced N use efficiency（NUE） and severe negative impacts on the environment. This research was conducted to determine the effects of increased plant density and reduced N rate on grain yield, total N uptake, NUE, leaf area index（LAI）, intercepted photosynthetically active radiation（IPAR）, and resource use efficiency in maize. Field experiments were conducted using a popular maize hybrid Zhengdan 958（ZD958） under different combinations of plant densities and N rates to determine an effective approach for maize production with high yield and high resource use efficiency. Increasing plant density was clearly able to promote N absorption and LAI during the entire growth stage, which allowed high total N uptake and interception of radiation to achieve high dry matter accumulation（DMA）, grain yield, NUE, and radiation use efficiency（RUE）. However, with an increase in plant density, the demand of N increased along with grain yield. Increasing N rate can significantly increase the DMA, grain yield, LAI, IPAR, and RUE. However, this increase was non-linear and due to the input of too much N fertilizers, the efficiency of N use at NCK（320 kg ha^（–1）） was low. An appropriate reduction in N rate can therefore lead to higher NUE despite a slight loss in grain production. Taking into account both the need for high grain yield and resource use efficiency, a 30% reduction in N supply, and an increase in plant density of 3 plants m^（–2）, compared to LD（5.25 plants m^（–2））, would lead to an optimal balance between yield and resource use efficiency.

Effects of Plant Density and Nitrogen Application Rate on Grain Yield and Nitrogen Uptake of Super Hybrid Rice

The nitrogen uptake, yield and its components for two super-high-yielding hybrid rice combinations, Guodao 6 and Eryou 7954 were investigated under different plant densities （15, 18, and 21 plants/m^2） and different nitrogen application rates （120, 150, 180, and 210 kg/hm^2）. The experiment was conducted on loam soil during 2004-2006 at the experimental farm of the China National Rice Research Institute in Hangzhou, China. In these years, the two hybrid rice cleady showed higher yield at a plant density of 15 plants/m^2 with a nitrogen application rate of 180 kg/hm^2. Guodao 6 produced an average grain yield of 10 215.6 kg/hm^2 across the three years, while the yield of Eryou 7954 was 9 633.0 kg/hm^2. With fewer plants per unit-area and larger plants in the plots, the two hybrid rice produced more panicles per plant in three years. The highest nitrogen uptake of the two hybrid rice was at a plant density of 15 plants/m^2 with a nitrogen application rate of 180 kg/hm^2. Further increasing nitrogen application rate was not advantageous for nitrogen uptake in super-high-yielding rice under the same plant density.

Use of Several Plant Materials and Chemicals to inhibit Soil Urease Activity and Increase Nitrogen Recovery Rate of Urea by Plant

Effects of residues of 9 plants, lemon eucalyptus (Eucalyptus citriodoraHook., P_1), robust eucalyptus (E. robusta Smith, P_2), Nepal camphortree (Cinnamomum glanduliferum(Wall.) Nees, P_3), tea (Camellia sinensis (Linn.) O. Ktze. f., P_4), oleander (Nerium indicum Mill,P_5), rape (Brassica campestris L., P_g), Chinese tallow tree (Sapium sebiferum L., P_7), tung(Vernicia fordii (Hemsl.), P_8), and croton (Croton tiglium L., P_9), 7 chemicals, boric acid (C_1),borax (C_2), oxalic acid (C_3), sodium oxalite (C_4), sodium dihydrogen phosphate (C_6), sodiumsilicate (C_7) and sodium citrate (C_8), and a natural organic substance, humic acid (C_5), onurease activity of a neutral purple soil and recovery of urea nitrogen by maize were studied throughincubation and pot experiments. Hydroquinone (HQ) was applied as the reference inhibitor. Afterincubation at 37℃ for 24 h, 7 inhibitors with higher ability to inhibit urease activity wereselected and then incubated for 14 days at 25℃. Results of the incubation experiments showed thatsoil urease activity was greatly inhibited by them, and the inhibition effect followed an order ofP_2>P_4>C_3>C_2>P_3>C_1>HQ>P_1. The 7 selected materials reduced the accumulative amounts of Nreleased from urea and the maximum urease activity by 11.7%～28.4% and 26.7%～39.7%, respectively,and postponed the N release peak by 2～4 days in the incubation period of 14 days under constanttemperature, as compared to the control (no inhibitor). In the pot experiment with the 7 materialsat two levels of addition, low (L) and high (H), the C_1 (H), C_3 (H), C_1 (L), P_4 (L) and C_2 (L)treatments could significantly increase the dry weights of the aboveground parts and the totalbiomass of the maize plants and the apparent recovery rate of urea-N was increased by 6.3%～32.4% ascompared to the control (no hibitor).

Optimum control strategy for all-variable speed chiller plant

The optimum control strategy and the saving potential of all variable chiller plant under the conditions of changing building cooling load and cooling water supply temperature were investigated. Based on a simulation model of water source chiller plant established in dynamic transient simulation program (TRNSYS),the four-variable quadratic orthogonal regression experiments were carried out by taking cooling load,cooling water supply temperature,cooling water flow rate and chilled water flow rate as variables,and the fitting formulas expressing the relationships between the total energy consumption of chiller plant with the four selected parameters was obtained. With the SAS statistical software and MATHEMATICA mathematical software,the optimal chilled water flow rate and cooling water flow rate which result in the minimum total energy consumption were determined under continuously varying cooling load and cooling water supply temperature. With regard to a chiller plant serving an office building in Shanghai,the total energy consumptions under different control strategies were computed in terms of the forecasting function of cooling load and water source temperature. The results show that applying the optimal control strategy to the chiller plant can bring a saving of 23.27% in power compared with the corresponding conventional variable speed plant,indicating that the optimal control strategy can improve the energy efficiency of chiller plant.

Planting Date, Seeding Rate, and Cultivar Impact Agronomic Traits and Semolina of Durum Wheat

Durum wheat (Triticum durum Desf.) is a market class of wheat subject to price discounts in the marketplace if quality standards are not met. This study was conducted in order to determine how certain agronomic practices might impact durum wheat quality. The effects of planting date (PD), cultivar, and seeding rate on agronomic and semolina quality traits were investigated in field trials conducted near Hettinger and Minot, ND in 2014 and 2015. The interaction of PD and cultivar was significant for many of the traits evaluated. There was a significant PD X cultivar interaction or PD and cultivar effect for yield in all environments. Planting date X cultivar interacted for test weight at all environments. In general, a delay in PD resulted in a significant decrease in yield and test weight for all cultivars. However, Carpio yielded more than other cultivars in high yielding environments while the yield and test weight of Joppa was more adversely affected by delays in PD. Seeding rate did not have a consistent effect on any agronomic or quality trait. Protein content, kernel yellow pigment content, falling number (FN), and vitreous kernels were more dependent on cultivar, regardless of PD and environment. Semolina extraction, gluten index (GI), and wet gluten (WG) values tended to decrease with a delay in PD. These data continue to support cultivar selection as a critical component for obtaining high-yielding, high-quality durum wheat. However, PD and environment can impact certain agronomic and end-use traits, regardless of cultivar grown.

Effects of soil nitrate:ammonium ratio on plant carbon:nitrogen ratio and growth rate of Artemisia sphaerocephala seedlings

Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.

Nitrogen management improves lodging resistance and production in maize(Zea mays L.)at a high plant density

Lodging in maize leads to yield losses worldwide.In this study,we determined the effects of traditional and optimized nitrogen management strategies on culm morphological characteristics,culm mechanical strength,lignin content,root growth,lodging percentage and production in maize at a high plant density.We compared a traditional nitrogen(N)application rate of 300 kg ha–1(R)and an optimized N application rate of 225 kg ha^(–1)(O)under four N application modes:50%of N applied at sowing and 50%at the 10th-leaf stage(N1);100%of N applied at sowing(N2);40%of N applied at sowing,40%at the 10th-leaf stage and 20%at tasseling stage(N3);and 30%of N applied at sowing,30%at the 10th-leaf stage,20%at the tasseling stage,and 20%at the silking stage(N4).The optimized N rate(225 kg ha^(–1))significantly reduced internode lengths,plant height,ear height,center of gravity height and lodging percentage.The optimized N rate significantly increased internode diameters,filling degrees,culm mechanical strength,root growth and lignin content.The application of N in four split doses(N4)significantly improved culm morphological characteristics,culm mechanical strength,lignin content,and root growth,while it reduced internode lengths,plant height,ear height,center of gravity height and lodging percentage.Internode diameters,filling degrees,culm mechanical strength,lignin content,number and diameter of brace roots,root volume,root dry weight,bleeding safe and grain yield were significantly negatively correlated with plant height,ear height,center of gravity height,internode lengths and lodging percentage.In conclusion,treatment ON4 significantly reduced the lodging percentage by improving the culm morphological characteristics,culm mechanical strength,lignin content,and root growth,so it improved the production of the maize crop at a high plant density.

Performance of a 270 MW Gas Power Plant Using Exergy and Heat Rate

The performance of a 270 MW (9 × 30 MW) AES Corporation barge mounted gas turbine power plant in Nigeria is evaluated using the heat rate and entropy generation by the components of the plant to characterize the irreversibility in each component when operating at different loads between 90% and 25%. The power plants have the peculiarity that three of the plants were supplied by three (3) different Original Equipment Manufacturers (OEM);A, B and C. This study is sequel to the fact that the gas turbines were the first independent power plants in the country and after more than fifteen years of operation, it is reasonable to evaluate the performance of the major components. By analyzing the thermodynamic performance of these components, the study demonstrates the utility value of exergy efficiency as an important parameter in the evaluation of major components in a gas power plant. Exergy efficiency is shown to be an important parameter in ranking the power plant components, identifying and quantifying the possible areas of reduction in thermodynamic losses and improvement in efficiencies. A new relationship is derived to demonstrate the correlation between the exergy efficiency and the heat rate of a 30 MW gas power plant. The prediction of the derived relationship correlates well with the observed operational performance of the 30 MW power plants. The combustion chamber in each of the plants provides the maximum exergy destruction during operation. Its exergy efficiency is shown to exhibit good correlation with its energy efficiency and the plant rational exergy. The implication is that from an operational and component selection viewpoint in the specifications of a gas power plant, knowledge of the Heat Rate which is usually provided by the OEM is adequate to make a reasonable inference on the performance of some critical components of the plant.

Reduced nitrogen application rate with dense planting improves rice grain yield and nitrogen use efficiency: A case study in east China

Dense planting could be a feasible method for reducing nitrogen(N) application rates without compromising rice grain yield in northeast and central China. It is still unclear whether reduced N application with dense planting(RNDP) can achieve higher rice yield and N use efficiency(NUE) in Jiangsu, east China. Three japonica inbred rice(JI) and three indica hybrid rice(IH) cultivars were grown in a field experiment. Their grain yield, NUE, and related traits were compared under two cultivation treatments:conventional high-yielding practice(CHYP) and RNDP. JI showed similar yields under the two treatments,while IH showed lower yield under RNDP than under CHYP, and the partial factor productivity of N and N use efficiency for grain yield increased(P < 0.05) in both JI and IH under RNDP. Compared with CHYP,RNDP reduced spikelets per panicle but increased panicles per m2 and filled-kernel percentage of JI and IH, and JI's kernel weight was increased(P < 0.05) under RNDP. Shoot biomass weight and nonstructural carbohydrate(NSC) content in the stem at heading and maturity of JI and IH were reduced under RNDP, while harvest index and NSC remobilization reserve were increased(P < 0.05) under RNDP, especially for JI. Our results suggest that RNDP could achieve a higher rice grain yield and NUE, particularly for JI, a dominant rice cultivar type in Jiangsu. For JI, the increased panicles per m2, sink-filling efficiency, harvest index, and NSC remobilization after heading under RNDP contributed to a grain yield similar to that under CHYP.

Grain Yield and Nitrogen Use Efficiency of Hybrid Rice in Response to High Plant Density and Nitrogen Rate

Increased plant density with low N rate was a recommended strategy to increase grain yield and N use efficiency(NUE);however,grain yield,NUE and the total N uptake(TNU)responses of hybrid rice to this strategy at different yield levels(medium yielding site(MYS)Luzhou City and high yielding site(HYS)Deyang City had not been described.Field experiments with hybrid rice Rongyou1015 were conducted to study the effects of two plant densities.High plant density(HD),low plant density(LD)and four N rates(without N,N_(0);a recommended N rate of 195 kg•hm^(-2),N_(CK);a 23%reduction in N rate,N_(-23%);a 46%reduction in N rate,N_(-46%)on yield attributes,grain yield,TNU and NUE of hybrid rice were studied under different yield levels in 2016-2017.The results showed that the grain yield and NUE of hybrid rice in response to plant density and N rate varied with yield levels.For MYS,reducing N rate by 46%result in significantly lower grain yield at LD treatment;whereas at HD treatment the grain yield of hybrid rice under N_(-46%) and N_(CK) were equal.For HYS,reducing N rate by 46% result in significantly lower grain yield regardless of low plant density and high plant density;however,a reduction in N rate by 23%increased grain yield,AE_(N) by 36%,PFP_(N) by 31% and RE_(N) by 11% over N_(CK) at HD treatment.Higher grain yield of hybrid rice under the combination of HD with low N rate was attributable to improvement in spikelets per panicle and harvest index.The results suggested that high plant density with low N rate might be an effective approach to improve grain yield and NUE in rice production,but reduction in N application rate was determined,according to yield levels.

植物免疫诱抗剂对玉米耐盐性及产量的影响

为探究植物免疫诱抗剂对玉米耐盐性及产量的影响,以智能聪(ZNC)为材料,于2022年在山东烟台开展试验,对盐分胁迫条件下不同浓度智能聪浸种处理的玉米种子发芽率、根系生长指标和产量进行比较分析。结果表明:在8、10 g/L NaCl溶液中,玉米种子发芽率分别为27.5%、17.5%,主根长度分别为19.8、13.0 mm,显著低于其在水溶液中的发芽率(52.5%)和主根长度(55.9 mm),说明盐溶液对玉米发芽和根系生长有抑制作用。20 ng/mL智能聪浸种处理后,8、10 g/L NaCl溶液下的玉米种子发芽率分别为38.0%、25.0%,主根长度分别为24.5、15.1 mm,说明智能聪浸种能够缓解盐溶液对玉米种子发芽和根系生长的抑制作用。采用智能聪拌种结合玉米生长期兑水喷施处理,玉米产量提高5.02%。综合分析,在盐分胁迫条件下,施用智能聪可促进玉米生长,提高其产量。

种植密度和施氮量对油菜生长发育及产量的影响

为探究氮肥与密度互作对甘蓝型油菜生长发育和产量的影响,以‘云油杂28号’为材料,设置3个密度梯度,D_(1):15万株/hm^(2);D_(2):28.5万株/hm^(2);D_(3):42万株/hm^(2),4个施氮量水平,N_(1):0 kg/hm^(2);N_(2):75 kg/hm^(2);N3:150 kg/hm^(2);N4:225 kg/hm^(2),测定不同处理下的生育期、农艺性状、干物质重量和产量等指标。结果表明:同一种植密度下,全生育期随施氮量的增加而延长,盛花期根茎粗、叶面积、总叶数和绿叶数在D_(1)密度下随施氮量的增加先上升后降低;干物重和产量在各密度下均随施氮量的增加先升高后降低,均在D_(1)N_(2)下达到最大值。同一施氮量下,全生育期随种植密度的增加呈缩短趋势;根茎粗、总叶数、绿叶数和叶面积在抽薹期和盛花期均随种植密度的提高而降低;各时期的干物重和产量随种植密度的增加而降低。种植密度和氮肥对油菜生长发育前期的影响较小,主要从抽薹期和开花期开始产生影响;调整种植密度对产量和干物重的影响大于施氮量,密度和施氮量主要通过单株有效角果数影响油菜产量。在密度与氮肥的互作处理下以D_(1)N_(2)处理(即密度为15万株/hm^(2),施氮为75 kg/hm^(2))最优,其株高最高,总叶数和绿叶数最多,根茎粗和叶面积较大,单株产量和小区产量最高。

2BP-2000型水稻育秧播种机分盘装置研制

针对现有育秧播种机分盘装置生产效率较低、高速作业时易出现卡盘和秧盘输送不连续等问题,该研究设计了一种生产效率不低于2000盘/h的机械气动式自动分盘装置,可快速、准确完成分盘和供盘,适配2BP-2000型水稻育秧播种机高速播种。阐述了分盘装置的基本结构和工作原理,开展分盘、接盘过程分析,确定装置稳定分盘、接盘作业的关键机构与工作参数。分盘稳定性试验结果表明,生产率为1600~2000盘/h时,分盘稳定性不低于98.67%。开展以层叠秧盘数、生产率和秧盘质量为试验因素,以接盘成功率为试验指标的三因素三水平正交旋转组合试验,得到影响接盘成功率的因素主次关系为生产率、层叠秧盘数、秧盘质量,其中生产率、层叠秧盘数对接盘成功率影响显著(P<0.05),秧盘质量对接盘成功率影响不显著(P≥0.05),表明分盘装置对不同质量的秧盘适应性较好,其最优参数组合为:生产率2000盘/h、层叠秧盘数6盘/层、秧盘质量750 g/盘,该条件下分盘装置的接盘成功率均值为98.43%,与预测值仅相差0.29个百分点。研究结果对提高水稻硬盘育秧播种机械化水平具有实用价值。

施氮量对不同夏玉米品种籽粒灌浆特性、产量和品质的影响

以脱水速率不同的2个夏玉米品种迪卡517(DK 517,脱水速率较快)和郑单1002(ZD 1002,脱水速率较慢)为材料,研究施氮量[0 kg/hm^(2)(N0)、180 kg/hm^(2)(N1)、300 kg/hm^(2)(N2)]对夏玉米籽粒灌浆特性、脱水速率、产量和品质的影响,以期为黄淮海夏玉米优质高效生产提供理论依据。结果表明,随着施氮量的增加,DK 517和ZD 1002籽粒干质量总体上均逐渐增加,行粒数和产量先增加后降低,籽粒粗蛋白含量增加,粗淀粉含量降低。N1处理总体上籽粒灌浆速率最大时的生长量和最大灌浆速率最高,活跃灌浆期最长,行粒数最多,进而产量最高,分别为9694.60 kg/hm^(2)和11204.56 kg/hm^(2),且籽粒粗蛋白含量较高。不同施氮量处理对不同脱水类型夏玉米品种籽粒灌浆特性影响不同。授粉后15~24 d,不同处理夏玉米籽粒含水量之间差异显著,授粉后58 d,DK 517籽粒含水量表现为N2>N1>N0,ZD 1002籽粒含水量表现为N1>N0>N2。授粉后49~58 d,N0处理籽粒脱水速率最高。与ZD 1002相比,DK 517籽粒灌浆速率最大时的生长量和最大灌浆速率较高,到达最大灌浆速率的时间较早,活跃灌浆期较短,籽粒含水量较低,灌浆前期籽粒脱水速率较低,中后期较高,行粒数、百粒质量和产量较低,籽粒粗脂肪含量较低,粗蛋白和粗淀粉含量较高。籽粒脱水速率与穗粗、秃尖长呈显著或极显著负相关,与穗长和粗淀粉含量呈显著或极显著正相关。综上,施氮180 kg/hm^(2)可促进夏玉米籽粒灌浆,提高产量和籽粒粗蛋白含量。

某核电厂电气仪控房间火灾排烟温度分析

对某核电厂电气厂房的2个电气仪控房间进行了火灾排烟温度模拟分析。模拟计算了排烟系统不同时刻启动时,这2个防火空间室内空气温度的变化情况。结果表明:排烟系统启动后房间空气温度迅速降低,然后逐渐升高,最后随着火灾热释放速率的降低而逐渐降低;对于手动启动的排烟系统,需及时启动才能有效排除火灾中的烟气;需合理设置排烟防火阀,以保护排烟风机等。

密肥对矮秆紧凑型杂交糯高粱产量和品质的影响

为探讨种植密度和施氮量对矮秆紧凑型杂交糯高粱产量和品质的影响,采用裂-裂区试验设计,主区为高粱品种,设‘金糯梁1号’、‘机糯梁1号’2个处理;裂区为种植密度,设12万、13.5万、15万、16.5万株/hm^(2)4个处理;裂-裂区为施氮量,设75、120、165 kg/hm^(2)3个处理。收获期调查分析籽粒产量及相关性状、品质指标。研究表明,品种、密度和施氮量对籽粒产量与主要品质性状均影响显著。随着种植密度的增加,增加施氮量对产量的影响效应逐渐变小,适当增加矮秆紧凑型杂交糯高粱种植密度可以作为氮肥减施技术的有效途径。适宜增密减氮还可以有效提高高粱粗淀粉与单宁含量。