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921.
922.
F. Alghabari M. Lukac H. E. Jones M. J. Gooding 《Journal of Agronomy and Crop Science》2014,200(1):36-45
Factorial pot experiments were conducted to compare the responses of GA‐sensitive and GA‐insensitive reduced height (Rht) alleles in wheat for susceptibility to heat and drought stress during booting and anthesis. Grain set (grains/spikelet) of near‐isogenic lines (NILs) was assessed following three day transfers to controlled environments imposing day temperatures (t) from 20 to 40 °C. Transfers were during booting and/or anthesis and pots maintained at field capacity (FC) or had water withheld. Logistic responses (y = c/1+e‐b(t ‐m)) described declining grain set with increasing t, and t5 was that fitted to give a 5 % reduction in grain set. Averaged over NIL, t5 for anthesis at FC was 31.7 ± 0.47 °C (S.E.M., 26 d.f.). Drought at anthesis reduced t5 by <2 °C. Maintaining FC at booting conferred considerable resistance to high temperatures (t5 = 33.9 °C) but booting was particularly heat susceptible without water (t5 = 26.5 °C). In one background (cv. Mercia), for NILs varying at the Rht‐D1 locus, there was progressive reduction in t5 with dwarfing and reduced gibberellic acid (GA) sensitivity (Rht‐D1a, tall, 32.7 ± 0.72; Rht‐D1b, semi‐dwarf, 29.5 ± 0.85; Rht‐D1c, severe dwarf, 24.2 ± 0.72). This trend was not evident for the Rht‐B1 locus or for Rht‐D1b in an alternative background (Maris Widgeon). The GA‐sensitive severe dwarf Rht12 was more heat tolerant (t5 = 29.4 ± 0.72) than the similarly statured GA‐insensitive Rht‐D1c. The GA‐sensitive, semidwarfing Rht8 conferred greater drought tolerance in one experiment. Despite the effects of Rht‐D1 alleles in Mercia on stress tolerance, the inconsistency of the effects over background and locus led to the conclusion that semidwarfing with GA‐insensitivity did not necessarily increase sensitivity to stress at booting and flowering. In comparison with effects of semidwarfing alleles, responses to heat stress are much more dramatically affected by water availability and the precise growth stage at which the stress is experienced by the plants. 相似文献
923.
924.
中国石化榆济输气管道在试运行过程中,因发生水合物冻堵事故,西源祠阀室、石门阀室、杨家峪阀室压力变化异常,通过分析上下游管道的运行参数和统计管道工程遗留的裸管段,初步确定两处裸管段为线路冻堵点:1#冻堵点位于西源祠阀室和石门村阀室之间的爬坡段,2#冻堵点位于石门村阀室和杨家峪阀室之间的U形弯管段。根据现场实际,在采取应急处置措施的基础上,将加注醇类抑制剂、管道天然气放空、全线降压运行和加装电伴热4种方法结合使用,很快缓解了冻堵现象,确保了管输安全。 相似文献
925.
为了研究饲粮能量水平对热应激奶牛产奶量、营养物质表观消化率和血液生化指标的影响,本试验采用单因素试验设计,选择25头健康的泌乳中期中国荷斯坦奶牛,随机分为5组,每组5头。各组分别饲喂5种不同能量水平的等氮饲粮,泌乳净能(干物质基础)分别为6.15(组1)、6.36(组2)、6.64(组3)、6.95(组4)和7.36 MJ/kg(组5)。试验期共45 d,预试期15 d,正试期30 d。结果表明:1)提高饲粮能量水平降低了呼吸频率,组4、5极显著低于组1、2(P0.01),与组3差异不显著(P0.05)。2)试牛干物质采食量与饲粮能量水平呈显著的负相关关系(R2=0.983 3,P=0.017),组5显著或极显著低于其他各组(P0.05或P0.01);产奶量最高的组4与最低的组1比较,提高了9.0%,差异极显著(P0.01)。3)除钙、磷和总能外,其他养分表观消化率均以组1最高,组5最低,差异显著或极显著(P0.05或P0.01)。4)组4血清皮质醇浓度显著或极显著低于组1、2、5(P0.05或P0.01),血清内毒素浓度显著或极显著低于其他各组(P0.05或P0.01),血清葡萄糖浓度显著高于组1和5(P0.05);组1、4血清肌酸激酶活性显著或极显著大于组2、3、5(P0.05或P0.01),其中组4与组2、3相比分别提高了32.87%和25.40%;血清谷丙转氨酶和谷草转氨酶活性为组1组2组4组3组5。综合考虑饲粮能量水平对奶牛产奶量、营养物质表观消化率和血液生化指标的影响,热应激条件下泌乳奶牛的饲粮适宜泌乳净能水平为6.95 MJ/kg。 相似文献
926.
分析了在油菜生产过程中遇到的油菜病态苗、油菜高温热害、油菜冻害、油菜早薹旱花、油莱干旱、油菜渍害和油菜收获后连续阴雨天等常见障碍的症状、发生原因,并针对各障碍提出了相应的防治对策. 相似文献
927.
长距离热油管道输送介质的组成一般比较复杂,为维持其经济输送温度,常出现蜡等重有机物固相沉积问题。当固相沉积超过一定程度时,不仅显著增加管道系统的动力消耗,而且严重威胁其运行安全。因此,合理预测热油管道稳定运行的进站温度对保障其安全经济运行尤为重要。依据阿尔善-赛汉塔拉输油管道2008-2010年的历史运行参数,结合苏霍夫温降理论,反算全线7个管段稳定运行期间的总传热系数K,提出不同管段的月推荐K值,以此预测各管段2011年上半年的进站温度,探讨偏差产生的主要原因与预测结果的可靠性。研究结果表明:由热油管道历史运行参数反算得出的推荐K值,可以较好地预测该管道今后的温降趋势,误差在-4~4℃内的可信度高于90%,但进站温度预测值可能因固相沉积而略低于实际值。 相似文献
928.
929.
Isabella Børja Jan Svĕtlík Valeriy Nadezhdin Jan Čermák Sabine Rosner Nadezhda Nadezhdina 《Scandinavian Journal of Forest Research》2016,31(5):450-457
Top dieback of Norway spruce (Picea abies), triggered by drought in 2004–2006, has been observed in Southeast Norway and trees died within four years after appearance of the first symptoms. The aim of our study was to use sap flux measurements as a diagnostic method for assessment of tree vitality. We used the heat field deformation method to monitor the sap flux density (SFD) in four pairs of healthy and declining trees in situ. To provide retrospective information on hydraulic performance of the trees we took samples for wood anatomical analysis. After felling the trees we used the modified differential translucence method (MDT) as a proxy for the SFD measurements. Healthy trees had three times higher SFD values as declining trees. In some healthy trees we detected decreasing SFD with time. The MDT method agreed with the SFD measurements. In conclusion, we detected sap flux dysfunction in declining trees and showed that the SFD reduction may occur during a short period, prior to occurrence of any visual symptoms. We suggest incorporating the SFD measurements into the repertoire of diagnostic tools in forest pathology. 相似文献
930.