Cotton lint yield variability in a heterogeneous soil at a landscape scale     

Hong Li  Robert J. Lascano  Jill Booker  L. Ted Wilson  Kevin F. Bronson 《Soil & Tillage Research》2001,58(3-4):245-258

Landscape variability associated with topographic features affects the spatial pattern of soil water and N redistribution, and thus N uptake and crop yield. A landscape-scale study was conducted in a center pivot irrigated field on the southern High Plains of Texas in 1999 to assess soil water, soil NO₃-N, cotton (Gossypium hirsutum L.) lint yield, and N uptake variability in the landscape, and to determine the spatial correlation between these landscape variables using a state-space approach. The treatments were irrigation at 50 and 75% cotton potential evapotranspiration (ET). Neutron access tubes were placed at a 15-m interval along a 710 m (50% ET) and 820 m (75% ET) transect across the field. Soil NO₃-N in early spring was autocorrelated at a distance varying between 60 and 80 m. Measured soil volumetric water content (WC), total N uptake, and lint yield were generally higher on lower landscape positions. Cotton lint yield was significantly correlated to soil WC (r=0.76), soil NO₃-N (r=0.35), and site elevation (r=−0.54). Differences of site elevation between local neighboring points explained the soil water, NO₃-N and lint yield variability at the micro-scale level in the landscape. Soil WC, cotton lint yield, N uptake, and clay content were crosscorrelated with site elevation across a lag distance of ±30–40 m. The state-space analysis showed that cotton lint yield was positively weighted on soil WC availability and negatively weighted on site elevation. Cotton lint yield state-space models give insights on the association of soil physical and chemical properties, lint yield, and landscape processes, and have the potential to improve water and N management at the landscape-scale.  相似文献   

不同形态氮素比例对不同小白菜品种生物量和硝酸盐含量的影响   总被引：46，自引：6，他引：46       下载免费PDF全文

陈巍  罗金葵  姜慧梅  沈其荣 《土壤学报》2004,41(3):420-425

利用NO-3 N∶NH 4 N为 10 0∶0、5 0∶5 0和 0∶10 0三个硝铵配比的营养液对 12个不结球小白菜品种进行水培试验。结果表明 :不同的硝铵配比对不同品种小白菜的生物量、叶绿素SPAD值、硝酸盐积累量等有着显著的影响 ,同一氮源培养下不同的小白菜品种间也表现出显著的差异 ;12个小白菜品种叶绿素SPAD值随营养液中的NH 4 N比例的增加而升高 ,两者间存在着显著的正相关 ;单株生物量除亮白叶 1号和五月慢在全硝培养中生物量较其他两种配比大外 ,其他 10个品种均在 5 0∶5 0硝铵营养液中表现最好 ;供试的 12个小白菜品种中有 9个品种的硝酸盐积累量随着NH 4 N比例的增加而下降 ,表明适当地配施铵态氮较纯硝营养液能获得更好的产量、更高的叶绿素SPAD值和较低的硝酸盐积累量。  相似文献   

不同水氮措施对芹菜-白菜轮作体系中氮素利用与土壤NO_3~--N残留的影响   总被引：1，自引：0，他引：1  

张学军  陈晓群  罗建航  吴礼树  胡承孝 《土壤通报》2007,38(5):906-910

在宁夏引黄灌区灌淤土设置田间试验,研究不同水氮措施对芹菜-白菜轮作体系中的氮素利用与平衡的影响,结果表明:节水灌溉的W2N3(推荐施氮)处理与传统灌溉(W1N3)(推荐施氮)的处理相比,芹菜的产量、吸氮量分别高12.2%、14.7%,白菜的产量、吸氮量分别高22.4%、4.4%。在氮素平衡方面,推荐施氮处理氮素损失比传统施氮损失分别低53kghm-2(传统灌溉)、30kghm-2(节水灌溉)。节水条件下推荐施氮处理的土壤剖面上的无机氮残留浓度,减少量分别达到3～13kghm-2。节水灌溉下与传统灌溉相比,节水灌溉的土壤残留硝态氮的含量均比传统灌溉低,而且主要分布在0～60cm表层,推荐施氮量的土壤残留硝态氮的含量又比习惯施氮量低。  相似文献   

Immediate and adaptational temperature effects on nitric oxide production and nitrous oxide release from nitrification and denitrification in two soils   总被引：3，自引：0，他引：3  

M. Gödde  R. Conrad 《Biology and Fertility of Soils》1999,30(1-2):33-40

 Nitrification and denitrification are, like all biological processes, influenced by temperature. We investigated temperature effects on N trace gas turnover by nitrification and denitrification in two soils under two experimental conditions. In the first approach ("temperature shift experiment") soil samples were preincubated at 25  °C and then exposed to gradually increasing temperatures (starting at 4  °C and finishing at 40–45  °C). Under these conditions the immediate effect of temperature change was assessed. In the second approach ("discrete temperature experiment") the soil samples were preincubated at different temperatures (4–35  °C) for 5 days and then tested at the same temperatures. The different experimental conditions affected the results of the study. In the temperature shift experiment the NO release increased steadily with increasing temperature in both soils. In the discrete temperature experiment, however, the production rates of NO and N₂O showed a minimum at intermediate temperatures (13–25  °C). In one of the soils (soil B9), the percent contribution of nitrification to NO production in the discrete temperature experiment reached a maximum (>95% contribution) at 25  °C. In the temperature shift experiment nitrification was always the dominant process for NO release and showed no systematic temperature dependency. In the second soil (soil B14), the percent contribution of nitrification to NO release decreased from 50 to 10% as the temperature was increased from 4  °C to 45  °C, but no differences were evident in the discrete temperature experiment. The N₂O production rates were measured in the discrete temperature experiment only. The contribution of nitrification to N₂O production in soil B9 was considerably higher at 25–35  °C (60–80% contribution) than at 4–13  °C (15–20% contribution). In soil B14 the contribution of nitrification to N₂O production was lowest at 4  °C. The effects of temperature on N trace gas turnover differed between the two soils and incubation conditions. The experimental set-up allowed us to distinguish between immediate effects of short-term changes in temperature on the process rates, and longer-term effects by which preincubation at a particular temperature presumably resulted in the adaptation of the soil microorganisms to this temperature. Both types of effects were important in regulating the release of NO and N₂O from soil. Received: 20 October 1998  相似文献   

内源性NO在雏鸡球虫感染中的作用   总被引：3，自引：0，他引：3  

李金贵  朱蓓蕾  蒋金书 《中国兽医学报》2002,22(6):601-603

以腹腔注射途径给予感染柔嫩艾美耳球虫 (E.tenella)雏鸡细菌脂多糖 (L PS)和地塞米松 (Dex) ,用铜离子活化镉还原法检测血清 NO- 2 水平 ,并通过测定 NBT阳性细胞百分率、雏鸡增重、免疫器官的脏器系数、OPG值以及盲肠病变记分等指标 ,探讨了 NO在雏鸡感染球虫过程中的作用。试验结果表明 ,与空白对照组相比 ,给予 L PS可使 NBT阳性细胞百分率明显升高 (P<0 .0 1) ,并使盲肠病变及球虫感染引起的增重下降有所减轻 ,这提示 L PS对雏鸡具一定的保护作用 ;而给予 Dex不仅降低了感染雏鸡血清 NO- 2 的水平、NBT阳性细胞百分率、增重和胸腺的脏器系数 ,还增加了 OPG值和盲肠病变记分 ,说明在雏鸡感染球虫过程中 ,Dex会减少 NO的生成 ,并使雏鸡抗球虫免疫力下降。  相似文献   

NO合酶抑制剂 L-NAME和NO前体L-Arg对小鼠体内卵母细胞成熟的影响     

卜淑敏  夏国良  王松波  汪建红 《农业生物技术学报》2003,11(3):291-294

摘要: 采用腹腔单独注射L-NAME(左旋硝基精氨酸甲基酯)或联合注射L-NAME和L-Arg, 取出卵母细胞体外观察，研究了NO对小鼠卵母细胞体内成熟的影响。结果表明,（1）单独注射5、10、20 mg / kg体重L-NAME均能显著抑制卵母细胞第一极体的释放(P <0.01)，尤以10 mg / kg 体重L-NAME组作用最为明显, 各剂量组对生发泡的破裂均无影响(P >0.05)；（2）10 mg / kg 体重L-NAME对卵母细胞成熟的抑制作用能被同时注射的100 mg / kg 或200 mg /kg 体重L-Arg逆转，其中以200 mg / kg体重作用最为明显;（3）L-NAME对卵母细胞畸形率的影响和培养时间有关，而对卵母细胞的存活率没有统计学影响。实验结果证明NO参与了小鼠卵母细胞的体内成熟调控。  相似文献   

外源硝酸钙对盐胁迫黄瓜幼苗生长和光合作用的影响     

程玉静  郭世荣  束胜  胡加如  薛林  陈国清  石明亮  黄小兰  陆虎华 《江西农业学报》2012,24(4):38-41,45

以较耐盐黄瓜品种新泰密刺为试材,采用营养液栽培,研究了叶面喷施Ca(NO3)2对盐胁迫(65 mmol/L NaCl)下黄瓜幼苗生长、叶片叶绿素含量、光合及叶绿素荧光参数的影响。结果表明,外源Ca(NO3)2显著提高了盐胁迫下黄瓜幼苗的干鲜重和叶片叶绿素含量;Ca(NO3)2也提高了盐胁迫下黄瓜叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、PSⅡ实际光化学效率(ФPSⅡ)、光条件下最大光化学效率(F'v/F'm)和光化学淬灭系数(qP),而对胞间CO2浓度(Ci)、暗条件下最大化学效率(Fv/Fm)和非光化学淬灭系数(qN)没有显著影响。这些结果说明外源Ca(NO3)2可能通过提高叶绿素含量和调节气孔限制,以缓解盐胁迫对黄瓜幼苗光化学效率的抑制,进而提高植株耐盐胁迫能力,促进其生长。  相似文献   

G-CSF对脑挫伤大鼠血清及脑组织中NO、MDA和SOD含量的影响     

孙琳  高虹 《河北北方学院学报(自然科学版)》2012,28(2):73-75,78

目的观察粒细胞集落刺激因子（G-CSF）对脑挫伤大鼠血清及脑组织中一氧化氮（NO）、丙二醛（MDA）和超氧化物歧化酶（SOD）含量的影响,探讨G-CSF在治疗脑挫伤中的作用.方法将大鼠随机分为治疗组、对照组和正常组,采用自由落体法致SD大鼠脑挫伤动物模型,正常组不致伤.治疗组脑挫伤2h后开始应用G-CSF（浓度为2mg/L）一次性皮下注射50μg/kg治疗.对照组和正常组皮下注射等量生理盐水.给药结束后24h检测治疗组、对照组及正常组大鼠血清及脑组织中NO、MDA和SOD的含量.结果脑挫伤后,对照组大鼠血清及脑组织中NO和MDA含量明显高于正常组,SOD的活性明显低于正常组.治疗组大鼠血清及脑组织中NO和MDA含量明显低于对照组,SOD的活性明显高于对照组.结论G-CSF能有效地提高脑挫伤大鼠血清及脑组织中SOD的活性,降低NO和MDA含量,保护脑组织,改善脑水肿,从而起到了一定的治疗作用.  相似文献   

被动式吸收采样分光光度法测定环境空气中二氧化氮分析方法研究     

付友生  姜秋俚  李艳红 《现代农业科技》2012,(21):242+247

对被动式吸收采集环境空气中NO2进行了研究,应用分光光度法测定了3种不同浓度标准溶液的相对标准偏差范围是1.80%~6.14%,2个实际样品的相对标准偏差分别为15.1%、13.8%,实际样品的加标回收率分别为103.9%、96.0%,该方法操作简便,适合广泛推广。  相似文献   

中草药方剂对哲罗鱼抗氧化能力的影响   总被引：1，自引：0，他引：1  

刘红柏  宿斌  王荻 《东北农业大学学报》2012,(9):127-134

哲罗鱼试验组每组60尾,每天按照表3分别投喂添加不同中草药(四种复方及5种单方)的饲料,对照组投喂基础饲料,连续投喂28 d,停食1 d后采集血液(分离血清及红细胞)及肝脏等样品,进行NO含量、NOS活性、SOD活性、MDA含量的测定.结果表明,血清中NO含量与对照组差异不显著,除当归组外NOS含量均有显著升高趋势;肝脏与血清相反,除当归组外NO含量均有上升,除黄芪高剂量组外NOS的活性均下降.血清中SOD酶活性没有明显变化,肝脏中,只有茯苓可以显著升高SOD活性,而红细胞中,黄芪、贯众和方二组可以使SOD活性有明显的升高;除方二、茯苓组,其余实验组均能明显降低血清中MDA的含量;除方五组外其他实验组均能显著降低MDA的含量.结果显示,中草药对哲罗鱼抗氧化能力的影响因药物种类、检测组织和指标而有所不同,但所选中草药均有一定程度增强机体抗氧化能力的作用.  相似文献