EFFECT OF NITRIC OXIDE ON ALFALFA SEED GERMINATION UNDER NaCi STRESS

以甘农4号、阿尔冈金2个品种苜蓿为材料,用一氧化氮（NO）供体硝普钠、NO清除剂c-PTIO、一氧化氮合酶抑制剂N-硝基．L-精氨酸甲脂、硝酸还原酶抑制荆钨酸钾及硝普钠类似物亚铁氰化钠（不产生NO）处理苜蓿种子,研究NO对盐胁迫下苜蓿种子萌发的生理效应。结果表明,盐胁迫显著抑制了2个苜蓿品种的发芽率、胚芽和胚根长及幼苗干重（P〈0．05）,降低种子萌发过程中α、β-淀粉酶、蛋白水解酶活性,抑制淀粉水解和可溶性糖积累（P〈0．05）;盐胁迫下添加外源NO则使2个品种苜蓿α、β淀粉酶、蛋白水解酶活性、种子发芽率显著提高（P〈0．05）,淀粉含量降低,可溶性糖含量升高、胚芽和胚根长及幼苗干重显著增加（P〈0．05）;NO供体SNP的类似物亚铁氰化钠对盐胁迫下苜蓿种子萌发的各项指标无明显影响;施用NO清除剂c-PTIO、硝酸还原酶抑制剂钨酸钾和一氧化氮合酶抑制剂N-硝基-L-精氨酸甲脂具有降低苜蓿种子萌发的效应（P〈0．05）。因此,盐胁迫抑制苜蓿种子的萌发,而添加外源NO是缓解这种抑制作用的有效途径,内源NO也可能参与盐胁迫下苜蓿种子萌发的调节,且通过NOS和NR途径产生的NO在缓解盐胁迫抑制苜蓿种子萌发中可能起关键作用。     

Effect of salinity on nitrogen metabolism in wheat

Objectives of our studies were to quantify effects of salinity on growth and nitrogen metabolism of wheat and to measure variation in response of different cultivars, hybrids, and classes. Methods and criteria for identifying resistance to salinity in wheat, particularly effects on nitrogen metabolism also were tested. Variation in response to salinity was measured by subjecting seedlings of six wheats to one control treatment (‐0.1 bars) and two stress treatments (‐3.5 and ‐10.4 bars) from NaCl, MgSO₄, and MgCl₂ in hydroponic solutions. Both stress treatments retarded growth; wheats significantly varied at ‐3.5 bars but not at ‐10.4 bars. Stress decreased root and shoot nitrate N and total N contents. Studies with one wheat cultivar showed that salinity decreased activity of nitrate reductase enzyme and stimulated accumulation of proline. Salinity more adversely affected vegetative stages than reproductive stages of plants grown to maturity. We concluded that salinity affected wheat by both osmotic effects and antagonism of nitrate metabolism from chloride. Absolute growth and relative growth at different stress levels were superior to differences in nitrogen metabolism as selection criteria for salinity tolerance.     

玉米产量潜力及超高产物质积累途径优化分析方法

作物产量潜力估计对于作物生产及超高产创建具有重要的理论指导意义。本文以玉米品种‘先玉335’为试验材料,于2005—2013年在吉林省3个不同生态类型区(乾安县、公主岭市和桦甸市)布置密度试验进行玉米超高产研究,利用获取的田间试验资料结合FAO-AEZ模型提出了一种基于优化模式的玉米产量潜力估计方法,解决了FAO-AEZ模型中收获指数常数的选择问题,并进一步建立玉米超高产生产中干物质积累途径分析方法。结果表明,玉米的产量与描述其干物质积累过程的Logistic方程参数密切相关,所建关系模型达到极显著水平(P0.01),并通过2012年和2013年实际产量统计检验;基于非线性优化理论,利用所建产量关系模型估算出乾安县和桦甸市的产量潜力,较FAO-AEZ模型潜力估计值年平均提高17.5%和16.1%;以实际生产数据作为约束条件,进一步求出乾安县、公主岭市和桦甸市产量达到15 000 kg·hm-2时的最低种植密度分别为7.7万株·hm-2、8.2万株·hm-2和7.9万株·hm-2,同时求出各生态区相应的干物质积累参数和各生育阶段的干物质积累量指标,为玉米超高产栽培播前决策和生育期调控提供理论依据。本文分析结果可作为吉林省玉米产量潜力估计及高产与超高产创建的理论依据,所建模型及相关分析方法也可作为其他地区作物产量潜力估计的参考。     

硒缓解植物重金属胁迫和累积的机制

硒(Se)在提高植物抗逆性、缓解重金属胁迫以及降低植物对重金属吸收方面有着重要的作用。本文综述了Se参与缓解植物重金属胁迫和累积的机制,Se能够缓解重金属的胁迫,主要是因为在植物体内由Se转化而来的相关产物的生理生化作用产生的综合效果。Se是谷胱甘肽过氧化物酶(GSH-Px)的必需组分,GSH-Px利用谷胱甘肽(GSH)将有毒的过氧化物还原成无毒的物质,清除由重金属引起的自由基。Se可以激活植物螯合肽(PC)合成酶及增加PC合成的前体,使植物产生更多的PC,形成更多的重金属-PC配合物。Se还可以与重金属形成大分子的复合物,降低重金属的毒害。Se能够与多种重金属元素产生拮抗效应,降低植物对重金属的吸收。     

龙门山断裂带主要森林类型凋落物累积量及其持水特性

采用野外实地调查与室内控制浸提相结合的方法,对龙门山断裂带常绿阔叶林、落叶阔叶林、针阔混交林、常绿针叶林4种森林类型的凋落物储量、持水量、吸水速率进行了研究。结果发现,不同森林类型凋落物总储量大小顺序为:常绿针叶林(8.26t/hm2)落叶阔叶林(6.80t/hm2)针阔混交林(5.52t/hm2)常绿阔叶林(4.61t/hm2),且未分解层累积量所占比例均小于半分解层。不同森林类型不同分解程度凋落物的持水量和持水率与浸泡时间均呈对数关系,其吸水速率与浸泡时间呈幂函数关系。研究区4种森林类型半分解层凋落物的持水能力均强于分解层,而落叶阔叶林和针阔混交林持水能力较强,其次是常绿针叶林,常绿阔叶林最低。研究表明,在该区森林植被恢复和重建过程中,应充分考虑半分解层凋落物对水土保持的作用,且宜优选落叶阔叶林和针阔混交林模式进行森林植被恢复。     

Studies on the effect of humic acid on availability of phosphorus

It is believed that some organic compounds form complexes with iron and aluminum and prevent the fixation of phosphate applied to soils.     

白洋淀芦苇湿地生态系统中植硅体的产生和积累研究

植硅体(phytoliths),又称植物蛋白石,存在于大部分植物组织细胞中,主要是依靠植物的根系吸取土壤溶液中的可溶性二氧化硅,在植物细胞或细胞内沉淀硅化而形成的一种固体的非晶质含水二氧化硅颗粒物[1].植硅体主要组成部分是二氧化硅(67％～95％)、水(1％～12％)、碳(0.1％～6％)及少量的无机元素Na、K、 Ca、 Fe、 AL、 Ti等[2],由于其具有较强的抗分解、抗腐蚀和耐高温等特性,可以长时间较稳定地保存在一些岩石和土壤中[3-5],在硅的生物地球化学循环中有着重要的作用,是全球硅循环的重要参与者[6].虽然植硅体作为生物硅的重要组成部分,在全球硅的生物地球化学循环中占据着重要地位,但在湿地生态系统中植硅体产生和积累研究则鲜见报道[7].     

模拟径流条件下工程堆积体陡坡土壤侵蚀过程

工程建设过程中形成的堆积体具有独特的土壤组成及复杂的下垫面条件,堆积体表面土壤结构体缺失、土质松散、植物根系及有机质缺乏等,导致其土壤抗冲性极差,径流条件下堆积体陡坡坡面的土壤侵蚀过程亦表现出不同的特点,该文通过野外放水试验,对高速公路沿线典型堆积体陡坡（36°）在模拟径流冲刷条件下的土壤侵蚀过程进行了研究,结果表明,次径流过程中径流强度变化与放水强度及径流含沙量密切相关,三者之间呈多元线性相关;重力侵蚀对径流含沙量的变化具有重要影响,试验条件下重力作用的临界放水条件在20～25 L/min之间;坡面产沙过程存在产沙量的突变、波动变化和稳定发展3个阶段;不同坡段产沙量的空间分布存在持续稳定减小和震荡式波动衰减2种变化形式;土壤剥蚀率与单宽流量呈线性关系,与时段产沙量及流宽呈幂函数关系;最后,时段产沙量与时段径流量呈幂函数关系,累积产沙量与累积径流量呈线性关系。     

Nutrient leaching from the plow layer by water percolation and accumulation in the subsoil in an irrigated paddy field

To estimate the impact of water percolation on the nutrient status in paddy fields, the seasonal variations of the concentrations of cations, anions, inorganic carbon (IC), and of dissolved organic carbon (DOC) in percolating water that was collected from just below the plow layer (PW-13) and from drainage pipes at the 40 em depth (PW-40), as well as in irrigation water were measured in an irrigated paddy field. Total amounts of Ca, Mg, K, Fe, and Mn leached from PW-13 during the period of rice cultivation were estimated to range from about 390 to 770, 65 to 130, 33 to 66, 340 to 680, and 44 to 87 kg ha^-1, respectively. Amounts of losses that were estimated from the differences between the input by irrigation water and the output by percolation water from the plow layer corresponded to 11 to 26, 22 to 47,5.9 to 12, and 13 to 26% of exchangeable Ca and Mg, amorphous Fe, and easily reducible Mn in the plow layer, respectively. The concentrations of Ca, Mg, K, Fe, and Mn in PW13 were higher than those in PW-40. The amounts of these nutrients that were retained in the subsoil between the 13 em and 40 em soil depth corresponded to 83, 86, 61, 99, and 89% of the amounts that percolated from the plow layer, respectively. Total amounts of IC and DOC that percolated from the plow layer ranged from 750 to 1,500 and 85 to 170 kg-C ha^-1, which corresponded to 5.0 to 10.0% and 0.6 to 1.1% of the total carbon content in the plow layer, respectively. Eighty eight % of IC in the percolating water from the plow layer was also retained in the subsoil.     

Effect of nutrient solution salinity and ionic concentration on parsley (Petroselinum crispum Mill.) essential oil yield and content

The growth and essential oil (EO) production of parsley were evaluated in response to salinity and nutrient solution concentrations in a soilless culture. Parsley plants that were 60 days old were potted in a coconut fiber and peat moss medium and were treated with four different nutrient solutions, including T1, T2, T3 and T4. The T1 nutrient solution was the standard, the T2 and T3 solutions contained incremental macronutrient concentrations with an electrical conductivity (EC) of up to 2.2 and 3.2 dS m^?1, respectively, and the T4 solution was the same as T2 but with sodium chloride (NaCl) and an incremental macronutrient concentration with an EC of 3.2 dS m^?1. Next, these plants were grown for 90 days in a greenhouse with natural daylight in Nador, Morocco. Shoot and root growth significant decreased with increasing EC. However, the salinity that resulted from the addition of NaCl did not affect plant growth in the nutrient solutions. The optimum obtained growth and EO production were 1.2 and 2.2 dS m^?1, respectively. Consequently, the optimum EC value (based on the EO production) of parsley in the soilless culture was 1.2–2.2 dS m^?1.