持续淹水对小麦养分吸收动态和产量的影响

为了研究持续淹水对小麦养分吸收动态和产量的影响,以沿淮低洼地砂姜黑土上的小麦为研究对象,共设6个处理,每个处理埋相应的根袋,在小麦生拔节期持续淹水9天,每天收取根袋,淹水结束后统一采集各处理的植株样。淹水严重影响了小麦的生长发育,降低生物量,减少产量,淹水时间越长,下降和减产也越严重;持续性淹水严重阻碍了小麦对氮、磷、钾的吸收,降低了地上部分氮素含量和累积量,经t检验与对照相比差异均达显著或极显著水平。淹水严重影响了小麦的生长发育,抑制了氮、磷、钾的吸收与积累,使生物量、产量有较大幅度的下降。     

Localized salt accumulation： the main reason for cotton root length decrease during advanced growth stages under drip irrigation with mulch film in a saline soil

High salinity in soil can prevent root growth of most plants. To investigate soil salinity dynamics under drip irrigation with mulch film(DI) and its effects on cotton root length, we conducted field experiments in saline soil based on a monolith method using flooding irrigation with mulch film(FI) as a control at the Korla Experimental Station of the Xinjiang Academy of Agricultural Sciences, China in 2009 and 2010. The results showed that the total root length decreased 120 days after sowing(DAS) under DI, and was mainly centered in the 0–30 cm soil layer and at distances of 30–70 cm from the drip-lines. There was almost complete overlap in the area of root length decline and salt accumulation. In the soil depth of 0–30 cm and at distances of 30–70 cm from the drip-lines at 110 to 160 DAS in 2009 and 171 DAS in 2010, the electrical conductivity(EC) in all soil samples was at least 3 mS/cm and in some cases exceeded 5 mS/cm under DI treatment. However, EC barely exceeded 3 mS/cm and no reduc- tion in root length was observed under FI treatment. Correlation analysis of soil EC and root length density indicated that the root length declined when the soil EC exceeded 2.8 mS/cm. The main reason for the decrease of root length in cotton under DI was localized accumulation of salinity.     

滴水观音叶绿素荧光参数对低温淹水处理的响应

以滴水观音为试验材料,研究了低温环境下淹水处理对其叶绿素荧光的影响。种植滴水观音的花盆置于水箱中,利用水位调节阀调节箱内水位。试验设计为不淹水(对照组,正常浇水)、1/4淹水、2/4淹水、3/4淹水和全淹,分别于淹水后的第10、20、30、40、50天进行各项指标的测定。试验结果显示:1/4淹水处理植株叶绿素荧光参数均高于对照处理,初始荧光产量、最大荧光产量、最大光能转化效率、光化学猝灭系数和非光化学猝灭系数分别为对照的106.6%、104.8%、107.8%、105.0%、153.6%,差异显著(P0.05);2/4淹水、3/4淹水、全淹组初始荧光产量、非光化学猝灭系数均高于对照组,最大荧光产量、最大光能转化效率和光化学猝灭系数均显著低于对照组,尤其全淹组分别低于对照组的20.4%、36.2%和17.2%。1/4淹水处理可提高滴水观音光合作用,高水位处理则抑制滴水观音生长。     

涝渍胁迫对白桦根系生长和生理的影响

为了解白桦(Betula platyphylla Suk.)根系对涝渍土壤条件的适应性,通过人工模拟涝渍胁迫,从形态和生理两方面探讨了涝渍胁迫对2年生白桦实生苗根系的影响。试验分为对照,渍水和淹水3个处理,处理时间为36d。结果表明:1)渍水和淹水处理下都使根部产生不定根,渍水处理产生不定根多于淹水处理;2)在淹水处理下,根系干物质含量显著低于对照;3)POD的活性变化与SOD活性变化相同,渍水和淹水处理下,SOD和POD活性都显著高于对照;4)淹水处理下,根系中的MDA含量显著高于对照;5)3个处理之间脯氨酸含量差异显著,渍水和淹水处理下,脯氨酸含量显著高于对照。表明白桦根系通过生成不定根和生理生化的改变,从而降低在涝渍胁迫对根系的伤害。     

三峡库区消落带土壤淹水对氮素转化及酶活性的影响

以三峡库区消落带典型的紫色土为试验材料,通过原位试验研究不同淹水深度(0、2、5和15m)对土壤氮素形态转化和酶活性的影响。结果表明:淹水180d后,随着淹水深度的增加,铵态氮和硝态氮含量均逐渐降低;与未淹水(0m)对比,水深2m处的铵态氮含量增加显著,而水深15m处的硝态氮含量显著(P0.05)减少。铵态氮和硝态氮含量对不同淹水深度的响应有显著差异(P0.05)。对土壤无机氮(铵态氮+硝态氮)而言,水深15m处的无机氮含量比未淹水(0m)减少3.96mg/kg。脲酶和亚硝酸还原酶活性随淹水深度增加有所下降,而羟胺还原酶和硝酸还原酶活性呈先下降后上升的趋势,并均在水深2m处达到最大值。除脲酶外,其他酶活性均高于未淹水(0m)处理。     

淹水条件下有机肥对土壤重金属形态转化及迁移的影响

采用土柱模拟试验,利用欧共体参比司提出的BCR连续提取法,探讨了重金属Zn,Cu,Pb,Cd在农田土壤中的化学形态及迁移风险。结果表明,施用不同有机肥对重金属向下迁移影响不大,淹水9个月后,Zn,Cu,Pb,Cd从表层土壤（0-20 cm）向下迁移了约2 cm,集中于20-22 cm土层,不易对深层土壤造成污染。添加有机肥后,0-10 cm土层中Zn,Cu,Pb,Cd的酸溶态比例随着淹水时间的增加而降低,而可还原态比例却随之升高,表明有机肥对重金属的有效性有一定的抑制作用。在此期间,可氧化态和残渣态的含量基本保持不变,两者百分比之和在各元素中均小于15%。     

Effects of anti-auxins on secondary aerenchyma formation in flooded soybean hypocotyls

In flooded hypocotyl of soybean (Glycine max), cell division in phellogen and the elongation of these cells are enhanced, and thereby a secondary aerenchyma with high porosity is produced. Auxin controls cell division and cell elongation in many plants, so we studied its role in secondary aerenchyma development. Soybean plants with fully expanded unifoliolate leaves were flooded for 6 d with solutions (100 μM each) of seven anti-auxins. TIBA, NPA, HFCA, 1-NOA, or CHPAA did not restrict the secondary aerenchyma formation, while MH moderately suppressed the aerenchyma development, and PCIB strongly inhibited the development of phellogen and secondary aerenchyma. However, the endogenous IAA concentrations in the flooded hypocotyls did not increase or decrease relative to the controls until 72 h, when a secondary aerenchyma was observed. From these results, it is unclear whether auxin plays an important role in the process of secondary aerenchyma formation under flooding.     

淹水历时与排水对夏玉米叶面积和产量的影响

通过防雨棚下测坑试验,研究了不同淹水历时和是否排水对夏玉米叶面积、产量及其性状、生物产量的影响,结果表明:夏玉米植株绿叶数和叶面积指数(LAI)随着淹水历时增加而急剧减少,与CK(无淹水)相比,排水条件下FD4、FD5、FD6、FD7和FD9绿叶数分别减少12.50%、10.71%、19.64%、32.14%和42.86%,无排水条件下FUD4、FUD5、FUD6分别减少21.43%、37.50%和51.79%;各处理LAI变化幅度类似于绿叶数,与CK相比,排水条件下LAI平均减少21.81%,无排水条件下LAI平均减少38.32%;相同淹水历时条件下,不排水处理对玉米叶面积抑制作用明显高于排水处理。夏玉米穗长、穗粒数、百粒重随着淹水历时增加呈减小趋势,秃尖长呈增大趋势,籽粒产量和生物产量减产幅度增加;与CK相比,排水条件下,淹水历时超5d后减产明显增加,淹水历时每增加1d,减产率增加7%左右;无排水的条件下,FUD4、FUD5和FUD6分别减产34.06%、49.64%和58.82%;相同淹水历时4d、5d和6d,排水与否减产率分别相差31.20个百分点、45.57个百分点和40.82个百分点。夏玉米排水指标为:在夏玉米抽雄期排水情况下,淹水历时应低于6d,籽粒产量减幅可控制在5%以内;在没有排水条件下,淹水历时应小于4d,否则减产在30%以上。     

淹水程度对滩地枫杨木材含水率和年轮宽度的影响

就淹水程度对2组枫杨材(湿林、气干材)年轮宽度、含水率的影响进行研究.结果发现,2组间湿材含水率均达到210.0%以上,气干材含水率约为13.0%;第1组和第2组生材含水率分别为89.9%和105.3%.在0.05水平上,经T-检验2组间只有生材含水率差异显著.年轮宽度由髓心向外逐渐变窄,但年轮宽度与树木年龄回归显著性不高,相关系数均小于0.5.     

稻草还田下非稻季持续淹水对稻季CH_4和CO_2排放的影响

稻草还田和非稻季持续淹水是我国最重要的稻田管理方式之一,此种管理方式下稻田碳排放并不清楚。本研究以江汉平原中稻-冬闲制度为对象,探讨稻草还田耦合非稻季持续淹水对稻季碳排放的影响,为准确评估稻田温室气体排放提供数据支撑和理论支持。结果表明,在稻草秸秆全量覆盖还田下,非稻季自然排水比持续淹水显著降低稻季CH_4累积排放量,稻季第一次排水晒田之前CH_4排放占总排放量的80%以上;非稻季持续淹水使稻季CO_2累积排放量比自然排水稍有降低,CO_2排放主要集中在第一次排水晒田之后,占总排放量的60%左右。非稻季淹水降低稻季土壤NO_3~--N、NH_4~+-N和DOC浓度以及10 cm土层土壤Eh值,但使乙酸浓度升高,这可能是稻草还田耦合非稻季淹水导致CH_4排放量增加的主要原因。