脱落酸对UV-C胁迫下小麦幼苗光合特性及抗氧化酶活性的影响

研究了UV-C辐射下短期和长期脱落酸（ABA）处理对小麦幼苗CO₂同化作用、羧化效率、光合CO₂响应以及抗氧化酶活性等的影响.结果表明,在无UV-C辐射情况下,短期和长期ABA处理能提高光合速率,比对照增加14.69%和20.46%,降低气孔导度,比对照降低14.74%和17.31%,但对胞间CO₂浓度和羧化效率影响不大.当受到UV-C辐射时,光合速率、羧化效率、气孔导度和胞间CO₂浓度逐渐降低.长期ABA处理变化最小,其次为ABA短期处理,对照降低最大.ABA处理能够提高小麦光合对CO₂的响应,UV-C辐射抑制光合对CO₂的响应.ABA处理能够提高小麦抗氧化酶（CAT、SOD、POD）活性而降低MDA含量.在UV-C辐射下,CAT活性先升高随后降低,在辐射处理1 h时活性达最大值,ABA处理的SOD和POD活性先升高后降低,且ABA长期处理比短期处理增加明显,对照则逐渐降低.ABA处理可能通过提高小麦CO₂同化作用和抗氧化酶活性增强对UV-C胁迫的抗性,且ABA长期处理比短期处理效果更明显.     

略论稻田养鱼与农田生态

稻田养鱼能够挖掘稻田生态系统的生产潜力 ,既提高稻谷产量又增加淡水鱼产量 ,又为发展养鱼提供大量优质鱼种。稻鱼群落能够产生单一种稻所不能有的经济、生态和社会诸方面的综合效益 ,稻田养鱼为合理地利用土地资源提供了一种特殊的、最佳的生态模式。1　稻田养鱼在农田生态系统中的作用农田的水、土、光、热和气等非生物因素和动物、植物、微生物等生物因素密切地相互关联、相互依存、相互制约 ,形成一个在功能上统一的系统 ,即农田生态系统。在这个系统内 ,生物群落同其生活环境进行着能量、物质转化和循环。稻田是一个典型的人工生态系…     

稻田养鱼：水稻田鱼的和睦相处

这里有明媚的山光,清澈的溪水,秀丽的梯田,还有一幅其乐融融的“稻鱼同乐”图：稻田里五彩斑斓的鱼儿欢快地嬉戏,绿色的水稻在鱼儿的陪伴下越发充满生机。这就是我国浙江青田县的龙现村。龙现村是一个千年山区古村落,1999年,该村被命名为中国田鱼第一村。村子里有400亩左右的农田,100多个水塘,具有得天独厚的稻田养鱼优势。     

北方稻田生态系统养分平衡研究

１９９４～１９９６年研究了５种不同模式水稻田生态系统养分平衡及养分效率．结果表明,不同模式的水稻田生态系统中,Ｎ输入输出基本相抵,处于平衡状态;Ｋ输入输出稍有盈余,唯Ｐ施用量较输出高１倍,使土壤中Ｐ有所积累．通过合理水肥调控措施,使水稻单产有所提高,肥料和养分利用率也得到不同程度的提高     

稻鸭共生对稻田水生动物群落的影响

通过稻田共生的田间试验,利用水生动物取样的方法,对稻鸭共生中稻田水生动物的种类及数量进行定性定量分析。结果表明:各类水生动物的种类数与水的动静有关,放鸭越多,种类数越少,水源区最少,为15种;且稻田水生动物种类出现频次的分布符合C.R aunk iaer频度定律。各类水生动物的数目和生物量均按水源区、对照区、少鸭区、多鸭区的顺序下降。用M arga lef多样性指数公式计算各处理的多样性指数,以对照稻田的多样性指数2.15为最高,水源区和放鸭的稻田均不高,放鸭越多,多样性指数越低。     

青海蚕豆根瘤菌共生固氮效应的研究

蚕豆根瘤菌属于快生型根瘤菌 ,2 4h形成菌落。在盆栽试验中 ,蚕豆根瘤菌Qx -2与蚕豆具有良好共生效应 ,其株高、茎叶干重及含氮量 ,株瘤数 ,根瘤重量以及固氮酶活性等 ,均明显高于不接种对照 ,固氮率提高 69.4 9%。接种根瘤菌是提高蚕豆共生固氮效应的技术措施。     

北方稻田生态系统水量平衡及水分效率研究

１９９３～１９９５年研究了５种不同模式水稻田生态系统水量平衡及水分效率结果表明,不同水稻田模式其总耗水量之间有明显差异,其中节水模式和节水节肥模式较常规模式节省灌溉水达１５～２３％,水分生产效率增加３０％以上．各模式蒸发蒸腾耗水量在同一生长季内基本相同．田间结构及调控管理对其无明显影响实测水稻生育期田间蒸发蒸腾量与计算的可能蒸发蒸腾量相差不过５％。     

稻田种养模式生态效益研究

１９９１年在湖北潜江进行了一个包括５个处理、３个重复的随机区组试验：处理Ａ,普通稻田,不养鱼（ＣＫ）;Ｂ,垄稻沟鱼,宽、深各３３ｃｍ的小沟中养鱼;Ｃ,Ｂ＋横沟或围沟,深５０ｃｍ,宽３３ｃｍ,或加一小坑,宽１－２ｍ,深１ｍ,长度以占小区８％的面积为准,养鱼;Ｄ,Ｂ＋大围沟,宽２ｍ,深２－２．５ｍ,占小区面积的１５％,养鱼;Ｅ,Ｄ＋鸭。结果表明,在酷暑７、８月份,宽而深的大沟的水温比窄而浅的更适于养鱼     

我国南北气候过渡地区稻米品质的地域分布

本文依据农业气候指标,运用模糊综合评判和定性聚类的方法,综合评价了所研究地区影响稻米品质的生态气候因子,并把该地区分为4个区域和9个亚区域,每个亚区的生态气候条件和稻米品质各有特色,且所有区域稻米品质变化具有共同的规律性.     

稻田CH4和N2O的排放及养萍和施肥的影响

用箱法对我国东北稻田ＣＨ４和Ｎ２Ｏ排放进行观测研究表明,东北稻田的ＣＨ４排放通量比南方稻田小,平均日排放通量和生长季节排放总量分别为０．０７和７．４ｇ·ｍ－２．稻田淹水期几乎没有Ｎ２Ｏ的净排放,但在非淹水期内却有大量Ｎ２Ｏ排放（平均通量５９μｇＮ２Ｏ·ｍ－２·ｈ－１）．稻田养萍和施肥明显促进ＣＨ４和Ｎ２Ｏ排放．稻田ＣＨ４和Ｎ２Ｏ排放之间存在消长关系．制定稻田温室气体减排技术措施时应充分注意这一关系．     

Cadmium,copper, and zinc levels in the rice and rice field soil of Houston,Texas

Fifty-one pairs of hulled rice samples and the soil from which each rice sample was grown were analyzed for heavy metals in August, 1979, in order to estimate the background contamination of cadmium (Cd), copper (Cu), and zinc (Zn) in rice grown in the Houston, Texas area. Both samples were divided into three groups by soil types and colors. The cadmium concentration in Texas rice was only one-half to one-quarter lower than that of Asian rice. However, the levels of Cu and Zn in rice in Texas were similar to those reported. Soil heavy metals were lower than ever reported, but these values were consistent with the geochemical characteristics of the Texas Houston area. No particular relationship was found between the three metals in rice and the metals in soil where the sampled rice was grown.     

南方双季稻田稻草还田的碳汇效应

利用长期稻草还田定位试验和短期不同稻草还田模式试验,研究稻草还田对南方双季稻田土壤固碳、甲烷排放和综合碳汇的影响.结果表明： 稻草还田能增加土壤有机碳,长期还田的耕层土壤碳汇年增长率为0.07 t C·hm^-2·a^-1,土壤有机碳的表观转化率随着稻草还田量的增加而减少.稻草还田导致稻田甲烷排放量显著增加,其中,NPK添加稻草（NPK+RS）处理早、晚稻期间甲烷排放通量比仅施NPK分别增加了75.0%和251.5%（P<0.01）.稻田甲烷排放随着稻草还田量的增加而增加,在水稻产量和耕作方式相近的条件下,稻草（茬）的甲烷表观转化率接近.综合土壤固碳和甲烷排放的稻田净碳汇,NPK+RS处理负碳汇效应显著,基本与其水稻生物固碳接近,比稻草不还田处理（NPK）增加158.3%;不同还田模式中,稻草覆盖免耕处理能显著减少甲烷排放,其净碳汇（负值）比高桩翻耕处理减少50.9%,有利于水稻高产稳产.     

Performance of different fish species for controlling weeds in rainfed lowland rice field

A field experiment was conducted during wet season to evaluate the performance of different fish species for biocontrol of weeds in rainfed waterlogged rice fields with fingerlings of three exotic carps – grass carp, Ctenopharyngodon idella (Val.) (Cyprinidae, Cypriniformes), silver barb, Puntius gonionotus (Bleeker) (Cyprinidae, Cypriniformes) and common carp, Cyprinus carpio (L.) (Cyprinidae, Cypriniformes) – and three Indian major carps – rohu, Labeo rohita (Ham.) (Cyprinidae, Cypriniformes), catla, Catla catla (Ham.) (Cyprinidae, Cypriniformes), mrigal, Cirrhinus mrigala (Ham.) (Cyprinidae, Cypriniformes). A total of 13 major weeds under the categories of grassy, sedges, broadleaf and aquatic weeds were observed in the rice fields. Grass carp reduced maximum weed biomass (weed control efficiency [WCE] 63% at 60 days after transplanting [DAT] and 62% at 100 DAT) followed by silver barb and common carp. Among the Indian carps, only rohu was effective in control of weeds (WCE, 23% at 60 DAT). The grain yield of rice (variety Varshadhan) slightly increased (4.2–4.5 t/ha), but straw yield was significantly higher (10.2–10.7 t/ha) under rice-fish farming. Fish yield was significantly higher in exotic carps (270–288 kg/ha/90days) due to higher specific growth rates (1.8–2% body weight/day). The study indicated that exotic carps (grass carp, silver barb and common carp in order) were more effective than Indian carps for control of weed in rainfed lowland rice fields and among the Indian carps, rohu showed potential for weed control.     

The effect of rice seeding rate and fish stocking on the floodwater ecology of the rice field in direct-seeded,concurrent rice-fish systems

Concurrent, rice-fish systems in the Mekong Delta, Vietnam, are characterized by a rice field surrounded by a trench. Rice is direct seeded and fish are reared in polyculture. The most common species for polyculture are silver barb Barbodes gonionotus (Bleeker), common carp Cyprinus carpio L. and Nile tilapia Oreochromis niloticus (L.). In a 1996–97 rice-fish experiment, the effects of (1) absence or presence of such a polyculture, and (2) different rice-seeding rates (100 and 300 kg pre-germinated rice per ha) on the field floodwater ecology were studied. Fish obtained from local nurseries were stocked in six out of 12 rice-fish plots at the Co Do experimental rice-fish station (10°10 N and 105°20 E). Silver barb, common carp and Nile tilapia were stocked in polyculture at densities of 3150, 310 and 550 fish ha^–1, respectively. About 50% of the observed variation in the floodwater could be attributed to the fish stocked and to rice-seeding rate. The above-ground dry weight of the rice plants increased in the presence of fish and by an increase in rice-seeding rate. Greater shading by denser plants resulted in changes in variables related to aquatic primary production, including the amount of chlorophyll-a, dissolved oxygen concentration and pH. The presence of fish quadrupled the ammonium concentration, but decreased that of ortho-phosphate. Though fish increased the ammonium concentration, this did not result in a higher aquatic photosynthesis. Light, not ammonium, was the most limiting factor. However, increased ammonium concentrations in the presence of fish did have a positive effect on the density of Euglenophyta and the amount of chlorophyll-a, though only at the lower rice-seeding rate. At the higher rice-seeding rate, light seemed to be lacking. At the lower rice-seeding rate, fish also had a significant effect on the Cladocera–Rotifera ratio. Rotifera numbers increased as fish stimulated phytoplankton. We also demonstrated that fish most probably do not reduce ammonia volatilization losses. The lower rice-seeding rate seemed better for fish production than the higher rate: at the lower rate, dissolved oxygen concentrations were higher throughout the rice cycle. In addition, the amount of chlorophyll-a and the density of Euglenophyta were higher at the lower rice-seeding rate. Finally, we could show that even at high rice-seeding rates, fish had an impact on the aquatic environment. Fish access to the field is not hindered by dense rice stands.     

田埂留草控制稻飞虱效果及对捕食性天敌多样性影响

为探讨稻田田埂保留杂草控制稻飞虱的效果及对捕食性天敌多样性的影响,以稻田田埂周年性保留杂草为处理,以稻田田埂不保留杂草为对照,对处理区和对照区稻田稻飞虱成若虫、捕食性天敌种类和数量进行系统调查和分析。结果表明,在调查期内(6—10月),田埂留草稻田百丛稻株稻飞虱数量为(891.11±133.12)头,较非留草稻田减少35.31%;田埂留草稻田捕食性天敌隶属5目23科35种,而田埂非留草稻田隶属5目21科33种;田埂非留草稻田捕食性天敌优势种为食虫沟瘤蛛Ummeliata insecticepsBoes.etStr.、拟水狼蛛Pirata subpiraticus Boes.etStr.和黑肩绿盲蝽Cyrtorrhinus livdipennis Reuter,而田埂留草后优势种为食虫沟瘤蛛U.insecticeps、草间小黑蛛Erigonidium graminicolum(Sundevall)、拟水狼蛛和拟环纹狼蛛Lycosa pseudoamulata(Bose.etStr.);田埂留草稻田捕食性天敌的个体数量、丰富度、多样性指数分别为(128.89±13.52)、(33.67±0.50)、(4.53±0.04)头/百丛,较田埂非留草稻田分别增加31.96%、25.73%、5.59%,而优势度指数和均匀性指数没有显著变化。研究结果为发展稻田景观多样化控害提供依据。