旱地玉米半耕整秆覆盖效果研究

经过２年的旱地玉米半耕整秆半覆盖试验结果表明，该措施可增加土壤耕作有机质，提高土壤含水量和土壤肥力，改善土壤耕层结构，达到增产目的。     

不同覆盖材料土壤生态效应与玉米增产效应研究

田间试验研究不同覆盖材料土壤生态效应与玉米增产效应结果表明,小麦秸秆、地膜、高粱秆片和纸板覆盖均有显著保水作用及明显水分表聚现象,即0～10cm表层土壤含水量明显高于下层土壤,地膜覆盖兼有显著增温效应,而小麦秸秆、高粱秆片和纸板覆盖土壤温度却明显低于对照。除纸板外其他覆盖材料均不同程度增加0～2 0cm土层土壤细菌、真菌和放线菌数量,且以秸秆覆盖增幅最大。各覆盖处理均显著增加玉米株高、茎粗和叶面积指数,不同程度提高玉米生育前期倒1、2、3叶净光合速率。小麦秸秆、地膜、高粱秆片、纸板覆盖处理分别比对照增产19.4 %、17.2 %、16 .1%和13.3% ,其增产原因主要是由于穗长和穗粒数的增加所致     

冻融期灌水和覆盖对南疆棉田水热盐的影响

为了探索不同冬灌定额和地表覆盖模式对棉田水热盐的影响,该文设置了冬灌裸地(winter irrigation with bare land,WIB)、冬灌留秆(winter irrigation with high cotton stubble,WICS)、冬灌玉米秸秆覆盖(winter irrigation with corn straw mulching,WICM)、免冬灌裸地(no winter irrigation with bare land,NWIB)、免冬灌留秆(no winter irrigation with high cotton stubble,NWICS)和免冬灌玉米秸秆覆盖(no winter irrigation with corn straw mulching,NWICM)6个处理。经过2013-11-15-2014-04-04和2014-11-15-2015-04-04冬季大田试验,得到:灌水和地表覆盖可以平抑土壤温度的变幅,免冬灌或冬灌条件下,温度变异幅度均为裸地留秆玉米秸秆覆盖。玉米秸秆覆盖更有利于土壤水分保持,WICM土壤储水量比WIB和WICS分别多29.10%和10.36%,NWICM土壤储水量比NWIB和NWICS分别多14.97%和2.21%,经过两年冻融过程NWIB、NWICS和NWICM 0~100 cm土壤储水量平均减少了18.32、7.36和2.62 mm。(免)冬灌0~30 cm土壤含盐量均为裸地留秆玉米秸秆覆盖;0~100 cm土壤范围冬灌盐分淋洗率为玉米秸秆覆盖(34.86%)留秆(15.82%)裸地(7.26%);免冬灌0~100cm积盐率为裸地(10.11%)留秆(7.96%)玉米秸秆覆盖(3.01%)。研究结果可为南疆冬季休闲期棉田土壤水热盐调控提供科学依据。     

不同覆盖材料对玉米幼苗生长和土壤养分含量及分布的影响

采用盆栽试验方法 ,研究了半腐熟的小麦秸秆和城市生活垃圾、地膜、高粱秆席片、纸板等覆盖材料对玉米幼苗生长以及土壤有机质和速效氮、磷、钾含量分布的影响。结果表明 :秸秆、地膜和席片覆盖显著地增加了玉米株高、地上部植株干重、根系干重和叶片数 ,促进了玉米幼苗的生长发育 ,而纸板和垃圾的作用不显著 ;与其它覆盖材料和对照相比较 ,秸秆和垃圾覆盖材料明显地提高了上 (0～ 7cm)、中 (7～ 14 cm)、下 (14～ 2 1cm) 3层土壤中的有机质和速效氮、速效钾的含量 ,而速效磷的增加上层土壤 (0～ 7cm )大于中层土壤 (7～ 14 cm ) ,下层土壤(14～ 2 1cm)没有增加。     

绿洲灌区玉米产量形成及水分利用特征对地膜覆盖方式及行距的响应

干旱绿洲灌区玉米生产普遍采用全膜覆盖方式,残膜污染问题严重。因此,研究地膜减投增效生产技术对缓解残膜污染有重要意义。在甘肃河西石羊河流域通过田间试验研究了不同覆膜方式(全膜覆盖、半膜覆盖)和不同种植行距(50 cm等行距、40 cm+80 cm宽窄行)对玉米产量、耗水量、耗水结构及水分利用效率的影响。结果表明,全膜宽窄行和半膜宽窄行种植条件下均可获得较高的玉米籽粒产量,分别达14 712.7kg·hm~(-2)和14 155.2 kg·hm~(-2),较半膜覆盖等行距处理高13.2%和8.9%(P0.05),与全膜覆盖等行距处理差异不显著。全膜宽窄行和半膜宽窄行获得较高籽粒产量的原因是提高了穗数和双穗率。全膜覆盖条件下宽窄行种植获得较高LAI峰值的同时,玉米全生育期平均LAI显著高于半膜覆盖处理。全膜覆盖显著降低了玉米生长前期(播种至大喇叭口期)的棵间蒸发量。半膜覆盖等行距和宽窄行种植玉米全生育期棵间蒸发量分别较全膜等行距种植高14.3%和21.9%,差异显著。半膜覆盖宽窄行种植条件下玉米水分利用效率达19.3 kg·mm~(-1)·hm~(-2),与全膜覆盖等行距和宽窄行处理均无显著差异。干旱绿洲灌区半膜覆盖宽窄行种植替代全膜等行距种植或宽窄行不会导致玉米产量和水分利用效率降低。     

机械化整秆覆盖膜侧沟播保护性耕作技术的试验研究

中国黄土高原地区由于干旱、无霜期短而严重影响春玉米产量,该文研究应用整秆覆盖免耕膜侧播种的耕作模式,在冬闲期采用机械将玉米秸秆整秆压倒覆盖免耕,在种植期带状起垄覆膜,膜侧播种,行间秸秆覆盖,集储水、保墒、增高地温于一体。结果表明,该技术与传统的露地深翻模式相比,具有明显的储水、保墒、增高地温和提高玉米产量的效果。     

晋北半干旱区免耕对玉米光合和蒸腾特性的影响

采用田间小区试验,对覆盖免耕、留茬免耕和传统翻耕三种耕作方式下玉米不同生育期土壤温度、土壤含水量以及玉米蒸腾速率和净光合速率进行观测。结果表明:与翻耕相比,免耕可降低0-20cm土层的土壤温度;覆盖免耕玉米地土壤温度的降低幅度较大,而留茬免耕地则较小;免耕对土壤温度的降低作用随着玉米的生长发育而减弱。免耕能够提高土壤含水量,尤其是0-60cm土层。免耕与翻耕相比,在玉米苗期,叶片的蒸腾和光合速率降低,其中覆盖免耕玉米日平均蒸腾与光合速率比翻耕分别降低了8.5%和9.7%,差异显著;留茬免耕略有降低,但差异不显著。在拔节前期,免耕与翻耕田玉米的蒸腾和光合速率无显著差异;在拔节后期、抽穗期和灌浆期,覆盖免耕玉米蒸腾和光合速率均比翻耕显著提高;留茬免耕在灌浆期玉米的蒸腾与光合速率均比翻耕显著提高,其它时期与翻耕差异不显著。     

辽西半干旱区整秸半覆盖技术及增产效应研究

秸秆覆盖能有效地集节天然降水、抑制蒸发 ,改善土壤物理性状 ,实现农业高产稳产。据在辽西低山丘陵半干旱区 5°～ 8°农坡地上进行的试验 ,玉米秸覆盖 90 0 0kg/hm2 ,土壤容重比对照下降 2 0 6%,最大毛管持水量增加 3 3 9%。坡地玉米最佳的玉米秸覆盖量为 15 0 0 0kg/hm2 、小麦秸覆盖量为 75 0 0kg/hm2 。在小麦秸最佳覆盖量条件下 ,玉米产量提高 2 9 4 5 %。秸秆覆盖量过大 ,不利于作物生长 ,产量易受到影响。     

旱地玉米覆盖栽培的土壤水热及产量效应

采用单因素随机区组设计,以春玉米沈单16号品种为试验材料,全膜双垄沟播(FMRFC)、沙膜二元覆盖沟种(FSMC)、全沙覆盖平作(SMC)和露地平作(CK)为处理,研究旱地玉米覆盖栽培的土壤水热及产量效应。结果表明:各覆盖处理玉米苗期-抽雄期0~25cm土层的平均地温均有所提高,对0~100cm土层的土壤水分的消耗增大,且都以FMRFC居首,比CK增温3.1~3.3℃、多耗水9.8%。收获后,各覆盖处理0~20cm土层的土壤水分得到了恢复,但20~100cm土层的水分没有恢复到播前状态。覆盖处理显著改善了穗粒数、穗粒重和百粒重等经济性状,增加了玉米产量,提高了作物水分利用效率(WUE),优先次序为FMRFCFSMCSMCCK。FMRFC是半干旱区玉米种植优先选择的覆盖方式,但对0~100cm土层土壤水分消耗较多,对年际水分平衡不利,需深化匹配水分高效调控技术的研究。     

不同覆盖方式对中度盐渍土壤的改良增产效应研究

地膜与秸秆覆盖是干旱半干旱地区防治土壤次生盐渍化,提高土壤水分利用效率的重要措施。为探索不同地面覆盖方式在盐渍土壤的应用效应及机理,在内蒙古河套灌区中度含盐土壤进行田间试验,试验共设7个处理:玉米粉碎秸秆覆盖量9 000 kg·hm-2(F0.9)、玉米粉碎秸秆覆盖量6 000 kg·hm-2(F0.6)、玉米整秆覆盖(YZ)、葵花整秆覆盖(KZ)、新地膜覆盖(DM)、地膜二次使用免耕(MG)、未覆盖(CK),研究不同地面覆盖方式对中度盐渍化向日葵农田的土壤水盐运动、向日葵产量和种植经济效益等影响,分析不同覆盖措施的改良增产效应。结果表明:在0~5 cm土层,处理F0.9、YZ、DM的含盐量收获后较播前降低,土壤表层脱盐,而MG、F0.6、KZ、CK土壤表层积盐。0~20 cm土层,土壤含盐量收获后与播前相比,处理F0.9、DM土壤耕层脱盐,而F0.6、YZ、MG、KZ、CK在土壤耕层积盐。各覆盖处理主要影响0~20 cm的土壤含盐量,随着土壤深度的增加,覆盖层因素对土壤含盐量的影响趋于一致。耕层土壤含盐量相比较,F0.9的含盐量最低,抑盐效果最好,DM与F0.6抑盐效果相近,不同秸秆覆盖处理间,F0.9、F0.6强于YZ、KZ,地膜覆盖之间,DM强于MG。在0~5 cm土层及0~20 cm土层,DM的生育期平均土壤含水率高于秸秆覆盖处理,粉碎秸秆覆盖(F0.9、F0.6)的生育期平均土壤含水率高于整秆秸秆覆盖(YZ、KZ)。处理DM、F0.9较CK显著提高了向日葵生育期内0~100 cm土壤储水量均值,F0.9、DM处理显著降低了0~100 cm土壤储水量变异系数,在生育期内保持了较稳定的土壤墒情。各覆盖处理均较CK显著增产,各处理产量效应是:DMF0.9YZF0.6MGKZCK。覆盖措施通过改善农田小环境提高了作物水分利用效率,DM、F0.9、YZ处理的作物水分利用效率显著高于其他处理。处理DM、MG、YZ、F0.9、F0.6的产投比显著高于CK,增收效果明显,DM和MG的纯收入及产投比显著高于秸秆覆盖处理。对于中度盐渍化耕地,新地膜覆盖DM是最有效的覆盖方式,秸秆覆盖处理中,F0.9为最优覆盖方式,与其他覆盖处理相比较,KZ处理的保墒、抑盐、增产等效果较差,因此向日葵秸秆不适合用作地面覆盖材料。结果可为覆盖技术在内蒙古河套灌区农业生产中的应用提供理论与技术支持。     

Isolation and partial characterization of banana starches.

Two varieties of banana green fruit growing in Guerrero, Mexico, were used for starch isolation. Chemical analysis and physicochemical and functional properties were studied in these starches. The "macho" variety presented higher starch yield than "criollo". In general, chemical compositions in both starches were similar, except in ash content, where the "criollo" variety showed a lower value than "macho". The results of freeze-thaw stability suggested that banana starches cannot be used in frozen products. Both starches presented similar water retention capacity values that increased when temperature increased. Solubility profiles showed that at low temperature "criollo" had lower solubility than "macho", but at higher temperature an inverse behavior was evident; also the solubility increased when temperature increased. Behavior similar to that for solubility was obtained in the swelling test. The banana starch studies indicate the "macho" and "criollo" varieties have different starch structures as evidenced by viscosity.     

适度局部水分胁迫提高玉米根系吸水能力

局部根区灌溉可以刺激灌水区根系吸水的补偿效应。为了揭示局部灌溉条件下玉米根系补偿效应的动态变化及其影响因素,以聚乙二醇6000(polyethylene glycol 6000,PEG-6000)营养液的渗透势模拟水分胁迫,采用分根技术,通过水培试验模拟局部根区水分胁迫,设置3个水分胁迫程度处理(-0.2、-0.4、-0.6 MPa)和1个对照处理(无营养液),于处理后0、0.25、0.5、1、3、5、7、9 d连续动态监测各根区根系的生长及导水率。结果表明,局部根区受中度及其以下(≥-0.6 MPa)经水分胁迫0.25 d内,所有处理胁迫区根系总导水率和单位根长导水率均与非胁迫区和对照无显著差异(P0.05)。胁迫持续时间超过0.25 d,胁迫区根系总导水率和单位根长导水率均显著小于非胁迫区(P0.05),降低程度随水分胁迫程度而增大,各处理间胁迫区根系总导水率的差异随胁迫持续时间延长也逐渐增大。对于非胁迫区,轻度胁迫(-0.2 MPa)持续0.5 d,单位根长导水率较对照高10.11%(P0.05),1~9 d与对照持平;-0.4 MPa胁迫持续9 d,单位根长导水率为25.08×10-11 m2/(MPa·s),显著高于对照(P0.05);中度胁迫(-0.6 MPa)持续0.5~3 d单位根长导水率显著小于对照(P0.05),较对照低19.05%~40.11%,5 d后与对照持平。说明局部根区水分胁迫能有效刺激非胁迫区根系吸水的补偿效应,这种补偿作用在局部水分胁迫0.5 d时就已发生,受到局部水分胁迫程度和持续时间的影响,且根系吸水补偿效应的临界胁迫程度为≥-0.4 MPa。该研究可为更好的发挥局部灌溉在农业节水中的作用提供理论依据。     

Morphological and molecular cytogenetic characterization of partial octoploid Tritileymus

This study used cytological observation, genomic in situ hybridization (GISH), and seed storage protein electrophoresis to characterize a partial octoploid Tritileymus M842-1 derived from Leymus mollis (NsNsXmXm, 2n = 28) and common wheat cv. 7182 (Triticum aestivum L.), and its relationship with alien chromosomes and those from wheat. Mitotic observations showed that the chromosome configuration of M842-1 was 2n = 56 = 28II. Mitotic and meiotic GISH using two different probes for L. mollis and Psathyrostachys huashanica indicated that M842-1 contained 14 Ns genome chromosomes from L. mollis, which formed seven pairs of uniform bivalents, and confirmed the genomic composition as AABBDDNsNs. The separation of seed storage protein by polyacrylamide gel electrophoresis indicated that M842-1 expressed some L. mollis-specific glutenin and gliadin bands. The seeds of M842-1 were as large as those of wheat cultivars, while they also had a long spike and were covered with wax on the leaves and stems. Disease screening demonstrated that M842-1 was immune to stripe rust, highly resistant to powdery mildew, and moderately susceptible to wheat scab during the adult plant stage. This study demonstrated that the partial octoploid Tritileymus M842-1 could serve as a donor source in wheat breeding programs for the introduction of novel variation to promote high yield and disease resistance.     

Microbial glucosylation of thaxtomin A, a partial detoxification

Thaxtomin A (1) and B (2), the two major phytotoxins associated with the common scab of potato disease, were transformed into C-14 linked beta-glucosides (3) and (4), respectively, when individually incubated with cultures of Bacillus mycoides in oatmeal broth at 26 degrees C. These biotransformation products when assayed on aseptically produced potato minitubers proved to be much less phytotoxic than the parent compounds.     

牛肉部分玻璃化转变温度研究

利用调制式差示扫描量热仪(MDSC)对牛肉糜和牛肉肌动球蛋白的部分玻璃化转变温度进行了测定，得出平均转变温度约为－52.54℃。实验研究了明胶、海藻酸钠和羧甲基纤维素钠对牛肉糜部分玻璃化转变温度的影响，结果表明3种添加剂对牛肉糜部分玻璃化转变温度均无显著影响。利用程序降温仪对牛肉糜进行冻结与解冻实验，结果表明在本实验的降温速率1～5℃/min范围内，降温速率越高，所需的冻结终温越低。     

Do partial marine reserves protect reef fish assemblages?

Fish assemblages in the Mimiwhangata Marine Park, an area closed to commercial fishing but open to most forms of recreational fishing, were compared with adjacent fished areas. Two survey methodologies were used; baited underwater video and underwater visual census. Snapper (Pagrus auratus), the most heavily targeted fish species in the region, showed no difference in abundance or size between the Marine Park and adjacent control areas. When compared to the fully no-take Poor Knights Island Marine Reserve and two other reference areas open to all kinds of fishing (Cape Brett and the Mokohinau Islands), the abundance and size of snapper at the Marine Park were most similar to fished reference areas. In fact, the Marine Park had the lowest mean numbers and sizes of snapper of all areas, no-take or open to fishing. Baited underwater video found that pigfish (Bodianus unimaculatus), leatherjackets (Parika scaber) and trevally (Pseudocaranx dentex) were significantly more common in the Marine Park, than in the adjacent control areas. However, none of these species are heavily targeted by fishers. Underwater visual census found similar results with five species significantly more abundant in the Marine Park and five species more abundant outside the Marine Park. The lack of any recovery by snapper within the Marine Park, despite the exclusion of commercial fishers and restrictions on recreational fishing, indicates that partial closures are ineffective as conservation tools. The data suggest fishing pressure within the Marine Park is at least as high as at other ‘fished’ sites.     

Computer modelling of partial specific volumes of humic substances

The determination of the structure of humic substances from peat soils and natural waters is a major problem in soil science. Humic substances are chemically heterogeneous and consist of molecules covering a wide distribution of molecular size. A quantity related to both molecular size and structure in the hydrated state is the volume of the humic molecules per unit mass or partial specific volume (ν₂). The partial specific volumes of humic substances have been estimated from atom and chemical group volume contributions for 17 proposed structures of fulvic and humic acids taken from the literature. The results show that the partial specific volume reflects the composition of humic substances, decreasing with increase in the carbon: hydrogen (C:H) molar ratio. The more oxidized the humic material the smaller is its partial specific volume. These trends agree with our experimental measurements of partial specific volumes for a range of humic materials (aquatic fulvics, aquatic and peat humics). The predicted values of partial specific volumes for the proposed structures, however, are overestimated by approximately 15% compared to the experimental values. There is little difference between values of ν₂ calculated from the detailed humic structures and those calculated from their empirical formulae; calculations of partial specific volumes using a random modelling approach leads to overestimation by approximately 37%. It seems that the estimates based on additivity of atom and chemical group volumes do not take into account an overall contraction of the structures because of hydrophobic interactions. In general terms the values of the partial specific volumes of humic substances suggest they are more compact molecules than globular proteins, and intrinsic viscometry studies suggest that aqueous salt solutions approach θ-solvent conditions for humic substances.     

Purification and partial characterization of chickpea 2S albumin

A chickpea 2S albumin has been purified by solubilization in 60% methanol and ion-exchange chromatography. Under denaturing conditions it is composed of two peptides of 10 and 12 kDa. Native molecular mass determined by gel filtration chromatography is 20 kDa. Amino acid composition shows that it is rich in sulfur amino acids, mainly cysteine with 4.6% of the total. On the other hand, it has antinutritional characteristics of being allergenic for chickpea-sensitive individuals and inhibitory against porcine chymotrypsin with a lesser degree toward trypsin. The results of interest from a nutritional point of view are discussed.     

Inhibitory effect of low partial pressures of acetylene on nitrification

The inhibiting effect of C₂H₂ on nitrification was investigated in two agricultural soils. Nitrification was totally inhibited at 10 Pa partial pressure of C₂H₂ which is lower than previously reported for soils. There were no differences in rates of nitrate production between flasks without C₂H₂ and flasks with C₂H₂ at 0.01 Pa, while there was an effect on nitrification at 0.1 PaC₂H₂. At 0.1 Pa no inhibition was noted during the first 3 days; after this period nitrification was partially inhibited. The inhibiting effect did not cease until 7 days after removal of C₂H₂. The sensitivity of nitrification to low concentrations of C₂H₂ should be noted when denitrification rates are determined by the use of the acetylene inhibition method (usually C₂H₂ at 10kPa).     

果树根系分区交替灌溉研究进展

通过对国内外分根区交替灌溉研究成果分析,综述了一种既能满足果树水分需求,又能控制植株长势、减少“奢侈”蒸腾、改善果实品质的果园节水灌溉新技术——果树根系分区交替灌溉,阐明了其理论体系和节水优产机理,概述了与该技术有关的部分根区干燥技术研究现状和存在的问题,提出了几种适合在果园应用的根系分区交替灌溉技术实施模式并对其可行性进行了探讨。分析了果树根系分区交替灌溉技术的应用前景和需要进一步研究的问题。