Digitaria sanguinalis seed dormancy release and seedling emergence are affected by crop canopy and stubble

Digitaria sanguinalis is a troublesome annual weed that causes important yield losses in different crops. Despite this, there is scarce information about different aspects of its biology under field conditions. New knowledge about the establishment process of this species will be of paramount importance in order to maximise the effectiveness of weed management. The aims of this paper were to evaluate the effect of stubble found on the surface on seed dormancy levels through the season, the effects of stubble and soyabean crop canopy on seedling emergence and to determine the field emergence pattern as a consequence of seed dormancy level at dispersal time. Seeds on the soil surface, which showed a high dormancy level at the beginning of autumn, were released from dormancy by low winter temperatures and germinated during spring as temperatures rose, showing a transient surface seedbank. Seeds covered by stubbles had delayed the emergence in the field due to lower alternating temperatures perceived by the surface seedbank. On the other hand, the presence of a soyabean crop and stubble together reduced the number of seedlings. Seeds with a high dormancy level at dispersal time showed a delayed emergence in the next season when compared with seeds with a lower dormancy level. However, the final number of seedlings was similar. Both stubble on surface and crop canopy are useful factors to lessen and delay the seedling emergence allowing the design of weed management strategies in order to diminish the population levels of this species.     

海藻提取物对干旱胁迫下苹果砧木幼苗抗旱性和养分吸收的影响

以1 a生苹果砧木M9T337幼苗为试材,设置正常供水（CK）、中度干旱（MD）、中度干旱+海藻提取物（MD+SE）、重度干旱（SD）、重度干旱+海藻提取物（SD+SE）5个处理,研究海藻提取物对不同程度干旱胁迫下幼苗的生物量、光合特性、抗氧化酶活性、渗透调节物质含量和植株养分含量的影响。结果表明：在中度干旱胁迫条件下,植株总生物量较MD处理提高了15.4%,净光合速率较MD处理提高了12.1%,SOD、POD、CAT和APX活性分别较MD处理提高了4.5%、8.4%、30.6%、9.8%,可溶性蛋白和脯氨酸等渗透调节物质较MD处理分别提高了19.1%和13.1%,植株氮、磷、钾含量较MD处理分别提高了19.2%、22.7%和40.5%;在重度干旱胁迫下,叶面喷施海藻提取物后总生物量较SD处理提高了13.7%,净光合速率较SD处理提高了10.2%,SOD、POD、CAT和APX活性较SD处理分别提高了16.6%、18.1%、30.2%、8.9%,可溶性蛋白和脯氨酸等渗透调节物质含量较SD处理分别提高了14.1%和13.1%,植株氮、磷、钾含量较SD处理分别提高了12.4%、21.7%和38.4%。不同程度干旱条件下喷施海藻提取物均有良好的缓解效果,以中度干旱胁迫缓解效果更显著。     

磁化水对不同土壤水分下黄瓜幼苗生长、光合和养分吸收的影响

采用二因素二水平完全试验设计,研究了砂培条件下磁化处理（分别为0.3T磁场强度处理的磁化蒸馏水和蒸馏水处理）对不同土壤水分条件下（正常水分处理：田间持水量的80%~85%;干旱处理：田间持水量的40%~45%,于黄瓜4~5叶期维持7 d）黄瓜幼苗生长、水分关系、光合作用和养分吸收的影响。结果表明,磁化水浇灌显著降低黄瓜幼苗的生长和水分利用,其中茎粗、地上部生物量、根生物量、总生物量、根体积、根表面积、整株耗水量和整株水分利用效率分别降低6.7%、8.9%、19.1%、9.9%、22.1%、18.5%、6.2%和10.9%;磁化水浇灌导致黄瓜幼苗叶SPAD值降低了3.7%,叶气孔导度和蒸腾速率则分别增加了21.8%和17.5%,叶瞬时水分利用效率降低了17.7%,但对净光合速率影响不大;磁化水浇灌使PSII最大光化学效率和电子传递速率分别降低了5.2%和18.6%,同时增加叶片中K含量。除叶片K含量外,干旱条件下磁化水对黄瓜生长和生理代谢影响不大,表明磁化水的作用依赖于土壤水分条件。     

新型塑料大棚规模化养猪舍环境状况的研究

对大棚舍、有窗舍和开放舍三种类型猪舍冬、夏季五项环境指标的测定与分析,研究新型塑料大棚规模化养猪舍环境状况与特点。结果表明,新型塑料大棚规模化养猪舍内冬季空气温度为１１．３℃,相对湿度为７２．３％,气流速度为０．１９ｍ／ｓ,二氧化碳浓度１０００ｐｐｍ;夏季,空气温度２６．５℃,相对湿度为８０．２％,气流速度为０．７２ｍ／ｓ,二氧化碳浓度为６４０ｐｐｍ。大棚舍内环境冬、夏季均优于有窗舍,夏季与开放舍差异不明显。     

Genetic resources of salt tolerance in wild Hordeum species

Salt tolerance was evaluated in 340 accessions of Hordeum, consisting of 41 brittle-rachis forms of Hordeum vulgare L. subsp. vulgare (H. agriocrithon) accessions, 154 H. vulgare L. subsp. spontaneum (H. spontaneum) accessions, and 145 accessions of ten other species or subspecies of wild Hordeum. Germination was carried out at concentrations of 171, 257, and 342 mM NaCl. The levels of salt tolerance for seed germination in wild Hordeum species were generally lower than those found by Mano et al. (1996) in cultivated barley; the NaCl tolerance level of the different species were as follows: H. agriocrithon > H. spontaneum > other wild Hordeum species. In addition, leaf injury index was used to assess tolerance at the seedling stage after treatment with 500 mM NaCl solution for four weeks. The levels of salt tolerance at the seedling stage in wild Hordeum species were generally higher than those found by Mano & Takeda (1995) in cultivated barley. Most wild Hordeum species showed high NaCl tolerance at the seedling stage and are considered good sources of germplasm for salt tolerance breeding. This revised version was published online in August 2006 with corrections to the Cover Date.     

徐州贾汪地区银杏幼苗死亡原因分析

调查研究结果认定立枯病是造成银杏幼苗死亡的主要原因,土壤水淹涝渍是诱发该病发生的环境条件,水泥粉尘污染削弱了幼苗对病害的抗御能力,在一定程度上加重了立枯病的危害。     

MY-7型育苗喷药机的研制

介绍了ＭＹ－７型育苗喷药机的总体设计、性能试验和主要技术规格,并对其应用效益加以分析     

塑膜容器育苗及容器苗造林中的几个技术问题

针对当前容器育苗、造林中产生的技术问题, 以油松、侧柏为主要树种, 从制定塑膜容器苗的苗木标准、进一步提高育苗技术水平、注意容器苗造林的适地适树、适时进行穴内间株等四个方面, 提出了技术建议。     

耕作制度对抛栽稻田杂草的群落影响

三年六熟五旱－水稻作,抛栽稻田的主要杂草（稗草,异型莎草,陌上菜和水莎草）发生频率和优势度降低,优势草种为鳢肠和下香蓼。麦田免耕３年,后茬抛栽稻田多年生杂草（眼子菜,矮慈菇,水莎草）的发生频率和优势度上升而一年生杂草（稗草、异型莎草）呈下降趋势,休闲３年,复种抛栽稻,稻田优势种为双穗雀稗,水芹,节节菜,眼子菜,水虱草等。     

不同光质对小麦幼苗谷氨酸合成酶及钙调系统酶活性的影响

加钙培养的小麦黄化苗和绿苗,经过红光（Ｒ）、远药光（ＦＲ）处理有效地提高谷氨酸合成酶（ＧＯＧＡＴ）的活性。不同光质对麦苗硝态氮代谢关键酶活性的影响与细胞内钙调系统及其作用靶酶－Ｃａ＾２＋－ＡＴＰａｓｅ、Ｈ－ＡＴＰａｓｅ活性有密切的联系。Ｃａ＾２＋－ＡＴＰａｓｅ、Ｈ－ＡＴＰａｓｅ的作用能改变细胞内Ｈ、Ｃａ＾２＋的浓度,从而调节细胞的内环境,进而对植物的代谢过程起调节作用