黄连木种子发芽和出苗研究

[目的]探讨黄连木种子发芽率和出苗率.[方法]采用不同种子处理方法、不同浓度赤霉素溶液处理、不同覆土深度进行试验.[结果]黄连木种子吸水性较好,浸种48 h吸水就达到31.4％,接近种子饱和吸水量;经100、200 mg/L赤霉素溶液处理12 h,种子发芽率分别为21.6％和28.6％,高于对照且差异显著;去除外种皮后,再用草碳土对种子进行揉搓可明显提高种子的发芽率,其种子发芽率可达45.1％;加盖地膜和覆土深度1 cm能显著提高种子的出苗率.[结论]该试验可显著提高种子的发芽率和出苗率.     

崖柏种子繁育研究

[目的]研究崖柏种子繁育中的技术需求，为该树种的拯救繁育奠定基础。[方法]利用重庆市城口县咸宜乡采集的崖柏种子，研究温度、基质对崖柏种子发芽率及出苗率影响，同时研究不同种类和不同浓度药剂对崖柏立枯病的影响。[结果]崖柏种子发芽适宜的温度为15~20℃，最适温度为20℃，发芽率可达95%，在25℃条件下崖柏种子基本上不能萌发。崖柏种子在40℃温水浸泡下露白数量最多，浸泡24 h后露白数量无明显增加。在容器育苗基质中，18号基质即锯末2/3、森林表土和一般土各占1/3，有利于崖柏容器苗出苗率。几种试剂中，硫酸亚铁对崖柏病虫害防治效果最好，累计发病度为15%，其次是敌克松为17%，波尔多液为21%，抗枯灵为22%，高锰酸钾效果最差。[结论]锯末对崖柏容器苗出苗的影响很大，可能与锯末保水透气性好有关。森林土含量过高不利于崖柏容器苗的出苗率，硫酸亚铁对崖柏病虫害防治效果最好。     

Crop residue position and interference with wheat seedling development

Unweathered crop residues can produce growth-inhibiting substances, stimulate pathogen growth, and immobilize nutrients. The location of seed relative to residue may be an important factor in the early health of a crop. This greenhouse study simulated sowing conditions possible under annual dryland winter wheat (Triticum aestivum L.) production to evaluate the likelihood of inhibitory effects. We placed newly harvested, unweathered winter wheat residue on the soil surface, mixed with the seed, immediately above the seed, or 3 cm below the seed. Treatments using a plastic residue substitute and treatments using pasteurized soil and residue provided comparisons to the natural soil and wheat residue. Residue mixed with or placed above the seed caused a temporary delay in emergence. Since this occurred with both wheat and plastic residue, the delay is explained by the physical impedance of coleoptile growth. Wheat residue 3 cm below the seed reduced the height and rate of wheat plant development, indicating a biological inhibitory effect of the wheat residue. This reduction in height and development rate at 20 days after planting did not occur when the soil and residue were pasteurized. We conclude that winter wheat seedling growth can be inhibited if roots encounter unweathered residues.     

生物助长剂对红皮云杉播种苗生长的影响

以红皮云杉作为研究对象,用生物助长剂进行浸种、叶面喷雾。通过室内试验和大田栽培试验,观测生物助长剂对红皮云杉种子发芽、出苗数量和幼苗生长长发育状况的影响情况。试验结果表明：生长助长剂能促进种子萌发,提高出苗数理和出苗速度,尤其是对幼苗苗高的增长、侧根数量的增加有显著的促进作用。     

华北平原一年两熟区保护性耕作技术研究进展

冬小麦-夏玉米一年两熟的种植方式在华北平原区的农业生产中占有极为重要的地位,但传统耕作方式使该区的农业生产不可持续。保护性耕作是一种先进的保水保土的生产技术,对该区的农业可持续发展作用甚大。阐述了保护性耕作的定义、原理及保护性耕作的历史与发展,归纳总结了保护性耕作对播种、出苗、田间杂草、作物生长发育及作物产量等方面的影响研究。以期为华北平原一年两熟区的保护性耕作研究提供一定的参考。     

环境因子对空心莲子草出苗和生长的影响

空心莲子草出苗和生长的最适宜温度为20~30℃,5℃以下不能出苗。在土壤湿度为30%时,出苗率最大,且在变湿条件下有利于出苗和生长。它具有很强的抗涝能力,耐旱性则较弱,出苗率和生长势随根茎含水量的降低而降低,当根茎含水量低于22.2%,则不能出苗、生长。其出苗和生长的适宜土深为0.5~1.0 cm,并随着土壤深度的增大而减弱。光对其出苗和生长的影响则不显著。这些结果不仅为空心莲子草的分布和危害提供了分析依据,也为防除提供了有效的控制措施,可结合冬耕或伏耕,将根茎翻至土表,受冻或干旱而丧失活力,或以深耕将根茎埋至20 cm以下,以阻止大量出苗和生长繁殖。     

Evaluation of Italian ryegrass (Lolium multiflorum Lam.) populations naturalized in the flooding pampa of Argentina: I – Morphological and physiological characters at the juvenile stage

Twenty populations of Italian ryegrass (Lolium multiflorum) naturalized in the flooding pampa of Argentina and a commercial cultivar were evaluated in two representative soils of the region (environments). Seeds were sown individually in pots and maintained outdoors to evaluate seedling emergence, growth habit, tillering and leaf characters at the juvenile stage, to determine the degree of genetic determination (DGD) and resource allocations. Variability in final emergence, growth habit, tiller number, tillering index, leaf width and leaf area per plant was detected among entries, while (soil × entry) interaction or differences between soils were observed for characters related to emergence and number and size of leaves. The DGD could not be estimated for some characters due to the variance of (soil × entry) interaction component exceded the genetic component, but it ranged from 14 to 72 for the other attributes. To improve DGD estimations in future experiments, modification of experimental design by increasing the number of environments, replications or plants was discussed for each character.     

黔西南烟区中草药残渣替代基质烤烟育苗的研究

[目的]充分利用中草药残渣资源,验证其烤烟育苗的可行性.[方法]用中草药残渣基质和常规烤烟育苗基质开展烤烟育苗试验,研究中草药渣基质育苗对烤烟出苗率、生育期及成苗期农艺性状的影响.[结果]从出苗率来看,中草药渣基质育苗对烟草种子出苗率与常规基质育苗存在显著差异,出苗率低于常规基质;从烟草生育期来看,中草药渣基质育苗与常规基质育苗在出苗期、大小十字期、猫耳期有一定差异,但差异不大;从成苗期农艺性状来看,中草药渣基质育苗在茎围和叶片数上与常规基质差异显著,而茎高和侧根数指标无显著差异.[结论]中草药残渣具备漂浮育苗的基本条件,可进一步推广与应用.     

Effects of seed priming, aggregate size and soil matric potential on emergence of cotton (Gossypium hirsutum L.) and maize (Zea mays L.)

Poor crop establishment, due to poor land preparation methods and inadequate soil moisture, continues to be a major constraint to crop production for smallholder farmers in the semi-arid tropics. On-farm seed priming (soaking seed in water) has been offered as a solution to this problem, but the ways in which this technology interacts with soil conditions are not well understood. The interactions between seed priming and soil physical conditions on cotton (Gossypium hirsutum L.) and maize (Zea mays L.) emergence and seedling growth were determined in laboratory pot experiments. The treatments included seed treatment (primed and non-primed), initial soil matric potential (−10, −50, −100, −200 and −1500 kPa) and aggregate size (<1, 1–2, 2–4.75 and 4.75–16 mm). Non-sieved soil was used as a control. The soil used (a Chromic Cambisol) was collected from Save Valley Experiment Station in the southeastern lowveld of Zimbabwe. The pots of soil were allowed to dry out after planting, to simulate a deteriorating seedbed. Emergence was subsequently monitored, and plant growth measured 8 days after planting. Final percent emergence and seedling growth decreased with initial matric potential but increased with priming in both crops. Large aggregate sizes generally had an adverse effect on emergence and growth. The data are consistent with the hypothesis that on-farm seed priming can partly compensate for the negative effects of low soil matric potential and large aggregate sizes on crop establishment.     

Variable effects of emergence-promoting rhizobacteria on conifer seedling growth under nursery conditions

Summary Inoculation of white spruce (Picea glauca Voss.) seed with Bacillus polymyxa strain L5 under nursery conditions significantly increased the number of seedlings that emerged after sowing. No significant effects on seedling emergence were detected when white spruce seed was inoculated with Bacillus polymyxa strain L6, or when Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seed was inoculated with either strain L5 or L6. However, white spruce seedlings originating from L5-inoculated seed had significantly lower root dry weights when measured 13 weeks after sowing, and reduced shoot dry weights 26 weeks after sowing compared with uninoculated controls. Inoculation of white spruce seed with strain L6 also resulted in seedlings with decreased root dry weights compared with uninoculated controls 13 weeks after sowing, but the significant inhibition of root growth was not apparent 26 weeks after sowing. Douglasfir seedlings originating from L5-inoculated seed had significantly lower root and shoot dry weights compared with uninoculated controls 13 but not 26 weeks after sowing. Inoculation of Douglas-fir seed with strain L6 resulted in seedlings with decreased root collar diameters and shoot dry weights 13 weeks after sowing, and lower root dry weights 26 weeks after sowing compared with uninoculated controls. These results demonstrate that the effects of bacterial inoculation on seedling emergence and on plant growth are independent, and that emergence-stimulating bacteria may inhibit subsequent seedling growth.