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111.
低温处理对天然牧草种子发芽的影响 总被引:1,自引:0,他引:1
温度是影响牧草种子发芽的主要因素之一。本研究以大针茅和克氏针茅种子为研究对象,采用低温处理和常温发芽方式进行发芽试验,分析低温处理对两种牧草种子发芽率和发芽势的影响。结果表明:低温处理不同程度地提高了两种牧草种子的发芽率,同时也加快了起始发芽时间。对于大针茅而言,低温处理和常温发芽的种子发芽势从开始发芽到最后都体现了由慢变快再变慢的趋势,温度处理对其发芽历期的影响不很明显。而克氏针茅低温处理和常温发芽的种子发芽势却体现了相反的变化趋势,经过低温处理的种子发芽势逐渐变慢,发芽历期长,常温发芽的种子发芽势逐渐变快,发芽历期短。 相似文献
112.
113.
Nigel J. H. Smith 《The Professional geographer》1987,39(1):1-8
The number of crop genebanks, designed to conserve crop genetic resources and make them available to breeders, has risen dramatically in recent years. While few dispute the need to conserve crop germplasm to help boost and sustain agricultural productivity, the role of genebanks and their global distribution has become embroiled in controversy. Some suggest that genebanks are servicing mainly multinational seed companies and that industrial countries harbor the lion's share of crop germplasm collections. This article describes the importance of genebanks, analyzes their distribution and beneficiaries, and outlines how geographers can become more involved in the conservation and use of crop genetic resources. 相似文献
114.
在室内人工飼养马氏珠母贝亲贝,进行早春育苗。比常规生产育苗提前二个月。生长快,贝体健壮,经养殖18个月长至壳高7.1厘米,体重52克。60%以上达施术贝标准,相当于常规生产贝苗26个月的生长水平。相对地缩短了养殖周期,提高了经济效益。且设备简单,操作方便,利于推广。 相似文献
115.
N.A. Provorov U.B. Saimnazarov I.U. Bahromov D.Z. Pulatova A.P. Kozhemyakov G.A. Kurbanov 《Journal of Arid Environments》1998,39(4):569-575
In field trials conducted at Uzbekistan, inoculation of mungbean (Phaseolus aureusRoxb.) with commercial strain CIAM1901 ofBradyrhizobiumsp. (Phaseolus) increased (on average for two cultivars) the herbage mass by 46·6±6·0%, seed mass by 39·2 ± 3·6%, mass of 1000 seeds by 16·0 ± 0·8%, nitrogen content in seeds by 58·3 ± 8·9%, starch content in seeds by 30·0 ± 5·5% and number of nodules by 254%. Inoculation with this strain produced the same herbage (seed) mass as NH4NO3application (120 kg ha−1of N), while the combined treatment of rhizobia and 60 kg ha−1of N produced significantly higher yields than rhizobia inoculation alone or application of 120 kg ha−1of N. The rhizobia strain M11 was isolated from Uzbekistan soils and significantly exceeded the commercial strain CIAM1901 in its influence on herbage mass by 3·9–10·6%. Two-factor analysis of variance demonstrated that the herbage mass and number of nodules are controlled mainly by the rhizobia strain genotypes, while seed yield, number of pods, mass of 1000 seeds and N and starch content in seeds are influenced by the plant cultivar genotypes. 相似文献
116.
Demel Teketay 《Journal of Arid Environments》1998,38(4):551-560
Seeds ofAcacia origena,A. pilispinaandPterolobium stellatumhave a hard seed coat that hampers imbibition of water and prevents maximum, uniform and rapid germination. Therefore, the seeds were subjected to different treatments involving mechanical scarification, concentrated sulphuric acid and boiling water to break the dormancy imposed by the hard seed coat. To determine the effects of different constant temperature regimes on germination, scarified seeds were incubated on a thermogradient at 10, 15, 20, 25 and 30°C. Germination of scarified seeds was also tested in light and dark. Mechanical scarification resulted in 100% germination for theAcaciaspecies and 94% forP. stellatum. ForA. origena, sulphuric acid treatments for 60, 90 and 120 min resulted in significantly higher per cent germination (>95%) than all the other treatments. ForA. pilispina, sulphuric acid treatments for 45 and 60 min, as well as immersing seeds for 1 min in hot water, gave significantly higher per cent germination (97%) than all the other treatments. ForP. stellatum, mechanical scarification and all the acid treatments applied resulted in significantly higher per cent germination (>85%) than the control and all hot water treatments. All seeds ofP. stellatumimmersed in hot water, even for 1 min, rotted soon after sowing, indicating that they are sensitive to high temperatures. Scarified seeds of the twoAcaciaspecies germinated to a higher degree (≥90%) between 10 and 30°C, while germination of scarified seeds ofP. stellatumranged from 48 to 82% between 10 and 30°C. Scarified seeds of the three species germinated to a large extent (>70%) both in light and dark, indicating that seeds do not require light for germination. 相似文献
117.
Water requirements for germination and early seedling establishment in four African savanna woody plant species 总被引:1,自引:0,他引:1
The aim of this study was to determine the water requirements for germination and early seedling establishment of four African savanna tree species, namelyAcacia karroo, A. nilotica, A. tortilisandMundulea sericea. The acacias are characteristic of nutrient-rich, andM. sericeaof nutrient-poor savannas. Imbibition times of scarified seeds ofA. karroo(4 h),M. sericea(6 h) andA. tortilis(8 h) were rapid relative toA. nilotica(28 h) and were inversely correlated with seed size. Imbibed water is lost in about 2 h after drying at 25°C for all species exceptA. nilotica(only 70% moisture loss). Seeds ofA. karrooandM. sericeakept at 40°C dried to below their original moisture contents within 2 h. Seeds ofA. niloticaandA. tortilisdried at 40°C lost viability relative to (undried) control seeds, while there was no significant loss of viability forA. karrooandM. sericea. For fully imbibed seeds to germinate in sandy savanna soils, all four species required at least the equivalent of 3 mm rainfall every 2 days under mild greenhouse conditions. However, most ungerminated seeds were still viable despite drying-out from a fully imbibed state. Maintenance of soil at 50% field capacity (FC), or watering to FC every 9th day is the maintenance requirements for 2-week-old seedlings ofA. niloticaandM. sericeato continue growth for a further 5 weeks under greenhouse conditions, althoughA. niloticamostly survived 25% FC with one seedling surviving 12·5% FC. Root penetration was rapid in sandy soils, withA. niloticaandM. sericeaattaining a depth of 40 cm within 15 days. Frequent, but not necessarily high, rainfall appears to be essential for germination and seedling survival over the first 7 weeks. 相似文献
118.
近几年,紫菜"高温烂菜"现象频发,为开发耐高温紫菜栽培种质,本文研究了4种温度(15、20、25、28℃)对皱紫菜壳孢子萌发及叶状体形态建成的影响,并观察了藻体的繁殖特性。结果显示,在试验设定的培养条件下,适宜皱紫菜壳孢子萌发生长温度为20—25℃,最适温度为20℃。皱紫菜壳孢子幼苗萌发初期细胞分裂为横分裂,叶状体细胞呈直线排列,生长至7—10个细胞后,细胞开始出现纵分裂。15、20℃温度组藻体多为不规则的半圆形裂片。25、28℃温度组藻体多为细长型叶片。有性生殖是皱紫菜主要的繁殖方式,但15—20℃培养组的部分藻体能够少量形成并放散类似无性生殖的单孢子并萌发形成叶状体。 相似文献
119.
利用自制的5kW微波等离子体化学气相沉积(MPCVD)装置对在不同衬底材料上外延生长的CVD金刚石进行了研究。利用HPHT金刚石、CVD异质形核生长的金刚石及Ia型天然金刚石样品作为籽晶,分析了不同CH4浓度与基片温度对外延CVD金刚石的影响以及通过扫描电子显微镜表征了CVD金刚石外延面的表面形貌。结果发现,HPHT金刚石为籽晶,由于其自身缺陷导致外延效果不佳;CVD异质形核生长的衬底因形核阶段的晶面生长难以控制而使其外延面较粗糙;经打磨的Ia型天然金刚石才是理想的籽晶。当CH4浓度约为10%、基片温度为1020℃时,CVD金刚石的外延生长速率可达到70.0μm/h。 相似文献
120.
IMPROVEMENT OF SANDY SOIL WITH WATERCONSERVING MEMBRANE AND ITS EFFECT ON CROP GROWTH 总被引:1,自引:0,他引:1
LIXiu-jun CUIXiang-hao LIQu-sheng 《中国地理科学(英文版)》2005,15(1):64-69
1INTRODUCTIONArid, semi-arid, and semi-humid areas abound in sandysoil, which causes water to leak into deep soil orgroundwater so that soil′s water-conserving capabilitybecomes lower and water is used with low efficiency.Water is one of the important fa… 相似文献