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91.
在高寒牧区巴音布鲁克种种青稞,南北向条播比东西向条播能充分利用太阳光能,可提高种子产量14.6%,南北向条播的适宜密度为330万株/hm^2,种子产量最高。 相似文献
92.
高寒地区一年生人工草地地上生物量动态及光能转化效率 总被引:12,自引:3,他引:9
对燕麦单播草地、燕麦+箭舌豌豆混播草地牧草组成及地上生物量动态,光能转化效率进行了观测和分析。试验结果表明,混播草地的两组分在生长发育节律和牧草产量积累过程方面均存在着较大的差异,箭舌豌豆与燕麦干物质之比随牧草生长发育的进展而逐渐增大。2种草地的干草产量在牧草生长期间差异不显著。8月中旬,单、混播草地干物质分别可达10.19、11.74t/hm2,地上净初级生产力分别为18874.69、21204.79kJ/(m2·a),光能转化率分别达0.3502%、0.3922%。 相似文献
93.
Munzer El-Naimi Hala Toubia-Rahme Omar F. Mamluk 《European journal of plant pathology / European Foundation for Plant Pathology》2000,106(5):433-437
Common bunt of wheat, caused by Tilletia laevis and T. tritici, is a major seed and soil-borne disease in West Asia and North Africa. The use of resistant cultivars and chemical seed-treatments are the current control measures used to combat this disease. The aim of this study was to investigate alternative control measures to chemical seed-treatments that are environmentally friendly to support cultivar resistance. Several organic nutrients [skimmed milk powder, hucket (local skimmed milk) and wheat flour] at a concentration of 160g per kg of seeds were used as seed-treatments on two susceptible bread and durum wheat cultivars (Bau and Sebou, respectively) to examine their effectiveness in controlling the disease. Field trials over four years showed that skimmed milk powder, hucket, and wheat flour reduced common bunt infection levels by 96%, 93% and 62%, respectively. In most cases, the effectiveness of the skimmed milk powder and hucket was equal to the chemical seed-treatment; thus, these organic nutrients offer an effective and environmentally safe alternative to chemical treatments. However, a study of their economic value as well as of their effect on seed germination, and field emergence is needed. 相似文献
94.
试验选用约2.5岁公牦牛8头,在三江源地区玉树县的高寒草甸草场,应用4N盐酸不溶灰分法(4N—AIA)和木质素标记物法测定了不同物候期(青草期和枯黄期)放牧牦牛日采食量及牧草营养成分的消化率。结果表明:2.5岁牦牛在青草期、枯黄期的100kg体重日采食量分别为3.69kg和2.96kg,差异极显著(P〈0.01);其不同物候期的千物质消化率分别为65.70%、61.72%(P〉0.05),粗蛋白的消化率为62.25%、39.00%(P〈0.01),粗脂肪为49.36%、58.18%(P〈0.05),ADF的消化率为57.88%、62.67%(P〉0.05),NDF的消化率为69.09%、79.38%(P<0.01)。 相似文献
95.
内蒙古地区农业干旱预测方法研究 总被引:2,自引:1,他引:2
为了提高内蒙古农区干旱预测的准确率,本文针对农区干旱的特点,提出了春旱和夏秋旱的标准。并利用数理统计方法,分析得出前冬80cm地温的正负距平区域可预测来年春季干旱的程度;前冬160cm地温距平区域可预测来年夏秋季干旱趋势。同时指出夏季以前开始的ENSO年内蒙古中西部农区春季、夏秋季易出现中~大旱,但夏季以后开始的EN-SO年,夏秋季以轻旱~不旱为主;ENSO次年内蒙古农区夏秋季基本是轻旱或不旱年;而在太阳黑子数下降期,内蒙古农区夏秋季也以轻旱或不旱年居多。 相似文献
96.
97.
David Ezra Tammy Kroitor Avraham Sadowsky 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(2):183-191
Mal secco disease of citrus caused by Phoma tracheiphila is a devastating disease in the Mediterranean basin. Susceptible citrus species include lemon, citron, lime and others. Trees
attacked by the fungus show characteristic symptoms; the smallest twigs die first, followed by the larger branches. Eventually,
the whole tree is killed. The symptoms are clear in the orchards but by the time they are visible the disease is already well
established. The need for a sensitive, reliable and rapid diagnostic method for the early identification of the fungus in
trees and fruit exists. We have developed a PCR-based method for the identification of P. tracheiphila from plant tissues including fruit. Any such method must take into account the genetic variability in the pathogen population.
Molecular methods were used to compare different isolates of P. tracheiphila. This study found no significant differences between different isolates from different citrus species from different parts
of Israel. 相似文献
98.
J. Jović T. Cvrković M. Mitrović S. Krnjajić Margaret G. Redinbaugh R. C. Pratt R. E. Gingery S. A. Hogenhout I. Toševski 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(1):85-89
Maize redness (MR), a disease causing midrib, leaf and stalk reddening and abnormal ear development in maize, has been reported
from Serbia, Romania and Bulgaria for 50 years. Recent epiphytotics reduced yields by 40%–90% in southern Banat, Serbia. MR
was recently associated with the presence of the stolbur phytoplasma, although the epidemiology of the disease remained unknown.
Diseased fields in southern Banat were surveyed for potential vectors of the phytoplasma during 2005 and 2006, and high populations
of Reptalus panzeri were found. In affected fields, 20% of the R. panzeri individuals and 85% of symptomatic maize plants carried the stolbur phytoplasma. When stolbur phytoplasma-infected R. panzeri were introduced into insect-free mesh cages containing healthy maize plants, midrib and leaf reddening developed on 48% of
plants and stolbur phytoplasma was detected in 90% of the symptomatic plants. No symptoms or phytoplasma-positive plants were
found in cages without insects. These data indicate that MR symptoms are associated with the stolbur phytoplasma. Reptalus panzeri is both abundant in affected fields and can transmit the stolbur phytoplasma, indicating the insect is likely to be a major
vector of MR. 相似文献
99.
Lia W. Liefting Anna C. Padovan Karen S. Gibb Ross E. Beever Mark T. Andersen Richard D. Newcomb David L. Beck Richard L.S. Forster 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(6):619-623
Sequence comparisons and phylogenetic analysis of the 16S rRNA genes and the 16S/23S spacer regions of the phytoplasmas associated with Australian grapevine yellows, papaya dieback and Phormium yellow leaf diseases revealed minimal nucleotide differences between them resulting in the formation of a monophyletic group. Therefore, along with Australian grapevine yellows, the phytoplasmas associated with Phormium yellow leaf and papaya dieback should also be considered as Candidatus Phytoplasma australiense. 相似文献
100.