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1.
Effects of the supply levels and ratios of nitrogen and phosphorus on seed traits of Chenopodium glaucum 下载免费PDF全文
《植物生态学报》2018,42(9):963
全球氮沉降不仅改变土壤氮和磷的有效性, 同时也改变氮磷比例。氮磷供应量、比例及其交互作用可能会影响植物种子性状。该研究在内蒙古草原基于沙培盆栽实验种植灰绿藜(Chenopodium glaucum), 设置3个氮磷供应量水平和3个氮磷比例的正交实验来探究氮磷供应量、比例及其交互作用对灰绿藜种子性状的影响。结果发现氮磷供应量对种子氮浓度、磷浓度和萌发率影响的相对贡献(15%-24%)大于氮磷比例(3%-7%), 而种子大小只受氮磷比例的影响。同时氮磷供应量和比例之间的交互作用显著影响种子氮浓度和磷浓度。同等氮磷比例情况下, 低量养分供应提高种子氮浓度、磷浓度和萌发率。氮磷比例只有在养分匮乏的环境中才会对种子大小和萌发率产生显著影响。总之, 灰绿藜种子不同性状对氮或磷限制的敏感性不同, 同时种子性状也对养分限制表现出适应性和被动响应。 相似文献
2.
Diurnal variation in ion content of the solution bathing roots of two plants growing together in sand culture was analysed
for three pairs of grass-legume species (Lolium multiflorum andTrifolium pratense; Zea mays andGlycine hispida; Avena sativa andVicia sativa) and their monospecific controls. Biomass and nitrogen content of plants were determined.
Ion concentration (NO
3
−
, NO
2
−
, NH
4
+
, and K+) and pH of root solutions were measured for Lolium-Trifolium plant pairs and controls at 6 hours intervals over 36 h, starting
at 8 am within a circadian cycle. Root solutions were regularly depleted in NO
3
−
by the grasses (Lolium-Lolium control) throughout the cycle. For associations involving the legume (Lolium-Trifolium and
Trifolium-Trifolium), NO
3
−
depletion was followed by NO
3
−
enrichment at night, from late afternoon to early morning; the enrichment was more marked for the Lolium-Trifolium association.
Solutions which did not contain NO
2
−
ions, were enriched by trace amounts of NH
4
+
ions, largely depleted in K+ and alkalanized for all associations throughout the cycle.
Repeating the experiment with the three pairs of species at the vegetative phase of development confirmed the previous results:
NO
3
−
enrichment during the night for associations with legumes. When the experiment was repeated with older plants which had almost
completed their flowering stage, depletion only was observed and no NO
3
−
enrichment.
These data suggest that NO
3
−
enrichment results from N excretion from active nodulated roots of the legume, accounting for the increase in both biomass
and nitrogen content of the companion grass in grass-legume association. The quantitative importance and periodicity of nitrogen
excretion as well as the origin of nitrate enrichment are discussed. 相似文献
3.
The interactive effect of low P supply (0, 10, 20 and 40 M) and plant age on nodule number, mass and functioning (ureide analysis technique), vegetative growth and pod production were investigated in glasshouse-grown nodulated cowpea (Vigna unguiculata L.cv. Kausband) in sand culture. Compared with 40 M P, P stress (0 M P) or very low (10 M P) supply markedly impaired nodulation, allantoin and amino-N concentrations and weight of N solutes in xylem exudates. Consequently, P stress reduced top growth and pod yields by 48 and 90%, respectively. N solutes in xylem exudates and total plant N assayed by Kjeldahl technique (as estimates of N2 fixation) responded similarly to P supply. However, the relative ureide index [(ureide-N/ureide N+amino-N)×100] remained constant (99%), irrespective of P supply, indicating the plants' complete dependency on symbiosis for growth, without implying that growth was markedly increased by N2 fixation. Although P concentrations in plant tops, roots and nodules increased with P supply, N concentrations in these plant tissues were unaffected by P supply. The concentrations of N and P in the nodules were 2–2 1/2 times higher than in plant tops. P application interacted strongly with plant age, with the largest P effect evidently achieved at the early podding stage. The significance and implications of these results are discussed. 相似文献
4.
人工樟子松—差不嗄蒿植被及其固沙作用 总被引:6,自引:2,他引:4
植物固沙是整治沙漠和沙漠化土地的一种有效措施。人工植被的建立是植物固沙的必然结果。人工植被的演替、稳定性及其对环境的影响直接关系到流沙的固定程度。因此,本文旨在探讨人工樟子松(Pinus sylvestris var. 相似文献
5.
The effect of phosphorus (P) concentration in barley seed on seedling growth has not been much investigated. Consequently,
two experiments were conducted in the greenhouse to determine the effect of P concentration in barley seed (Hordeum vulgare L., cv. Empress) on the seedlings grown in sand-filled boxes receiving a culture solution without P. Seeds were selected
with three P concentrations: high-P (113.0 mmol P kg−1), medium-P (80.7 mmol P kg−1) and low-P (54.9 mmol P kg−1). At 21 days after sowing, the shoot and root yield or shoot height was the least with seedlings from low-P seed. In the
other experiment, high-P and low-P seeds were wetted with distilled water or with a solution of 25.8 cmol L−1 of NaH2PO4 for 24 h, and then grown for 31 days. Solution P had been imbibed by seeds whether low or high in native P, but only the
imbibed P held by low native P seed benefited seedling dry matter accumulation and shoot elongation. The lack of benefit from
seed-imbibed P on seedlings grown from high-P barley seed was associated with low recovery of the imbibed P in those seedlings. 相似文献
6.
Kristel Eggermont Inge J. Goderis Willem F. Broekaert 《Plant Molecular Biology Reporter》1996,14(3):273-279
We describe here a reliable high-throughput method for extraction of RNA from fresh or frozen plant tissue that obviates laborious
and time-consuming homogenisation by mortar and pestle. The method is based on homogenisation by high-speed reciprocal shaking
in presence of a mixture of inexpensive abrasive materials; i.e., quartz sand and glass beads. After homogenisation, the method
follows a standard procedure for RNA extraction by phenol/LiCl. Yield and quality of RNA obtained by homogenisation with the
sand/glass bead mix are identical to those obtained by mortar and pestle. 相似文献
7.
We examined the function of the vertical bar pattern on maleswordtails (Xiphophorus multilinneatus) as a signal in bothmale-male competition and female choice. This pattern had previouslybeen described as an aggressive signal because males intensifiedthe bars during male-male encounters in the laboratory. Ourfield observations supported this observation and also showedthat bars intensified when males courted females. The intensityof bars was correlated with access to females in the field.Within the size range of males that have bars, however, neitherbar number nor male size appeared to influence access to females.We used freeze-branding to remove the bars from males in thelaboratory so that we could control for characters correlatedwith bar intensity, and tested males and females separatelyso that we could separate the influence of these two componentsof sexual selection. We compared the responses of males andfemales to males that had their bars removed and control malesfreeze-branded between the bars. Test males responded more aggressivelyto males without bars as compared to control males. In addition,females showed a preference for control males over males thathad their bars removed. These results suggest that the barsmay function as a signal that deters rival males and attractsfemales. 相似文献
8.
The soil fauna: the other last biotic frontier 总被引:4,自引:0,他引:4
Different approaches to biodiversity yield global totals as small as 3 million or as large as 80 million species. Erwin's calculation and estimation leads to an estimate of ca 30 million species and relies on four assumptions of which one concerns the ratio between the number of canopy insects and those found elsewhere, especially in the soil. A short survey of the microarthropods living in coastal sand dunes and collected with a new flotation method yielded amazing results. In spite of the severity of the habitat (low organic matter content and extreme dryness), the density of microarthropods varied between 175 000 and 1 400 000 individuals per square metre, i.e., densities 3 to 10 times higher than densities usually observed in any other type of soil. A total of 31 species was recorded, most undescribed and smaller than 200 m. The consequences of these findings on the estimation of the number of species are discussed. It is suggested that the soil, including the deepest horizons and the rhizosphere, might constitute a huge reservoir for biodiversity. 相似文献
9.
Population studies on a South African carrageenophyte: Iridaea capensis (Gigartinaceae,Rhodophyta) 总被引:1,自引:1,他引:0
An intertidal population of Iridaea capensis in the south-western Cape Province of South Africa has been studied in detail for a year. The species is generally restricted to sand-inundated rocky shores, which appears not to be the case for Iridaea species in the Pacific. In early winter (June) biomass, plant density and plant size were at a minimum. A small increase in these parameters occurred in August, but there was a massive increase in plant numbers and biomass in October. The largest plants were recorded in summer (February). The population was over 70% sporophytes in April, but switched to almost 80% gametophytes following heavy recruitment between August and October, and remained significantly gametophyte-dominated through April of the following year. Carrageenan levels were high (ca 42% of dry weight) in late winter-spring, and lowest (ca 30–35%) in summer-autumn. Strong offshore wind conditions in early summer caused a reduction in biomass, and it is hypothesized that the associated upwelling of nutrient rich water may be implicated in the lower carrageenan levels at this time. 相似文献
10.
D. T. Crisp 《Journal of fish biology》1993,43(4):656-658
Artificial redds were used to examine the effect of layers of sand at the gravel surface upon the emergence of trout and salmon. Alevins of both species can negotiate sand layers up to 8 cm thick. 相似文献