首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
Data on the morphology and radiocarbon ages of humus of dark vertic quasigley nonsaline clayey soils with alternating bowl-shaped (Pellic Vertisols (Humic, Stagnic)) and diapiric (Haplic Vertisols (Stagnic, Protocalcic)) structures are discussed, and the genetic concept for these soils is suggested. The studied soils develop on loesslike medium clay in the bottom of a large closed depression on the Eisk Peninsula in the lowest western part of the Kuban–Azov Lowland. The lateral and vertical distribution of humus in the studied gilgai catena displays a lateral transition of a relatively short humus profile of the accumulative type with a maximum near the surface and with a sharp increase in 14C dates of humus in the deeper layers within the diapiric structure to the extremely deep humus profile with a maximum at the depth of 40–80 cm, with similar mean residence time of carbon within this maximum, and with a three times slower increase in 14C dates of humus down the profile within the bowl-shaped structure. The development of the gilgai soil combination is specified by the joint action of the lateral–upward squeezing of the material of the lower horizons from the nodes with an increased horizontal stress toward the zones a decreased horizontal stress, local erosional loss of soil material from the microhighs and its accumulation in the adjacent microlows, leaching of carbonates from the humus horizons in the microlows, and the vertical and lateral ascending capillary migration of the soil solutions with precipitation of calcium carbonates in the soils of microhighs.  相似文献   

9.
Cotton (Gossypium hirsutum L.) plants grown under low pressure sodium lamps (LPS) developed chlorosis which was similar in appearance to iron‐stress induced chlorosis, while plants under cool white fluorescent lamps (CWF) at the same level of photosynthetically active radiation (PAR) developed normally. These illumination sources differ in spectral irradiance; CWF lamps emit ultra violet (UV), whereas LPS lamps do not. Ultraviolet radiation is capable of reducing Fe3+ to Fe2+ through a chlorotic leaf which may be important in establishing an active iron fraction in the leaf. Root reduction of Fe3+ to Fe2+ was lacking in Fe‐stressed cotton under LPS light, but was present under CWF light. Net photosynthesis, photosynthetic electron transport, and leaf chlorophyll content were lower under LPS than CWF light in most of the growing media studies (soil or solutions with nitrate‐ or ammonium‐nitrogen supplied). Chloroplast ultrastructure and leaf thickness were also altered by LPS irradiance. Electron microscopic studies with plants grown in nutrient solutions for 4 weeks suggested that chioroplastic granal disorganization was more directly associated with diminished iron supplies than with light source. However, plants grown in soil for 6 weeks under LPS light had granal disorganization similar to that found in iron‐stressed plants. These studies suggest an important role for UV radiation in influencing the activity of iron in plants.  相似文献   

10.
11.
12.
He  Shanying  Guo  Haihui  He  Zhenli  Yang  Chunping  Yu  Tao  Chai  Qiwei  Lu  Li 《Journal of Soils and Sediments》2019,19(3):1297-1305
Journal of Soils and Sediments - The increasing land application of sewage sludge and animal manure has accelerated the input of 17α-ethynylestradiol (EE2) into soils and environment, which...  相似文献   

13.
14.
Berries and seeds of two subspecies (ssp. sinensis and mongolica) of sea buckthorn (Hippopha? rhamnoides L.) were compared in terms of triacylglycerols, glycerophospholipids, tocopherols, and tocotrienols. The berries of ssp. mongolica contained less oleic acid (4.6 vs 20.2%, p < 0.001) and more palmitic (33.9 vs 27.4%, p < 0.01) and palmitoleic (32.8 vs 21.9%, p < 0.05) acids in triacylglycerols than those of ssp. sinensis. The proportions of linoleic acid (32.1 vs 22.2%, p < 0.01, in berries; 47.7 vs 42.7%, p < 0.05, in seeds) and palmitic acid (21.1 vs 16.4%, p < 0.001, in berries; 17.0 vs 14.1%, p < 0.05, in seeds) in glycerolphospholipids were higher in ssp. mongolica than in ssp. sinensis, and vice versa with oleic acid (4.3 vs 18.5% in berries, 10.0 vs 22.2% in seeds, p < 0.001). A higher proportion of alpha-linolenic acid was also found in the glycerophospholipids of ssp. sinensis berries (16.2 vs 10.1%, p < 0.001). alpha-, beta-, gamma-, and delta-tocopherols constituted 93-98% of total tocopherols and tocotrienols in seeds, and alpha-tocopherol alone constituted 76-89% in berries. The total contents of tocopherols and tocotrienols varied within the ranges of 84-318 and 56-140 mg kg(-1) in seeds and whole berries, respectively. The seeds of ssp. mongolica were a better source of tocopherols and tocotrienols than those of ssp. sinensis (287 vs 122 mg kg(-1), p < 0.001). The compositional differences between the two subspecies should be considered when the berries are bred and exploited for nutritional purposes.  相似文献   

15.
The nature of soil is modified differently depending upon the artificial condition such as its utilization or management. It is therefore expected that the microbiological characteristic of soil is changed also. Greaves1) and Williams2) reported that the reclamation of virgin soil brought about a change of bacterial count. Suzuki et al3) observed that the kind of fungi differed between a virgin and a cultivated soil and that the vegetative mycelium was numerous in the former than in the latter. On the other hand, according to W aksman and Starkey4), the bacterial count differed depending upon the fertility of soil. Singh5) reported also that the number of fungi and actinomycetes was higher in a fertile than in an infertile soil. Lochhead6), and Lochhead and Chasen studied the bacterial flora of a fertile (long-continued application of manure) and an infertile (no fertilizer for many years) soil and found that a certain difference could be observed when morphological, physiological and nutritional classification are tried.  相似文献   

16.
The research was carried out in the spruce forests of Barania Góra (Silesian Beskids, Poland) affected by pandemic dying of trees. Twenty-seven samples were collected from the O layer in two plots: 17 in a cut down forest infested with insect pests (bark beetle) and ten in a 120-year-old healthy forest. The analyses covered basic parameters (pH(H2O), pH(KCl), w(org), C(tot), N(tot), CEC) and the concentrations of aluminium in the fractions leached with 0.1?M BaCl(2) (Al(exch)), 0.5?M CuCl(2) and 0.1?M Na(4)P(2)O(7) (Al(bio)) solutions. The total aluminium concentration in the soil was assayed digesting samples with hydrofluoric acid. The effect of pH and organic matter content on the amount of exchangeable (Al(exch)) and bioavailable (Al(exch)) aluminium in the soil was analysed. It has been found that the soils in both plots are strongly acidic and contain 550 to 1,700?mg?kg(-1) of exchangeable aluminium and 1,200 to 4,800?mg?kg(-1) of bioavailable aluminium. The lack of disease symptoms in the spruce trees in plot 2 can be explained by the higher content of organic matter in the soil. Unfortunately, one might expect that the high concentration of exchangeable aluminium will also cause the trees in the area to wither.  相似文献   

17.
Genetic Resources and Crop Evolution - Comfrey Symphytum officinale L. (true comfrey) and S.?×?uplandicum Nyman (a hybrid between S. asperum Lepech?×?S. officinale...  相似文献   

18.
Four Scythian kurgans of the burial site Beloe Lake-3 were studied in the Turan–Uyuk Depression in the Republic of Tyva. They were constructed about 2565–2390 calendar years ago (calibrated with deviation 1 σ). Soil formation after 2500 yrs of the construction of the kurgans was examined in the interkurgan area. The properties of the background surface and ancient buried soils have much in common, and the difference between the soils of the four kurgans is small. This attests to the fact that the paleoclimatic conditions in the period of the necropolis construction remained stable and were similar to the modern climatic conditions. According to palynological data, the climate at the stage of the construction of the first two kurgans was a little more humid in comparison with the modern climate; it became somewhat drier after 95 years, during the construction of the third kurgan (2425 cal. BP) and again tended to humidification at the final stage of the necropolis creation. These changes in the paleoclimatic conditions are indicated by variations in the structure and composition of associations of xerophytes, mesophytes, hydrophytes, and ruderal plants. At the Uyuk stage, the area was mainly occupied by steppe phytocenoses with a predominance of xerophytes over mesophytes, and hydrophilous vegetation was allocated to moistened habitats near water reservoirs. Larch forests grew near water bodies. The variable anthropogenic impact on the landscape was stronger at the initial and final stages of the construction of the Uyuk culture necropolis.  相似文献   

19.
Naturally occurring/spontaneously produced polyploids with six/more genomes are rarely found in Alliums. A hexaploid form of Allium tuberosum with 2n = 48 chromosomes has been isolated for the first time amongst the open-pollinated seedlings of a hypotetraploid plant (2n = 4x = 31); latter being the seed-derived product of a normal tetraploid stock (2n = 4x = 32) growing in Jammu University Botanical Garden. Except for the guard cells and pollen grains that are of increased size, this form compared to its progenitor is dwarf, has smaller leaves and bears inflorescences with few flowers. This plant is also different from its progenitor in having nearly one-fourth (27.8 %) of its pollen mother cells (PMCs) with varying chromosome number viz. 27–64, with the remaining cells having somatic or double the somatic number of chromosomes. To assess the nature of hexaploid form, its chromosomes were studied for morphological details, putative grouping and pairing properties during reduction division. Morphological similarity in the chromosomes of the present cytotype and its progenitor, arrangement of 48 chromosomes in eight groups of six chromosomes each and presence of 21.88 % euploid cells with eight hexavalents pointed towards the autopolyploid nature of the present strain. Regarding the origin of this strain, observation made on the meiosis in the two sex mother cells of the progenitor provides some clues. In the later plant, presence of most of embryo-sac mother cells with 62 chromosomes that showed 31:31 segregations and existence of majority of the PMCs with 31 chromosomes exhibiting erratic segregations indicate that the hexaploid strain has probably originated as a result of the fusion of reduced male (n = 17) and unreduced female gamete (2n = 31).  相似文献   

20.
Abstract

The performance of the Polish rootstocks P2 and P22 under Norwegian growing conditions was evaluated over 10 years (1983–92). Tree vigour of the apple cultivar ‘Gravenstein’ on P2 and P22 was 64 and 16% of that on M9, respectively. Trees on P2 had the highest yield efficiency, but less total yield per tree than M9. Owing to very dwarfing growth, trees on P22 failed to establish a sufficient canopy and produced significantly smaller apples. P2 and P22 affected apple soluble solids in a favourable way, but did not influence fruit acidity.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号