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Publication date: Available online 19 June 2013 Source: Aquatic Botany Author(s): Dong Yang , Wei Li The soil seed bank and aboveground vegetation were investigated on the shores of the Tian-e-zhou oxbow in China along a successional gradient (i.e. mud flat, sedge and graminoid marsh, sedge and reed meadow, and willow shrub). We expected to explore the following questions: (1) Does seed density and species richness of the soil seed banks decline during succession? (2) Does the similarity between the soil seed bank and aboveground vegetation decrease during succession? (3) Can soil seed banks be considered as a potential source of material for wetland restoration? Results revealed that 19 species (about 61% of the species in the mud flat stage) were found in all successional stages. Both seed density and species richness increased with succession. Species of the soil seed bank showed greater compositional similarity (Sørensen's index) across four stages than did the aboveground vegetation. The similarity between soil seed bank and aboveground vegetation increased as succession proceeds. In conclusion, the seed bank of Tian-e-zhou oxbow wetland contains a relatively abundant seed density and species richness. The soil seed bank could thus play an important role in the restoration management of oxbow wetlands. However, the high dominance of mudflat annuals and the absence of most dominant perennials in the soil seed bank suggest that target species may require active introduction for further restoration
Forage legumes have the potential to provide high quality feed to small land-holder farmers’ swine production, but forage management schemes that ensure both quantity and suitable quality as a swine feed are needed. Five forage legumes (aeschynomene [Aeschynomene histrix ‘BRA 9690’], canavalia [Canavalia brasiliensis ‘CIAT 17009’], stylo ‘CIAT 184’ and ‘Composite’ [Stylosanthes guianensis ‘CIAT 184’, ‘Composite’] and vigna [Vigna unguiculata ‘CIAT 1088-4’]) were grown during 2009–2010 in Lao PDR, and subjected to three harvesting interval treatments (21, 30 and 45 days). The yield and chemical composition of these legumes were determined. Stylo ‘Composite’ produced the highest average dry matter (DM) yield, followed by stylo ‘CIAT 184’, aeschynomene, canavalia and vigna. Harvesting every 45 days produced higher DM yields than the other treatments. Differences in crude protein (CP) content between species and treatments were small with stylo ‘CIAT 184’ and stylo ‘Composite’ having the lowest values. CP content was highest with the shortest harvesting interval, while the opposite was true for the fiber content (crude fiber, acid detergent fiber and neutral detergent fiber). All legumes produced a higher DM yield with a higher CP content in the wet season than in the dry season. The array of essential amino acids in relation to requirements for growing swine was excellent for all forage legumes except for canavalia. In conclusion, stylo (‘Composite’ and ‘CIAT 184’) and aeschynomene can be recommended for use by swine land-holder farmers in Lao PDR.
Bioclimatology based vegetation classification models play an important role in the response of terrestrial ecosystems to global climate change. In this paper, three periods (1911–1940, 1941–1970 and 1971–2000) of Potential Natural Vegetation (PNV) maps were created based on the CSCS (Comprehensive Sequential Classification System) model and the CRU_TS 2.1 datasets. A model of the mean center was used to calculate the shift distance and direction for each broad vegetation category during the three periods. Results indicate that: (i) the area of tundra and alpine steppe and desert decreased by 5.1 and 5.5%, while the area of forest and grassland increased by 2.3 and 3.8% from 1911 to 2000 at global scale, respectively. However, there was a significant difference in the magnitude of area change in northern and southern hemispheres. And (ii) the tundra and alpine steppe, semi-desert, savanna, temperate forest and subtropical forest shifted towards the poles; the frigid desert and temperate humid grassland shifted towards the equator, while the warm desert shifted towards southwest, the tropical forest shifted towards southwest in the northern hemisphere and southeast in the southern hemisphere, and the steppe shifted towards northeast in the northern hemisphere and northwest in the southern hemisphere. The shift distance of the warm desert in the southern hemisphere was the largest among the 10 broad vegetation categories.
Accurately estimating grassland net primary productivity (NPP) plays an important role in the study of global carbon budgeting. The six different methods (Miami Model, Schuur Model, Chikugo Model, Beijing Model, Synthetic Model and Classification Indices-based Model) were compared in terms of their performance in predicting grassland NPP with NPP derived from field-observed data at eight study sites along an altitudinal gradient in the Helan Mountain range and the surrounding desert in the Alxa Rangeland, Western Inner Mongolia, China. One hundred and twenty plot-based NPP sets from the eight study sites were used, which were obtained from 2003 to 2005, within areas classified as alpine meadow, cold temperate-humid montane meadow, cool temperate-subhumid meadow steppe, cool temperate-semiarid temperate typical steppe and cool temperate-arid temperate zonal semi-desert according to the Integrated Orderly Classification System of Grassland (IOCSG). The relative high model efficiency in predicting grassland NPP using the Classification Indices-based Model and Chikugo Model indicates that these models outperform others. On the basis of input data requirements and the number of free parameters involved in each model, the Classification Indices-based Model was found to be the best choice for the given grassland classes. The results presented in this study were not only specific to this region, but more importantly, were specific to the given grassland classes according to the IOCSG approach, which can be scaled up from plots to estimate landscape-scale effects.
Identifying drought tolerant turfgrass for semiarid Central Great Plains (CGP) of Wyoming is imperative because of limited water availability for irrigation. This study evaluated the performance and quality of different turfgrass species/cultivars under irrigated and rain-fed conditions in southeastern Wyoming. The species/cultivars evaluated in the study included Kentucky bluegrass (Poa pratensis L. ‘Bandera’, ‘Common 85/80’ and ‘Midnight’), tall fescue (Schedonorus arundinaceus [Schreb.] Dumort., formerly Festuca arundinacea Schreb.; ‘Blackwatch’, ‘Tar Heel II’ and ‘Watchdog’), buffalograss (Bouteloua dactyloides [Nutt.] J.T. Columbus; ‘Bison’, ‘Bowie’ and ‘Cody’), and blue grama (Bouteloua gracilis [Willd. ex Kunth] Lag. ex Griffiths; ‘Alma’, ‘Bad River’ and ‘Hachita’). The study was planted in a randomized complete block with four replicates in a factorial design. Coverage of turfgrasses used in the study was similar in both irrigated and rain-fed conditions. In general, better performance and turf quality in terms of vigor and color were obtained in irrigated conditions compared to rain-fed. Plant vigor and color rankings were in the order of tall fescue > Kentucky bluegrass > buffalograss > blue grama under irrigated conditions. However, plant vigor and color were superior for the warm-season turfgrass species (buffalograss and blue grama) under rain-fed conditions. Overall performance of the turfgrass species tested in the study was tall fescue ≥ Kentucky bluegrass > blue grama ≥ buffalograss. Tall fescue cultivars ‘Tar Heel II’ and ‘Watchdog’, blue grama cultivar ‘Bad River’, and buffalograss cultivar ‘Cody’ were among the most promising drought tolerant cultivars.
A promising new cultivar of rice (Oryza sativa L.) ‘Tachisuzuka’ has been developed for silage use with improved feeding value due to a radical decrease in spikelets. However, ‘Tachisuzuka’ has the problem of inefficient seed production. We investigated the effect of planting density on the spikelet number in ‘Tachisuzuka’ to find out how seed yields of this cultivar can be increased by means of cultivation methods. ‘Tachisuzuka’ was cultivated at six different planting densities, in the range of 7.4–22.2 hills m−2. Unlike in ordinary cultivars, there was a negative correlation between the spikelet number per unit area and hills per unit area. Moreover, the spikelet number increased by 67% under the low planting density. This result implies that the efficiency of seed production of ‘Tachisuzuka’ could be improved by low planting density through an increase in spikelet number per unit area.
Controlled-release urea (CRU) is a new type of urea, which may increase crop nitrogen (N)-use efficiency compared with conventional urea (CU), but the conditions where it outperforms urea are not well defined. A field experiment assessing responses of plant growth and grain yield of maize to CRU and irrigation was conducted on a typical agricultural farm in Shandong, China. Five treatments of the two types of urea (75, 150 kg N ha–1, 0 kg N ha–1) were applied as basal fertilizer when sowing maize, and two water treatments (W0 and W1) were used 23 d after anthesis. Net photosynthetic rate (PN) and chlorophyll concentration as well as leaf-area index (LAI) increased significantly by both CRU and CU application, with the increases being larger in CRU-treated plants than in CU-treated plants at grain filling and maturing stages. CRU significantly enhanced the maximum photochemical efficiency (Fv / Fm), PSII coefficient of photochemical fluorescence quenching (qP), and actual quantum yield of PSII electron transformation (ΦPSII) but decreased the nonphotochemical quenching (NPQ). Cob-leaf N concentration of CRU-treated plants was significantly higher than that of CU-treated plants under no irrigation, but not in the irrigation treatment 30 d after anthesis. Significant positive correlations were found between cob-leaf N concentration and PN both with and without irrigation. Grain yield of maize was significantly higher in the CRU treatment than in the CU treatment under both irrigation conditions. In conclusion, CRU as a basal application appeared to increase the N-use efficiency for maize relative to CU especially by maintaining N supply after anthesis.
The objective of this study was to compare the residual effect of zinc (Zn) from three Zn chelates (Zn-aminelignosulfonate, Zn-AML; Zn-polyhydroxyphenylcarboxylate, Zn-PHP; and Zn-ethylenediaminedisuccinate, Zn-EDDS), applied at two rates (5 and 10 mg Zn [kg soil]–1, respectively) to a previous crop, for a flax crop (Linum usitatissimum L.). For the greenhouse experiment, two different soils were used: a weakly acidic soil, classified as Typic Haploxeralf (Soilacid), and a calcareous soil, classified as Typic Calcixerept (Soilcalc). Plant availability of soil Zn was evaluated using the DTPA-triethanolamine (TEA), Mehlich 3, and low-molecular-weight organic acids (LMWOAs) methods. Easily leachable Zn was determined, and soil Zn status was characterized based on the Zn distribution in different fractions obtained by a sequential extraction. The Zn reserves after the previous crop were substantial and ranged from 2.85% to 5.61% of available Zn (Mehlich 3-extractable) with respect to the applied Zn. Plant parameters such as dry-matter yield, total Zn, and soluble Zn concentrations were measured, and Zn utilization by plants was calculated. In both soils, the highest concentrations of available Zn were associated with the application of Zn-AML at a rate of 10 mg Zn kg–1. In Soilacid the largest quantity of easily leachable Zn was also observed with Zn-AML fertilizer. Similarly, Zn-AML resulted in the highest Zn concentration in flax seeds (229 mg Zn kg–1 and 72 mg Zn kg–1 for the highest rate of Zn application to Soilacid and Soilcalc, respectively). The results suggest that these Zn chelates resulted in a residual effect in soils with appropriate concentrations of the most labile fractions of Zn and available Zn, particularly when Zn-AML was applied at the highest rate. This chelate was more effective in Soilacid than in Soilcalc. In the weakly acidic soil at the lowest Zn level it was associated with the highest percentage of Zn utilization by the flax plant and the most effective Zn transfer from soil to the plant.
Silicon (Si), although not considered essential, has beneficial effects on plant growth which are mostly associated with the ability to accumulate amorphous (phytogenic) Si, e.g., as phytoliths. Phytogenic Si is the most active Si pool in the soil–plant system because of its great surface-to-volume ratio, amorphous structure, and high water solubility. Despite the high abundance of Si in terrestrial biogeosystems and its importance, e.g., for the global C cycle, little is known about Si fluxes between soil and plants and Si pools used by plants. This study aims at elucidating the contribution of various soil Si pools to Si uptake by wheat. As pH affects dissolution of Si pools and Si uptake by plants, the effect of pH (4.5 and 7) was evaluated. Wheat was grown on Si-free pellets mixed with one of the following Si pools: quartz sand (crystalline), anorthite powder (crystalline), or silica gel (amorphous). Silicon content was measured in aboveground biomass, roots, and soil solution 4 times in intervals of 7 d. At pH 4.5, plants grew best on anorthite, but pH did not significantly affect Si-uptake rates. Total Si contents in plant biomass were significantly higher in the silica-gel treatment compared to all other treatments, with up to 26 mg g–1 in aboveground biomass and up to 17 mg g–1 in roots. Thus, Si uptake depends on the conversion of Si into plant-available silicic acid. This conversion occurs too slowly for crystalline Si phases, therefore Si uptake from treatments with quartz sand and anorthite did not differ from the control. For plants grown on silica gel, real Si-uptake rates were higher than the theoretical value calculated based on water transpiration. This implies that Si uptake by wheat is driven not only by passive water flux but also by active transporters, depending on Si concentration in the aqueous phase, thus on type of Si pool. These results show that Si uptake by plants as well as plant growth are significantly affected by the type of Si pool and factors controlling its solubility.
After the publication of our study , we became aware of errors in the proofreading of the article that caused a description mistake in the experimental methods section. These mistakes do not affect the final information in the analysis and results.