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1.
水稻突变体对镉的吸收及其亚细胞分布和化学形态特点   总被引：12，自引：0，他引：12  
Wild-type （Zhonghua 11） and mutant rice （Oryza sativa L.） plants were used to investigate the effect of cadmium （Cd） application on biomass production, to characterize the influx of Cd from roots to shoots, and to determine the form, content, and subcellular distribution of Cd in the roots, leaf sheaths, and leaves of the rice plants. Seedlings were cultivated in a nutrient solution and were treated with 0.5 mmol L^-1 of Cd^2＋ for 14 d. The sensitivity of rice plants to Cd toxicity was tested by studying the changes in biomass production and by observing the onset of toxicity symptoms in the plants. Both the wild-type and mutant rice plants developed symptoms of Cd stress. In addition, Cd application significantly （P ≤ 0.01） decreased dry matter production of roots, leaf sheaths, and leaves of both types, especially the mutant. The Cd content in roots of the mutant was significantly （P ≤0.05） higher than that of the wild-type rice. However, there was no significant difference in the Cd content of roots, leaf sheaths, and leaves between the wild-type and mutant rice. Most of the Cd was bound to the cell wall of the roots, leaf sheaths, and leaves, and the mutant had greater Cd content in cell organelles than the wild type. The uneven subcellular distribution could be responsible for the Cd sensitivity of the mutant rice. Furthermore, different chemical forms of Cd were found to occur in the roots, leaf sheaths, and leaves of both types of rice plants. Ethanol-, water-, and NaCl-extractable Cd had greater toxicity than the other forms of Cd and induced stunted growth and chlorosis in the plants. The high Cd content of the toxic forms of Cd in the cell organelles could seriously damage the cells and the metabolic processes in mutant rice plants.  相似文献   

2.
A field laboratory was established in Prince Edward Island, Canada, to determine the effects of 2- and 3-year crop rotations, with conventional and minimum tillage treatments, on the severity of soilborne diseases of potato. The 2-year rotation consisted of spring barley and potato (cv. ‘Russet Burbank’), and the 3-year rotation was barley (undersown with red clover), red clover and potato. Examination of potato stem, stolon, and tuber tissues revealed significantly (P=0.05) lower levels of canker and black scurf caused by Rhizoctonia solani, in plants grown in 3-year vs. 2-year rotations. The severity of dry rot (Fusarium spp.) and silver scurf (Helminthosporium solani) was significantly (P=0.05) lower in tubers from plots managed with 3-year rotations and minimum tillage practices. Potato tubers harvested from 3-year rotational soils were significantly (P=0.05) less diseased than those from 2-year rotational soils following inoculation with Phytophthora erythroseptica, causal agent of pink rot. In greenhouse experiments using field soils from 2- and 3-year rotations, we found that potato plants growing in 3-year rotational soils were significantly (P=0.05) less diseased than those growing in 2-year rotational soils following inoculation with P. erythroseptica. Analysis of root zone bacteria recovered from the rhizosphere (exoroot) and potato root tissues (endoroot) showed that the greatest antibiosis activity inhibiting the growth of soilborne pathogens in vitro occurred in bacterial isolates recovered from the endoroot tissues of 3-year rotation crops under minimum tillage management. Our evidence supports the view that soil agroecosystems can be modified through rotation and conservation tillage practices to improve disease suppression by enhancing the antibiosis abilities of endophytic and root zone bacteria (endo- and exoroot).  相似文献   

3.
通过比较阴坡和阳坡优势种（阴坡:山杨、油松、辽东栎和刺槐;阳坡:荆条、山桃、狼牙刺和黄刺玫）叶功能性状（比叶质量、膨压损失点对应的叶水势、叶碳同位素组成δ13C及叶N、P和K含量）的差异,探讨了植物对不同坡向的生存和适应机制。结果表明:（1）阳坡优势种较阴坡优势种具有高的叶δ13C,且在旱季具有较高的K含量,表明高水分利用效率和K素累积是阳坡植物适应其生境的重要手段。（2）阳坡优势种间叶性状差异小于阴坡优势种,阳坡植物叶性状表现出明显的趋同性。（3）8种优势植物中,刺槐的比叶质量最小,叶N和P含量最高,叶δ13C相对较高,反映了其高光合和高水分利用效率的特性,表明刺槐采取竞争性生存策略。相比之下,油松的比叶质量最大,其叶δ13C、N、P和K含量最低,表明油松采取防御性生存策略,其他6种植物介于中间。  相似文献   

4.
A field experiment based on controlled traffic concept was conducted over three rainy seasons in a bimodal rainfall area during 1982–1983 with the objective of, firstly, determining the effects of traffic-induced compaction on soil physical properties, root growth and leaf nutrient concentration in maize (Zea mays L.) cowpea (Vigna unguiculata (L.) Walp) and soya bean (Glycine max Merr.) and secondly, characterizing soil compaction by evaluating soil physical properties which closely correlated with crop yields. Main treatments of tillage methods compared discing (to 20 cm depth followed by harrowing) to a no-tillage system. Traffic treatments of 0, 2 and 4 passes of a 2-Mg roller were subplots in a split-plot design experiment. The roller simulated field traffic in the 1.5–2.5 Mg weight range and exerted an average contact pressure of 113 kPa per pass on soil. Traffic-induced compaction decreased water infiltration rate and increased soil dry density and penetrometer resistance. Vertical root growth of maize and cowpea was consequently reduced down to 21 cm depth and that of soya bean down to 14 cm depth. Lateral root distribution was also markedly reduced. In the third consecutive growing season, traffic-induced soil compaction reduced the leaf nutrient concentration of Mg in no-tillage and P, Ca, K and Mn in discing for maize; Mg in discing for cowpea; and Ca in discing for soya bean. Traffic-induced soil compaction reduced grain yields of maize, cowpea and soya bean in all three seasons under both no-till and disced treatments, but the severity of this compaction increased considerably in the third consecutive season and was particularly more marked on the disced plots than on the no-till plots. The water infiltration rate was found to be the most sensitive soil property in characterizing soil compaction on this Alfisol in relation to crop yield.  相似文献   

5.
Differences in weed population dynamics with respect to within-field heterogeneity are not well documented despite increasing interest in site-specific management of agro-ecosystems. The focus of this study was to determine if mechanical weed management (cultivation) and/or soil factors help to explain observed within-field distributions of feral common sunflower (Helianthus annuus L.). The ridges and furrows created by the ridge–tillage system adds additional microsites to existing spatial heterogeneity for soil characteristics such as soil organic carbon (SOC) concentration. Experimental areas were selected on the basis of naturally high or low SOC concentration. Cultivation resulted in 100% mortality of H. annuus seedlings growing in the middle of furrows. Cultivation of pre-emergence herbicide treated and no-herbicide ridges resulted in small but statistically significant ( = 0.05) reductions in seedling survival. No differences were detected in H. annuus canopy height, stem diameter, stem length, or vegetative biomass between high and low SOC environments. Neither total reproductive biomass (P = 0.49) nor the biomass of flowers near physiological maturity (an estimate of fecundity; P = 0.59) were affected by SOC environment. Late season H. annuus lodging was observed to reduce reproductive biomass. Juvenile plants that survived mechanical weed control efforts grew and produced reproductive biomass similarly across SOC environments. The lack of difference in vegetative and reproductive characteristics between high and low SOC environments suggests that SOC (or the edaphic conditions associated with greater or lesser SOC level) was not critical in contributing to the observed distribution of H. annuus from juvenile to flowering stages of growth within well-fertilized, irrigated agricultural habitats.  相似文献   

6.
刘正佳    邵全琴 《水土保持研究》2014,21(6):334-339
为揭示气候变化对三江源地区草地生态系统的影响及适应机制,研究以SPOT-VGT为基础数据,利用像元二分模型估算了三江源地区1998—2012年的植被覆盖度,分析了年最大覆盖度的变异特征,并对植被覆盖度与气候因子之间的响应关系进行了深入探讨。结果表明:在区域尺度上,15 a来研究区生长季植被覆盖度呈极显著增加的趋势（P < 0.01）,平均每年增加0.004。在草地生态系统类型上,高寒草甸植被覆盖度与生长季温度的相关关系更加密切（r=0.802,P < 0.01）;高寒草原植被覆盖度与生长季温度呈显著相关关系（r=0.515,P < 0.05）。与生长季降水量相比较,5—7月降水量对高寒草原植被覆盖度变化的影响更加关键,但在高寒草甸上却不存在这种差异。  相似文献   

7.
Abstract

In the current multiplication technique first-generation seed tubers produced in the field by transplanting plants raised on peat in plastic rolls from plants cultured by repetitive multiplication using tip- and stem-cuttings and truncated plants are compared with in vitro micro-plants from the aspect of obtaining optimal-sized, disease-free seed tubers.

The objective of the study is to compare the dynamics of total plant dry mass and tuber dry mass of field-grown potato plants, and analyse the effect of the year and variety. Two local late-maturing potato varieties, Ants and Vigri, were used in the study. The field experiments were carried out in 2005–2007.

Significant impact of the multiplication method and experimental year on total plant dry mass and tuber dry mass was observed. The plants multiplied in vitro from micro-cuttings produced lower total dry mass and also lower tuber dry mass per m2. The plants multiplied by tip- and stem-cuttings as well as truncated plants proved to be more adaptable to unfavourable weather conditions than in vitro plants; in a favourable year, however, the differences were insignificant. In the early phase of growth the ratio of the tuber dry mass to total plant dry mass increased more rapidly in the case of in vitro plants, whereas by the end of the growing season the relevant ratio was similar for all multiplication methods and years.

All developed multiplication methods are suitable for practical seed potato production in the field and ensure a reasonable potato crop.  相似文献   

8.
The results of an experiment to study the effects of subsoil loosening on root growth and water use of barley plants grown in 1.0-m-deep, 65-mm-diameter plastic tubes are reported. Changes in the dry bulk density (1280–1530 kg m−3) of the 0.2-m-deep soil layer immediately below the plough layer hand disproportionate effects on rates of root growth, and following this on crop water use and dry matter yield. Increasing the number of large pores in the sieved sandy loam soil at a depth of between 0.2 and 0.4 m allowed roots to proliferate easily and at the same time to extract the water held at relatively low suctions. When no extra water was added, these plants came under water stress sooner than those grown in containers with relatively compacteds ubsoil. Reduced rates of root growth meant that water was made available over a longer period of time. The variable and unpredictable yield responses of crops to subsoil loosening reported in the literature must be owing in part to the patterns of rainfall distribution during the season in relation to root growth and the development stage of the crop. Under certain conditions subsoil loosening will increase crop water stress and reduce yield.

The validity of the techniques used for observing root growth was supported by the linear (β=1.09) relationship obtained at the end of the experiment between the length of root at the soil/plastic interface and the corresponding number of root ends observed at the centre of the soil core (r2=70%, N=216), although there was still a considerable degree of scatter in the position of individual points.  相似文献   


9.
ABSTRACT

Sweet pepper plants (Capsicum annuum L.) grown under greenhouse conditions differed widely in the rate of production of their total dry mass and their harvestable weight, although there was not shortage in water or nutrient supply. Plants were grown in aerated nutrient solutions along two different growing seasons. The differences in plant productivity were mainly due to the environmental conditions of the growth cycle. During the increasing day length season, from the beginning of spring to summer (13.0 to 14.8 h day? 1), plants produced the largest amount of fruits, but with a 10% blossom-end rot incidence. In the season of short photoperiod, progressing from the beginning of autumn to winter with 13.3 to 10.3 light h day? 1, the total dry weight and yields gradually decreased, but blossom-end rot in fruit did not appear. Different growth patterns were found for morphological and physiological parameters, because of the different light loads received by the canopy, being adjusted to the seasonal variables. Reduced light load markedly reduced leaf area and leaf thickness, but increased specific leaf area, which gave plants an increased ability to intercept light. Not only the amount of initial biomass, but radiation and the age of the pepper plants were the main growing driving factors, influencing relative growth rate, nitrogen (N)-use efficiency, and calcium (Ca) partitioning. Moreover, mathematical approaches for prediction of biomass production and N accumulation as a function of radiation are given in order to establish in the future a sweet pepper growth model.  相似文献   

10.
Nitrate reductase activity of green leaves of red oak, hemlock, basswood, sugar maple and beech were studied in relation to soil ammonifier and nitrifier populations and available mineral N of associated soils in a forest community near Ithaca, New York. Significant intersite, i.e. interspecific, differences were found for all plant and soil factors studied. Extractable NH+4-N was higher than NO3−-N under all species. Nitrate reductase activities (NRA) of the green leaves of the five dominant species were significantly correlated with soil NO3−-N beneath the tree canopies (P < 0.001). Nitrosomonas and Nilrobacter counts were intercorrelated (P < 0.001), and Nitrobacter was found to be related to both soil NH+4 (P < 0.05) and soil NO−3 (P < 0.001). Nitrosomonas and Nitrobacter counts were highest under basswood, and leaf NRA was 20–50 times higher in basswood leaves than in any of the other four species. Basswood also had the highest total leaf N, 5.02 ± 0.06%. Our data suggest that in these forest stands, green-leaf nitrate reductase activity is a reliable index of soil mineral N usage by the five species. Moreover, we believe that the data support the notion that Nitrobacter populations, and thus nitrification rates, are inhibited by the dominant tree species to result in a more ammonium-based nutrition, which on the system level ultimately has a conserving effect on the N economy of these stands.  相似文献   

11.
The effect of radiation interception on leaf conductance and leaf water potential in six-years old lychee trees (Litchi chinensis Sonn. cv. Bengal) was investigated during the dry season in subtropical Queensland, Australia. A high degree of exposure of leaves to direct radiation raised leaf-air water vapour concentration gradient (Δw) and resulted in lower leaf conductance and leaf water potential. Interior leaves of the south side of trees were less sensitive to atmospheric and radiation effects and are the best indicator of drought stress in lychee. Completely random or stratified sampling is necessary to estimate a true mean value for calculation of canopy transpiration or photosynthesis.  相似文献   

12.
川西亚高山森林凋落物中大量养分元素的年和月动态   总被引：11，自引：0，他引：11  
Macronutrients （N, P, K, Ca, Mg, and S） in litter of three primarily spruce （Picea purpurea Masters） （SF）, fir （Abies faxoniana Rehder ＆ E. H. Wilson） （FF）, and birch （Betula platyphylla Sukaczev） （BF） subalpine forests in western China were measured to understand the monthly variations in litter nutrient concentrations and annual and monthly nutrient returns via litteffall. Nutrient concentration in litter showed the rank order of Ca 〉 N 〉 Mg 〉 K 〉 S 〉 P. Monthly variations in nutrient concentrations were greater in leaf litter （LL） than other litter components. The highest and lowest concentrations of N, P, K, and S in LL were found in the growing season and the nongrowing season, respectively, but Ca and Mg were the opposite. Nutrient returns via litterfall showed a marked monthly pattern with a major peak in October and one or two small peaks in February and/or May, varying with the element and stand type, but no marked monthly variations in nutrient returns via woody litter, reproductive litter, except in May for the BF, and moss litter. Not only litter production but also nutrient concentration controlled the annual nutrient return and the monthly nutrient return pattern. The monthly patterns of the nutrient concentration and return were of ecological importance for nutrient cycling and plant growth in the subalpine forest ecosystems.  相似文献   

13.
The main function of deep tillage is to alleviate subsoil compaction, but how long do the benefits of this technique remain? Traffic on loose soil causes a significant increase in soil compaction. Subsoiling and chisel plowing were carried out at 450 and 280 mm depth, respectively on a compacted soil in the west Rolling Pampas region of Argentina. The draft required, physical soil properties, root growth, sunflower (Helianthus annus L. Merr.) yield and traffic compaction over the subsequent two growing seasons were measured. Cone penetrometer resistance was reduced and sunflower yields increased following deep tillage operations. Subsoil compaction caused changes to the root system of sunflower that affected shoot growth and crop yields. Although subsoiling and chiseling had an immediate loosening effect, it was evident that after just 2 years, when traffic intensity was >95 mg km ha−1, re-compaction and settling had occurred in the 300–600 mm depth range.  相似文献   

14.
One year field exposures of leaf litter from replicated plots of Pinus caribaea var. hondurensis Barrett and Golfari, Carapa guianensis Aubl., Euxylophora paraensis Hub., a Leguminosae combination (Dalbergia nigra Fr. All., Dinizia excelsa Ducke, Parkia multijuga Benth.), and adjacent upland (terra firme) forest at the Curuá-Una Forest Reserve, Pará, Brazil were used to examine the factors controlling leaf litter decay and N dynamics in a lowland tropical environment. Initial leaf litter N concentrations ranged from 4.4 (P. caribaea) to 16.3 mg g−1 dry matter (Leguminosae), and initial lignin concentrations from 190.8 (Leguminosae) to 459.3 mg g−1 dry matter (forest). Pinus caribaea leaf litter lost the least mass (28%), and the Leguminosae leaf litter the most (61%), during the year long incubations. Initial and 1-y proximate C fractions, N concentrations and polyphenol concentrations were not related to mass loss. Annual N accumulation or depletion from leaf litter under the plantations and forest was related to C loss (R2=0.93, P=0.007) and holocellulose loss (R2=0.84, P=0.02). When leaf litter was placed outside its stand of origin, there was a significant location effect on decay rates, indicating that differences in the physical and biological microenvironments under the monospecific plots affected litter decomposition.  相似文献   

15.
Although the effects caused in plants by the calcium (Ca)–phosphorus (P) interaction in calcareous soils are well documented, very few studies report on such effects in nutritive solutions or hydroponic cultivation. In a sand and perlite (1:1 volume) hydroponic system, effects of various P (21, 42, and 63 ppm) and Ca (120, 180, and 240 ppm) concentrations on potato tuberization were studied. A factorial experiment based on a completely randomized design with three replications was conducted. For maximum tuber yield and tuber number production, 21 and 42 ppm P was sufficient, respectively. Increase in P and Ca concentrations in nutrient solutions in early growing season resulted in an increase in shoot and root weight, leaf area, and shoot length linearly, but tuber yield and tuber number did not follow this trend. The maximum tuber specific gravity and total solid percent were also observed in 42 ppm P. The highest tuber number and tuber yield were observed in 120 ppm Ca concentration.  相似文献   

16.
Limited information is available on the influence of high surface residue tillag systems and the interaction of weed control methods, cultivar maturity, and phosphorus fertilizer placement on yield parameters of dry bean (Phaseolus vulgaris L.) A 3-year field study was conducted on a Fargo clay (fine, frigid, montmorillonitic Vertic Haplaquoll) to evaluate the influence of surface or deep band placed phosphorus fertilizer, tillage systems (PLOW, SWEEP, STRIP, NOTILL) and weed control methods on harvest plant populations, seed yield and seed weight of ‘Upland’ (early maturity) and ‘C-20’ (late maturity) dry bean cultivars. Yield variables were influenced by cultivar planted and climatic conditions. Zinc deficient plants and decreased yield were observed with the ‘C-20’ cultivar when grown on PLOW system plots where phosphorus fertilizer was surface applied. Zinc deficient plants were not present when the phosphorus fertilizer was deep banded or none was applied. No zinc deficient plants were observed on NOTILL, STRIP and SWEEP system plots. Both cultivars matured 7 to 10 days earlier with NOTILL, STRIP and SWEEP systems when compared with the PLOW system. Dry bean yields were reduced 180 to 310 kg ha−1 by cultivation for weed control. Little difference in yields occurred among tillage systems when climatic conditions were normal. During a cool wet season, seed yields on PLOW system plots were 150 to 400 kg ha−1 higher than on plots of systems with surface residue. Seed weight, although lower on the late maturity cultivar, was not greatly changed by tillage or weed control method. Results from this study indicate that dry beans can be successfully grown with small grain surface residue systems in northern climatic areas where growing degree days exceed 1200 and growing season precipitation does not exceed 400 mm. Further, deep band placement of phosphorus fertilizer is essential in dry bean rotations to eliminate potential zinc deficiency on soils low in zinc. Switching to a high residue management system may require a special cultivator design to eliminate yield loss due to pruning of shallow roots present with high surface residue.  相似文献   

17.
The seasonal pattern of morphological leaf characteristics, leaf nutrient and carbohydrate contents in two energy forest stands growing on fertile clay soil and consisting of Salix viminalis (L.) was investigated. One of the stands was irrigated and liquid fertilized (IL) daily from May to August while the other stand was untreated (C). The study was carried out on shoots growing for their second year on five-year-old roots. A pronounced seasonal variation in length, weight, and area of leaves of the same developmental stage was observed, while differences between the stands were small. The leaf content of carbohydrates and starch was low. Nitrogen was the only nutrient that was significantly higher in the IL stand compared with the C stand throughout the growing season. The small differences between stands were most probably an effect of the initially high soil fertility. Different bases for expressing plant nutrient status during the growing season, i.e. nutrient amount per leaf dry weight with and without carbohydrates, nutrient amounts per leaf or leaf area, nutrient proportions in leaves, and nutrient amounts in the total canopy, were compared and discussed. It was concluded that the common expression, nutrient weight per dry weight of leaves, without correction for non-structural carbohydrates, was adequate to describe the nutrient situation in well-growing basket willow plantations. The most appropriate time for leaf sampling was proposed to be the phase of most intensive growth.  相似文献   

18.
The objective of this study was to test if the effects of different nitrogen forms on potato growth depend on the plant growth stage. Plants from different potato cultivars were treated with different forms of nitrogen before tuber initiation and after tuber formation. A nitrification inhibitor was used to prevent the transformation of ammonium (NH4+) to nitrate (NO3?). Plant growth, tuber formation, leaf area, leaf chlorophyll content, and tuber yield were assessed. The results obtained over 2 years indicate that plants treated with NO3-nitrogen (N) before or at tuber initiation produced more tubers per plant than those treated with NH4-N. However, plants treated with NH4-N develop tubers earlier. Additionally, after tuber formation, plants treated with NH4-N had better shoot growth than plants treated with NO3-N. A larger leaf area with higher leaf chlorophyll content resulted in greater dry matter accumulation and higher tuber yield at harvest for plants treated with NH4-N.  相似文献   

19.
Mechanically loosened subsoil has been shown to be prone to recompaction. We addressed a sandy loam that had been mechanically loosened by a subsoiler to a depth of 35 cm in 1997 and again in 1998. Perennial grass/clover was grown with limited traffic intensity in 1999 and 2000. A recompaction experiment was conducted in 2001 and 2002 when the soil was grown with oat and winter wheat, respectively. Using the formerly loosened plots, on-land ploughing was compared with traditional mouldboard ploughing with the tractor wheels in the furrow. In addition, the loosened plots were either light-trafficked (<6 Mg axle load and <100 kPa inflation pressure) or heavy-trafficked (10–18 Mg axle load and 200 kPa inflation pressure), respectively. Finally, the soil loosened by non-inversion deep tillage was referenced with a conventional ploughing–harrowing tillage system that never received the subsoil treatment. The conventional treatment was also grown with the grass/clover in 1999 and 2000. On-land ploughing and light traffic was applied in 2001 and 2002 instead of traditional ploughing and traffic for the conventional treatment. Penetration resistance and bulk density was recorded in the field. Undisturbed soil cores were taken in 1998, 1999 and 2002 from the 7–14, 18–27 and 25–30 cm layer and used for measuring total porosity, pores >30 μm and air permeability at −100 hPa matric potential. The results showed that on-land ploughing mitigated recompaction of the upper part of the formerly loosened subsoil. In contrast, only small differences in recompaction between heavy and light traffic were observed. The mitigation of subsoil recompaction was needed for the loosened soil to provide an upper subsoil with similar—not better—pore characteristics than the non-loosened soil in the conventional treatment. The structural conditions in the plough pan improved for the conventional treatment from 1998 to 2002 as indicated by an almost doubling in air permeability. This was interpreted as being related to the growing of grass/clover ley in 1999 and 2000 combined with a shift from traditional tillage and traffic to on-land ploughing and light traffic when growing cereals in 2001 and 2002. Results on root growth and crop yield are reported in an adjoining paper.  相似文献   

20.
Average in-field water application efficiency in furrow-irrigated cotton (Gossypium hirsutum L.) in Australia is less than optimal, and The underlying reasons may include surface sealing, exposure of sodic soil by laser levelling, and soil compaction due to wheel-trafficking. The objective of this study was to quantify the effects of reducing traffic and tillage intensity on furrow soil properties in an irrigated Vertisol. Soil was sampled during the growing seasons of 2001–02, 2003–04 and 2005–06 from the surface 50-mm of adjacent wheel-tracked and non-wheel-tracked furrows in an experiment in north-western New South Wales, Australia. The treatments were: cotton sown either after conventional tillage (disc-ploughing and incorporating cotton stalks to 0.2 m, chisel ploughing to 0.3 m followed by bed construction) or on “permanent beds” (slashing cotton plants after harvest, followed by root cutting and bed renovation with a disc-hiller). Irrigation water was alkaline but had low salinity and sodium adsorption ratio. Soil properties measured were pH, EC1:5, geometric mean diameter (GMD) and specific volume (SV) of dry soil aggregates, exchangeable cations and plastic limit. Permanent bed systems had generally lower pH and higher SOC than conventionally tilled furrows, although differences were small. Soil pH and SOC averaged over the three growing seasons was 6.9 and 0.89 g/100 g, respectively, in permanent bed furrows, and 7.1 and 0.84 g/100 g, respectively, in conventionally tilled furrows. Compared to non-wheel-tracked furrows, plastic limit was lower (0.24 vs. 0.25 g/g), and EC1:5 (0.24 vs. 0.20 dS/m) and GMD (2.6 vs. 2.1 mm) higher in wheel-tracked furrows. Intra-seasonal changes in soil properties of furrows were also small, and are unlikely to significantly affect any hydrological processes. Inter-seasonal differences were, however, significant, and could affect hydrological processes in this soil.  相似文献   

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