Effects Of Different Water Regimes Research Articles

Nitrogen pools and flows during lab-scale degradation of old landfilled waste under different oxygen and water regimes.

Nitrogen emissions from municipal solid waste (MSW) landfills occur primarily via leachate, where they pose a long-term pollution problem in the form of ammonium. In-situ aeration was proposed as a remediation measure to mitigate nitrogenous landfill emissions, turning the anaerobic environment to anoxic and subsequently aerobic. As in-depth studies of the nitrogen cycle during landfill aeration had been largely missing, it was the aim of this work to establish a detailed nitrogen balance for aerobic and anaerobic degradation of landfilled MSW based on lab-scale experiments, and also investigating the effect of different water regimes on nitrogen transformation during aeration. Six landfill simulation reactors were operated in duplicate under different conditions: aerated wet (with water addition and recirculation), aerated dry (without water addition) and anaerobic (wet). The results showed that more than 78 % of the initial total nitrogen (TNinit) remained in the solids in all set ups, with the highest nitrogen losses achieved with water addition during aeration. In this case, gaseous nitrogen losses (as N2 due to denitrification) amounted up to 16.6 % of TNinit and around 4 % of TNinit was discharged via leachate. The aerated dry set-up showed lower denitrification rates (2.6-8.8 % of TNinit was released as N2), but was associated with the highest N2O emissions (3.8-3.9 % of TNinit). For the anaerobic treatment the main pathway of nitrogen discharge was the leachate, where NH4 accounted for around 8 % of TNinit. These findings provide the basis for improved management strategies to enhance nitrogen removal during in-situ aeration of old landfills.

Responses of microbial community and acidogenic intermediates to different water regimes in a hybrid solid anaerobic digestion system treating food waste

This study investigated the effects of different water regimes in an acidogenic leach bed reactor (LBR) during 16-day batch mode food waste digestion. LBRs were operated under five water replacement ratios (WRRs) (100%, 75%, 50%, 25% and 5% in LBRs R1, R2, R3, R4 and R5, respectively) and methanogenic effluent (ME) addition with two leachate recirculation frequencies (once in 24h and 12h in LBRs R6 and R7, respectively). Results showed that 50–100% WRRs accelerated the hydrolysis and acidogenesis with butyrate as the dominant product (∼35% of COD); whereas 5–25% WRRs promoted propionate production. The ME recirculation enhanced protein decomposition and reduced ethanol production. Lactobacillus dominated in LBRs with water addition (R1–R5), while Clostridium and hetero-fermenting lactic acid bacteria dominated in LBR with ME addition (R7). The highest volatile solid degradation (82.9%) and methane yield (0.29L-CH4/g VS) were obtained with ME addition at 0.7d hydraulic retention time.

Effect of Different Water Regimes on Yield and Quality of Apple under Semi-Humid Region, Libya

Effect of Different Water Regimes on Yield and Quality of Apple under Semi-Humid Region, Libya

Yield, water use and radiation use efficiencies of kenaf (Hibiscus cannabinus L.) under reduced water and nitrogen soil availability in a semi-arid Mediterranean area

Kenaf is a warm-season species that recently has been proved to be a good source of biomass for cellulose pulp for the paper industry in Mediterranean countries, where the use of hemp is problematic for legal reasons. A two-year research program aiming at studying the effects of different water regimes and nitrogen fertilization levels, upon plant growth, leaf area index, biomass accumulation, water and radiation use efficiency, was carried out on kenaf under a typically semi-arid Mediterranean climate of South Italy. In cv. Tainung 2, four different water regimes (I0=no irrigation, I25, I50 and I100=25, 50 and 100% ETc restoration, respectively) and three nitrogen levels (N0=no nitrogen, N75 and N150=75 and 150kgha−1 of N, respectively) were studied. The amount of water applied strongly affected plant growth (in terms of LAI, plant height and biomass) and final total and stem dry yield, which significantly increased from I0 to I100. Nitrogen did not exert any beneficial effect upon dry yield. Radiation Use Efficiency (RUE), calculated in the second year only, was the highest (1.95gDMMJ−1) in fully irrigated treatment (I100) and the lowest (0.86gDMMJ−1) in the dry control.Water use efficiency (WUE) was rather similar among water regimes, whilst irrigation water use efficiency (IWUE) progressively increased with the decrease of total volume of water distributed to the crop by irrigation, from 3.47 to 12.45kgm−3 in 2004 and from 4.27 to 7.72kgm−3 in 2005. The results obtained from this research demonstrate that in semi-arid areas of South Italy, irrigation at a reduced rate (50% ETc restoration) may be advantageous, since it allowed a 42–45% irrigation water saving, when compared to the fully irrigation treatment, against a 23% (in 2004) and 36% (in 2005) yield reduction, and a still good efficiency (near that potential) in transforming the solar radiation in dry biomass was maintained (RUE=1.76gDMMJ−1, against 1.95gDMMJ−1 in fully irrigated treatment).

Simulation of the growth of banana (Musa spp.) cultivated on cover-crop with simplified indicators of soil water and nitrogen availability and integrated plant traits

To reduce chemical inputs while maintaining crop yield, disturbed ecosystem functions must be restored, for example by cover-crops. In these cropping systems, because of competition between species, soil resources must be carefully managed. Dedicated tools and models are needed that account for the adverse effects of the cover-crop on the cash crop in terms of resource availability. Besides classical agronomic calculations of stress indices, which are difficult to generalize and require numerous parameters, recent work in ecology has related plant traits, like the biomass accumulated, to the resource availability during the whole plant cycle. Following such a simple approach, the objectives of this study were (i) to determine the effects of water and nitrogen limitations on banana growth and development and to test whether simple integrated traits can highlight the effects of these stresses on banana growth, (ii) to parameterize a simple generic module of soil water and nitrogen availability linked to SIMBA GROW, the growth module of the banana crop model SIMBA, (iii) to assess the ability of the model to simulate banana growth and development in the environmental conditions of a banana/cover-crop system, with particular attention on the effects of changes in plot temperature on model outputs. Three experiments were conducted on whole production cycles to investigate the effects of different water regimes, different nitrogen fertilization levels, and the cover-crop Neonotonia wightii on banana growth, nutritional status, and date of flowering. Results showed low nitrogen availability affected banana growth only weakly but decreased leaf nitrogen content and delayed flowering. Low water availability delayed flowering and decreased banana growth. In both cases, the delayed flowering allowed longer banana growth, which balanced the negative effect of low availability on the growth rate. The cover-crop modified both the rooting depth of the banana, and thus the amount of resources accessible to the banana roots, and the plot microclimate, especially air temperature. The model correctly reproduced the differences of date of flowering and leaf area index at flowering for a first cycle of production between a bare-soil and a cover-crop system, provided air temperature was reduced by 2–3% due to the cover-crop. To conclude, this study showed that in fairly constant environmental conditions (temperature, radiation and rainfall) a simplified model using resource availability over the growing period and integrated plant traits satisfactorily simulates banana growth in an intercropped system.

Responses of CO2 flux components of Alaskan Coastal Plain tundra to shifts in water table

The Arctic stores close to 14% of the global soil carbon, most of which is in a poorly decomposed state as a result of water‐saturated soils and low temperatures. Climate change is expected to increase soil temperature, affecting soil moisture and the carbon storage and sink potential of many Arctic ecosystems. Additionally, increased temperatures can increase thermokarst erosion and flooding in some areas. Our goal was to determine the effects that water table shifts would have on the CO2 sink potential of the Alaskan Coastal Plain tundra. To evaluate the effects of different water regimes, we used a large hydrological manipulation at Barrow, Alaska, where we maintained flooded, drained, and intermediate water levels in a naturally drained thaw lake basin over a period of three seasons: one pretreatment (2006) and two treatment (2007–2008) seasons. To assess CO2 flux components, we used 24 h chamber‐based measurements done on a weekly basis. Increased water table strongly lowered ecosystem respiration (ER) by reducing soil oxygen availability. Flooding decreased gross primary productivity (GPP), most likely by submerging mosses and graminoid photosynthetic leaf area. A decrease in water table increased GPP and ER; however, the increase in root and microbial activity was greater than the increase in photosynthesis, negatively affecting net ecosystem exchange. In the short term, ER is the CO2 flux component that responds most strongly to changes in water availability. Our results suggest that drying of the Alaskan Coastal Plain tundra in the short term could double ER rates, shifting the historic role of some Arctic ecosystems from a sink to a source of CO2.

The effects of differentiated water supply after anthesis and nitrogen fertilization on δ15N of wheat grain

The delta(15)N signature of plants integrates various processes in soil and plant. In this study, the effect of different water regimes applied during the period of grain growth of winter wheat on grain delta(15)N was examined in a 4-year field experiment. The treatments comprised water shortage (S), an ample water supply (W), and rain-fed crop (R). Zero fertilization (N0) and 200 kg N.ha(-1) in mineral fertilizer (N1) treatments were studied. The grain (15)N was determined during grain growth and at maturity. The water regime, nitrogen application and year had a significant effect on mature grain delta(15)N (p < 0.001). Water and nitrogen explained 54.6% of the variability of delta(15)N in the experiment, the year accounted for 10.7% and the interactions for another 19.6% of the total variability. The analysis of non-mature grain delta(15)N showed significant effects of N and year but not of water. Nitrogen fertilization reduced the delta(15)N of mature grain in years by 0.7-6.3 per thousand in comparison with N0 plants; the reduction was more pronounced under stress (average reduction by 4.1 per thousand) than under rain-fed (2.4 per thousand) and ample water supply (2.2 per thousand). Water stress decreased the grain delta(15)N in fertilized wheat, by 0.1-2.1 per thousand and 0.6-3.6 per thousand in experimental years, on average by 1.30 per thousand and 1.79 per thousand in comparison with the R and W water supply, respectively. The effect of water supply was not significant in non-fertilized wheat. A significant negative linear relationship between grain N concentration and delta(15)N in maturity or during the grain growth (R(2) = 0.83, R(2) = 0.76, respectively) was found. The observed sources of grain delta(15)N variability should be taken into consideration when analyzing and interpreting the data on the delta(15)N signature of plant material from field conditions.

Water management and water uptake efficiency by potatoes: A review

Lack of adequate availability of water can adversely impact the total as well as marketable quality of potato tuber production. Tuber initiation stage is the most critical growth stage for water stress. In this paper, effects of different water regimes on tuber yield and quality under different production systems are discussed. Deficit irrigation in general showed negative impact on the tuber yield as well as quality. Soil water management influences the fate and transport of nitrogen in soils, therefore, best management practice of both water and nitrogen are critical to optimize uptake efficiencies and minimize leaching losses.

バイオディーゼル植物Jatropha curcas L.の初期成長に及ぼす土壌含水量および潅水間隔の影響

バイオディーゼル植物Jatropha curcas L.の初期成長に及ぼす土壌含水量および潅水間隔の影響

Effects of different water regimes on the anatomical characteristics of roots of grasses promising for revegetation of areas surrounding hydroelectric reservoir

The objective of this study was to evaluate the effect of different water regimes on some aspects of root anatomy of three grasses: Echinochloa pyramidalis (canarana), Setaria anceps (setária) and Paspalum paniculatum (paspalo). The plants were cultivated in a greenhouse and submitted to three water regimes: daily watering; suspension of watering and suspension of watering followed by submersion of the root system. Segments of the middle part of the roots were taken and submitted to classical techniques in botany for slide making and tissue analysis. Anatomical differences were observed among the three grasses submitted to water regimes regarding the number of cell layers in the external cortex and thickening of lignin and suberin. The submerged roots of the three species presented an increasing tendency in the proportion of the area of the cortex destined for the aerenchyma besides thickening of the endodermis and the cells of the medullar parenchyma. The aerenchyma presence in the three water regimes suggested it is a characteristic of these species. The adaptations developed by these species contributed to the understanding of their occurrence in areas that are subject to drought periods and successive floods.

Effects of different water regimes on field-grown determinate and indeterminate faba bean ( Vicia faba L.). II. Yield, yield components and harvest index

Faba bean yields are highly sensitive to variations of water availability. For indeterminate faba bean, high levels of water could promote excessive vegetative growth at the expense of pod growth. Therefore, the present study was undertaken with the objective of comparing the yield and harvest index of determinate and indeterminate faba bean under different water regimes and finding how the balance between vegetative and reproductive growth responds to variations in water availability. Two field experiments were carried out in 1989 and 1990 at Reading, United Kingdom, using the determinate cultivar ‘Tina’ and the indeterminate cultivar ‘Gobo’. Rainshelters and trickle irrigation were used to establish four different water regimes: unsheltered and well-irrigated (W 1); sheltered at flowering and subjected to post-flowering water stress (W 2); sheltered throughout the season and subjected to continuously increasing water stress (W 3); open rainfed (W 4). High water availability (W 1) promoted vegetative growth and decreased the harvest index (HI). The decreases in HI were more pronounced in the indeterminates with reductions up to 48% as compared to 25% in the determinates. Except for the indeterminate W 1 in 1989, final pod yields were higher in W 1 (4.6–7.6 t/ha) than the rest (1.4–5.4 t/ha) in both cultivars. Under irrigation, the indeterminates required a longer post-flowering duration ( D f) to produce high pod yields because irrigation promoted post-flowering vegetative growth and delayed the onset of pod-filling. Consequently, in the shorter 1989 season, the indeterminate W 1 produced a lower pod yield than the rest whereas the opposite occurred in the longer 1990 season. In the water-stressed treatments, final pod yield was determined by the LAI at the onset of pod-filling, with higher values resulting in higher pod yields. Pod growth rate was maximal around a critical LAI of 4. Except in the 1989 indeterminate W 1, there was a positive linear relationship between pod yield and post-flowering leaf area duration. Seed yield was correlated with the numbers of pod-bearing nodes and pods per m 2 in both cultivars. No significant correlations were found between yield components, thus ruling out the presence of yield compensatory mechanisms in these cultivars. It is recommended that for the environment where this experiment was done, the determinates are preferable for late-spring plantings under irrigation. For early-spring plantings under irrigation and for both early- and late-plantings under rainfed conditions, indeterminates are more suitable.

Effects of different water regimes on field-grown determinate and indeterminate faba bean ( Vicia faba L.). I. Canopy growth and biomass production

Soil water shortage has been identified as a major constraint in increasing faba bean production. However, high water availability could cause excessive vegetative growth in indeterminate faba bean. Therefore, the present study was conducted with the objectives of quantifying canopy growth and biomass production of determinate and indeterminate faba bean under a range of water availability and thereby finding the suitability of different cultivars for different water regimes. Two field experiments were carried out in 1989 and 1990 at Reading, United Kingdom, using the determinate cultivar ‘Tina’ and the indeterminate cultivar ‘Gobo’. Rainshelters and trickle irrigation were used to establish four different water regimes: unsheltered and well-irrigated (W 1); sheltered at flowering and subjected to post-flowering water stress (W 2); sheltered throughout the season and subjected to continuously-increasing water stress (W 3); open rainfed (W 4). Leaf initiation, expansion and biomass production were significantly reduced by soil water deficits. A linear relationship was observed between final biomass and total leaf area duration. The relationship was common for all water treatments and both cultivars. This indicated that for the two cultivars tested, the effects of water stress were more on canopy size than on photosynthetic efficiency. A constant photothermal duration, which was similar for both cultivars, determined the durations from seedling emergence to flowering and maturity. Crops were planted 3 weeks earlier in 1990 than in 1989. Due to lower temperatures and photoperiods during the early part of growth, the 1990 crops took a longer duration to flower and mature as compared to 1989 crops. In the absence of water stress, a longer post-flowering duration allowed the indeterminates to develop a larger canopy and achieve a high final biomass (21 t/ha in 1990). The determinates were unable to produce a high biomass due to cessation of leaf production after flowering. In the shorter 1989 season, the determinate W 1 had a higher biomass (12 t/ha) than the indeterminate W 1 (10 t/ha). With increasing post-flowering water stress, the final biomass was mainly determined by the LAI at flowering. A higher LAI at flowering produced a greater final biomass. Only the indeterminates had the flexibility in phenology to take advantage of the post-flowering irrigation in W 2. It is concluded that if the whole biomass is to be utilized, indeterminate faba bean are more suitable for early-spring plantings with adequate water availability and for both early- and late-spring plantings under increasing water stress. Determinate faba bean are recommended only for late-spring plantings at sites with adequate water availability which could be predicted by analysis of past rainfall data. The determinates had less season-to-season variability in biomass. Efforts should be made to increase their overall biomass production potential while retaining this stability.

Evaluation of the silymarin content in Silybum marianum (L.) Gaertn. Cultivated under different agricultural conditions

AbstractAn HPLC assay for the determination of silymarin in the fruits of Silybum marianum is given. The effect of different water regimes and nitrogen fertilization levels on the silymarin content of cultivated plants grown in reclaimed desert land have been studied. The highest silymarin contents were obtained upon nitrogen fertilization with 100, 150 kg/feddan (1 feddan = 4200 m2) and a 60% water regime without fertilization compared to the content of silymarin in wild plants.

The effect of different water regimes on plant growth and nodule structure of greenhouse‐grown winged bean (Psophocarpus tetragonolobus)

SUMMARYPlants of Psophocarpus tetragonolobus cv. Chimbu Illinois were germinated under uniform conditions, after which they were transferred to three water treatments, ‘wet’, control and ‘stress’. Those plants given most water (i. e. ‘wet’) grew best and produced most root nodules.Water stress delayed nodule formation and quantitative microscopic examination showed that nodules from stress plants had more bacteroid‐containing cells per unit area up to 4 wk than nodules from either of the other treatments. Bacteroid‐containing cells were found to be vacuolated in P. tetragonolobus.

The Effect of Different Water Regimes on Growth and Nodule Development of Greenhouse-GrownVicia faba

Plants of Vicia faba cv. Maris Bead were germinated under uniform conditions; some were then transferred to conditions of water excess or stress for the vegetative growth phase. Those on the excess water regime grew best, produced most root nodules, and fixed most nitrogen. Microscopic examination showed that control and water-stressed plants did not develop all those nodules which had previously been initiated. Average nodule weight and specific activity were unaffected, but nodules showed a progressive increase in size and a more open structure as water supply was increased. Transfer between treatments resulted in adaptation to the new environment within a few days. It is concluded that established plants of V.faba are far more likely to be adversely affected by

Studies on the composts for raising seedlings of vegetable in hot beds

The experiments were conducted to clarify the effects of different water-regimes and temperature of irrigation water on the growth of tomato seedlings. Seeds of “Kurihara” variety were sown in flat. When two or three leaves developed, uniform plants were transplanted to the metal containers on the bench in the greenhouse. The containers were 30×30×10cm in size and were provided with 25 holes on their bottom for drainage. Small gravels were placed 2cm thick on the bottom of each container, and 7.2l of soil was stuffed on it. Ample water was applied to the soils, and after surplus water was completely drained, moisture contents were determined, and they were defined as water capacities (WC). Permanent wilting percentages (PWP) of the soils were determined by BALIR's method using dwarf sunflowers. The soil moisture between WC and PWP was regarded as available water (AW). Compost (volcanic ash soil-1 part : leaf mold-1 part in volume), volcanic ash soil, and sand were used for experiments. Water loss was weighed everyday and, when necessary, a measured volume of water was added to the soil. 1. To set up the plots differing in water-regime, water enough to bring the soil moisture to WC was applied everyday or when 25, 50, 75 or 100% of AW was lost. Growth of the tomato seedlings was markedly affected by the water-regimes in every soil; the most vigorous growth was obtained in the plots in which water was applied everyday, and the drier the soil, the less the growth of seedlings. Growth of the seedlings was closely correlated with the total amounts of water applyed during the experiments. Flower bud developments paralleled to the vegetative growth of the seedlings. 2. Effect of applying limited amount (not enough to bring the soil moisture to WC) of water on the growth of seedlings was tested. Watering the soil to 25 or 50% levels of AW, when 50 or 75% of AW was lost, was compared with the watering to the WC when 25 or 50% of AW was lost. The results obtained, were similar to those of the experiment mentioned above, that is, the growth of seedlings was closly correlated with the amount of water added. This shows that the limited watering which has been prevailing in practical forcing culture of fruit vegetables is unfavorable for the growth of seedlings. 3. Effect of temperature of irrigation water was tested by applying the water differing in temperature (0°, 20° and 40°C) to the tomato seedlings in the plots having narrow and wide water-regimes (100-75, 100-25%). There was no difference due to the water temperature, though significant difference was found due to the water-regime. It is suggested that even if temperature of irrigation water is rather low, it is better for the growth of the tomato seedlings in hot beds to keep, the soil, moist by applying water than to withhold watering.

The Effects of Different Water-Regimes on The Growth of Plants Under Glass: IV. Vegetative Growth and Fruit Development in The Tomato

The Effects of Different Water-Regimes on The Growth of Plants Under Glass: IV. Vegetative Growth and Fruit Development in The Tomato

The Effects of Different Water-Regimes on the Growth of Plants Under Glass: II. Experiments With Lettuces (Lactuca Sativa Linn.)

The Effects of Different Water-Regimes on the Growth of Plants Under Glass: II. Experiments With Lettuces (Lactuca Sativa Linn.)

The Effects of Different Water-Regimes on the Growth of Plants under Glass: I. Experiments with Tomatoes (Lycopersicum EsculentumMill.)

The Effects of Different Water-Regimes on the Growth of Plants under Glass: I. Experiments with Tomatoes (<i>Lycopersicum Esculentum</i>Mill.)

Effects of different water-regimes on the growth of tomatoes under glass.

THE relationship between the growth of glasshouse crop plants and the level of their water supplies is still uncertain. In order to investigate possible effects of soil moisture on the rate of growth and yield of tomatoes (varieties of Lycopersicum esculentum Mill.) under glass, tomato plants have been subjected to four different water-regimes for a continuous period of about five months with interesting results. During that time, the soil moisture in each treatment has been allowed to fluctuate only between field capacity and a predetermined level of dryness as indicated by the moisture tension at a depth of 15 cm. below the surface.