Effects Of Soil Water Status Research Articles

Response of dew and hydraulic redistribution to soil water in a rainfed dryland jujube plantation in China’s Hilly Loess Region

Soil desiccation occurs widely across China’s Loess Plateau due to long-term water demand in excess of water supply. Hydraulic redistribution (HR) - the movement of water from wet to dry soil via roots - and canopy dew (CD) are crucial to water replenishment in dryland ecosystems. However, much is still not known about the response of CD and HR to soil water deficits (including no deficit, slight deficit, moderate deficit, and severe deficit water conditions) in dryland jujube (Ziziphus jujuba Mill.) plantations in China’s Hilly Loess Region. To this end, the duration and intensity of dew were monitored using dielectric leaf wetness sensors to better understand the effects of soil water status on dew. Also, soil water content, sap flow, and meteorological variables were measured during the jujube growing seasons in 2017–2019. The results showed that the time of occurrence of CD under the no deficit condition came earlier than the time of occurrence of CD under slight, moderate, and severe soil water deficit conditions. Peak CD appeared at 5:00–6:30 am and ended at 6:30–9:00 am local time under the four soil water conditions. The amount, duration, and frequency of CD decreased with increasing soil water deficit. The amount and duration of CD under the no deficit condition were significantly higher than under the slight, moderate, and severe soil water deficit conditions (p < 0.05). The amount and frequency of HR (in the 20–60 cm soil layer) increased with increasing soil water deficit. Under the no deficit condition, HR was significantly lower than under the slight, moderate, and severe soil water deficit conditions (p < 0.05). While HR was influenced by CD, CD enhanced HR under the no deficit condition, but inhibited HR under slight, moderate, and severe soil water deficit conditions. For the growing season, the contribution of CD to total actual evapotranspiration (ETc act, CD/ ETc act ratio) was highest under the no deficit condition (maximum CD/ ETc act ratio of 0.21). The contribution of HR to ETc act (HR/ ETc act ratio) was higher under slight, moderate, and severe soil water deficit conditions (maximum of 0.11). The mutual effects of CD and HR lessened soil water deficit, making them important ecohydrological processes affecting the response of dryland jujube plantations to soil desiccation.

Modeling biomass and yield production based on nitrogen accumulation in soybean grown in upland fields converted from paddy fields in Japan

ABSTRACT Crop models can help in identifying constraints to crop production and enhancing crop yield. Because one of the major constraints is the availability of nitrogen for seed production, evaluation of nitrogen accumulation is important for soybean crop models. In the present study, we developed a soybean crop model to evaluate biomass production and nitrogen accumulation of Japanese soybean cultivars grown in upland fields converted from paddy fields. The model simplified the effects of leaf nitrogen deficit on biomass production by reducing only the leaf area while maintaining leaf nitrogen concentration, and we introduced a zero-order reaction kinetics model to estimate soil nitrogen supply. The proposed model was observed to simulate the accumulation of aboveground biomass and nitrogen content in both nodulating and non-nodulating soybean cultivars until the mid-seed filling period. The model accounts for 94% of the observed variations in aboveground biomass and nitrogen content and for 69% of the observed variation in seed biomass. The normalized root mean square errors of aboveground biomass, nitrogen content, and seed biomass are 19.3%, 19.6%, and 20.2%, respectively. Because the model does not include the effects of soil water status on pod formation and nitrogen fixation, seed biomass was overestimated in some cases. However, our model quantified the effects of changes in the soil nitrogen supply and biological nitrogen fixation on soybean production and will be useful for identifying and eliminating production constraints in Japanese soybeans.

Nitrogen deposition does not reduce water deficit in Ailanthus altissima seedlings

Water deficit and nitrogen (N) deposition are two important factors affecting plant growth in the context of global change. Here we selected Ailanthus altissima, a locally important tree species in North China, to study the combined effects of soil water status and N addition on plant growth. Ailanthus altissima seedlings were exposed to two soil moisture conditions (35% and 75% of the saturated soil moisture content) and three N treatments (0, 5, and 15gNm−2year−1) in a greenhouse experiment. After 50 d of treatment, plant growth, biomass production and allocation, and leaf physiological parameters were determined. Water deficit significantly restricted some parameters of growth and biomass accumulation, like height and basal diameter, total biomass, lateral root biomass, leaf biomass, and stem biomass. Some physiological parameters were also affected significantly by water deficit, leaf N content and qP decreased as soil moisture decreased and WUE was highest in water deficit condition. However, the high N load increased crown area and total biomass, lateral root biomass, and root biomass. With respect to physiological parameters, net photosynthetic rate, leaf N content, ΦPSII and ETR were clearly higher in the high N addition group than in the control group. Overall, an interaction between water deficit and N load had no significant effects on plant growth. Based on the present study with A. altissima seedlings, considering their rapid growth rate, we conclude that this species is better adapted than other deciduous trees to water deficit and high N additions under future global change scenarios, making it suited for vegetation restoration and reconstruction projects in the warm temperate zone of China.

Rhizosphere Nitrification and Nitrogen Nutrition of Rice Plants as Affected by Water Management

Redox status shapes the biogeochemistry and dominant biogeochemical processes in soil environment. Nitrification is a microbiologically mediated transformation affected by the oxygen availability in soil. Nitrification rate often determines the agronomic N use efficiency (NUE) since it affect the pool size of plant available N forms (NH 4 + ) and NO 3 - ) in soil. A mesocosm experiment was conducted using three rice varieties (PI312777, IR55423 and IR80508) to test the effect of soil water status on plant characters and nitrification in the rhizosphere. Two irrigation treatments as aerobic cultivation (AC) and continuously flooded condition (CF) were imposed. Plants were grown until 50 days after germination (DAG). At harvest, leaf nitrate reductase activity, physiological nitrogen use efficiency (PNUE), air-filled pore-space of roots, and biomass accumulation were determined. Also potential nitrification rate in the rhizosphere, soil moisture, pH, and NH 4 + and NO 3 - contents at three soil depths were determined. Biomass production was nearly 50% lower under AC than under CF. Rooting depth and rhizosphere nitrification were significantly higher under AC than CF. Rice variety and water management affected the activity of nitrifies in the rice soils. Measured soil properties and plant traits correlated significantly (p Tropical Agricultural Research Vol. 24(1): 1-11 (2012) DOI: http://dx.doi.org/10.4038/tar.v24i1.7984

Effects of soil water status on the spatial variation of carbon dioxide, methane and nitrous oxide fluxes in tropical rain-forest soils in Peninsular Malaysia

Abstract:To assess the effects of soil water status on the spatial variation in soil carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes, we examined these gas fluxes and environmental factors in a tropical rain forest in Peninsular Malaysia. Measurements of soil CO2, CH4and N2O fluxes were taken ten, nine, and seven times, respectively over 30 mo at 15 or 39 sampling point within 2-ha plot. Mean (± SE) value of spatially averaged CO2flux was 4.70 ± 0.19 μmol CO2m−2s−1and observed spatial variation in CO2flux was negatively related to the volumetric soil water content (VSWC) during the dry period. Over the wet period, extremely high CO2emissions were positively correlated with VSWC at some locations, suggesting that no spatial structure of CO2flux was because of such hot-spot CO2emissions. Flux of CH4was usually negative with little variation, with a mean value of –0.49 ± 0.15 mg CH4m−2d−1, resulting in the soil at our study site functioning as a CH4sink. Spatial variation in CH4flux was positively related to the VSWC throughout the entire study period (dry and wet). Some CH4hot spots were observed during dry periods, probably due to the presence of termites. Mean value of spatially averaged N2O flux was 98.9 ± 40.7 μg N m−2h−1and N2O flux increased markedly during the wet period. Spatially, N2O flux was positively related to both the VSWC and the soil N concentration and was higher in wet and anaerobic soils. These findings suggest that denitrification is a major contributor to high soil N2O fluxes. Additionally, analysis by adjusting confounding effects of time, location and interaction between time and location in mixed models, VSWC has a negative effect on CO2flux and positive effects on CH4and N2O fluxes. We found that soil water status was related temporally to rainfall and controlled greenhouse gas (GHG) fluxes from the soil at the study site via several biogeochemical processes, including gas diffusion and soil redox conditions. Our results also suggest that considering the biological effects such as decomposer activities may help to explain the complex temporal and spatial patterns in CO2and CH4fluxes.

Special issue on water management in grapevines

Population growth, economic development, environmental demands, and climate change converge into a scenario of water scarcity worldwide (Fereres and Gonzalez-Dugo 2009). Water supply may therefore constraint grape production for quality wine. In this context, deficit irrigation (DI) strategies to stabilize yield and maintain or improve wine quality are critical. Recently, the use of regulated deficit irrigation (RDI) has expanded in vineyards to improve (sometimes to reduce) water application, yield per unit water supply, berry composition, and wine quality. The objective of RDI is to apply water deficits of predetermined levels during certain phenological stages when their effects on fruit growth and quality are neutral or positive, while keeping vineyard vigor in balance with potential production (Girona et al. 2006, 2009; Pellegrino et al. 2006; Greven et al. 2005). The short and long-term impact of deficit irrigation on production and quality vary with vineyard conditions, namely soil texture and depth, variety, atmospheric environment, and viticultural practices. These factors make it difficult to predict the best timing for imposing water deficits. Also, the desired intensity of deficit is not easy to impose uniformly over the whole vineyard, and the risks of excessive water deficits must be avoided through careful monitoring. Furthermore, there is a trade-off between regulated water deficit to improve yield per unit water supply and the need to maintain well-watered vines to reduce heat damage in warm and hot regions (Sadras and Soar 2009; Soar et al. 2009). Understanding the effects of timing and amount of irrigation on yield and berry composition is key to achieve the desired yield and berry quality. Thus, the correct determination of vineyard water requirements (or evapotranspiration, ET) and the monitoring of soil and vine water status are critical to apply the appropriate deficit irrigation strategies. The conventional crop coefficient (Kc) approach provides a simple and convenient way to estimate vineyard water requirements for a variety of soil and climatic conditions, but a major uncertainty in this approach is that the empirical nature of Kc which requires local calibration and monitoring of plant water status. Vine water status can be monitored with predawn, noon leaf, and stem water potentials, which integrate the effects of soil water status on both the environment (soil and atmosphere) and the vine (root and canopy size, stomatal conductance). However, there is no general agreement on which method is the most reliable to evaluate vine water status. This discrepancy may be explained by the combined effect of variety and rootstock, soil type and depth, range of soil water deficit, variability of weather conditions throughout the growing cycle, atmospheric evaporative demand, and source/sink ratio as affected by growing conditions and management practices shifting the balance between leaf area and fruit load. Midday stem water potential of horticultural trees, for example, is lower with high source/sink ratio (Sadras and Trentacoste 2011). Communicated by R. Evans.

The effect of soil water status on fertiliser, topsoil and subsoil phosphorus utilisation by wheat

Crop phosphorus (P) content is controlled by P uptake from both banded P fertiliser and from P throughout the soil profile. These P supply factors are in turn controlled by soil, climatic and plant factors. The aim of this experiment was to measure the contribution of fertiliser, topsoil and subsoil P to wheat plants under wet and dry growing season conditions. An isotopic tracer technique was used to measure P uptake from fertiliser at seven agricultural field sites under wet and dry growing season conditions. At three of these sites a dual isotopic technique was used to distinguish between wheat uptake of P from fertiliser, topsoil (0–15 cm) and subsoil (below 15 cm). The amount of P fertiliser used by wheat was in the order of 3–30% of the P applied and increased with increasing rainfall. Topsoil P was the most important P source, but when sufficient P was present in the subsoil, P fertiliser addition stimulated the use of subsoil P. Most crop P uptake was from the topsoil, however P fertiliser banded below the seed increased plant P uptake and stimulated the use of subsoil P in one soil type in a decile 7 (above average rainfall) growing season.

Starch Granule Size Distribution in Grains at Different Positions on the Spike of Wheat (Triticum aestivum L.)

AbstractThe present study was carried out to characterize the effects of soil water status, cultivar and grain position on starch granule size distribution. The starch granule size distribution and protein and starch content were determined from three wheat cultivars with reference to the position of the grain on the spike. The results showed that the contents of A‐, B‐ and C‐type starch granules were affected by soil water, genotype and soil water×genotype interaction. Grain position was significant for A‐ and C‐type starch granules. Genotype×grain position and soil water×genotype×grain position interactions only affected C‐type starch granules. Both basal and distal grains on middle spikelets contained three types of starch granules: smaller C‐type granules with diameters &lt;2.0 μm, medium B‐type granules with diameters 2.0–9.8 μm and large A‐type granules with diameters &gt;9.8 μm at maturity. Both percent volume and percent surface area distribution of starch granules in basal grains showed the typical three populations, and those in distal grains exhibited a two‐peak curve. The volume and surface area percentage of C‐type granules and protein content in basal grains were higher than that in distal grains, but those of A, B‐type granules in basal grains were lower than that in distal grains. Compared with irrigation, the percent volume and surface area of B, C‐type starch granules and protein content in basal and distal grains were significantly increased, and those of A‐type were evidently decreased in rainfed condition.

Effect of soil water status and mulching on N 2 O and CH 4 emission from lowland rice field in China

Cultivation of rice in unsaturated soils covered with mulch is receiving more attention in China because of increasingly serious water shortage; however, greenhouse gas emission from this cultivation system is still poorly understood. A field experiment was conducted in 2001 to compare nitrous oxide (N2O) and methane (CH4) emission from rice cultivated in unsaturated soil covered with plastic or straw mulch and the traditional waterlogged production system. Trace gas fluxes from the soil were measured weekly throughout the entire growth period using a closed chamber method. Nitrous oxide emissions from unsaturated rice fields were large and varied considerably during the rice season. They were significantly affected by N fertilizer application rate. In contrast, N2O emission from the waterlogged system was very low with a maximum of 0.28 mg N2O m−2 h−1. However, CH4 emission from the waterlogged system was significantly higher than from the unsaturated system, with a maximum emission rate of 5.01 mg CH4 m−2 h−1. Our results suggested that unsaturated rice cultivation with straw mulch reduce greenhouse gas emissions.

Effect of Soil Water Status on the Physioecological Traits and the Ecological Replacement of Two Endangered Species, Changium Smyrnioides and Chuanminshen Violaceum

Both Changium smyrnioides Wolff and Chuanminshen violaceum Shen et Shan are monotypic species of the family Umbellaceae. They have narrow distribution areas and can only be found in the Yangtze River basin in China. Changium is distributed from the east to middle subtropical zone of China, and Chuanminshen from the middle to the west; they almost meet in the middle of the Yangtze basin. Because the climate varies from humid to semi-humid, an experiment was carried out to find out the two species' demand for soil water and analyze their niche separation by determining changes in their physio-ecological and structural traits in response to different soil water statuses. Results showed that the two species have similar structural characters and functional intensity. Diurnal variations, daily mean values, and relationships of irradiation and temperature to PN, E and WUE among the three treatments indicate that Chuanminshen has more tolerance to drought than Changium. Changes in morphological traits also suggest that Changium adapts to medium to wet soil conditions while Chuanminshen adapts to drought soil conditions. The differences in the adaptation of physiological and morphological traits to the water environment should be part of the reason these two species have become geographically vicarious species. The results indicate that, at least, the mechanism and the approach to conservation for the two species are similar.

Measurement and analysis of evapotranspiration and surface conductance of a wheat canopy

AbstractThe characteristics of evapotranspiration and canopy surface conductance of winter wheat have been measured and analysed by using the Bowen ratio–energy balance (BREB) method. In order to understand better the effect of soil water status on evapotranspiration and conductance of wheat, the daily and seasonal variations of leaf stomatal resistance under different soil water conditions have also been monitored and analysed. The experiments have been carried out at Luancheng Experimental Station of Agro‐ecosystem (LESA), Heibei, People's Republic of China. During the growing seasons after turning to green, most of the available energy (Rn − G) of the wheat field is partitioned into latent heat. In the daily course, generally, the Bowen ratio (H/LE) for winter wheat is less than one‐third; sometimes, it can reach a value of around 0·4. The seasonal trend of LE/Rn shows a parabola curve. The ratio of LE/Rn varies from 71 to 93%, with the peak occurring in the blooming stage. G/Rn shows a declining logarithmic trend during the observation period, and reaches its minimum value of around 6–8% after blooming. According to the BREB method, the daily mean evapotranspiration rate from jointing to maturity is 3·9 mm day−1, which is very close to the value 4·1 mm derived from the water balance equation. The daily average value for canopy conductance gc is about 7·8 mm s−1. Seasonal trend of leaf stomatal resistance shows that the stomatal resistance in blooming and milking are lower than that in other growing stages. This is possibly determined by the characteristic of water requirement of winter wheat. The stomatal conductance is strongly dependent on soil water status in natural conditions. When the extractable soil water content (ESW) of the 0–40 cm layer is less than 50%, the leaf stomatal conductance gst is linearly dependent on ESW, whereas there is no relation between ESW and gst when ESW is more than 50%. Therefore, the ESW of 50% can be considered as a threshold value of extractable soil water content for controlling the leaf stomatal conductance, or as an indicator of incipient stomatal closure. The slope of the gst–ESW line varies through the growing stages, with the largest slope occurring in the milking stage. Based on the analysis of gst–ESW relations, we construct a simple but realistic model of stomatal conductance–soil moisture relations. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Spatial distributions of expansion rate, cell division rate and cell size in maize leaves: a synthesis of the effects of soil water status, evaporative demand and temperature.

The spatial distributions of leaf expansion rate, cell division rate and cell size was examined under contrasting soil water conditions, evaporative demands and temperatures in a series of experiments carried out in either constant or naturally fluctuating conditions. They were examined in the epidermis and all leaf tissues. (1) Meristem temperature affected relative elongation rate by a constant ratio at all positions in the leaf. If expressed per unit thermal time, the distribution of relative expansion rate was independent of temperature and was similar in all experiments with low evaporative demand and no water deficit. This provides a reference distribution, characteristic of the studied genotype, to which any distribution in stressed plants can be compared. (2) Evaporative demand and soil water deficit affected independently the distribution of relative elongation rate and had near-additive effects. For a given stress, a nearly constant difference was observed, at all positions of the leaf, between the relative elongation rates of stressed plants and those of control plants. This caused a reduction in the length of the zone with tissue elongation. (3) Methods for calculating cell division rate in the epidermis and in all leaf tissues are proposed and discussed. In control plants, the zone with cell division was 30 mm and 60 mm long in the epidermis and in whole tissues, respectively. Both this length and relative division rate were reduced by soil water deficit. The size of epidermal and of mesophyll cells was nearly unaffected in the leaf zone with both cell division and tissue expansion, suggesting that water deficit affects tissue expansion rate and cell division rate to the same extent. Conversely, cell size of epidermis and mesophyll were reduced by water deficit in mature parts of the leaf.

Transpiration and Leaf Area Under Elevated CO2: Effects of Soil Water Status and Genotype in Wheat

Transpiration rate, leaf area expansion, water use and water-use efficiency (WUE) of spaced plants of wheat (cvv. Matong and Quarrion), were examined at ambient and twice ambient CO2 concentrations in wet and drying soil regimes. A hypothesis tested was that both stomatal conductance (gs) and leaf area development are so regulated by the plant in relation to soil water status that the reduction of approximately 40% in gs in high CO2 has no permanent impact on whole-plant water use. Whereas, during a soil drying cycle, leaf area increase under elevated CO2 counterbalanced closely for reduced gs in terms of soil water depletion as reported elsewhere, this counterbalance was neither exact at all times, nor did it apply when the soil was continuously wet. In wet soil, leaf area was not enhanced much by elevated CO2, probably because, under the high radiation and nutritional conditions used, the tillering rate was almost maximal anyway. Quarrion, having a 40% lower gs than Matong genetically, did not counter-balance a reduced transpiration rate with a larger leaf area under either drying or wet soil conditions. These results support rejection, for wheat, of the hypothesis posed; elevated CO2 increased leaf area mainly by virtue of the direct photosynthetic increase rather than changed soil water status. In wet soil, low gs Quarrion had a higher CO2 effect on WUE (+ 73 to 82%) than did Matong (+54 to 65%). In drying soil, both cultivars had a similar increase in WUE at high CO2 (+60 to 68%).

Effects of soil water status on infection of soft red winter wheat by soilborne wheat mosaic virus

(1992). Effects of soil water status on infection of soft red winter wheat by soilborne wheat mosaic virus. Canadian Journal of Plant Pathology: Vol. 14, No. 2, pp. 147-151.

The effect of soil water status on critical phosphorus concentrations inStylosanthes hamata cv. Verano

The effect of soil water status on the critical phosphorus concentration (CPC) determined in apices and whole tops ofStylosanthes hamata cv. Verano was investigated in a glasshouse trial. The species was grown with six rates of P and three ranges of soil water potential and was harvested at 10 and 14 weeks after germination. The CPC of both whole tops and apices decliced between the two harvests. At the first harvest the CPC of both whole tops and apices increased as the soil water potential decreased but at the second harvest there was no effect of soil water potential on CPC. It is suggested that at the earlier harvest water stress was delaying physiological development, resulting in a CPC characteristic of chronologically younger tissue, but that by the second harvest the decline in CPC with age had ceased for all water treatments.