Increasing Irrigation Amount Research Articles

Drip Irrigation Affects the Morphology and Distribution of Olive Roots

Under field conditions, this study investigated the influence of the irrigation amount on olive root morphology and spatial distribution. Soil samples were taken with an auger at distances of 30, 60, and 90 cm from the tree trunks in four directions. The roots were analyzed using an Epson Twain Pro root scanning system. The results indicated that under different irrigation treatments, the indicators of root morphology of different varieties showed different responses to the irrigation amount. The root length density (RLD), root surface area (RSA), and root volume (RV) of Arbosana first increased with increasing irrigation amount but then decreased; however, those of Arbequina monotonically increased with increasing irrigation amount. The root average diameter of the two varieties was inversely proportional to the irrigation amount. In the vertical dimension, the RLD and RSA of each treatment decreased with increasing soil depth and were mainly distributed in the surface soil (0–20 cm in depth). The RLD and RSA in the vertical direction (VD) of the drip irrigation belt were higher than those of the belt in the parallel direction (PD), and the range was 12% to 86%. Compared with the roots of the 0- to 20-cm soil layer, the roots of the 20- to 40-cm and 40- to 60-cm soil layers were more influenced by the irrigation amount. Horizontally, the RLD and RSA decreased with increasing radial distance. The 30-cm radial area contained most roots, the proportion of roots in this region increased with increasing irrigation capacity. The influence of irrigation quantity in the PD of the drip irrigation belt was greater than that in the VD. The results suggest that irrigation does not change the root spatial distribution pattern but does promote root growth. The two varieties had different responses to irrigation. In terms of soil moisture levels after irrigation, 75% of field capacity is appropriate for ‘Arbosana’, whereas 100% is advisable for ‘Arbequina’. To improve water use efficiency, moisture should be irrigated within the 30-cm radial distance from the trunk, and irrigation depth is not easy to more than 20 cm. This study provides a scientific basis for the efficient water management of olive trees.

English

Different cultivation patterns affect the grain yields of winter wheat by regulating growth and development. In this study, the growth of wheat was observed for two years (2008‒2009 and 2009‒2010). We established three cultivation patterns: 25 cm uniform row planting pattern; “20 cm + 40 cm” wide-narrow row planting pattern (wide-narrow row spacing is 40 cm and 20 cm respectively); and “20 cm + 40 cm” furrow planting pattern (double lines in the furrow with 20 cm spacing, 40 cm between furrows, and ridge height of 15 cm). Three irrigation treatments viz. 90, 135 and 180 mm were established. Results showed that furrow planting pattern improved the ratio of variable over maximum fluorescence (Fv/Fm).With increasing irrigation amount, Fv/Fm increased, the amplification declined, and the net photosynthetic rate in flag leaves increased. However, such effect was not obvious beyond the irrigation range stipulated. Therefore, we recommend the furrow planting pattern, which resulted in stable yield and 135 mm deficit irrigation as optimum considering the water shortage in the area. © 2016 Friends Science Publishers

Modeling Cotton Lint Yield Response to Irrigation Management as Influenced by El Niño–Southern Oscillation

The declining High Plains or Ogallala Aquifer motivates U.S. producers to optimize water use and yield of drought‐tolerant crops like cotton [Gossypium hirsutum (L.)]. Systematic sea surface temperature anomalies (SSTA) drive the El Niño–Southern Oscillation (ENSO), resulting in predictable weather patterns in North America that could be exploited by irrigation strategies. Our objective was to compare cotton yield response to irrigation as altered by La Niña, Neutral, or El Niño phases for the Texas High Plains. We used actual 1959 to 2000 weather records with the simulation model GOSSYM to estimate lint yields for three progressively later emergence dates under 50 or 75% initial soil water conditions and all combinations of irrigation duration (0, 4, 6, 8, and 10 wk) and rate (2.5, 3.75,and 5.0 mm d−1). Simulated lint yield and its ratio to evapotranspiration generally decreased with emergence delays and increased with increasing irrigation amount and application rate. Growing season precipitation varied with ENSO phase, but April to June phase classification was inconsistent with fall conditions except for La Niña. Compared with yield estimates for Neutral and El Niño phases, limited rain during La Niña years reduced lint yields from 5 to 30% when initial soil water was 75 and 50%. Yield increased with increasing irrigation rate and duration during drier La Niña growing seasons, but irrigation benefits decreased during Neutral and El Niño years having greater precipitation. Early ENSO based extended forecasts for La Niña related consistently to irrigation effects on yield and could determine application strategies.

Radiation Use Efficiency and Yield Response of Winter Wheat to Planting Patterns and Irrigation in Northern China

The objective of the study was to investigate the effect of planting patterns and irrigation on radiation use efficiency and yield of winter wheat (Triticum aestivumL.) in northern China from 2008 to 2009 and 2009 to 2010. A factorial experiment consisting of three planting patterns: 25 cm uniform row planting pattern (U), “20 + 40” wide‐narrow row planting pattern (wide row spacing [RS] of 40 cm and narrow RS of 20 cm, WN), and “20 + 40” furrow planting pattern (double lines in the furrow with 20 cm spacing, and 40 cm between furrows, ridge high 15 cm, F). Three irrigation treatments were 90, 135, and 180 mm. The leaf area index (LAI) of F planting was higher than that of U and WN under the same irrigation amount. The planting pattern of WN and F, especially the latter, significantly improved the photosynthetic active radiation capture ratio at 0 to 40 cm above the ground surface. Under the same irrigation amount, grain yields of F were significantly higher (P< 0.05) than those of U and WN planting patterns. With the increasing irrigation amount, grain yield of winter wheat was not significantly increased between 135 and 180 mm irrigation from 2009 to 2010 (P< 0.05). In conclusion, considering the water shortage, the F and 135 mm irrigation should be a good agronomic measure to increase grain yield.

有限供水下冬小麦全程耗水特征定量研究

为明确冬小麦不同水分条件下全生育过程日耗水及阶段耗水特征，在北京地区利用蒸渗仪系统连续监测了几种灌溉处理（W4：起身水+孕穗水+开花水+灌浆水；W2：拔节水+开花水；W1：拔节水；W0：无灌水）耗水动态变化。结果表明：冬小麦全生育期的耗水动态可分为3个阶段：（1）播种至11月底的冬前阶段，这个阶段日耗水量波动明显，一般低于3 mm/d；（2）12月上旬至来年2月底的冬季阶段，这个阶段日耗水量低于0.4 mm/d，且波动很小；（3）3月初小麦返青至收获的春后生长阶段，这个阶段日耗水量总体上是一个先升高后降低的过程，但波动很大，每次灌水都会引起1个日耗水高峰的出现。耗水日变化呈单峰或双峰曲线，高峰出现在正午前后，高峰值因灌水处理而有明显差异，灌水多则耗水峰值显著升高，而夜间耗水量及其在不同处理间差异均很小。拔节至成熟期是冬小麦耗水的主要时期，该期耗水占总耗水60%以上。减少灌溉会增加土壤贮水消耗，但降低了总耗水量。综合比较表明，在有限灌溉下，拔节水和开花水组合是高产和高水分效率相统一的灌溉模式。;From October of 2011 to June of 2012, water consumption of a winter wheat cultivar Jingdong 22 under four irrigation treatments was monitored continuously using 24 weighing lysimeters in Beijing, China. The weighing lysimeters monitored water consumption of winter wheat at an interval of five minutes. Soil water content within all the lysimeters was adjusted to field capacity before plantation. The four irrigation treatments were W0 (no irrigation after plantation), W1 (one irrigation after plantation at the jointing stage), W2 (two irrigations after plantation at the jointing and flowering stages, respectively), and W4 (four irrigations after plantation at the erecting, booting, flowering and grain-filling stages, respectively). The amount of water applied in each irrigation was 40 mm. Rainfall during the growth season was kept away from the lysimeters with an automatic rain-proof shelter. The experiment results showed that water consumption during this winter wheat season could be divided into three stages. The first stage was from the plantation date to the stable freezing date at early December of 2011. Daily water consumption during this stage fluctuated significantly and was usually less than 3 mm/day. Total water consumption during this stage was between 32 to 35mm. The second stage was during freezing season spanned from early December of 2011 to early March of 2012. During this stage, daily water consumption was less than 0.4 mm/d and fluctuated little. Total water consumption during this stage was between 21 to 24 mm. The third stage was from green-up in early March of 2012 to harvest. During this stage, daily water consumption increased first, reached the highest value around heading stage, remained at high value until mid-grain-filling and decreased quickly approaching ripening, with large increase of daily water consumption after each irrigation. Changes of evapotranspiration rates showed patterns of single or double peak curves for each day, with different peaks appearing around midday for the four treatments. Evapotranspiration rates were significantly correlated to total radiation, temperature, and relative humidity, with the highest correlation coefficient with total radiation. Night water consumption and its variation were small for all irrigation treatments. Water consumption of winter wheat mainly happened after the jointing stage. With increasing irrigation amount, more irrigation water and less soil water were consumed. In the treatments of W1 and W0, soil water contributed 62% and 76% of total water consumption, respectively. In the W2 treatment, irrigation water contributed 32%, and soil water contributed 50% of water consumption. Irrigation water contributed to 50%, and soil water contributed 36% of water consumption of the W4 treatment. Grain yield levels of the four treatments were in the order of W4 > W2 > W1 > W0, whereas water use efficiencies of the four treatments were W2 > W4 > W1 > W0. Among the deficit irrigation treatments, incorporation of irrigations at the jointing and flowering stages leaded to high grain yield and water use efficiency, while water use efficiencies for the four treatments were similar (about 15 kg/hm²/mm).

Effects of deficit irrigation on daily and seasonal variations of trunk sap flow and its growth in Calligonum arborescens

Water deficit in arid and semiarid regions affects whole-plant sap flow and leaf-level water relations. The objectives of this study were to clarify how sap flow of Calligonum arborescens responds to different drought stress conditions and to understand its acclimation mechanism to drought environments. A field experiment was conducted for C. arborescens during the growing season to evaluate the effects of deficit irrigation on the daily and seasonal variations of trunk sap flow in the shelterbelt along the Tarim Desert Highway, Xinjiang, China. Three different water regimes (2,380, 1,960 and 1,225 m3/hm2) were applied at different stages of plant growth. From 1 May to 30 October 2007, a heat-balance stem flow gauge was used to monitor the sap flow dynamics of C. arborescens under different water regimes. Atmospheric evaporation demand and soil moisture conditions for differentially irrigated C. arborescens were also monitored. The result showed that sap flow exhibited a clear diurnal pattern regardless of treatments; the diurnal patterns of sap flow and vapour pressure deficit were very similar under different water regimes and growing seasons, while the slope of the linear regression of this correlation confirmed an increasing water regime. The sap flow decreased under reduced water regimes and there was nocturnal sap flow regardless of water regimes, which was mainly contributed to nocturnal transpiration and water recharge. The sap flow peaked before midnight and dropped afterwards with obviously higher values in summer than in other seasons. It is speculated that the water consumption of C. arborescens during the day can be supplemented through the sap flow at night, which increased with increasing irrigation amount. Net radiation was the most significant correlated factor that influenced sap flow velocity and transpiration under different water regimes (R 2>0.719). Compared with the commonly practiced water regime, the growth of C. arborescens was significantly slower in the stress deficit irrigation, but not significantly different from that in the moderate deficit irrigation. The moderate deficit irrigation would not affect the stability of the shelterbelt and was a more efficient use of water resources compared with the current watering amount.

Effect of irrigation amount and water salinity on water consumption and water productivity of spring wheat in Northwest China

Sustainable development of agriculture is restricted by fresh water shortage and water quality deterioration in some arid and semi-arid areas. Therefore, deficit irrigation and saline water irrigation have to be applied for sustaining crop yield. In order to determine the rational irrigation management practice in an arid region of Northwest China, field experiments were conducted in 2008, 2009 and 2010 to study the effects of irrigation amount and water salinity on water consumption and water productivity of spring wheat. Altogether nine irrigation treatments including three levels of irrigation water amount with 375, 300, and 225mm (w1, w2 and w3) and three levels of irrigation water salinity with 0.65, 3.2, and 6.1dSm−1 (s1, s2 and s3) were arranged in a randomized split-plot design with three replications for each treatment. In 2008, yield increased with increasing irrigation amount under both fresh and saline water irrigation. However, in 2009 and 2010, the highest yield at the same salinity level under saline water irrigation was obtained by w2. Actual evapotranspiration (ETa) decreased with decreasing irrigation amount. Therefore, w2 got higher water use efficiency (WUE) (1.25–1.63kgm−3) and irrigation water use efficiency (IWUE) (2.11–2.36kgm−3) than w1, which indicated that irrigation amount 300mm is beneficial to yield and water use efficiency at water salinity 3.2 and 6.1dSm−1. Thus, for the purpose of highest yield and WUE, irrigation amount should be controlled at appropriate level under saline water irrigation. The effect of irrigation water salinity on ETa was significant in 2009 and 2010, while the effect on yield, WUE and IWUE was only significant in 2010. However, the differences of yield, ETa, WUE and IWUE between s2 and s1 were statistically insignificant in the 3 years. It can be concluded that irrigation water salinity 3.2dSm−1 has no significant effect on wheat yield and water productivity. The interaction effects of irrigation amount and water salinity on yield, ETa and WUE were statistically insignificant in the experiments.

Experimental Investigation of Soil Evaporation and Evapotranspiration of Winter Wheat Under Sprinkler Irrigation

Sprinkler irrigation is one of the typical irrigation technologies used for the winter wheat-summer maize double cropping system in the North China Plain. To evaluate the evapotranspiration (ET) of winter wheat under sprinkler irrigation in Beijing area, field experiments were conducted in growing seasons through 2005–2008, in the experimental station located in Tongzhou County, Beijing, China, with different irrigation depths. Results indicated that a relatively large variation of soil water content occurred within 0–40 cm soil layer. The seasonal ET of winter wheat generally increased with increasing irrigation amount, while the seasonal usage of soil water had a negative relationship with irrigation amount. Soil evaporation (E s) was about 25% of winter wheat ET during the period from reviving to maturity. E s increased while E s/ET decreased with increasing irrigation amount. Sprinkler irrigation scheduling with relatively large irrigation quota and low irrigation frequency can reduce E s and promote the irrigation water use efficiency.

Modelling the effects of climate variability and water management on crop water productivity and water balance in the North China Plain

Abstract In the North China Plain (NCP), while irrigation using groundwater has maintained a high-level crop productivity of the wheat–maize double cropping systems, it has resulted in rapid depletion of groundwater table. For more efficient and sustainable utilization of the limited water resources, improved understanding of how crop productivity and water balance components respond to climate variations and irrigation is essential. This paper investigates such responses using a modelling approach. The farming systems model APSIM (Agricultural Production Systems Simulator) was first calibrated and validated using 3 years of experimental data. The validated model was then applied to simulate crop yield and field water balance of the wheat–maize rotation in the NCP. Simulated dryland crop yield ranged from 0 to 4.5 t ha−1 for wheat and 0 to 5.0 t ha−1 for maize. Increasing irrigation amount led to increased crop yield, but irrigation required to obtain maximum water productivity (WP) was much less than that required to obtain maximum crop yield. To meet crop water demand, a wide range of irrigation water supply would be needed due to the inter-annual climate variations. The range was simulated to be 140–420 mm for wheat, and 0–170 mm for maize. Such levels of irrigation applications could potentially lead to about 1.5 m year−1 decline in groundwater table when other sources of groundwater recharge were not considered. To achieve maximum WP, one, two and three irrigations (i.e., 70, 150 and 200 mm season−1) were recommended for wheat in wet, medium and dry seasons, respectively. For maize, one irrigation and two irrigations (i.e., 60 and 110 mm season−1) were recommended in medium and dry seasons, while no irrigation was needed in wet season.

Water Consumption Characteristic and Dry Matter Accumulation and Distribution in High-Yielding Wheat

Water resource deficiency is one of major problems in wheat(Triticum aestivum L.) production in North Plain of China. Irrigation plays an important role to obtain high grain yield and quality. Currently,many reports on the basis of different experiments and cultivars have suggested several irrigation regimes in wheat,but no consistent conclusion is available due to interactions between eco-environment and cultivar. In this study,two winter wheat cultivars were used under high-yielding cultivation in 2005–2007 growing seasons(with precipitations of 128.0 and 246.4 mm,respectively) to reveal the effects of irrigation amount on water consumption characteristics and dry matter accumulations in various organs. The results showed that the yield of treatment W2(irrigated each 60 mm before sowing and at jointing) was the highest and the WUE of treatment W2 was significantly higher than that of other irrigation treatments in 2005–2006 and 2006–2007 wheat growing seasons. And when the precipitation was 246.4 mm from sowing to maturity in 2006–2007,the ratios of precipitation,irrigation amount and soil water amount to water consumption amount in treatment W2 were 47.32%,23.04%,and 29.64%,respectively. Compared with in treatment W0,dry matter accumulation amount after anthesis and contribution of dry matter accumulation amount after anthesis to grains in irrigated treatments increased significantly with the highest of 8 241.59 kg ha-1 and 84.18% respectively in W2. However over-irrigation significantly reduced the photosynthate and grain yield. Water consumption amount increased significantly with increasing irrigation amount,and the ratio of irrigation amount to water consumption amount increased too,but the ratio of precipitation to water consumption amount and the ratio of soil water amount to water consumption amount both decreased. The variation in the ratio of soil water amount to water consumption was larger than others. As far as grain yield,WUE and WUE ofirrigation concerned in the experiment,the most appropriate treatment for recommendation was treatment W2,which was irrigated 60 mm before sowing and at jointing stage respectively. The ratio of soil water amount to water consumption amount and the WUE of irrigation were higher in treatment W1 than in treatment W2,and the grain yield in treatment W1 was 8 797.73 kg ha-1 when the precipitation was 246.4 mm. The results can offer a useful reference for formulating water-saving cultivation techniques in the areas with different water resources.