scholarly journals Estimating the Root Water Uptake of Surface-Irrigated Apples Using Water Stable Isotopes and the Hydrus-1D Model

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1624 ◽  
Author(s):  
Lijian Zheng ◽  
Juanjuan Ma ◽  
Xihuan Sun ◽  
Xianghong Guo ◽  
Qiyun Cheng ◽  
...  

The future production of irrigated fruit orchards in the Loess Plateau of China is threatened by a shortage of freshwater. To improve water use efficiency under conditions where irrigation is limited, it is necessary to quantify the root water uptake (RWU) of apple trees. The RWU of apple trees was estimated under surface irrigation using water stable isotope technology and the Hydrus-1D model. Using the Romero-Saltos and IsoSource models, the stable isotopes of water in stems, different soil depths, and different precipitation were analyzed in a 5-year-old dwarfing apple orchard during two seasons 2016 and 2017. Hydrus-1D model was able to simulate the RWU of apple using the maximum coefficient of determination (0.9), providing a root mean square error of 0.019 cm3 cm−3 and a relative error of 2.25%. The results showed that the main depth of RWU ranged from 0–60 cm during the growth season, with the main contribution occurring in the 0–40 cm depth. These findings indicated that reducing the traditional surface irrigation depth will be important for improving the irrigation water use efficiency.

2009 ◽  
Vol 58 (4) ◽  
pp. 393-405 ◽  
Author(s):  
Liwei Shao ◽  
Xiying Zhang ◽  
Suying Chen ◽  
Hongyong Sun ◽  
Zhenhua Wang

2013 ◽  
Vol 52 (13-15) ◽  
pp. 2805-2810 ◽  
Author(s):  
C.X. Li ◽  
X.G. Zhou ◽  
J.S. Sun ◽  
H.Z. Wang ◽  
Y Gao

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 495 ◽  
Author(s):  
Pingfeng Li ◽  
Huang Tan ◽  
Jiahang Wang ◽  
Xiaoqing Cao ◽  
Peiling Yang

Although water-saving measures are increasingly being adopted in orchards, little is known about how different irrigation methods enhance water use efficiency at the root system level. To study the allocation of water sources of water absorption by cherry roots under two irrigation methods, surface irrigation and drip irrigation, oxygen isotope tracing and root excavation were used in this study. We found that different irrigation methods have different effects on the average δ18O content of soil water in the soil profile. The IsoSource model was applied to calculate the contribution rate of water absorption by cherry roots under these irrigation methods. During the drought period in spring (also a key period of water consumption for cherry trees), irrigation water was the main source of water absorbed by cherry roots. In summer, cherry roots exhibited a wide range of water absorption sources. In this case, relative to the surface irrigation mode, the drip irrigation mode demonstrated higher irrigation water use efficiency. After two years of the above experiment, root excavation was used to analyze the effects of these irrigation methods on the distribution pattern of roots. We found that root distribution is mainly affected by soil depth. The root system indexes in 10–30 cm soil layer differ significantly from those in other soil layers. Drip irrigation increased the root length density (RLD) and root surface area (RSA) in the shallow soil. There was no significant difference in root biomass density (RBD) and root volume ratio (RVR) between the two irrigation treatments. The effects of these irrigation methods on the 2D distribution of cherry RBD, RLD, RSA and RVR, which indicated that the cherry roots were mainly concentrated in the horizontal depths of 20 to 100 cm, which was related to the irrigation wet zone. In the current experiment, more than 85% of cherry roots were distributed in the space with horizontal radius of 0 to 100 cm and vertical depth of 0 to 80 cm; above 95% of cherry roots were distributed in the space with the horizontal radius of 0 to 150 cm and the vertical depth of 0 to 80 cm. Compared with surface irrigation, drip irrigation makes RLD and RSA more concentrated in the horizontal range of 30–100 cm and vertical range of 0–70 cm.


2018 ◽  
Vol 69 (2) ◽  
pp. 163 ◽  
Author(s):  
Wenzhi Zeng ◽  
Guoqing Lei ◽  
Yuanyuan Zha ◽  
Yuanhao Fang ◽  
Jingwei Wu ◽  
...  

A variance-based global sensitivity analysis (extended Fourier amplitude sensitivity test, EFAST) was applied to the Feddes module of the HYDRUS-1D model, and the sensitivity indices including both main and total effects of actual root water uptake (RWUa) to seven Feddes parameters were quantified at different growth stages of sunflower (Helianthus annuus L.): seedling, bud, flowering and maturity. The effects of soil salinity, climate conditions, and crop root growth on parameter sensitivity were explored by analysing three precipitation frequencies and two maximum root depths across four field locations with different soil salinity levels in China’s sunflower-growing regions. Uncertainties for RWUa were evaluated at four stages with varying Feddes parameters for different field locations, precipitation frequencies and maximum root depths. We found that the water stress factor concerning ceasing root water uptake (h4), and two salt stress factors ht and Sp, indicating the salinity threshold and the slope of the curve determining the fractional decline in root water uptake per unit increase in salinity below the threshold, respectively, were three most important Feddes parameters for RWUa estimation in HYDRUS-1D. In addition, the effects of soil salinity and precipitation frequencies were stronger than maximum root depth on the order of the parameters’ impacts on RWUa. Our study suggested that h1, h2, h3h, and h3l might be determined by an economical method (e.g. literature review) in saline soils with limited observations, but it is better to calibrate wilting point (h4) and salt stress parameters (ht and Sp) based on local measurements.


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