Temporal and Spatial Changes in Crop Water Use Efficiency in Central Asia from 1960 to 2016

Water resources among five Central Asian countries are distributed unevenly. Since the collapse of the Soviet Union, the conflict between water and land use has become increasingly serious. Due to limited data, the temporal and spatial characteristics and trends of crop water use efficiency in Central Asia over the past 60 years remain unclear. This paper combines state-level agricultural statistics data and cultivated land data (1975, 2005 and 2015) from remote sensing imagery and calculates crop water use efficiency based on the FAO crop coefficient method. The results are as follows: (1) the development of crop cultivation in Central Asia is divided into an expansion period (1960–1990), a reduction period (1990–2000), and a recovery period (2000–2016); (2) the grain yield in Central Asia increased from 0.9 to 1.9 t/ha during 1960–2016, with Uzbekistan having the highest, reaching 4.2 t/ha in 2016. Cotton yield increased during 1960–1990 and decreased from 1990 to 2016. (3) The grain water use efficiency in Central Asia increased from 0.22 kg/m3 to 0.39 kg/m3 during 1960–2016. The cotton water use efficiency increased from 0.23 kg/m3 to 0.30 kg/m3 during 1960–1990, has decreased since 1990, and is currently close to the 1960s level.

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High-Throughput Phenotyping of Crop Water Use Efficiency via Multispectral Drone Imagery and a Daily Soil Water Balance Model

Remote Sensing ◽

10.3390/rs10111682 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1682 ◽

Cited By ~ 13

Author(s):

Kelly Thorp ◽

Alison Thompson ◽

Sara Harders ◽

Andrew French ◽

Richard Ward

Keyword(s):

Water Balance ◽

Water Use Efficiency ◽

Soil Water ◽

Water Use ◽

High Throughput ◽

Soil Water Balance ◽

Balance Model ◽

Crop Water ◽

Crop Water Use ◽

Use Efficiency

Improvement of crop water use efficiency (CWUE), defined as crop yield per volume of water used, is an important goal for both crop management and breeding. While many technologies have been developed for measuring crop water use in crop management studies, rarely have these techniques been applied at the scale of breeding plots. The objective was to develop a high-throughput methodology for quantifying water use in a cotton breeding trial at Maricopa, AZ, USA in 2016 and 2017, using evapotranspiration (ET) measurements from a co-located irrigation management trial to evaluate the approach. Approximately weekly overflights with an unmanned aerial system provided multispectral imagery from which plot-level fractional vegetation cover ( f c ) was computed. The f c data were used to drive a daily ET-based soil water balance model for seasonal crop water use quantification. A mixed model statistical analysis demonstrated that differences in ET and CWUE could be discriminated among eight cotton varieties ( p < 0 . 05 ), which were sown at two planting dates and managed with four irrigation levels. The results permitted breeders to identify cotton varieties with more favorable water use characteristics and higher CWUE, indicating that the methodology could become a useful tool for breeding selection.

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