Abstract
We investigated whether leaching fraction (LF) is able to modify the effects of irrigation water salinity (ECiw) on evapotranspiration (ET). We conducted an experiment with a completely randomized block design using five levels of ECiw and two LFs. Results showed that the electrical conductivity of drainage water (ECdw) in an LF of 0.29 was considerably higher during the 21–36 days after transplanting (DAT), and considerably lower after 50 DAT than in an LF of 0.17. The hourly, nighttime, daily, cumulative and seasonal ET all decreased considerably as a result of an increase in the ECiw. The daily ET started to be considerably higher in the LF of 0.29 than in the LF of 0.17 from 65 DAT. Compared with the LF of 0.17, the seasonal ET in the LF of 0.29 under various ECiw levels increased by 4.8%–8.7%. The Maas and Hoffman and van Genuchten and Hoffman models both corresponded well with the measured relative seasonal ET and the LF had no marked effects on these model parameters. Collectively, an increase in the level of ECiw always decreased the ET substantially. An increase in the LF increased the ET considerably, but there was a time lag.
Highlights
Evapotranspiration (ET), causing the movement of water, nutrients and minerals from the roots to the plant organs, plays an important role in growth and water productivity
The electrical conductivity of drainage water (ECdw) became a linear function of effects of irrigation water salinity (ECiw) and there were considerable differences among treatments after the second application of saline water (17 days after transplanting (DAT)) for the two leaching fraction (LF)
The ECdw reached the ECiw level approximately 25 days after the treatment had been initiated for both LFs
Summary
Evapotranspiration (ET), causing the movement of water, nutrients and minerals from the roots to the plant organs, plays an important role in growth and water productivity. Bhantana and Lazarovitch[7] showed a 10% reduction in the seasonal ET of two young pomegranates per unit increase of ECe with a threshold of 1 dS m−1 using the Maas and Hoffman salinity yield response model. In addition to ET, the level of ECiw affects the salinity of the root zone. In an experiment using bell peppers[2], the salinity of the drainage water leaving the root zone (ECdw) was 1.5–2 times higher than for an ECiw level of 7–9 dS m−1. A limited number of studies have been conducted to analyze the effects of LFs on drainage water salinity and ET. There is scant information for nighttime ET under varying ECiw levels and LFs, which accounted for a considerable proportion of the total daily ET and lower crop water productivity.
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