| Study on the drought classification index of edible sunflower in Hetao area |
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| DOI：10.7606/j.issn.1000-7601.2021.03.27 |
| Key Words: sunflower soil relative humidity crop growth parameters drought grade index Hetao area |
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| Abstract: |
| It is crucial for preventing and mitigating drought damage and guiding irrigation production by establishing and monitoring edible sunflower drought disaster indicators to assess water\|saving irrigation services in Hetao area. In this study, we conducted the field experiments of manipulating soil moisture, using the relationship model between soil relative humidity index and crop growth parameters to assess the drought grade of sunflower in three maturity stages including Ⅰ: emergence to inflorescence formation， Ⅱ: inflorescence formation\|one week after flowering, and Ⅲ: one week after flowering to maturity. The drought grade index was classified as light\|, moderate\|, severe\|, and extreme\|drought. We also used the historical data from the agricultural meteorological observatory (2005-2019) to verify whether these drought indicators were reasonable and can be used in practical irrigation guidance, analyzing the soil relative humidity index before irrigations to determine the accuracy of upcoming drought events. We found that according to the soil relative humidity index, the critical values of light\|drought in the three growth stages of sunflower were 65%, 70% and 60%, respectively; the values of moderate\|drought were 55%, 60% and 50%, respectively; the values of severe\|drought were 45%, 50% and 40%, respectively; and the values of extreme\|drought were 35%, 40% and 30%, respectively. Furthermore, we used the historical data for verifying these drought indicators, suggesting that the drought grade index fit well with the results of manipulated experiments. Therefore, it is concluded that the index can be used in practical irrigation guidance. |
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