Spring safflower water use patterns in response to preseason and in-season irrigation applications

Authors: BHATTARAIA, BISHWOYOG - Texas Tech University; SINGH, SUKHBIR - Texas Tech University; ANGADI, SANGAMESH - New Mexico State University; Begna, Sultan; SAINI, RUPINDER - Texas Tech University; AULD, DICK - Texas Tech University

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2019
Publication Date: 2/20/2020
Citation: Bhattaraia, B., Singh, S., Angadi, S., Begna, S.H., Saini, R., Auld, D. 2020. Spring safflower water use patterns in response to preseason and in-season irrigation applications. Agricultural Water Management. https://doi.org/10.1016/j.agwat.2019.105876.
DOI: https://doi.org/10.1016/j.agwat.2019.105876

Interpretive Summary: A field experiment was conducted to assess soil water use patterns, evapotranspiration and oil yield of two spring safflower cultivars under different preseason and in-season irrigation levels. Half of the experimental blocks received 164 (1st) and 153mm (2nd year) of preseason irrigation, while the other half remained unirrigated. Five in-season irrigation levels (I1–I5) ranging from 83 to 392mm were applied to preseason and no-preseason irrigation blocks. Safflower extracted more of the stored soil moisture in the preseason than in the no-preseason irrigation treatments. This led to an increase in in evapotranspiration (ET), water use efficiency (WUE), and oil yield in preseason compared to no-preseason irrigation treatment. Average water extraction decreased with increasing level of in-season irrigation and a decline of 32, 27, and 25% in soil moisture at the end of the season compared to initial soil moisture were observed in I1, I3, and I5, respectively. Since, WUE was not much affected by in-season irrigation treatment in both years, limiting the in-season irrigation level to I4 can save 17% of irrigation with a corresponding 9% reduction in oil yield. The difference between cultivars in water extraction and WUE was small. Overall, safflower was able to use preseason irrigation more efficiently in semi-arid SHP. Growers can pre-irrigate safflower and reduce its in-season irrigation to allocate more water to high water requirement traditional-crops such as corn.

Technical Abstract: The deep root system of safflower (Carthamus tinctorius L.) is an important adaptive trait under rainfed conditions in semi-arid agriculture. Lower water requirements and ability to tolerate abiotic stresses make safflower a potential alternative crop for the Southern High Plains (SHP). However, information on water extraction patterns of safflower and its role in oil yield formation under center pivot irrigation system that keeps only the surface soil profile wet with frequent irrigations is limited. Therefore, a field experiment was conducted in a split-plot design at Clovis, New Mexico during 2012 and 2013 growing seasons to assess the soil water use patterns, evapotranspiration, and oil yield of two spring safflower cultivars under different preseason and in-season irrigation levels. Half of the experimental units received 164 and 153mm of preseason irrigation in 2012 and 2013, respectively, while the other half remained unirrigated. Five in-season irrigation levels (I1–I5) ranging from 88 to 392mm in 2012 and from 83 to 373mm in 2013 were applied to preseason and no-preseason irrigation blocks. On average, safflower extracted 70 and 28mm of stored soil moisture in the preseason and no-preseason irrigation treatments, which significantly increased evapotranspiration (ET), water use efficiency (WUE), and oil yield in preseason compared to no-preseason irrigation treatment. Average water extraction decreased with increasing level of in-season irrigation and a decline of 32, 27, and 25% in soil moisture at the end of the season compared to initial soil moisture were observed in I1, I3, and I5, respectively. Since, WUE was not much affected by in-season irrigation treatment in both years, limiting the in-season irrigation level to I4 can save 17% of irrigation with a corresponding 9% reduction in oil yield. The relatively smaller differences were observed for water extraction and WUE among the cultivars. Overall, safflower was able to use preseason irrigation water more efficiently in semi-arid SHP. Growers can pre-irrigate safflower and reduce its in-season irrigation to allocate more water to high water requirement traditional-crops such as corn.