Spring Safflower Water Extraction Patterns Under Different Irrigation Management Strategies In The Southern High Plains.

Deep root system of safflower is an important adaptive trait under rainfed conditions in the semi-arid agriculture. Lower water requirements and ability to tolerate abiotic stresses make safflower a potential alternative crop for the Southern Great Plains. However, information on water extraction patterns of safflower and its role in seed yield formation under center pivot irrigation system that keeps only the surface soil profile wet with frequent irrigations is limited. A field experiment was conducted during 2012 and 2013 seasons at Clovis, NM to assess seasonal patterns of water extraction of two diverse spring safflower cultivars under different irrigation levels with or without refilled profile moisture. Half of experimental blocks were pre-irrigated with ≈160 mm of water to refill the empty profile from previous crop of corn (PI), while the other half remained depleted (NPI). Of five irrigation levels used in the trial, three levels I₁ (75 mm), I₃ (225 mm), and I₅ (375 mm) were used for the assessment of seasonal patterns of water extraction. Pre-irrigation and in-season irrigation levels had significant impact on water extraction patterns. During the first observation period from 17 to 50 days after planting (DAP), the extraction depth and amount varied by both pre-irrigation and irrigation levels. Water extraction increased by 40 to 77% in PI over NPI at I₁ and I₃ irrigation levels. However, further increasing irrigation level to I₅ decreased reliance on soil moisture, especially under NPI. During this period almost all of water extraction was from the top 0.9 m depth. The next 35 days period (50 to 85 DAP) saw steep increase in water extraction from almost all depths to 1.5 m. Water extraction during this period from PI blocks was 36 to 59 % higher over NPI including I₅. About 25 to 60% of that increased extraction was from 0.9 to 1.5 m depth (deep water extraction), the lower per cent being in I₅ treatments. Although the total extractions during the period were higher in PI compared to NPI, fraction of water extracted below or above 0.9 m remained the same. The water extraction during the final 34 days (85 to 119 DAP) saw steep decline in water extraction and the major fraction of extraction was coming from below 0.9 m depth. Second year results will be added to the poster.