54-1 Grain Sorghum Response to Water Supply and Environment.
J. Broeckelman, I. Ciampitti, G. Kluitenberg, G. Cramer, K. Roozeboom, T. Newell, E. Adee, P.V.V. Prasad, A. Schlegel, and J. Holman
Irrigation water is becoming limited in many semi-arid crop production regions. Increasing water use efficiency (WUE) and crop productivity are the main grand-challenges for long-term sustainability of semi-arid cropping systems. Therefore, this project studies the response of four grain sorghum hybrids (Pioneer 85Y40, Pioneer 84G62, Pioneer 87P06, and Dekalb 53-67) under different irrigation levels in five environments across Kansas (East Central, North Central, South Central, and Western Kansas). Across all sites, maximum evapotranspiration, total water evaporated and transpired by the plant (ET) was measured. Water use ranged from 760 mm under full irrigation conditions in East Central Kansas, to 370 mm for dryland in Western Kansas. Sorghum grain yield ranged from 6.1 Mg ha-1 to 11.1 Mg ha-1 in low to high ET environments, respectively. Hybrid impacted WUE, yield, and water use parameters, but relative hybrid performance was not consistent across sites. Water use efficiency consistently averaged 72.7 kg cm-1 with ET of 510 mm and less, but dropped off as the crop increased its water uptake. Average WUE decreased to 64.4 kg cm-1 for an ET of around 560 mm, and dropped to 56.2 kg cm-1 for an ET of 760 mm. Yield and ET were correlated, portraying the differential WUE with varying ET conditions. This study will provide better understanding of the yield-water use ratio for modern sorghum hybrids, serving as guidance for producers and consultants who are making decisions to maximize productivity and water savings in semi-arid cropping systems.