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The effect of water and nitrogen on the response of sorghum cultivars with contrasting nitrogen use efficiency

Teshome Regassa, University of Nebraska - Lincoln


Water and nitrogen (N) are important environmental factors limiting sorghum production. Information is lacking on the combined effects of water and N for cultivars with different degrees of water and/or N stress tolerance. Sorghum cultivars known for N and water stress tolerance difference were evaluated to identify plant characteristics contributing to N use efficiency (NUE). Cultivars San Chi San and CK-60 were evaluated at Mead, NE on a Sharpsburg silty clay loam soil under water (stress and non-stress), and N (0, 40, 80, and 120 kg ha−1) rates. Experimental units were arranged in split-split plot and treatments were assigned to the whole units using randomized complete block. In the greenhouse, factorial combinations of cultivars, water, and three N rates (10, 20, and 40 mg L−1 N) were evaluated in a randomized complete block. A second greenhouse experiment included the cultivar B-35 in order to further evaluate water (no stress and stress at 8–9 leaf stage) and N (stressed and adequate) responses. ^ Responses of plant characteristics such as plant height, internode length, flag leaf internode length, flag leaf area, leaf senescence, percent dry matter and N partitioned to nonreproductive plant parts showed a distinct difference between cultivars. Characteristics exhibited by the N-use-efficient cultivar were modified under low N particularly plant height and leaf greenness. These modifications made this cultivar appear undesirable by traditional agronomic standards. Both cultivars had similar performance when neither water nor N was limiting. High N and severe water stress masked NUE of San Chi San plants. Under low N, CK-60 partitioned a greater proportion of DM and N to stems and leaves. This was reversed by increased N application. It is not clear if increased accumulation of DM and N in stems is a drought tolerance attribute or a liability causing N inefficiency. Differences in cultivar preference for NO3 as a principal N source, and root or shoot as the major site of N reduction is proposed for causing the observed difference in response between the N-use-efficient and inefficient cultivar. ^

Subject Area

Agriculture, Agronomy|Agriculture, Plant Culture|Biology, Plant Physiology

Recommended Citation

Regassa, Teshome, "The effect of water and nitrogen on the response of sorghum cultivars with contrasting nitrogen use efficiency" (2004). ETD collection for University of Nebraska - Lincoln. AAI3126963.