Yield response factor to water (Ky) and water use efficiency of Carthamus tinctorius L. and Solanum melongena L.

Results of a study carried out on safflower and eggplant, in order to calculate the yield response factor to water (Ky) and the water use efficiency (WUE) changes in relation to soil water availability are reported. The final aim of this study is to verify the possibility to use the Ky coefficient to select the better irrigation scheduling criteria for these species. In particular, we considered the WUE at different scale levels, through an up-scaling process of this parameter from the leaf level to the total and marketable yield, and we evaluated the validity of the relation proposed by Kirda [Kirda, C., 2002. Deficit irrigation scheduling based on plant growth stages showing water stress tolerance. Deficit Irrigation Practice. Water Rep. 22. FAO, Rome, pp. 3–10] that relates the WUE to the Ky parameter.