IRRIGATION FREQUENCY AND SYSTEM AFFECT POINSETTIA GROWTH, WATER-USE, AND RUNOFF

Euphorbia pulcherrima Willd. Ex. Klotzsch 'Gutbier V-14 Glory' plants were grown with N at 220 mg.L-1 (20N-4.4P-16.6K) using hand (HD), micr otube (MT), ebb- and-flow (EF), and capillary mat (CM) irrigation syst ems and were irrigated either daily (daily = D) or as needed (intermit tent = I). For all irrigation systems, daily irrigation produced plant s with the greatest total dry mass and reduced the amount of nutrients lost as runoff, but plant quality was reduced in one of two years due to excessive, weak growth. Plants irrigated by MT-D and EF-D had the greatest total dry masses. HD produced lower total plant dry mass than all other irrigation systems and frequencies. Runoff from MT-D and EF -D treatments had the lowest concentration of NO3-N, NH4-N, and PO4-P. The MT-D, EP-D, and EF-I treatments were the most water-efficient, wh ereas the CM system had the lowest water efficiency and used the great est amount of water. Daily irrigation with the MT or EF systems produc ed optimum plant growth, but intermittent MT irrigation was more water -efficient. Daily irrigation is a viable production system, but only w here water conservation is not a concern.