Effect of Water Stress and Potassium on Growth, Flowering, and Proline Content of Zinnia hybrid

This field study was conducted in lath house to produce Zinnia x hybrid as flowering potted plant during spring of 2023. The experiment included two factors; the first representd water irrigation at three levels (100, 75, and 50% of field capacity FC). The second factor was addition of potassium at four concentrations (0, 1, 2, 3 g l -1 ). The experiment was laid out according to the randomized complete block design (R.C.B.D) with a split-plot system. There were foure pots in each experimental unit with three replications. The results were as follow: the irrigation treatment of 100% of FC was significantly superior in plant height(117.50 cm), plant diameter (21.24 cm), and highest potassium content in the leaves (3.006%). Irrigation with 75% of FC also recorded significant plant height (118.00 cm). Treating 50% of FC displayed highest value of proline acid in the plant leaves (8.102 mg g -1 ) and the number of flowers per plant (7.67 Plant -1 ). Potassium addition at (3 g l -1 ) had significant superiority in all of the traits studied. Interaction between the two factors was significant. Irrigating 100% FC with potassium at (3 g l -1 ) significantly increased plant height (125.00 cm). Number of leaves (125.00 plant -1 ), plant diameter (21.30 cm), and potassium content (3.633%) were also influnced. The treatment of 50% FC with 3 gm l -1 potassium had the highest values of proline acid and number of flowers. Each of which reached 8.620 mg g -1 and 8.306 flowers plant -1 , respectively.