Cellulosic Water and Polyacrylamide Gels Can Delay Wilting and Extend Watering Intervals for Potted Poinsettias Displayed in Interiorscapes

Abstract

Poinsettias (Euphorbia pulcherrima) are popular for their colorful bracts and long keeping quality under indoor conditions. However, along with the long display life comes the maintenance issue of labor-intensive repeated waterings. Three experiments were conducted to determine whether using cellulosic water (CW) applied to the surface of the soilless growing medium as postproduction treatment could extend the days to wilt and intervals between waterings under simulated home/office conditions. CW is a gel composed of water bound in a cellulose matrix; as the cellulose is broken down the water is released. In addition, polyacrylamide (PAM) granules, applied dry into holes in the growing medium or hydrated to the medium surface, were evaluated for the same purpose in the final experiment. In the first experiment, pots containing cultivar Advent Red were treated with 0, 150, or 300 g of CW gel. In the second experiment, pots with ‘Prestige Early Red’ plants received 0, 125, or 250 g of CW gel. Pots were weighed and monitored for wilt daily. The days-to-wilt response was positively linear with CW application rates. Days to wilt (time between waterings) increased by over 3 days for each 100 g of CW applied to the pots during both Expts. 1 and 2 (y = 20 + 0.031x, r2 = 0.54 and y = 18.6 + 0.032x, r2 = 0.624, respectively, where y = days to wilt and x = grams of CW). In the third experiment, CW results were similar to those of the previous experiments. In addition, PAM initially also increased days to wilt compared with the control, with hydrated PAM applied at the same rate as CW providing the same benefits. However, PAM did not rehydrate adequately upon rewatering after the first wilt to delay the second wilt. This may have been due to fertilizer salts and to limited contact with the growing medium. Transpiration rates measured on the days before the untreated plants started wilting were not different among the treatments; therefore, the increased days to wilt provided by CW and PAM were due only to their providing additional water. Both CW and PAM gels were effective when used postproduction to supply supplemental water and lengthen the time period before the potted poinsettias wilted when held in interiorscapes.