Critical Tissue Moisture Levels Needed for Maintenance of Rose Plant Viability.

Abstract

<jats:p>Field grown `Mr. Lincoln' rose plants were dug and wrapped in plastic to reduce moisture loss during transport to the lab. Plants were then pruned, weighed, and returned to the plastic cover. After recording initial weights, plants were allowed to dry for 0, 1, 4, 7, or 24 hours at 16°C. Plants were then oven dried, potted, or soaked in water for 20 hours before potting for each drying time treatment. The potted plants were forced to first flower in a glasshouse at which time growth measurements were made. Undried plants had a moisture content of 48%. Seven hours drying reduced moisture content to 41%, but had no effect on growth or flowering. The 24 hour drying time resulted in a plant moisture content of 33%, a plant loss of 44%, and delayed growth initiation and flowering by up to 15 days compared to undried controls. Soaking after 24 hours drying increased plant survival from 38 to 75%. Plants that survived the excessive drying produced flowering growth comparable to plants with a moisture content of &gt; 40%. A critical moisture level for rose plant survival was found to be between 33 and 41%.</jats:p>

Postharvest Moisture Loss from Bare-root Roses Affects Performance of Containerized Plants

“…Increasing drying time linearly reduced performance rating from 3.2 to 2.0 when data were pooled over all cultivars. Previous studies reported delayed onset of flowering, fewer flowers, and overall poorer performance of roses exposed to desiccating conditions before field planting (Pemberton and Roberson, 1990;Schuch et al, 1995;Welch and Cameron, 1990). This study shows that moisture loss resulting in plant moisture content below 43% has a negative effect on rose plants forced in containers as well.…”

“…3). A previous study of containerized roses found that moisture content between 33% and 41% was critical for survival (Pemberton and Roberson, 1990). Also, packaged plants with moisture content between 28% and 43% resulted in reduced new growth and greater mortality for some cultivars after field planting when compared with packaged rose plants with plant moisture of 50% (Welch and Cameron, 1990).…”

“…In both studies, the rate of drying was much lower than in our study reported here. Loss of 1% or less moisture per hour was reported by Pemberton and Roberson (1990) and a much lower rate of drying over a period of 4 weeks of simulated marketing where roots were packaged (Welch and Cameron, 1990). A slower rate of moisture loss from dormant plants improved survival of red oak compared with the faster loss of moisture in norway maple and washington hawthorn (Englert et al, 1993).…”

“…The tolerance for moisture loss below a critical threshold that affects survival varies by species. A critical level of postharvest moisture content for the survival of 'Mister Lincoln' rose plants was found to be between 33% and 41% when the treated plants were evaluated at the end of the first growth flush after potting (Pemberton and Roberson, 1990). For norway maple (Acer platanoides L.) and washington hawthorn that lost 20% of their fresh weight, survival dropped to 40% and plant dieback increased to 90% (Englert et al, 1993).…”