Translocation of Calcium and Effects of Temperature, Defoliation and Ethephon on Reducing Upper Leaf Necrosis in Lilium ‘Star Gazer’
Date Issued
2010
Date
2010
Author(s)
Tsai, Ya-Hsun
Abstract
Upper leaf necrosis (ULN) of oriental hybrid lilies is a calcium (Ca) deficiency disorder, commonly observed as leaf tipburn. This study mainly aimed to understand calcium translocation within Lilium ''Star Gazer'' plant and to develop methods to reduce ULN. Mechanism of ethylene production from ethephon for reducing ULN severity in Lilium ''Star Gazer'' was also examined.
To investigate Ca translocation in lilies, strontium (Sr) was used as a tracer for Ca. Regular bulbs and Sr-enriched bulbs of Lilium ‘Star Gazer’ were harvested from plants treated with Ca(NO3)2 and Sr(NO3)2 in the previous growing season, respectively. Stem relative Sr content, defined as Sr / (Sr + Ca), decreased with time from 0.16 to 0.01 in the first experiment, and from 0.12 to 0.006 in the second experiment. The relative Sr contents in mid- and upper-part of shoot decreased with time from 0.024 to 0.015 and 0.032 to 0.01, respectively. The results demostrated bulb was the main source of Ca in the initial stage of shoot elongation. At 40 days after planting, the lower shoot had higher relative Sr content, suggesting that calcium requirements of upper shoot were provided via root absorption. Moreover, Lilium ‘Star Gazer’ supplemented with Sr in the growing season, Sr content of shoot had a rapid increase from 30 to 40 days after planting, suggesting that soil was the main source of Ca in the rapid growth phase of lily.
Severity of ULN was positively correlated with time required to complete leaf unfolding. Lilium ‘Star Gazer’ plants were transfered to phytotrons at 20 days after planting and grown at day / night temperature of 15/13, 20/15, 25/20 and 30/25 oC. Low temperatures resueted in longer period of leaf unfolding and more sever ULN. Removing 8, 16, or 24 leaves from the base at 33 days after planting reduced ULN severity and increased number of flowers. Increasing immersion surface area during ethephon dipping reduced ULN severity after planting, but increased number of blind buds. Effective period of ethephon on reducing ULN increased with increasing ethephon concentration. At the same ethephon concentration, solution with temperature of 15 to 45 oC and pH of 3 to 11 resulted in the same effective duration. Whole-bulb dipping in 125 mg∙L-1 ethephon solution for three minutes, regardless of solution temperature (15 to 45 oC) and pH (3 to 11), all reduced ULN severity, suggesting no adjustment of solution temperature and pH is required.
Subjects
lily
lilium
star gazer
Ca
calcium
ULN
upper leaf necrosis
Sr
strontium
remove leaf
ethephon
Type
thesis
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