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Progressive loss of desiccation tolerance in germinating pea ( Pisum sativum ) seeds
Author(s) -
Reisdorph Nichole A.,
Koster Karen L.
Publication year - 1999
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1999.105211.x
Subject(s) - radicle , germination , recalcitrant seed , desiccation tolerance , imbibition , epicotyl , desiccation , sativum , pisum , population , biology , dehydration , water content , botany , seedling , horticulture , agronomy , biochemistry , demography , geotechnical engineering , sociology , engineering
Loss of desiccation tolerance during germination has been described in general terms for many orthodox seeds and has been used as a framework to elucidate the mechanisms that confer tolerance to quiescent embryos. A more detailed description of the time course during which desiccation tolerance is lost will allow us to build a more comprehensive picture of the events that contribute to the loss of tolerance. To more thoroughly characterize the loss of desiccation tolerance, we monitored the viability of germinating pea ( Pisum sativum L. cv. Alaska) seeds after drying them to a range of moisture contents. Desiccation tolerance is lost in different embryonic tissues at different times during germination. Thus, we looked separately at the effects of drying on radicle and epicotyl survival and on electrolyte leakage from the whole embryonic axis. Using statistical and graphical analysis, we calculated the moisture content at which the population of germinating seeds began to be damaged by dehydration (threshold moisture content, TMC) and at which dehydration damaged the majority of the population (critical moisture content, CMC). CMCs and TMCs differed for each tissue and increased as germination progressed. TMCs appeared at 18 h of imbibition for radicle survival and electrolyte leakage and at 24 h for epicotyl survival. CMCs appeared at 21 h for radicle survival and electrolyte leakage. Among the axis tissues, epicotyls were the least sensitive to dehydration during germination. CMCs for epicotyl survival did not appear until 30 h of imbibition and did not increase to the extent that they did for either radicle survival or electrolyte leakage. Results from these experiments can be used as a framework to correlate the progression of biochemical and anatomical changes to the progressive loss of desiccation tolerance in germinating pea embryos.