Seed Germination of Five Populations of Rhododendron vaseyi, Ploidy Manipulation of Rhododendron 'Fragrantissimum Improved' and the Effects of S-ABA on the Physiology and Marketability of Various Container-Grown Taxa During Short-Term Desiccation

desiccation tolerance;polyploidy;seed germination

Hebert, Cary Joseph ; Darren H. Touchell, Committee Member,Candace H. Haigler, Committee Member,Thomas G. Ranney, Committee Member,Frank A. Blazich, Committee Member,Anthony V. LeBude, Committee Chair,Hebert, Cary Joseph ; Darren H. Touchell ; Committee Member ; Candace H. Haigler ; Committee Member ; Thomas G. Ranney ; Committee Member ; Frank A. Blazich ; Committee Member ; Anthony V. LeBude ; Committee Chair

University:North Carolina State University

关键词: desiccation tolerance;    polyploidy;    seed germination;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/344/etd.pdf?sequence=1&isAllowed=y

美国|英语

来源: null

【 摘 要 】

Seeds of five populations of Rhododendron vaseyi A. Gray (pinkshell azalea), representing a sampling of the entire native distribution of the species, were germinated at 25C (77F) or an 8/16-hr thermoperiod of 30/20C (86/68F) with daily photoperiods at each temperature of 0 (total darkness), 8, 12, or 24-hr. The response to light and temperature of all populations was similar. Light was required for germination regardless of population or temperature. As photoperiod increased, germination increased for all populations with the alternating temperature partially compensating for the light requirement. The highest cumulative germination for all populations ranged from 51% to 67% and was achieved at 30/20C with a 24-hr photoperiod. These germination percentages, although not high, were due in part to rigorous grading of the seeds prior to initiation of the study suggesting seed viability of R. vaseyi is inherently low.Rhododendron ‘Fragrantissimum Improved’ is an attractive cultivar with showy, fragrant flowers, but has limited potential for breeding as it is a sterile wide hybrid. Protocols for in vitro regeneration and polyploid induction were developed for this cultivar as a means of vegetative propagation and to potentially restore fertility and enhance ornamental traits. Combinations of TDZ (0, 2, 10, 15 μM) and NAA (0, 5, 10 μM) were used to induce shootregeneration from leaves. Shoot regeneration was optimized (96% of leaf segments produced shoots) using 8.8 μM TDZ and 10 μM NAA. To induce polyploidy, regenerative callus was treated with 7.5, 15, 30, 60 or 90 μM concentrations of the mitotic inhibitor oryzalin for 1, 3, 5, 7 or 14 days, in various combinations. Oryzalin significantly affected survival and shoot regenerative capacity. A percentage of homogenous, tetraploid shoots were recovered from treatments of 30 μM oryzalin for 1 (13%) and 3 (13%) days and 7.5 μM oryzalin for 7 (20%) and 14 (7%) days.Reduced post harvest care of woody plant material in mass retail settings can decrease the number of days plants remain marketable. If plants are sold on consignment for growers, reduced sales can lead to poor profitability. This study investigated the effect of spray applications of s-abscisic acid (s-ABA) (ConTego™, Valent Biosciences Corp.) to increase the number of days of marketability for various woody taxa in a simulated retail setting. In the first stage of the study, various well-watered container-grown taxa were treated with a spray application of either 0, 1000 or 2000 mg∙L-1 s-ABA and water was withheld. Daily, desiccation symptoms were recorded to determine if plants had reached the critical wilting point and thus became unmarketable. Marketability was increased approximately 2-3 days for plants treated with 2000 mg∙L-1 s-ABA treatment compared to nontreated plants. In the second stage, marketability and physiology of Ligustrum japonicum ‘Recurvifolium’ (wavy leaf privet) was monitored after plants were treated with spray applications of 0, 500, 1000, 1500 or 2000 mg∙L-1 s-ABA. Stomatal conductance (gs)declined for all plants depending on the concentration applied. Plants treated with s-ABA had lower gs rates and remained marketable longer than nontreated plants. All plants fully recovered to pretreatment gs rates provided they were rewatered immediately upon reaching the critical wilting point. Therefore, spray applications of s-ABA can increase shelf life of select woody ornamentals.